Charles Bosk PhD
- Professor of Sociology and Medical Ethics, University of Pennsylvania,
- Philadelphia, Pennsylvania
Is tube repair of aortic aneurysm followed by aneurysmal change in the common iliac arteries antibiotic medical abbreviation purchase generic roxithromycin. Dacron versus polytetrafluoroethylene for Y-aortic bifurcation grafts: a six-year prospective antibiotic resistance today purchase 150mg roxithromycin free shipping, randomized trial infection eyelid buy generic roxithromycin line. Natural history of atherosclerotic renal artery stenosis associated with aortic disease virus in michigan purchase 150 mg roxithromycin with visa. Simultaneous aortic and renal artery reconstruction: evolution of an eighteenyear experience taking antibiotics for acne while pregnant discount roxithromycin uk. Prophylactic repair of renal artery stenosis is not justified in patients who require infrarenal aortic reconstruction. A perioperative strategy for abdominal aortic aneurysm in patients with chronic renal insufficiency. Mesenteric infarction after aortoiliac surgery on the basis of 1752 operations from the National Vascular Registry. Ischaemic disease of the colon and rectum after surgery for abdominal aortic aneurysm: a prospective study of the incidence and risk factors. Quality of life, impotence, and activity level in a randomized trial of immediate repair versus surveillance of small abdominal aortic aneurysm. Elimination of iatrogenic impotence and improvement of sexual function after aortoiliac revascularization. Prospective follow-up of sexual function after elective repair of abdominal aortic aneurysms using open and endovascular techniques. The incidence of deep venous thrombosis in patients undergoing abdominal aortic aneurysm resection. Infrarenal abdominal aortic aneurysm: factors influencing survival after operation performed over a 25-year period. Long-term survival after elective repair of infrarenal abdominal aortic aneurysm: results of a prospective multicentric study. Abdominal aortic aneurysms: survival analysis of four hundred thirty-four patients. Long term relative survival after surgery for abdominal aortic aneurysm in western Australia: population based study. Comparison of long-term survival after successful repair of ruptured and non-ruptured abdominal aortic aneurysm. Aneurysm rupture is independently associated with increased late mortality in those surviving abdominal aortic aneurysm repair. Long-term survival and late complications after repair of ruptured abdominal aortic aneurysms. Late survival in abdominal aortic aneurysm patients: the role of selective myocardial revascularization on the basis of clinical symptoms. Preoperative imaging is essential prior to any planned endovascular intervention in order to evaluate aortic anatomy, particularly aortic neck diameter and length, as well as the iliofemoral arterial system. Endografts have different features, such as profile, deliverability, and flexibility, which render them more appropriate for certain anatomies. They are generally placed via arteriotomy in the common femoral artery, although percutaneous access is growing in popularity. Some of the initial approaches involved techniques similar, in some fashion, to modern endovascular techniques. Early techniques ranged from simple aortic ligation to aortic wrapping with cellophane. In 1951, the first replacement of an aortic aneurysm with an aortic homograft was described by Dubost. Although excellent results have been obtained with conventional aneurysm repair, it remains a complex, challenging operation that initiates great physiologic stress for patients. This approach allowed for the intraluminal exclusion of an aneurysm with the placement, through the femoral arteries, of an endograft. The hope was that this would decrease the morbidity and mortality of aneurysm repair and allow repairs to be performed in patients with significant comorbidities. The original endograft was constructed of a Dacron tube sutured to a Palmaz stent. Several generations of endografts have since been developed, tested, and put into general clinical use. Our understanding of the complexities of this mode of treatment is only just being realized and examined. The classic teaching is that rupture rates for aneurysms depend on the size of the aneurysm. Rupture rates of 5% to 7% per year are estimated for aneurysms between 5 and 7 cm in diameter, and a greater than 20% rupture rate per year is estimated for larger aneurysms. It at most requires small femoral incisions instead of a large abdominal incision, which may decrease the incidence of postoperative pulmonary complications. The avoidance of extensive retroperitoneal dissection decreases the risk for perioperative bleeding. The period of aortic occlusion is minimal and accounts for the lower incidence of intraoperative hemodynamic and metabolic stress compared with patients undergoing open surgery. There are key aspects of each device and aortic anatomy to be aware of when assessing a patient as a potential candidate for endograft repair. Preprocedural imaging is paramount to properly assess the proximal and distal sites of fixation, as well as to assess the path the endograft will traverse before taking its postdeployment position. Imaging Successful endograft placement is completely dependent on adequate and accurate preoperative planning. Preprocedural imaging allows the surgeon to determine whether a patient is an acceptable candidate for endovascular aortic grafting and which device is best suited for a particular patient; this ultimately allows for determining the proper size of the endograft. Preoperative angiography is now rarely employed and reserved for cases where an adjunctive therapeutic intervention. This technique uses the spin rate of the C-arm around the gantry to acquire images. This technology appears valuable in complicated aortic cases, such as fenestrated branched endovascular aneurysm repair, due to its ability to image graft to graft and graft to aorta apposition without the use of contrast. The axial images may "cut" vessels at an angle, particularly iliac arteries that have some degree of tortuosity-thus creating an ellipse as opposed to visualization of the true lumen diameter. Due to this problem, some physicians recommend three-dimensional (3-D) image processing as a better method to evaluate aortoiliac anatomy for endograft therapy. Its usefulness, however, is often limited by availability and physician expertise. Unless the catheter remains centerline within the aorta, the images produced will be elliptical, which may also provide shorter than required length measurements. Its primary use is at the time of stent graft placement to assess graft position relative to the renal artery ostia; this can help to diminish the amount of contrast agent required. First, it is the site of proximal fixation that will prevent the device from migrating distally. Second, a circumferential seal must be obtained between the graft and the aorta in this area in order to prevent leakage of blood into the aneurysm sac. The exact length of aortic neck required is somewhat device dependent, but most commercially available devices require a 10- to 15-mm length of aortic neck below the level of the most caudal renal artery. D1 represents the diameter at the proximal aspect of the aortic neck, and D2 represents the diameter at the distal aspect of the aortic neck. The distance between D1 and D2, in general, must be 10 to 15 mm in order to adequately place an endograft. In addition, the difference between the diameter at D1 and D2 should not exceed 10%. D4 and D5 represent the diameter within the common iliac artery where the distal fixation point of the aortic endograft occurs. Additionally, several devices employ the use of a suprarenal, uncovered (or bare) stent to provide additional protection against graft migration. Suprarenal stent fixation may be useful, particularly in patients who have a shorter aortic neck, as it transfers protection against migration to a more normal segment of aorta. The suprarenal stent, however, does not provide any function with regard to creating a circumferential seal. In addition to the length of the neck, other anatomic characteristics are important when determining whether patients are suitable candidates for endovascular aneurysm repair. These include aortic neck angulation, the shape of the neck, and the quality of the neck. Neck angulation refers to an alteration in the direction the aorta takes with regard to the centerline pathway. Aortic neck angulation of greater than 60 degrees compared with the centerline is often considered prohibitive for endovascular aneurysm repair. There are devices undergoing preliminary trials that would allow for greater neck angulation, up to 90 degrees. The shape of the aortic neck also affects the ability of the graft to obtain a seal as well as fixation. The diameter at D1 is 23 mm and at D2 is 28 mm, representing a greater than 10% increase. Iliac Arteries the iliofemoral arterial system is important in endograft placement for two reasons. First, most endografts are placed through the common femoral artery and must traverse the iliofemoral system to reach the aorta. Iliac artery diameter and tortuosity can adversely affect the ease with which the endograft traverses this course. Certainly, the presence of significant atherosclerotic disease can cause arterial narrowing that inhibits the placement of the device. Second, the iliofemoral system is important because it is the site of the distal seal between the endograft and the iliac artery, preventing retrograde flow of blood into the aneurysm sac. Many of the features necessary for an adequate aortic neck are also necessary for the distal landing zone. The presence of thrombus, calcification, and tortuosity can significantly hinder the iliac limb seal. Ectatic or aneurysmal iliac arteries obviously affect the ability of the graft to seal against the iliac limb. Most available endograft systems require a femoral artery of 8 mm and common iliac artery diameter of 8 to 25 mm. Some endograft systems, such as Medtronic Endurant, require at least a 15-mm segment of iliac artery to be of adequate caliber and free of significant disease in order to obtain a distal seal, whereas others, such as Zenith from Cook Medical and Excluder from Gore, only require 10-mm distal landing zone. The degree of tortuosity may be underestimated in the direct anterior-posterior view, but on a more oblique angle (B) a more significant degree of tortuosity is visible. Endograft design Endograft design can greatly affect the ability of the device to be placed in patients, particularly in patients with complex anatomy. Delivery System Standard endograft insertion involves placement of the device through an arteriotomy in the common femoral artery, from where the graft traverses the external iliac and common iliac arteries. The ability to deliver the endograft safely and effectively in this fashion is a prerequisite for effective repair. Inadequate diameter or the presence of extensive calcifications can exclude standard endograft placement. It is intuitive that the size of the delivery system cannot be larger than the size of the iliac arteries that it traverses. Most sheaths are sized based on inner diameter, so knowledge of the outer diameter of the sheaths is therefore required for safe graft placement. Most delivery systems easily traverse an iliofemoral segment of 7 to 8 mm in diameter (or a sheath that does not exceed 21 French [Fr] outer diameter), although several designs that provide a lower profile system are now available. A recent meta-analysis demonstrated no difference between percutaneous approach versus surgical cut-down for common femoral artery access including short-term mortality, aneurysm exclusion, wound infection, bleeding complications, and hematoma. Tortuous iliac vessels can be "straightened" with the use of stiff guidewires, but this is not always possible or desirable. The ideal delivery system easily traverses these arteries on the basis of an intrinsic degree of flexibility. Again, different delivery systems have different abilities to track through tortuous iliac arteries, and thus some may be more successfully placed than others in this anatomic variant. Delivery systems composed of long, flexible, tapered tips pass more easily than those with short, stiff, blunt tips. In addition, other aspects of device construction, such as metallic struts that provide columnar strength, increase device rigidity and limit use in tortuous vessels. As stated previously, long, flexible, tapered tips pass more easily than short, blunt, stiff ones. This allows for easier maneuverability through tortuous vessels, as well as past sites of narrowing. Larger-caliber devices are also more difficult to deliver, particularly in patients with smaller-diameter arteries. This can greatly affect the placement of specific endografts in specific anatomic variants. The complexity of the delivery system also affects the ease with which it is placed. Some devices generally provide a simple maneuver to deploy the graft, whereas others have several complicated steps. However, there are some devices that allow for bareback device deployment without the use of sheath. Endograft Features the ideal endograft should be flexible enough to maneuver through tortuous and angulated vessels but also rigid enough to prevent kinking. It should have a low profile (having a small external diameter) that would allow it to be placed through as small of an arteriotomy as possible. Generally, there is a main body that may have one attached limb and one or two docking limbs.
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Abdominal aortic aneurysm screening in elderly males with atherosclerosis: the value of physical exam infection line up arm roxithromycin 150mg fast delivery. Screening guidelines antibiotics low blood pressure roxithromycin 150mg for sale, geared toward current/former male smokers antimicrobial in mouthwash purchase discount roxithromycin line, are slowly being implemented antibiotic antimycotic purchase on line roxithromycin. Rupture risk generally depends on maximum aortic diameter antibiotics for uti toddler generic roxithromycin 150 mg online, rate of expansion, comorbid conditions, and some anatomic features, among other variables. Traditional open repair has a tested durability record, but is morbid and poorly tolerated by many patients. Further, aneurysm-free survival remains equivalent between open and endovascular repair options. Definition Most aortic aneurysms are true aneurysms, involving all layers of the aortic wall, and are infrarenal in location. As shown by Pearce and colleagues,14 normal aortic diameter gradually decreases from the thorax (28 mm in men) to the infrarenal location (20 mm in men). At all anatomic levels, normal aortic diameter is approximately 2 mm larger in men than in women and increases with age and increased body surface area. Although such definitions are useful for large patient groups, in clinical practice with individual patients it is more common to define an aneurysm based on a greater than or equal to 50% diameter enlargement compared with the adjacent, nonaneurysmal aorta. After 3 years, patients who had undergone early surgery had better late survival, but the difference was not significant. It was notable that more than 60% of patients randomized to surveillance eventually underwent surgery at a median time of 2. The early surgery group had a higher rate of smoking cessation, which may have contributed to a reduction in overall mortality. An additional 12% of surveillance patients underwent surgical repair during extended follow- up, to bring the total to 74%. Fatal rupture occurred in only 5% of men but 14% of women in the surveillance group. Patients with severe heart or lung disease were excluded, as were those who were not likely to comply with surveillance. However, compliance in these carefully monitored trials of select patients was high. Modern imaging techniques were not available to accurately measure these aneurysms. Probability of rupture increased with diameter: less than 4 cm, 10%; 4 to 7 cm, 25%; 7 to 10 cm, 46%; and greater than 10 cm, 61%. Thus the rupture rates assigned to specific aneurysm diameters by autopsy studies likely overestimate true aneurysm rupture risk. Further data regarding rupture risk were obtained from high-risk patients who were deemed too fragile to undergo elective repair. Aneurysm-related mortality was determined postmortem and reaffirmed once more that rupture risk correlates with aneurysm size and exponentially increased with increasing aortic diameter. The mean diameter for ruptures was 1 cm lower for women (5 cm) compared with men (6 cm). Ouriel and colleagues30 have suggested that a relative comparison between aortic diameter and the diameter of the third lumbar vertebra may increase the accuracy for predicting rupture risk, by adjusting for differences in body size. However, to date, these novel predictive tools remain difficult to validate in vivo and are still some time away from widespread clinical use. Family history and rapid expansion are probably risk factors for rupture, whereas the influences of thrombus content and diameter ratio remain less certain. For a 1-year time interval, this formula predicts an 11% increase in diameter per year, nearly identical to the 10% per year calculation reported by Cronenwett and colleagues39 in 1990. Risk factors for expansion specifically included elevated diastolic blood pressure and active smoking, whereas diabetes mellitus was protective of aneurysm expansion. Multiple studies have previously correlated dyslipidemia with coronary disease and peripheral vascular disease alike. Interestingly, it appears that the clinical salutary effects of statin therapy persist irrespective of their effect on lipid lowering. These effects may involve endothelial cells, smooth muscle cells, platelets, monocytes and macrophages, and finally inflammation. Elective operative risk As expected, considerable variation in operative risk occurs among individual patients and depends on specific risk factors. The most important risk factors for increased operative mortality were renal dysfunction (creatinine > 1. Age had a limited effect on mortality when corrected for the highly associated comorbidities of cardiac, renal, and pulmonary dysfunction (mortality increased only 1. This scoring system takes into account the seven independent risk factors plus the average overall elective mortality for a specific center. To demonstrate the impact of the risk factors on a hypothetical patient, it can be seen that the predicted operative mortality for a 70year-old man in a center with an average operative mortality of 5% could range from 2% if no risk factors were present to more than 40% if cardiac, renal, and pulmonary comorbidities were all present. The review of Hallin and colleagues6 supports the findings of Steyerberg that renal failure is the strongest predictor of mortality with a fourfold to ninefold increased mortality risk. Older age and female gender appeared to be associated with increased risk, but the evidence was not as strong. Valuable data regarding predictors of operative risk have been generated by prospective trials. Female gender has also been found to be associated with higher operative risk in several population-based studies using administrative data. One- and 4-year survival was determined to be 83% and 68%, respectively, among the symptomatic group which compared favorably to the elective group with 89% and 73% 1- and 4-year survival. However, decision analyses and cost-effectiveness modeling have previously demonstrated that individual patient rupture risk, operative risk, and life expectancy need to be considered to determine the optimal threshold for intervention. It seems logical to consider other factors that may make rupture more likely during surveillance as well. This subgroup of patients could be offered surgery at a time when it is convenient for them, with the understanding that waiting for expansion to 5. In these cases, patient preference should weigh heavily in the decision-making process. In addition, the ability of the patient to comply with careful surveillance should be considered. Moreover, with a progressively aging population in mind, quality-of-life assessments should likely also be factored into decisionmaking analyses. Furthermore, physicians play a critical role in educating patients and remain the primary source of information for them. Assessments of activity level, stamina, and stability of health are important and can be translated into metabolic equivalents to help assess both cardiac and pulmonary risks. In some cases, preoperative treatment with bronchodilators and pulmonary toilet can reduce operative risk. Serum creatinine is one of the most important predictors of operative mortality79 and must be assessed. The impact of other diseases, such as malignancy, on expected survival should also be carefully considered. The development of this technique was based in part on the failure of previous "nonresective" operations, now of historical interest, including aneurysm ligation, wrapping, and attempts at inducing aneurysm thrombosis that yielded uniformly dismal results. This approach uses laparoscopic techniques to dissect the aneurysm neck and iliac arteries followed by a standard endoaneurysmorrhaphy through a mini-laparotomy. Furthermore, two publications describe early experiences with robotic aortic aneurysm repair with comparable hospital stay, complications, and mortality rates. Decision analysis suggests that there is little difference between open and endovascular repair for most patients. Open surgery may be preferred for younger, healthier patients in whom there is little difference in operative risk between the two strategies, and for whom long-term durability is a concern, although contemporary stent grafts appear to have improved durability from their initial constructs and are currently recommended for most patients with reasonable anatomy. However, the ultimate treatment needs to be individually tailored to specific patients, especially those with high associated surgical risk. Ongoing rapid advances in stent graft technology will need to be considered in the future because device applicability and accompanying morbidity may change. In select patients, pulmonary artery catheters may be used to guide volume replacement and vasodilator or inotropic drug therapy in the early postoperative period and the intensive care unit. Mixed venous oxygen tension measuring, available with these catheters, can provide an additional estimate of global circulatory function. However, studies have concluded no demonstrable benefit is derived from these catheters with regards to patient-level outcome,142,143 and therefore selective use is probably more appropriate than routine application, especially given the associated risk profile. Therefore intraoperative autotransfusion, as well as preoperative autologous blood donation, has become popular, primarily to avoid the infection risk associated with allogeneic transfusion. However, studies of the cost-effectiveness of such procedures question their routine use. One study has shown that a postoperative hematocrit of less than 28% was associated with significant cardiac morbidity in vascular surgery patients. The only predictor of intraoperative hypothermia was female gender, whereas prolonged hypothermia was related to initial hypothermia, indicating the difficulty in rewarming cold patients. The technique involves sequential clamping of each common iliac artery for 10 minutes followed by 10 minutes of respective reperfusion. The authors demonstrated that patients undergoing remote ischemic preconditioning had both diminished rates of postoperative myocardial infarction and diminished critical care length of stay compared with the control groups. The supplemental use of continuous epidural anesthesia, begun immediately preoperatively and continued for postoperative pain control, is increasing in popularity. Additional benefits may include a reduction in the sympathetic-catecholamine stress response, which might decrease cardiac complications. One randomized trial comparing general anesthesia with combined general-epidural anesthesia demonstrated decreased deaths, cardiac events, infection, and overall complications. Furthermore, it is possible that the major benefit of epidural anesthesia accrues in the postoperative period, rather than intraoperatively. A significant reduction in mortality extending 2 years after discharge was observed in the atenolol-treated patients (3% vs. In a separate analysis, they noted that atenolol-treated patients had a 50% lower incidence of myocardial ischemia during the first 48 hours after surgery and a 40% lower incidence during postoperative days 0 to 7. This study compared the effects of perioperative extended-release metoprolol succinate to placebo among patients undergoing noncardiac surgery. Results demonstrated that there was a significant reduction in the composite end point of cardiovascular death, nonfatal myocardial infarction, and nonfatal cardiac arrest among patients receiving perioperative -blocker therapy. However, the study also revealed that there were more deaths and strokes among the treated group compared with placebo. However, the authors found no significant change in the rate of postoperative myocardial infarctions despite the increase in -blocker use during this time period. However, chronic -blocker use is now known to improve outcomes in patients with heart failure. Midline, transperitoneal incisions can be performed rapidly and provide wide access to the abdomen, but they may be associated with more pulmonary complications due to postoperative splinting from upper abdominal pain. Transverse abdominal incisions, just above or below the umbilicus, require more time to open and close but may be associated with fewer pulmonary complications and late incisional hernias, although this has not yet been proven. Retroperitoneal incisions, from the lateral rectus margin extending into the 10th or 11th intercostal space, afford good exposure of both the infrarenal and suprarenal aorta but limit exposure of the contralateral renal and iliac arteries. In addition, this exposure does not allow access to intraabdominal organs unless the peritoneum is purposely opened. The left retroperitoneal approach is usually favored over the right for exposure of the upper abdominal aorta because the spleen is easier to mobilize and retract than the liver. The right retroperitoneal approach is used when specific abdominal problems, such as a stoma, preclude the left-sided approach. However, randomized trials have reached different conclusions about the potential advantages of retroperitoneal over transabdominal incisions. In one randomized trial, Sieunarine and colleagues166 found no differences in operating time, cross-clamp time, blood loss, fluid requirement, analgesia requirement, gastrointestinal function, intensive care unit stay, or hospital stay for transperitoneal versus retroperitoneal approaches for aortic surgery. However, in long-term follow-up, there were significantly more wound problems (hernias, bulging, and pain) in the retroperitoneal group. Transperitoneal incision patients had a higher likelihood of wound dehiscence while the retroperitoneal patients had a slightly higher rate of postoperative pneumonia. However, after adjusting for confounding, the only significant difference was a slightly higher rate of reintubation for pulmonary complications in the retroperitoneal patients. However, both the transperitoneal and retroperitoneal approaches have advantages in certain patients. Relative indications for retroperitoneal exposure include a "hostile" abdomen due to multiple previous transperitoneal operations, an abdominal wall stoma, a horseshoe kidney, an inflammatory aneurysm, or anticipated need for suprarenal endarterectomy or anastomosis, mindful that the retroperitoneal approach provides facilitated access to the visceral aorta or even supraceliac aortic segments. The advantages of each approach make it advisable for surgeons to become proficient with both techniques. Transperitoneal Approach After entering the abdomen through a transperitoneal incision, the abdomen is thoroughly explored to exclude other pathology and to assess the extent of the aneurysm. The transverse colon is then retracted superiorly, and the ligament of Treitz is divided to allow retraction of the small bowel to the right. A longitudinal incision is made in the peritoneum just to the left of the base of the small bowel mesentery to expose the aneurysm. This incision extends from the inferior border of the pancreas proximally to the level of normal iliac arteries distally. Care must be taken to avoid the ureters, especially if exposure includes the iliac bifurcation where the ureters normally cross. Autonomic nerves to the pelvis course anterior to the proximal left common iliac artery and should be retracted with associated retroperitoneal tissue rather than incised, to prevent sexual dysfunction in men.
Risk factors for descending aortic aneurysm formation in medium-term follow-up of patients with type A aortic dissection antibiotic generations buy discount roxithromycin 150mg on-line. Endovascular aneurysm repair patients who are lost to follow-up have worse outcomes antibiotics for uti prevention 150 mg roxithromycin with visa. Bavaria Abstract Aortic dissection is a complex disease entity antibiotic x-206 order roxithromycin amex, posing a formidable challenge to cardiovascular surgeons worldwide antibiotics for sinus infection cipro discount 150 mg roxithromycin otc. Medical management of acute ascending aortic dissection is associated with high mortality antibiotic 2012 purchase genuine roxithromycin. Therefore prompt surgical treatment to replace the ascending aorta remains the mainstay of therapy, and prevents the life-threatening complications of pericardial tamponade, acute aortic insufficiency, and coronary ischemia. However, many patients will be left with residual dissection of the thoracoabdominal aorta, which is vulnerable to aneurysm degeneration and late malperfusion. Endovascular and open surgical therapies are often required to address these entities. Acute dissection confined to the descending aorta without complicating features has traditionally been managed with medical therapy; however, there is new interest in early endovascular intervention to potentially alter the subsequent aortic remodeling pathways. Keywords acute aortic dissection; chronic aortic dissection; cerebral perfusion strategies Morgagni described the first cases of aortic dissection in 1773, and Maunoir coined the entity "aortic dissection. De Bakey and Cooley first successfully operated on a patient with a descending thoracic aortic aneurysm using a lateral resection. In 1956 De Bakey and Cooley replaced the ascending aorta using cardiopulmonary bypass and homograft for conduit. The hemostatic qualities of synthetic grafts have been improved by modifications in textile engineering through the impregnation of collagen or gelatin. The routine use of cardiopulmonary bypass and widespread availability of synthetic graft material ushered in the modern era of surgical treatment for aortic dissection. Nevertheless, surgical management of aortic dissection remains a formidable challenge to surgeons. In addition to the inherent weak nature of the aortic tissues, patients may present with a wide spectrum of anatomic and physiologic derangements. Surgical decision making hinges on three primary considerations: (1) anatomic location of the dissection, (2) the time course in respect to onset of symptoms, and (3) the presence of complications related to the dissection. The Stanford system categorizes aortic dissection in two functional groups and is widely incorporated in clinical practice due to its simplicity. Any dissection involving the ascending aorta is categorized as type A, irrespective of the entry tear site or distal extent. The primary limitation of the Stanford classification is that it is based solely on the presence (type A) or absence (type B) of ascending aortic involvement; it does not provide information about distal aortic involvement, a factor that has important management and prognostic implications. Timing of the operation in relation to onset of symptoms is important because surgical repair becomes safer as the dissection becomes older and the aorta less fragile. Risks posed by tissue fragility must be weighed against the competing risk of acute complications, which include rupture, severe aortic regurgitation, heart failure, and malperfusion. Although somewhat arbitrary, the Society of Thoracic Surgeons has differentiated timing of aortic dissection into the following categories: hyperacute (< 48 hours), acute (48 hours to 2 weeks), subacute (> 2 weeks to 90 days), and chronic (> 90 days). Aortic dissections can cause numerous potentially lethal complications that warrant emergent surgical intervention. The combination of these potential complications with severe physiological derangements and extreme tissue fragility make aortic dissection one of the most formidable conditions treated by cardiovascular surgeons. Weakened aortic wall can rupture at any location and often results in fatal exsanguination. Aortic dissection can lead to acute cardiac failure via (B) extension into coronary ostia, causing myocardial ischemia, and (C) disruption of aortic valve commissures, causing acute valvular insufficiency. Complications of branch vessel malperfusion include (D) stroke or upperextremity ischemia when brachiocephalic branches are involved, paraplegia when segmental intercostal and lumbar arteries are compromised, (E) renal failure or mesenteric ischemia when visceral vessels are disrupted, and (F) lower-limb ischemia when iliac arteries are occluded. The three previously listed considerations form the basis for surgical intervention and operative strategies for aortic dissection. Surgical procedures to address proximal aortic dissections involving the ascending aorta and transverse aortic arch differ distinctly from strategies for treating distal aortic dissections involving the descending thoracic and thoracoabdominal aorta. Type a Aortic Dissection Natural History Elective aortic replacement in patients with ascending aortic aneurysm may prophylactically prevent aortic catastrophes such as acute type A aortic dissection, which harbors a very high mortality. The grim natural history of untreated acute type A aortic dissection is underscored by data reporting 50% mortality at 48 hours. In a study involving only octogenarians, 25% of patients were unfit to undergo surgery and successfully managed medically. Indications for Operation Aortic repairs for type A aortic dissection undertaken in the chronic phase invariably have superior results compared to those performed in the acute timeframe. Unfortunately, the high risk associated with early operation is outweighed by the even greater risk of a patient suffering a fatal complication. Therefore, the presence of an acute type A aortic dissection has traditionally been considered an absolute indication for emergency surgical repair and remains the standard approach. Elderly Patients Emergent repair of type A dissection in patients with advanced age greater than 80 years remains controversial. In recent literature, operative mortalities of nearly 50% have been reported for octogenarian patients. One may argue that surgical treatment is not warranted in the elderly because it does not alter the unfavorable natural history of the disease. Extensive operations such as total arch or aortic root replacement should be weighed against the mortality risk associated with these prolonged and technically challenging operations. In patients whose compromised physiological reserve makes them poor candidates for emergency aortic repair, initial medical optimization followed by semielective surgery may be a reasonable treatment strategy. Severe Malperfusion Branch-vessel obstruction due to dissection may cause a wide spectrum of malperfusion syndromes ranging from mild. In many cases of mild malperfusion, repair of the proximal aorta restores predominant flow through the true lumen and corrects distal malperfusion. However, patients in whom ischemia has caused severe end-organ dysfunction are unlikely to benefit from immediate ascending aortic repair. Stroke with resulting coma and bowel infarction with frank peritonitis remain ominous conditions in the setting of type A aortic dissection. Due to these observations, some centers advocate a strategy of delayed surgical treatment in patients with severe malperfusion. Delayed proximal aortic operation is undertaken once the patient has recovered from the malperfusion. The optimal treatment strategy in these critically ill patients remains a topic of debate. Type A Dissection After Prior Cardiac Surgery Delayed management with elective operation has been proposed for patients who have had previous cardiac surgery. The presence of prosthetic aortic valves, aortic suture lines, coronary bypass grafts, and mediastinal adhesions surrounding the aortic wall are theoretically considered protective. Their presence can potentially prevent rupture, avoid valvular insufficiency, and minimize coronary malperfusion. Acute type A aortic dissection during the early postoperative period carries a high risk of rupture and tamponade; these patients should undergo early reoperation. Patients with ongoing chest pain should also undergo prompt surgical repair as well. Transport to Specialized Centers Patients with type A aortic dissections frequently require transport to centers where cardiac surgery services are available. Even in centers that offer cardiac surgery, transfer to high-volume centers may be considered in hemodynamically stable patients. There is evidence of improved outcomes in patients transferred to specialized centers. Aggressive pharmacological management should be initiated and metabolic derangements addressed. Consistent administration and titration of vasoactive infusions during transport can be facilitated by central venous and arterial catheters. Inotropic agents and diuretic therapy can be given to patients presenting with low cardiac output and acute ventricular distention due to aortic valvular insufficiency and volume overload. If patients with pericardial tamponade must be transferred, a pericardial drain should be placed to allow intermittent drainage during transport. Whenever possible, patients with limb-threatening ischemia should undergo revascularization-usually via femoral-to-femoral artery bypass-before transport to minimize the severe metabolic derangements that result from prolonged limb ischemia and improve chances of survival. Standardized treatment protocols have been developed to optimize the hemodynamic management of patients with type A aortic dissection during transport. Surgical Repair Preoperative Considerations There are several important considerations that may influence conduct of the operation, including the presence of connective tissue disorder, preexisting aortic root or arch aneurysm, and presence of severe malperfusion. A dissection that occurs in the setting of a preexisting aneurysm will likely require complete replacement of that segment. The extent of aortic valve incompetence on preoperative echocardiography and any contraindications to anticoagulation will also dictate the need for aortic valve replacement and prosthesis type (mechanical vs. Cardiopulmonary Bypass Median sternotomy provides access to the heart and proximal aorta. There are numerous options for arterial access to safely establish cardiopulmonary bypass. Peripheral options in cannulation for arterial inflow include the femoral artery and axillary artery. The femoral artery is a reliable option, which can provide rapid access in patients who are in extremis, although malperfusion and retrograde atheroembolization can occur. The axillary artery usually allows perfusion of true lumen and simplifies antegrade cerebral perfusion. Most surgeons perform type A aortic dissection repair utilizing a period of hypothermic circulatory arrest. Furthermore, this strategy avoids additional intima tears that may occur from an aortic clamp positioned across the fragile aorta. Neuroprotection Strategies Two fundamental concepts in neuroprotection are hypothermia and cerebral perfusion. Surgeons must be cognizant of time periods of circulatory arrest in order to ensure satisfactory outcomes. Ample literature has shown that longer periods of circulatory arrest are associated with worse outcomes. Ongoing research trials are underway to determine the optimal core body temperature for performing complex aortic reconstructions utilizing circulatory arrest. Accumulating evidence suggests that this technique does not provide cerebral oxygenation, but rather provides benefit by maintaining cerebral hypothermia and flushing the cerebral circulation of air and loose debris. There are multiple techniques for accomplishing this, but a widely adopted approach is via the right axillary artery. An atraumatic vascular clamp or snare is placed at the base of the innominate artery upon initiating circulatory arrest with antegrade cerebral perfusion via a cannula in the axillary artery. This maneuver often corrects the situation if there is an intact circle of Willis. Alternatively, with the aorta open, selective use of left carotid perfusion by a separate balloon-tipped catheter can be performed, depending on the anticipated length of circulatory arrest. Distal Reconstruction Once the ascending aorta is resected and circulatory arrest established, the transverse aortic arch can be carefully inspected, and decisions made regarding the extent of aortic arch resection (Box 33. Most patients will require replacement of the segment of the ascending aorta between the sinotubular junction and the origin of the innominate artery. In the setting of emergent operation for acute dissection, more extensive total arch replacement has been associated with increased early morbidity and mortality, although recent studies have shown equivalent results. If malperfusion was present preoperatively owing to true lumen compression in the descending thoracic aorta, true lumen expansion can be improved by open antegrade deployment of an endovascular stent-graft in the descending thoracic aorta. Whether this intervention influences the natural history of the residual dissected thoracoabdominal aorta is currently a matter of intensive research. There are multiple described techniques for performing a hemostatic suture line to dissected aorta. A felt "sandwich" technique has been described whereby a felt buttress is applied on both the inner and outer layer of the aortic wall, thus leading to a robust suture line. An appropriate size graft is then anastomosed to the distal aorta with 4-0 or 3-0 polypropylene in an "onlay" type anastomosis with the graft invaginated into the distal aorta. Restoration of true lumen flow often alleviates any mild distal malperfusion that was present preoperatively. Total Aortic Arch Replacement Extensive aneurysms involving the entire arch usually require total arch replacement. Primary tears affecting the greater curvature or any of the brachiocephalic branch vessels should be resected. The distal anastomosis is created beyond the primary tear at the transverse arch or at the proximal descending thoracic aorta, using a tube graft. There are prefabricated aortic grafts with three separate limbs for great vessel reimplantation. Alternatively, each of the three limbs of a trifurcated arch graft can be separately anastomosed to the individual arch vessels and the main limb anastomosed to the ascending graft. In extreme cases, the aneurysm extends past the arch and into the descending thoracic aorta. This can be managed using the elephant trunk technique described by Borst for total arch replacement. In addition to directing flow into the true lumen, this "trunk" can be used to facilitate repair of the descending thoracic aorta during a subsequent thoracotomy approach to repair the descending aorta.
This incidence was approximately five times higher than that reported from Norway virus january 2014 order genuine roxithromycin on line, where the incidence was calculated to be 2 virus 71 purchase roxithromycin amex. Part of the difficulty in understanding this disorder has been the heterogeneity of the affected population virus warning generic roxithromycin 150 mg with visa. Determining the nature of this dysfunction has also been challenging because control of cutaneous blood flow depends on an intricate interplay of systemic and local signals and is not completely understood antibiotics ok during pregnancy roxithromycin 150 mg for sale. Thermoregulatory control of human skin blood flow is vital to maintenance of normal body temperatures during challenges to thermal homeostasis antibiotic 10 days 150 mg roxithromycin with mastercard. Sympathetic neural control of skin blood flow includes the noradrenergic vasoconstrictor system and a sympathetic active vasodilator system, the latter being responsible for 80% to 90% of the substantial cutaneous vasodilation that occurs with wholebody heat stress. With body heating, the magnitude of skin vasodilation is striking; skin blood flow can reach 6 to 8 L/min during hyperthermia. The pathophysiology appears to relate to disorders of local or reflex thermoregulatory control of skin circulation. However, paradoxically, this increased blood flow is accompanied by local hypoxia. Although there is increased perfusion during attacks, the values for transcutaneous oxygen tension are critically low, low, or unchanged-in other words, during symptoms, transcutaneous oximetry values decrease or do not change. If available blood is shunted away from normal skin capillaries, the skin will be hypoxic. Thus their hypothesis is that dilation of arteriovenous anastomoses is directly responsible for shunting nutritive blood flow away from the superficial vascular plexus. Pain relief by cooling could be explained by a resultant decrease in the metabolic rate and a corresponding decrease in the need for oxygen. As noted earlier, Raynaud phenomenon has been described in patients with erythromelalgia. Several lines of evidence suggest that a neuropathy is associated with erythromelalgia, because the disorder has been described in association with many types of neuropathy. Both large- and small-fiber neuropathies are observed in a large proportion of patients with erythromelalgia (see Box 48. In addition, an active contribution of mechanoinsensitive fibers to chronic pain was postulated. Uno and Parker41 reported that the density of both acetylcholinesterase-positive and catecholamine-containing nerve terminals in the periarterial and sweat gland plexuses was much less in the skin of the erythermalgic foot than in the unaffected skin of the same patient and much less than in the foot skin of a healthy person. Layzer42 wrote that it seems plausible to regard erythromelalgia as a problem of polymodal C fiber receptors in sensitized skin. In the largest reported series, the proportion of cases that are inherited was approximately 5%. Clinical onset in familial cases usually occurs in childhood, most frequently prior to the age of 5 or 6, but occasionally is seen up to 10 or 12 years of age and, in rare families, at even older ages. Gain-of-Function Mutations in Sensory Nerves and Consequent Nerve Hyperexcitability In the inherited forms of erythromelalgia, there have been developments in understanding the disease. It currently appears that mutations in particular sodium channels in the nociceptors of sensory nerves lead to firing of nerves with little provocation; in other words, sensory nerves are hyperexcitable. It seems that this mutation renders dorsal root ganglion neurons hyperexcitable, partially explaining the etiopathogenesis of this disorder (28990532). Recognition of the associated myeloproliferative disease is vital because in these specific types of erythromelalgia, aspirin provides immediate and long-lived relief from symptoms. Thrombin, platelet function, and genetics have been considered in studies of erythromelalgia. Disordered platelet function affecting the microvasculature has been implicated in thrombocythemia-related erythromelalgia. Does a neuropathy cause the vasculopathy, or does the vasculopathy cause a neuropathy In the inherited form, mutations in the sodium channel lead to hyperexcitability of sensory nerves. Similar mutations have not been described in the sporadic form, which accounts for 95% of cases. Schechner31 pointed out that it is unknown whether shunting of blood through arteriovenous anastomoses alone can induce hypoxia severe enough to induce pain, particularly in areas that contain few arteriovenous anastomoses. Potentially inadequate compensatory dilation, or even inappropriate constriction of the precapillary sphincter, may compound the effects of the relative hypoperfusion. Both autonomic neuropathy33 and endothelial injury60 have been observed in patients with erythromelalgia, but it is not known whether this damage to critical vasoregulatory components is primary or secondary to chronic hypoxia. Differential diagnosis Any condition causing extremity pain could be mistaken for erythromelalgia. In particular, unwarranted diagnosis of erythromelalgia can result from any clinical situation that includes burning sensations in the limbs. Get a detailed history, and perform a physical examination with respect to each element of the history outlined earlier. If signs of erythromelalgia are not present during the examination, ask the patient to photograph the affected area when symptoms are apparent. Results of these tests are useful to confirm the diagnosis and help to guide therapy. The histopathological changes in cases of erythromelalgia related to thrombocythemia showed arteriolar inflammation, fibromuscular intimal proliferation, and thrombotic occlusions. Biopsies from a few patients with drug-induced erythromelalgia have been described. Biopsies from a patient with verapamil-induced erythromelalgia showed mild perivascular mononuclear infiltrate and moderate perivascular edema. Contrary to other painful conditions of the lower extremities, erythromelalgia patients have normal epidermal nerve fiber density on skin biopsy. However, although the number of fibers is not decreased, functionality is impaired as evidenced by abnormal sweat test results, pain thresholds, and blood pressure or heart rate control. Causes of death included myeloproliferative disease, cardiovascular disease, and cancer. In a series of patients with pediatric erythromelalgia, one patient had committed suicide. Over time in the patients with erythromelalgia, the condition gradually became worse. In patients with primary or secondary acute erythromelalgia, the condition improved, and in patients with primary or secondary chronic erythromelalgia, the condition remained stable. Thus overall, it can be concluded from these studies that the course of the disease is unpredictable; some patients become worse, some have a stable course, and some get better or even have full resolution of erythromelalgia with time. The questionnaire is a standard survey that measures health-related quality-of-life outcomes and measures each of eight health concepts (or domains) on a five-point Likert scale: physical functioning, role limitations due to physical disease, bodily pain, general health, vitality (energy and fatigue), social functioning, role limitations due to emotional problems, and mental health (psychological stress and psychological well-being). There are no randomized controlled studies of treatments for erythromelalgia, and no single treatment is effective in all cases. The literature is replete with case reports and small case series describing a response to one treatment or another. When a larger group of erythromelalgia patients was surveyed, the majority reported that no treatment was very effective. Pain rehabilitation program73 Aspirin3,74 has been reported to abolish erythromelalgia, especially in initial reports of the syndrome. It has become increasingly evident that aspirin may be effective in erythromelalgia due to myeloproliferative disease, but it is rarely effective in other forms of erythromelalgia. Mexiletine normalizes aberrant gating properties of the L858F gain-of-function mutation in Nav1. Patient-controlled epidural analgesia and interferon -2b provided relief of erythromelalgia symptoms in a patient with polycythemia vera. Calcium antagonists have been reported to both relieve and exacerbate erythromelalgia. Anesthetics have been used, including topical lidocaine (lidocaine patch),68 a combination of topical amitriptyline and ketamine,70 and epidural infusion of narcotic analgesic medications such as bupivacaine, sometimes in combination with other narcotic drugs. Pizotyline, a benzocycloheptathiophene derivative used primarily for migraine prophylaxis, has been used for erythromelalgia. Nonmedicinal therapies such as acupuncture, biofeedback, hypnosis, and magnets have been variably effective. On a rare vaso-motor neurosis of the extremities and on the maladies with which it may be confounded. Erythermalgia (erythromelalgia) of the extremities: a syndrome characterized by redness, heat, and pain. Clinical observations and experiments relating to burning pain in extremities and to so-called "erythromelalgia" in particular. Erythromelalgia and other disturbances of the extremities accompanied by vasodilatation and burning. Microvascular arteriovenous shunting is a probable pathogenetic mechanism in erythromelalgia. Thrombocythemic erythromelalgia, primary erythermalgia, and secondary erythermalgia: three distinct clinicopathologic entities. Pediatric erythromelalgia: a retrospective review of 32 cases evaluated at Mayo Clinic over a 37-year period. Neurophysiologic and vascular studies in erythromelalgia: a retrospective analysis. Skin blood flow in adult human thermoregulation: how it works, when it does not, and why. Reduced skin capillary density during attacks of erythromelalgia implies arteriovenous shunting as pathogenetic mechanism. Mechanisms other than shunting are likely contributing to the pathophysiology of erythromelalgia. Autosomal dominant erythermalgia associated with a novel mutation in the voltage-gated sodium channel alpha subunit Nav1. Pain thresholds, supra-threshold pain and lidocaine sensitivity in patients with erythromelalgia, including the I848Tmutation in NaV 1. Olmsted syndrome with erythromelalgia caused by recessive transient receptor potential vanilloid 3 mutations. Erythromelalgia in essential thrombocythemia is characterized by platelet activation and endothelial cell damage but not by thrombin generation. Intervention for erythromelalgia, a chronic pain syndrome: comprehensive pain rehabilitation center. Erythromelalgia: association with hereditary sensory neuropathy and response to amitriptyline. Mexiletine as a treatment for primary erythromelalgia: normalization of biophysical properties of mutant L858F NaV 1. Erythromelalgia in a patient with systemic lupus erythematosus treated with clonazepam. A refractory case of secondary erythermalgia successfully treated with lumbar sympathetic ganglion block. Lumbar sympathetic pulsed radiofrequency treatment for primary erythromelalgia: a case report. Secondary erythromelalgia successfully treated with patient-controlled epidural analgesia and interferon alpha-2b: a case report and review of the literature. Prostacyclin reduces symptoms and sympathetic dysfunction in erythromelalgia in a double-blind randomized pilot study. Resolution of refractory symptoms of secondary erythermalgia with intermittent epidural bupivacaine. A case of primary erythromelalgia successfully treated with high-dose intravenous immunoglobulin therapy. Olin Abstract Pernio, commonly known as chilblains, is a cold-induced localized inflammatory condition presenting as skin lesions predominantly on unprotected acral areas. Pernio most commonly affects females in adolescence and early adulthood, but may occur at any age and in either sex. Since the primary trigger for development of pernio is cold exposure, prevention is the mainstay of management. Keywords chilblains; pernio; cold-induced; vascular disease; vasospasm Pernio, commonly known as chilblains, is a cold-induced localized inflammatory condition presenting as skin lesions predominantly on unprotected acral areas. The numerous names that were used to describe this syndrome created much confusion and misunderstanding of this entity (Box 49. Distribution around nail beds (A) and swollen toes with brownish yellow and red lesions (B) are characteristic of pernio. Although pernio is most common in young women, it has also been reported in all ages and both sexes. Pathophysiology the first response to cold exposure is vasoconstriction in the dermis and subcutaneous tissue. Heat loss is minimized by shutting down distal capillary beds and diminishing blood supply to the acral portions of the extremities to maintain central body temperature. Stasis and shunting of blood flow away from the superficial vessels occurs secondary to arteriolar constriction, venular relaxation, and cold-associated increased blood viscosity. Indeed, there is a higher frequency of vasomotor instability, cold hands and feet, and Raynaud phenomenon in women. The exposed skin of affected subjects remains cool longer and warms slower than that of controls, further highlighting the importance of individual susceptibility for development of pernio after cold exposure. Raynaud phenomenon and pernio frequently coexist in the same patient, so these diseases may be part of a continuum, with Raynaud phenomenon representing acute and readily reversible vasospasm, and pernio representing more prolonged vasospasm with more chronic changes.
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