Biomedical subjects
Publications and source records attributed to W R Jamieson.
Tuberculosis is increasing in prevalence in North America, mainly due to HIV infection. We describe an unusual case of TB of the thymus in a HIV sero-negative Filipino immigrant who preoperatively was thought to have a thymoma. We describe the clinical, radiologic and pathologic findings and review the literature on TB of the thymus.
From 1975 to 1989, over 1400 patients in the elderly population and over 1700 patients under 65 years of age received the Carpentier-Edwards standard (CE-Standard) and supra-annular porcine (CE-SAV) bioprotheses. The mean ages of the patients receiving the two protheses within the three subgroups of the elderly population-65-69 years, 70-79 years, and 80 years and over-were relatively similar. There was no statistically significant difference in the performance of the prostheses regarding structural valve deterioration (SVD) at seven years. The freedom from SVD for aortic valve replacement in the 65-69 years group at seven years was 98.7% +/- 1.3% for the CE-Standard and 98.7% +/- 1.0% for the CE-SAV, for both the 70-79 years group and the 80 years and over group the figure was 100% for both prostheses (p = NS). The freedom from SVD after mitral valve replacement in the 65-69 years group at seven years was 90.0% +/- 4.3% for the CE-Standard and 84.8% +/- 7.5% for the CE-SAV, for the 70-79 years group it was 95.3% +/- 3.2% and 95.5% +/- 3.6% respectively and for the 80 years and over group the figure was 100% for both prostheses (p = NS within groups). The long term freedom from SVD after aortic valve replacement was 98.4% +/- 3% at 15 years for the CE-Standard in the 65-69 years group, 94.9% +/- 5% at 13 years for the 70-79 years group and 100% at 13 years for the 80 years and over group.(ABSTRACT TRUNCATED AT 250 WORDS)
The Duromedics (Baxter Healthcare Corp., Edwards CVS Div., Irvine, Calif.) mechanical cardiac valvular prosthesis was implanted in 480 patients between 1984 and 1987 at the Montreal Heart Institute, the Hospital Clinic of Barcelona and the teaching hospitals of the University of British Columbia. The mean age of the patients was 52 years. The early mortality was 7.9% and the late mortality was 4.1% per patient-year. The overall survival at 4 years for aortic valve replacement (AVR) was 87.0% +/- 3.7% and for mitral valve replacement (MVR) was 81.9% +/- 2.9%. There were 16 valve-related reoperations in 14 patients--for prosthetic valve endocarditis in 9 patients, for thromboembolism in 1 patient and for nonstructural dysfunction in 4 patients. The freedom from thromboembolism at 3 and 4 years was 94.3% +/- 3.1% for AVR and 95.1% +/- 1.8% for MVR. The freedom from prosthetic valve endocarditis at 3 and 4 years was 95.3% +/- 2.2% for AVR and 96.2% +/- 1.6% for MVR. The freedom from structural valve deterioration for all positions was 100%. The freedom from reoperation at 4 years was 95.3% +/- 2.1% for AVR and 92.3% +/- 4.3% for MVR and from valve-related death was 98.7% +/- 1.3% for AVR and 96.2% +/- 1.6% for MVR. The freedom from all valve-related complications at 4 years was 87.7% +/- 3.8% for AVR and 85.7% +/- 2.9% for MVR. Long-term evaluation of the Duromedics prosthesis is required to determine the influence of documented structural valve deterioration.
The efficacy of pharmacologic agents for prevention and control of oxygen-derived free radical damage in ischemia-reperfusion injury of the spinal cord was assessed in a swine model of thoracic and thoracoabdominal aortic crossclamping. Animals were exposed to 30 minutes of ischemia that induced lethal, irreversible injury and paraplegia. The experimental groups were as follows: group A (n = 7), control group, receiving no pharmacologic intervention; group B (n = 7), deferoxamine 50 mg/kg/day administered intravenously over 3 to 4 hours before ischemia; group C (n = 7), allopurinol pretreatment 50 mg/kg/day for 3 days; and group D (n = 7), superoxide dismutase 60,000 units administered with 50,000 units before removal of the aortic crossclamp and 10,000 units over 10 minutes of reperfusion. Proximal hypertension was controlled with sodium nitroprusside and volume depletion. The methods of assessment were neurologic by a modified Tarlov criteria and blood flow by radiolabeled microspheres. Results of blood flow assessment confirmed a true ischemic episode of 30 minutes for all animals in all groups. The blood flow fell significantly during ischemia (p less than 0.01) and a hyperemic response was evident in the early reperfusion period. All animals in control group A were paraplegic. The group B (deferoxamine) results were superior; 85% had grade III function on a modified Tarlov scale, with animals in the group standing and even walking with difficulty. Only one animal in this group had good movements of hind limbs but was unable to stand or walk. Neurologic recovery was limited in the allopurinol group (group C), with 85% showing slight neurologic recovery with limited movement of the hind limbs. The animals in the superoxide dismutase group (group D) all had good recovery, with strong motor response of hind limbs, but were not able to stand. In summary, the results of this experimental protocol confirmed the possible role of oxygen-derived free radicals in the pathophysiology of spinal cord injury, induced by aortic crossclamping. Moreover, it proved that ischemia-reperfusion injury could be altered by pharmacologic interventions.
Between 1983 and 1987 the Mitroflow pericardial prosthesis was implanted in 354 patients, ranging in age from 14 to 94 years (mean 60.1 years). The early mortality was 5.7% and the late mortality 2.9% per patient-year. The total cumulative follow-up was 853 years (mean 2.4 years). Patient survival at 4 years for aortic valve replacement (AVR) was 81.5% and for mitral valve replacement (MVR) 74.8%. The overall rate of valve-related complications was 4.8% per patient-year (41 complications): thromboembolism, 15; hemorrhage related to antithromboembolic therapy, 1; prosthetic valve endocarditis, 15; nonstructural dysfunction, 3; and structural valve deterioration, 7. At 4 years the freedom from thromboembolism was 91.5% +/- 2.7% for AVR and 91.1% +/- 4.0% for MVR, from prosthetic valve endocarditis 93.5% +/- 2.3% for AVR and 94.0% +/- 2.9% for MVR, from structural valve deterioration 97.3% +/- 2.1% for AVR and 92.6% +/- 3.2% for MVR, from valve-related mortality 96.9% +/- 1.4% for AVR and 97.5% +/- 1.8% for MVR, and from reoperation 93.5% +/- 2.8% for AVR and 83.1% +/- 5.1% for MVR. The freedom from the composite of all valve-related complications at 4 years was 81.1% +/- 4.2% for AVR and 75.3% +/- 2.8% for MVR. The Mitroflow valve has provided satisfactory clinical performance at the 4-year evaluation. Structural valve deterioration is greater in the mitral position than in the aortic position. Long-term evaluation of the Mitroflow valve is necessary to determine the impact of structural valve deterioration on its clinical performance.
Hypothermic patients have been successfully rewarmed by a number of methods. However, when cardiac arrest occurs, as it frequently does at core temperatures of less than 27 degrees C, prolonged cardiopulmonary resuscitation (CPR) is required, because defibrillation can rarely be achieved until the patient has been rewarmed to 30 degrees to 34 degrees C. Five cases of accidental hypothermia with cardiac arrest treated with cardiopulmonary bypass are discussed. The first patient died as a result of inadequate low-flow cardiopulmonary bypass by the femorofemoral route. The second patient had prolonged CPR by closed-chest cardiac massage and warm peritoneal lavage followed by transthoracic cardiopulmonary bypass. This patient regained consciousness but was found to be paraplegic and died from bowel infarction related to peritoneal rewarming without adequate perfusion. In the last three patients, high-flow cardiopulmonary bypass was rapidly achieved using a no. 28 French chest tube for femoral venous cannulation, and they recovered completely. In cases of accidental hypothermia with cardiac arrest, rapid institution of full cardiopulmonary bypass provides excellent circulatory support and rapid rewarming. This avoids the complications of prolonged inadequate circulation that occur when closed-chest cardiac massage and external rewarming are used.
The preservation of heart and lung for transplantation remains a major concern in extended ischemic intervals. This experiment evaluated the effect of high molecular weight deferoxamine and a platelet-activating factor antagonist (CV-3988) in ischemic reperfused tissue. Heart-lung transplantation was performed in a swine model after 4 hours 45 minutes of ischemia. Animals were divided into three groups. Group A was a control without pharmacological intervention. In group B, high molecular weight deferoxamine, 50 mg/kg, was used, and in group C, platelet-activating factor antagonist CV-3988, 10 mg/kg, was used. The results of functional variables (cardiac index, stroke index, lung water, oxygen and carbon dioxide tensions, alveolar-arterial gradient, and alveolar-arterial ratio) demonstrated superior heart and lung function for groups B and C compared with the control group. These alterations of heart and lung function were significantly less (p less than 0.001) in group C, in which the platelet-activating factor antagonist (CV-3988) was used. The study revealed that formation of hydroxyl radicals and platelet-activating factor play an important role in the pathogenesis of ischemia reperfusion injury. Prevention of hydroxyl radical formation with high molecular weight deferoxamine and inactivation of platelet-activating factor with CV-3988 reduce the ischemia-reperfusion injury significantly.
The Carpentier-Edwards standard porcine bioprosthesis was implanted in 1,195 patients in 1,213 operative procedures between 1975 and 1987, with the majority of implants performed prior to 1982 at the University of British Columbia. The mean age of the patient population was 57.2 years (range 8 to 85 years). The mean follow-up was 7.4 years per patient. The freedom from the combination of thromboembolism and antithromboembolic therapy-related hemorrhage at 15 years was 79.5% for aortic valve replacement (AVR), 72% for mitral valve replacement (MVR), and 84% for multiple valve replacement (MR) (p less than 0.05, AVR greater than MR greater than MVR). The freedom from structural valve deterioration at 15 years was 71% for AVR, 41% for MVR, and 41% for MR (14 years) (p less than 0.05, AVR greater than MVR greater than MR). The freedom from nonstructural dysfunction and prosthetic valve endocarditis did not distinguish the valve positions (p = NS). The freedom from valve-related mortality from all causes including reoperation was 92% for AVR, 78% for MVR, and 77% for MR at 15 years (p less than 0.05, AVR greater than MVR greater than MR). The freedom from residual morbidity was not significantly different between valve positions (p = NS). The freedom from treatment failure (valve-related mortality and residual morbidity) at 15 years was 87% for AVR, 72% for MVR, and 75% for MR (p less than 0.05, AVR greater than MR greater than MVR). The freedom from all complications at 14 years was 50% for AVR, 25% for MVR, and 27% for MR (p less than 0.05, AVR greater than MR greater than MVR).(ABSTRACT TRUNCATED AT 250 WORDS)
The Carpentier-Edwards supra-annular porcine bioprosthesis has been utilized at the University of British Columbia since its introduction in 1982. The prosthesis was designed to improve hemodynamics with the supra-annular configuration and to reduce tissue failure with low-pressure glutaraldehyde preservation of the porcine aortic tissue. The prosthesis was inserted in 1,956 patients with 2,129 prostheses between 1982 and 1989. The mean age of the patient population was 62.7 years (range 13 to 87 years). The mean follow-up was 3.7 years per patient. The freedom from thromboembolism and antithromboembolic therapy-related hemorrhage at 8 years was 92% for aortic valve replacement (AVR), 83% for mitral valve replacement (MVR), and 92% for multiple valve replacement (MR) (p less than 0.05, AVR greater than MR greater than MVR). The freedom from structural valve deterioration was 86% for AVR, 73% for MVR, and 96% for MR at 8 years (p less than 0.05, AVR greater than MR greater than MVR). The freedom from nonstructural valve dysfunction and prosthetic valve endocarditis was not different between positions (p = NS). The freedom from valve-related mortality at 8 years was 98% for AVR, 94% for MVR, and 98% for MR (p less than 0.05, AVR greater than MR greater than MVR). The freedom from residual morbidity was not different at 8 years (p = NS). The freedom from treatment failure (valve-related mortality and residual morbidity) was 96% for AVR, 89% for MVR, and 94% for MR (p less than 0.05, AVR greater than MVR greater than MR).(ABSTRACT TRUNCATED AT 250 WORDS)
The present study compares simple hypothermic storage and hypothermic perfusion in a swine model of heart transplantation using metabolic and functional assessments. In both groups the hearts were initially protected with iso-osmolar potassium Tyers' cardioplegia. The donor hearts of group A were placed in simple hypothermic storage for 5 h. The donor hearts of group B were placed onto a perfusion apparatus for 5 h with perfusion pressure maintained at 28 cm of H2O and a myocardial temperature of 8-10 degrees C. The perfustate consisted of Tyers' solution with the addition of 2 mg/L of mannitol, 12.5 mg/L of glucose, 5 units/L of insulin, and 95% oxygen. The ischemic interval within both groups was 6 h, including orthotoipic transplantation. Investigation was conducted at three time periods: prepreservation (T1) in the donor, and postpreservation (T2) and immediately after loading (T3) in the recipient. Following volume loading for the hypothermic perfusion group there was significant improvement of myocardial function (cardiac index, p less than .05; stroke index, p less than .05) with no significant change in systemic vascular resistance, systemic blood pressure, and heart rate. There was also significant improvement in myocardial performance (p less than .05) for the hypothermic perfusion group following volume loading. Results of fatty acid turnover using 15-p-iodo (123I)-phenylpentodecanoic acid indicate significantly greater increase in metabolic rate for the perfusion group than for the hypothermic storage group. (p less than .05). This indicates improved metabolic status of the heart treated with the hypothermic perfusion technique. We conclude that a combination of functional and metabolic assessments is a good method for deduction of ischemic-reperfusion injury. We also conclude that hypothermic perfusion is superior to hypothermic storage for in vitro preservation of hearts for heart transplantation.
Long-term performance of biological prostheses and course of pregnancy, labor, and delivery were evaluated in women less than 35 years of age. Between 1975 and 1987, 87 female patients received a porcine (n = 86) or pericardial valve (n = 1); the mean patient age was 26.8 years, with a range of 8 to 35 years. A total of 17 of these patients experienced 37 pregnancies. A total of 25 babies were delivered, of which 19 were babies of normal birth weight born at term and six were born prematurely (two of these were stillborn). There were six spontaneous abortions and five therapeutic abortions. The mean time from primary operation to first delivery was 29 months. Of the 17 pregnant patients, 14 were in normal sinus rhythm and three were in atrial fibrillation. One of those in fibrillation had a therapeutic abortion while receiving warfarin therapy, and another was successfully delivered of her neonate after 7 months of warfarin therapy. The remaining 15 patients were treated through 35 pregnancies without anticoagulants or antiplatelet agents. Of the total population of 87 patients, 32 (36.8%) were treated for valve-related complications. Structural valve deterioration occurred in eight patients (47.1%) of the pregnancy group and 10 patients (14.3%) of the nonpregnancy group (p less than 0.05). The freedom from structural valve deterioration at 10 years was 23.3% +/- 14% for the pregnancy group and 74.2% +/- 8.5% for the nonpregnancy group (p less than 0.05, age as a determinant, p not significant). There were eight valve-related deaths (1.5%/patient-year). Reoperation was performed in 59% of the pregnancy group and 19% of the nonpregnancy group, primarily for structural valve deterioration manifested as valvular obstruction from aggressive calcification (p less than 0.05). The freedom from reoperation at 10 years parallels freedom from structural valve deterioration (20.3% +/- 12.4% and 64.3 +/- 9.1% for the pregnancy and nonpregnancy groups, respectively, with p less than 0.05; with age added as a determinant, p not significant). The overall reoperative mortality was 8.7% (two patients). The biologic prostheses afforded successful pregnancy without fetal wastage or congenital anomalies and without significant maternal morbidity or mortality.
The performance of the Carpentier-Edwards supra-annular (CE-SAV) porcine bioprosthesis is compared with the Carpentier-Edwards standard (CE-S) porcine bioprosthesis at 7 years. The standard prosthesis was implanted in 1,195 patients between 1975 and 1987, while the supra-annular prosthesis was implanted in 1,956 patients between 1982 and 1989. The total follow-up for the standard prosthesis was 8,850 patient-years with a mean follow-up of 7.4 years, while for the supra-annular prosthesis it was 7,317 years with a mean of 3.7 years. The follow-up for the standard prosthesis was 96.7% and for the supra-annular prosthesis was 97.6%. The freedom from structural valve deterioration (SVD) for aortic replacements is 96.1 +/- 0.9% for CE-S and 97.6 +/- 1.4% for CE-SAV at 7 years (p = NS). The freedom for mitral replacements from SVD is 89.1 +/- 1.7% and 88.6 +/- 2.8%, respectively, for CE-S and CE-SAV (p = NS). The freedom for multiple replacements at 7 years was 80.0 +/- 4.5% for CE-S and 97.8 +/- 1.5% for CE-SAV (p less than or equal to 0.05). The freedom from SVD for the age group equal to or less than 35 years is 79.0 +/- 4.7% for CE-S and 85.0 +/- 9.4% for CE-SAV (p = NS). The freedom for the age group 36-50 years is 85.2 +/- 2.8% and 90.4 +/- 4.5%, respectively, at seven years for the CE-S and CE-SAV prostheses (p = NS).(ABSTRACT TRUNCATED AT 250 WORDS)
Acute traumatic injury of the thoracic aorta is a relatively common injury of deceleration accidents, usually high-speed motor vehicle accidents. The limiting factor to successful hospital management of these victims is early diagnosis and prompt treatment. Between the years 1969 and 1989, 116 patients (87 men and 29 women) were diagnosed with acute traumatic injury of the aorta. The mean age was 38.8 years, and the range was from 11 to 82 years. All patients who presented to the hospital emergency departments were included in the evaluation. The diagnosis of aortic rupture was firmly established by either aortography, surgery, or autopsy. The site of injury in 105 (90.5%) was the aortic isthmus, that is, distal to the origin of the left subclavian artery. In nine patients (7.7%) the injury was in the distal thoracic aorta. Two patients had injuries of the aortic arch. Associated injuries were present in 110 patients (95%); 16 patients (14%) had no external evidence of chest injury. Only 50 patients (43%) had the opportunity for definitive surgical management. The nonsurgical group comprised 66 patients (57%), and all of these died; the cause of death was unsuspected, suspected, or diagnosed after hospital admission from the emergency department. Of the surgical group, 36 patients (72%) survived, whereas 14 patients (28%) died. The surgical management comprised partial cardiopulmonary bypass in 31 patients that included seven deaths, simple aortic cross-clamping in 14 that included six deaths, and nonheparinized bypass in four that included one death. The incidence of paraplegia was 3.2% (one patient) with cardiopulmonary bypass, 28.5% (four patients) with simple aortic cross-clamping and none with nonheparinized bypass.(ABSTRACT TRUNCATED AT 250 WORDS)
Almost exclusive use of Carpentier-Edwards porcine bioprostheses for cardiac valve replacement in 1194 patients between 1975 and 1987 at the authors' institutions has afforded the opportunity for a more scientific basis for prosthesis selection for subsets of patients, with regard to age and valve-related complications. The present study, performed according to previously established guidelines, investigated the influence of patient age and valve position as determinants of durability of 1315 porcine implants in terms of the following valve-related complications: structural valve deterioration, nonstructural dysfunction, thromboembolism, antithromboembolic therapy-related hemorrhage and prosthetic valve endocarditis. Age groups were as follows: 35 years and younger, 36 to 50 years, 51 to 65 years, and 66 years or older. Thromboembolism was found to be less common in the younger age groups, and significantly less common in patients following aortic compared to mitral valve replacement. The age group assessment for antithromboembolic therapy-related hemorrhage, nonstructural dysfunction and prosthetic valve endocarditis revealed no difference between positions or age groups. Patient age was found to be the major predictor of, and inversely related to, structural valve deterioration. In addition, porcine bioprostheses in the aortic position were shown to have durability superior to that of similar valves in the mitral position. Structural valve deterioration has very little influence on valve-related mortality and residual morbidity. This study thus supports the implantation of porcine bioprostheses in somewhat younger patients than would be advisable for mitral prostheses. The authors now recommend the selective implantation of porcine bioprostheses in the aortic position in patients over 65 years of age, and in the mitral position in patients over 70 years of age.
The purpose of this study was to examine the longitudinal effect of gradual coronary occlusion on regional myocardial metabolism of 15-p-123I-iodophenylpentadecanoic acid [( 123I]IPPA). Adult dogs were imaged using [123I]IPPA and planar gamma imaging. A thoracotomy was performed and an ameroid constrictor of appropriate size permanently positioned on the left anterior descending coronary artery. The dogs were imaged after injection of 3-5 mCi [123I]IPPA at various times over a 2-week period. With imaging on days 7 and 14, the dogs were paced at a rate of 185. Time-activity curves were generated and t1/2 values calculated using monoexponential curve fitting. Results indicate a significant increase in t1/2 between control and 14 days after surgery in the apical wall (29 +/- 7 to 53 +/- 18 min; P less than 0.05). Although there was also an increased t1/2 in the lateral wall, this was not significant (27 +/- 8 to 78 +/- 99 min; P greater than 0.05). There was no significant change in t1/2 in the septal wall (27 +/- 9 to 33 +/- 8 min; P greater than 0.05). We conclude that [123I]IPPA is a useful indicator of developing myocardial ischemia.
A large-animal model is essential for the assessment of functional parameters in cardiovascular surgical research. To date the canine model has been used successfully because of its availability and tolerance to cardiopulmonary bypass. However, because of decreased availability and increased cost, an alternative animal model is now needed. The swine model has been used in experimental cardiac procedures, but complications during cardiopulmonary bypass have presented a formidable challenge. These complications include enormous fluid shifts from the vascular bed, increased metabolic acidosis, and marked hemoglobinuria. To eliminate these deleterious complications within the swine model, a number of technical alterations were achieved. The priming solution used for the extracorporeal circuit was altered to consist of 1000 mL lactated Ringer's solution. 500 mL 20% mannitol, 500 mL 6% dextran in 5% detrose solution. 50 mEq sodium bicarbonate, and 10,000 IU heparin. The extracorporeal circuit employed the use of membrane oxygenation. Three different blood flow rates (150, 175, and 200 mL/kg min-1) were studied. We conclude that the optimum blood flow rate for cardiopulmonary bypass in swine is in the range of 175-200 mL/kg min-1. Membrane oxygenation results in less damage to blood during cardiopulmonary bypass. The asanguinous hyperosmolar priming solution is beneficial for cardiopulmonary bypass in swine to greatly reduce fluid shifts, prevent metabolic acidosis, and eliminate hemoglobinuria.
The role of allopurinol in the prevention of ischemia-reperfusion injury was assessed in a model of heart-lung transplantation. Fourteen swine were divided into two groups (seven donors and seven recipients). All heart and lung blocks were placed in hypothermic storage after perfusion with cold iso-osmolar cardioplegic solution and modified Collins solution, respectively (t = 8-10 degrees C for heart and t = 16-18 degrees C for lungs). The total ischemic time including the orthotopic transplantation was 6 h. Animals (donors and recipients) were pretreated with allopurinol given orally at a dosage of 50 mg/kg for 4 days. Animals were assessed by monitoring heart and lung function, including extravascular lung water at three time intervals, which included pretransplantation (donor), and 30 min and 2 h posttransplantation (recipient). Erythrocyte peroxidation susceptibility was assessed for 3 days, and surgery was performed on day 4. The malondialdehyde levels determined from erythrocyte exposure to in vitro peroxidative challenge classified three paired donor and recipient animals as responders and four paired donor and recipient animals as nonresponders to the allopurinol pretreatment. A persistent deterioration of lung function was observed over time in nonresponders (p less than .05) (increase of lung water, decrease of partial pressure of oxygen, increase in alveolar-arterial gradient, and decrease in arterial-alveolar tension ratio). Responders showed no significant alterations in lung function. This study in swine, a species devoid of myocardial xanthine oxidase activity, indicates that allopurinol may have a mechanism of action other than xanthine oxidase inhibition in the prevention of ischemia-reperfusion injury. The parallelism between protection of lung function and of red blood cells suggests the involvement of a generalized increase in tissue antioxidant capacity.
Aortic dissection, the most common acute disease of the thoracic aorta, is associated with high mortality and morbidity. The authors reviewed their experience over the last 20 years with 258 patients who had aortic dissection (259 dissections). The diagnosis was made at autopsy in 69 (27%) patients (59 type A, 10 type B). Of the remainder, 97 patients had type A dissection (78 acute, 19 chronic) and 93 had type B dissection (56 acute, 37 chronic). The sudden onset of severe, unremitting chest pain associated with hyper- or hypotension or a history of hypertension are suggestive of acute aortic dissection. The diagnosis should be followed by prompt investigation and treatment. The 30-day survival rate for patients with type A dissection who underwent surgical treatment was 62%; survival rates for patients with type B dissection, acute and chronic, were 70% and 86% respectively with pharmacotherapy and 66% and 91% with surgery. The authors stress the importance of early, accurate diagnosis and immediate surgical treatment for all patients who have type A dissection and complicated or unresponsive (carefully monitored pharmacologic control of blood pressure) type B dissection.