Biomedical subjects
Publications and source records attributed to M Yacoub.
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The effects of coronary artery bypass graft operation were studied in 32 patients with daytime ambulatory ST segment changes and 14 patients with daytime and nocturnal angina and ST segment changes. Patients had ambulatory ST segment monitoring and exercise testing before and after operation and coronary arteriography was repeated in 34 patients after operation. Before operation, patients with daytime and nocturnal ischaemia tended to have more severe coronary artery disease, lower exercise tolerance, and more frequent ambulatory ST segment changes than those who had daytime ST segment changes only. After operation chest pain recurred in 22% of patients and ST segment depression during exercise testing or ambulatory ST segment monitoring recurred in 37% of the patients and was significantly more frequent in those with nocturnal ischaemia than in those with daytime ischaemia. Graft patency rates were similar in patients with and those without recurrence of ischaemia. After operation the frequency and magnitude of ST segment changes and exercise duration were improved in patients with preoperative daytime angina and also in those with daytime and nocturnal angina. The improvement was more pronounced in the latter groups. Thus, absence of postoperative angina is not a reliable indicator of the absence of reversible myocardial ischaemia. After revascularisation, patients with rest and nocturnal angina can expect relief from ischaemia, and if this recurs postoperatively, the threshold is improved and pain usually occurs only on exertion.
We evaluated the tolerance of heart transplant recipients to acute betablockade during maximal dynamic exercise. Although the increase in rate and systolic blood pressure were attenuated, exercise tolerance was reduced by only about 15%, which is similar to that previously reported in normal individuals. Betablockade attenuated the increases in heart rate of the denervated donor hearts to a greater extent compared to the increases in the innervated recipient hearts in patients with heterotopic heart transplantation. Therefore, betablockers may be safely used in heart transplantation for appropriate indications such as hypertension.
The major theoretical advantage of anatomic correction of transposition of the great arteries compared with intraatrial repair is that the left ventricle becomes the systemic pump. In 10 patients we analysed 5-12 months after anatomic correction the left ventricular echocardiographic pressure-dimension loop, meridional wall stress and left ventricular stiffness from the simultaneous recordings of the left ventricular pressure and M-mode echocardiogram. The low left ventricular diameters, left ventricular hypertrophy in 4 patients, and increased peak meridional wall stress in 3 patients indicate that left ventricular adaption to systemic impedance is still incomplete 5-12 months after anatomic correction. The cycle efficiency was reduced in 2 patients, indicating incoordinate left ventricular contraction and relaxation. In one of these patients the left ventricular stiffness was severely increased, while in another patient there was a slight increase in left ventricular stiffness. In all patients the right ventricular internal diameter was increased due to the long-standing preoperative pressure and volume overload.
Thirty-two patients with mitral regurgitation secondary to ruptured chordae tendineae were studied by cross-sectional echocardiography. Twenty of them subsequently underwent operation. Three signs are described. (1) Non-coaptation of the leaflets (55%). (2) Systolic fluttering echo in the left atrium originating from the mitral valve (20%). (3) A previously not described small diastolic chaotically moving echo in the short axis section of the left ventricle at the level of the papillary muscles (65%). The combined sensitivity of these three signs was 85%. The specificity of the three signs when compared with those of 107 patients with mitral regurgitation of different aetiologies studied by cross-sectional echocardiography was 99%, 100% and 99%, respectively. Six patients were studied after mitral valve repair; restriction of the surgical treated leaflet and reduction of its valve area was seen in all of them, and the disappearance of the valvar signs of ruptured chordae noted. The persistence of the small echo sign in the short axis of the left ventricle indicated its chordal origin.
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The employment status of 100 consecutive male patients between the ages of 30 and 60 years (mean, 49.5 years) operated on for angina and followed for a minimum of 5 years was analysed. There were no early and 4 late deaths. The probability of employment at 1 year was 90%, which was similar to that of a sample from the general population matched for age. This rate, however, showed steady, slow deterioration to 87.6% at 2 years, 82.1% at 3 years, 75.7% at 4 years, and 73.4+ at 5 years. Seventeen patients retired over the 5-year period. There was no correlation between the rate of employment and age (under or over 50) at operation, previous myocardial infarction, or number of grafts inserted.
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Anomalous origin of the right coronary artery (RCA) from the pulmonary artery (PA) is very rare, and may be an isolated defect, or associated with other congenital cardiac or non-cardiac defects. The anomalous right coronary artery may appear grossly normal if it arises near an aorto-pulmonary window, and will be perfused by oxygenated blood. However, it may be vein-like and perfused in a retrograde fashion from the left coronary artery (LCA). This was once thought to be a benign lesion, and an incidental finding during cardiac catheterization or surgical repair of the associated congenital cardiac anomaly, but, sudden cardiac deaths have been reported. Associated congenital cardiac defects reported include tetralogy of Fallot (2 cases), aorto-pulmonary window (3 cases), and atrial septal defect (1 case). Another case associated with tetralogy of Fallot is described. Surgical correction of these associated lesions should include anatomical correction of the anomalous right coronary artery.
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.
Between October 1969 and June 1978; 878 patients underwent coronary bypass grafting at Harefield Hospital. Five hundred and fifty-four patients (63%) were restudied postoperatively by coronary angiography in order to evaluate graft patency in relation to time, runoff, influence of endoarterectomies, clinical condition, age, sex, risk factors and the progression of the disease in native vessels. Patency rate was 85% in 197 patients restudied between 1 and 6 years postoperative (mean 26 months). Patency rate of 63 endoarterectomized vessel restudied between 1 and 6 years postoperatively was 84%. Restudy of 343 patent grafts shows a good runoff in 299 (87%). The effects of runoff on long term patency were evaluated in a group of 81 patients restudied twice with mean interval of 18.3 months between the first and second investigation. Eighty-six percent of 147 grafts showed a good runoff at the second study. Age, sex and risk factors do not appear to influence long term patency rate. Two hundred and sixty out of 354 patients followed up postoperatively from 6 to 86 months (mean 28.2 months) were asymptomatic and the graft patency rate was 87%. Seventy-four of these patients had all their grafts patent. Sixteen symptomatic patients had a patency rate of 55%, thirty-seven percent of them had all the grafts patent. Progression of the disease in native vessels was observed in 23 out of 132 non grafted vessels (17%) and distal to the graft in 7 out of 252 bypassed vessels (3%).
Between October 1969 and October 1979 120 patients (78 males and 42 females, mean age 48 years) underwent surgical correction of floppy mitral valve at Harefield Hospital. Family history of mitral valve disease was present in 3 patients and 6 had skeletal manifestations of Marfan syndrome. The presenting symptom was shortness of breath in 110 (92%), chest pain in 18 (15%), and palpitations in 29 (24%). Thirty-two patients had more than one symptom. A history of bacterial endocarditis was obtained from 18 patients. At the time of operation 88% of the patients were in class III-IV NYHA. Forty-five patients had mitral valve replacement and the remaining 75 had a conservative procedure. Findings at operation were: rupture of posterior chordae in 72 (60%); rupture of anterior chordae in 15 (13%); rupture of anterior and posterior chordae in 6 and elongation of chordae without rupture in 27 (22%). Hospital mortality for isolated replacement was 6.5%. Twenty-seven patients (22%) died subsequently (mean follow-up of 75 months). Hospital mortality for repair was 3.2% and late mortality mean follow-up 34 months) was 6.5%. Sixty-seven patients are asymptomatic and 21 are improved. A conservative approach to floppy mitral valve disease has been adopted in all patients since 1974 and has given better early and late results compared to valve replacement.
Four male patients with pulmonary arterio-venous fistulae are reported. Familiar occurrence was noticed in 2 brothers. Physiological effects, clinical pictures and treatment of these lesions depend on the size and number of the fistulae. A 4-day-old baby presented with severe cyanosis and cardiomegaly. Cardiac catheterization and angiography demonstrated a large arterio-venous fistula affecting the whole of the right upper lobe and a small ventricular septal defect resulting in a high output cardiac failure. The patient underwent emergency lobectomy with good early and long-term results. The other 3 patients (mean age of 7.6 years) developed progressive cyanosis and polycythemia. Cardiac catheterization showed normal intracardiac pressures and peripheral arterial desaturation. Pulmonary angiogram demonstrated multiple fistulae in both lungs. Surgery was not performed because of the diffuse nature of the lesions. The patients reported in this paper illustrate the wide spectrum of clinico-pathological conditions of this anomaly.
Between May 1976 and January 1981 a two-stage anatomic correction was performed in 25 patients with simple transposition of the great arteries, ranging in age from 41/2 to 46 1/2 months (mean 14.8). A first-stage operation, consisting of banding of the pulmonary artery to redevelop the left ventricle, including a Blalock-Taussig-anastomosis in 4 patients was performed prior to anatomic correction. Of 33 patients, who underwent first-stage correction there were 3 early deaths (9%). The interval between the first and second stages was 5 weeks to 9 months (mean 4.3 months). After the first-stage operation, the peak systolic left ventricular pressure rose from 34 +/- 11 mmHg to 80 +/- 16 mmHg with no significant change in enddiastolic pressure. After anatomic correction there were 5 early deaths (20%) of whom 4 were due to left heart failure. There was no correlation between death and the age of the patients at the time of anatomic correction. By our current criteria the ventricles were not adequately prepared for correction in these four patients. The coronary arteries, with different types of origin, could be reimplanted to the posterior vessels without kinking, tension or torsion in all cases. After correction, the ECG and vectorcardiogram rapidly changed toward normal. The arterial oxygen saturation was higher than 95% in all patients. Recatheterization performed in 11 patients, 3 weeks to 27 months after correction, showed normal left ventricular pressure at rest in all children, except in 2 recatheterized early after correction, who had moderately elevated left ventricular enddiastolic pressure. Right ventricular peak systolic pressure decreased to normal limits. The aortic and coronary anastomoses showed normal growth in cineangiography. Although the two-stage corrections of simple TGA may have its own problems, investigation suggests that results are encouraging.
Between October 1969 and April 1980, 132 patients underwent operation for floppy mitral valve. The 46 patients in group A underwent valve replacement using an inverted, fresh, unstented, antibiotic-sterilized aortic homograft and the 86 patients in group B underwent valve repair. The onset of symptoms was sudden. More than 80% of the patients in both groups were in New York Association functional class III or IV. The dominant lesion in both groups was ruptured chordae to the posterior cusp (72% in group A and 58% in group B). There were five early deaths (11%) and 15 late deaths (32%) in group A and four early deaths (5%) and five late deaths (7%) in group B. The actuarial survival rate at 5 years was 62% in group A and 90% in group B. In group A, five patients (11%) had valve failure, which led to late death in two. Four patients (8%) in group A required reoperation. Two patients in group B developed a loud mitral systolic murmur soon after operation and required reoperation. Two patients in group B had thromboembolism before routine anticoagulation. Sixteen patients (61%) in group A and 56 (76%) in group B were functional class I after operation.
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A rare case of anomalous origin of the right coronary artery from the pulmonary artery associated with a large aortopulmonary window in a 4-month-old boy is reported. The right coronary artery is exposed to systemic pressure and carries fairly well-oxygenated blood to the myocardium. Angiographic diagnosis could be difficult because of the simultaneous filling of both great arteries which obscures the origin of the anomalous vessel. Closure of the aortopulmonary window alone could result in acute myocardial ischaemia. A plastic procedure for correction of this association of defects, which should allow normal growth, is described.