Biomedical subjects
Publications and source records attributed to D N Ross.
A case in which the right distal internal mammary artery (IMA) was used to graft the posterior descending branch of the right coronary artery is presented. The retrograde blood flow at dissection was 60 ml per minute, no electrocardiographic signs of myocardial ischemia were detected postoperatively. The patient is well and fully active 6 months after surgery.
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Ninety-seven patients with pulmonary atresia underwent right ventricular outflow tract reconstruction using a homograft conduit. There were 46 hospital deaths (47%). Hospital mortality was significantly related to irreversible pulmonary hypertension (p less than 0.001) and thoracotomy for ligation of bronchial collaterals (p less than 0.01). The actuarial survival was 37 +/- 7% at 10 years. Sixteen patients undergoing recatheterization at a mean of 6 years had a mean transconduit gradient of 24 +/- 15 mm Hg. Obstructed conduits (i.e., with a gradient of greater than 50 mm Hg) were replaced in 3 patients, corresponding to 13 +/- 8% at 10 years. In each instance, the obstruction was due to neointimal hyperplasia in the Dacron tube rather than calcification of the homograft valve. The fresh, antibiotic-sterilized aortic homograft is the conduit of choice for right ventricular outflow tract reconstruction. The valve itself appears more resistant to calcification than its xenograft counterpart, and the absence of Dacron removes the problem of fibrinous peel obstructing the conduit. We now construct a tube of autologous pericardium to increase the length of the conduit and avoid complementary thoracotomy for ligation of bronchial collaterals.
Two hundred two autologous pulmonary valves were transplanted into the aortic position between 1967 and 1982 at the National Heart Hospital in London. The indication for operation was congenital or acquired aortic valve disease, and the patients were followed for periods from 1 to 4 years. The patients were not anti-coagulated, but the entire series has been completely free from thromboembolism or bleeding. The actuarial prediction of freedom from valve-related deaths was 82 +/- 6% at the end of the fourteenth year after operation; deaths were due to reoperations for technical failure and to infective endocarditis. Event-free survival of the autologous pulmonary valve in the aortic position was 73 +/- 6% after 14 years at risk. Valve failure resulted mainly from technical problems encountered during the early years of surgical experience. There was no macroscopic or histological evidence of calcification in any of the failed valves. The right ventricular outflow was reconstructed with an aortic homograft in the majority of patients; 81 +/- 5% of these homografts demonstrated event-free performance over a 12-year follow-up period. It is concluded that the long-term performance of a pulmonary autograft inserted for aortic valve disease is superior to that of any other valve substitute and that the operation offers an almost ideal means of aortic valve replacement in appropriate patients.
A patient with rheumatic mitral stenosis and previous cerebral embolism had a myocardial infarction during cardiac catheterisation. She later developed severe mitral regurgitation one year after open valvotomy and at valve replacement was found to have a papillary tumour of the mitral valve. Unexplained low cardiac output occurred four days after operation. Postmortem examination showed thrombotic occlusion of the xenograft prosthesis, a complication not previously seen with tissue valves. Both of these rare events were suggested by the patient's clinical course and could have been diagnosed with cross sectional echocardiography.
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This article reports the successful surgical treatment of six patients who presented with prosthetic endocarditis and uncontrolled bacteremia. They were treated by replacement of the aortic root with a preserved homograft aortic valve. With this technique, ventricular-aortic continuity was established with a centrally flowing valve together with its attached aorta. The weakened aortic and the associated root abscess were thereby excluded from the high-anulus pressure systemic circulation. There were no operative deaths, and the longest postoperative survival time is 10 years. Two patients have conduction disturbance and symptoms relating to their malfunctioning aortic valves. The remaining four patients are all well at 5 years, 2 years, 9 months, and 6 months with no further evidence of infection. Homograft aortic root replacement is a suitable treatment for this potentially lethal condition.
The origin and early branching of the coronary arteries is fairly constant. Anomalous origin of the coronary arteries, which produced significant abnormalities of myocardial perfusion, were documented in 13 adult patients undergoing investigation because of chest pain. All underwent surgical treatment with relief of the presenting symptoms. They can be divided into four groups: (1) Origin of the left anterior descending branch of the left coronary artery (LCA) from the pulmonary artery (PA) (three cases); (2) origin of the LCA from the anterior sinus. Acute angulation of the ostium and compression of the intramural segment of this coronary produced severe myocardial ischaemia in three patients. (3) Origin of the LCA from the right coronary artery with its proximal segment closely related to the noncoronary sinus (one patient) in whom relief of symptoms was obtained by surgery. (4) Origin of the LCA from the PA with reversal of coronary flow and left to right shunting (six patients). It is concluded that anomalies of the origin of the coronary arteries are rare, but can produce specific clinicopathological entities that can be diagnosed with confidence and corrected surgically. Moreover, the study emphasises the need for angiographic awareness of these coronary anomalies, even in adult patients in whom atherosclerotic disease would be the most likely finding at cardiac catheterisation.
The first case of non-operative occlusion of a large coronary to bronchial anastomosis is described. The patient who had severe angina had also a critical stenosis of the anterior descending coronary artery which was successfully dilated by an angioplasty procedure. An occluding balloon was detached in the large distal circumflex coronary artery, beyond all the normal branches. At a repeat catheterisation study seven months later the balloon was intact and in position, and the anastomosis remained occluded.
Three hundred thirteen patients underwent aortic valve replacement with 319 Starr-Edwards caged-ball prostheses and have been followed for 1 to 14 years. Hospital mortality (24.8%) and first-year mortality (4.8%) suggest that this is a high-risk group. Overall postoperative patients survival was 37.1%, with 18.8% free from any event, at 14 years. Thromboembolism was the most significant single event (a probability of 18.7% at 14 years), and the Series 2300/2320 valves were associated with a probability of hemolysis of nearly 80% over 13 years. Patients who underwent valve replacement before 1973 had a significantly greater probability of late death (31.1%) and of complications (47.1%) during the first 5 years. Those patients undergoing replacement after 1973 had a significantly greater probability of thromboembolic episodes (15.4%). Starr-Edwards cage-ball prosthesis provide an acceptable valve replacement for high-risk patients. However, the overall complication rate of 81.2% over 14 years, compared with 78% for homograft valves for the same period, does not support the adoption of this prosthesis as the valve of first choice at this hospital.
In 78 (0.9%) of 8,283 patients without associated congenital heart disease studied by angiography, one or more major elements of the coronary arterial system originated in an ectopic manner. Symptoms attributable to the aberrant vessel more present in 20 of the 78 patients and in 15 patients these anomalies were treated surgically. The hemodynamically significant anomalies which lead to abnormalities of myocardial perfusion are of particular surgical importance. There are 4 major types: 1) aberrant origin of the left anterior descending branch from the pulmonary artery; 2) origin of the left coronary artery from the right aortic sinus; 3) origin of the left coronary artery from the pulmonary artery and 4) severe atherosclerotic occlusive disease in an aberrant vessel. The incidence, angiographic features and surgical aspects of these anomalies are discussed.
The timing of surgery in chronic aortic regurgitation remains a difficult problem. To identify variables predictive of postoperative haemodynamic improvement, changes in left ventricular mass, volume, morphology, and histochemistry were analysed in 67 patients undergoing surgery for chronic aortic regurgitation. Patients were divided into two groups: those in whom the left ventricular echo diameters returned to normal after operation (51 patients, group A), and those with postoperative dilatation (16 patients, group B). A preoperative biopsy was obtained in all patients; postoperative tissue samples were available in 13 patients (five from group A, eight from group B). Data were correlated with the postoperative clinical, haemodynamic state over a follow-up period of three years. Regression of hypertrophy was usually incomplete. Echocardiographic and angiographic data could not define the type and degree of dysfunction which was irreversible. Massive fibre hypertrophy (mean 34.1 micrometers), moderately or severely increased interstitial fibrous tissue, reduced levels of the myofibrillar and mitochondrial enzymes adenosine triphosphates and succinate dehydrogenase in pre- and post-operative tissue samples correlated with persistent dilation, cardiac failure, and early death (group B). Irreversible morphological and functional changes contributed to a depressed cardiac function after operation. Preoperative ventricular biopsies are thus of prognostic importance in volume overload.
Porcine aortic valves stored in various concentrations of sucrose (50-80%) for up to 52 weeks were examined both histologically and by electron microscopy. The valves were compared with porcine aortic valves stored in a nutrient and antibiotic medium for 12 weeks. Overall preservation was better in those porcine valves stored in sucrose solution than in nutrient and antibiotic medium, the best preservation being in 50% sucrose. Despite wide separation of collagen at that concentration seen on electron microscopy (not noted histologically), tissue preservation was good after storage in sucrose solutions at concentrations up to 80%, at which clumping of collagen and distortion of fibroblasts occurred. It is suggested that sucrose solution is acceptable for the long-term preservation of biological valves.
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Composite graft replacement of the ascending aorta and aortic valve was performed in 78 patients over an 8 1/2-year period. Degenerative lesions of the aortic root in Marfan's syndrome (annuloaortic ectasia) was the indication for operation in 56 cases; the other 22 patients had other causes of aortic root dilatation and aortic valve disease. Overall hospital mortality was 8%. Follow-up ranged from 1-9 years (average 5 years). Reoperation was required in six of the 72 hospital survivors. Overall 5-year actuarial survival was 77%, and 85% of the survivors have shown significant clinical and radiologic improvement. Composite graft replacement reduces the risk of aneurysm formation of the sinuses of Valsalva and eliminates paraprosthetic leakage; postoperative hemorrhage is also reduced. It appears to be the method of choice for patients with degenerative lesions in the ascending aorta and valve, particularly annuloaortic ectasia.
Measurements on plastic flexible frames for heart valves have shown that the design influences the creep potential of any one plastic material. This has been shown for both in vitro accelerated fatigue tests and after clinical implantation of more than 10 years. The flexibility of the plastic, a polypropylene, was not affected either by fatigue testing, shelf storage or clinical implantation. The possibility of 30 years freedom from creep for a flexible plastic frame for a tissue heart valve has been examined.
Composite graft replacement of the ascending aorta and aortic valve was performed in 71 patients over an 8-year period. Degenerative lesions of the aortic root in Marfan's syndrome (annuloaortic ectasia) was the indication for operation in 51 cases. Other causes of aortic root dilatation and aortic valve disease were present in the remaining 20 patients. Overall hospital mortality was 8%. Reoperation was required in 6 of the 65 hospital survivors. Follow-up has ranged from 1 to 9 years (average 41/2 years). Four year actuarial survival was 77%. Composite graft replacement eliminates paraprosthetic leakage and the risk of aneurysm formation of the sinuses of Valsalva; postoperative hemorrhage is also reduced. It appears to be the method of choice for the aortic root complications of the Marfan's syndrome.
The first 101 patients to undergo aortic, mitral or double valve replacement with a Carpentier-Edwards bioprosthesis at the National Heart Hospital are reviewed. A total of 112 valves were replaced (69 aortic, 43 mitral), with an operative mortality of 12.9%. The 88 operative survivors were followed for up to 52 months. There were 9 thromboembolic episodes (3.9% per patient year), most of which were not confined to the early postoperative months. They were most common after mitral valve replacement (6.3% per patient year), particularly in the presence of atrial fibrillation. A low incidence of prosthetic endocarditis was noted, principally involving the valve in the aortic position. Three valves were removed for calcific degeneration and small structural defects were noted incidentally in 3 valves removed for other reasons. The possible etiology and significance of these is discussed. Seven of the 10 reoperations and 5 of the 9 late deaths were considered to be xenograft-related. Over a 4-year follow-up period there was a 9% incidence of valve-related deaths, an overall survival of 87% and a complication-free survival of 73%.