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Biomedical subjects

B S Jenkins

Publications and source records attributed to B S Jenkins.

At least 37 records · Page 2Linked to original sources
PubMed1980

Assessment of prognostic factors in patients undergoing surgery for non-rheumatic mitral regurgitation.

Twenty-four patients who had undegone mitral valve surgery for pure non-rheumatic mitral regurgitation were studied non-invasively six months to six years postoperatively. The long-term results of operation were assessed on the basis of clinical history, echocardiography, and treadmill stress testing using a points scoring system. The score so obtained was used to divide the patients into those with a good response to surgery (group 1) and those responding poorly (group 2). The effects on the long-term surgical outcome of several intraoperative and preoperative factors were then analysed both together and separately. A short symptomatic history (less than 1 year), a normal left ventricular end-diastolic volume index (less than or equal to 100 ml per m2), and a large post-ectopic potentiation of KV max (greater than 50 s-1) were found to be favourable prognostic factors when analysed independently. An angiographic ejection fraction less than 0.5 was uniformly associated with a poor outcome, and 71 per cent of patients in atrial fibrillation at the time of operation also responded badly. In those patients with good long-term function, cold potassium cardioplegia was more commonly used than intermittent aortic cross clamping as the means of intraoperative myocardial preservation, though this difference did not reach conventional significance. A standard analysis of variance allowed assessment of length of history, left ventricular end-diastolic volume index, and type of valve prosthesis simultaneously. This indicated that both length of history and left ventricular end-diastolic volume index were highly significant prognostic factors. The use of a Björk-Shiley as opposed to a Starr-Edwards prosthesis also emerged as significantly favouring a good long-term result. The state of the left ventricular myocardium before operation and the type of valve prosthesis used were thus shown to be the prime determinants of surgical outcome in these patients. The optimum time for operation was shown to be within one year of the onset of symptoms, and before the left left ventricular end-diastolic volume index exceeds 100 ml per m2, or the ejection fraction falls to less than 0.5. At such a time, irreversible changes in myocardial function sufficient to negate the beneficial effects of mitral valve surgery have not yet occurred.

Angiocardiography↗
PubMed1980

Effects of propranolol on myocardial oxygen consumption, substrate extraction, and haemodynamics in hypertrophic obstructive cardiomyopathy.

Myocardial substrate extraction, coronary sinus flow, cardiac output, and left ventricular pressure were measured at increasing pacing rates before and after propranolol (0.2 mg/kg) in 13 patients with hypertrophic obstructive cardiomyopathy (HOCM) during diagnostic cardiac catheterisation. At the lowest pacing rate myocardial oxygen consumption varied considerably between patients and very high values were found in several individuals (range 10.1 to 57.5 ml/min). These large differences between patients were not explicable by differences in cardiac work; consequently, cardiac efficiency, estimated from the oxygen cost of external work, varied between patients and was lower than normal in all but two. The pattern of substrate extraction at the lowest pacing rate was similar to results reported for the normal heart, and measured oxygen consumption could be accounted for by complete oxidation of the substrates extracted; thus there was no evidence of a gross abnormality of oxidative metabolism, suggesting that low efficiency lay in the utilisation rather than in the production of energy. Each of the four patients with the highest myocardial oxygen consumption and lowest values of efficiency sustained progressive reductions in lactate and pyruvate extraction as heart rate increased, and at the highest pacing rate had low (< 3%) or negative lactate extraction ratios. In three of these four, coronary sinus flow did not increase progressively with each increment in heart rate. One patient with low oxygen consumption and normal efficiency also failed to increase coronary flow with the final increment in heart rate, and produced lactate at the highest pacing rate. Thus the five patients in whom pacing provoked biochemical evidence of ischaemia all had excessive myocardial oxygen demand and/or limited capacity to increase coronary flow. Propranolol did not change lactate extraction significantly at any pacing rate in either the ischaemic or non-ischaemic groups. In only one patient was ischaemia at the highest pacing rate abolished after propranolol, and this was associated with a 30 per cent reduction in oxygen consumption. These results do not demonstrate a direct effect of propranolol upon myocardial metabolism in patients with HOCM, but emphasise the potential value of beta-blockade in protecting these patients from excessive increases in heart rate.

Adolescent↗
PubMed1980

Correlations of fibrosis in endomyocardial biopsies from patients with aortic valve disease.

The amount of fibrosis in endomyocardial biopsies from 55 patients with aortic stenosis and 42 patients with aortic regurgitaion was measured. Sixty per cent of the patients with aortic stenosis had some degree of fibrosis; the degree of fibrosis correlated strongly with ejection fraction, peak systolic gradient, symptoms of cardiac failure, and mortality. In patients with aortic regurgitation, fibrosis was found in 40 per cent and was never severe. A correlation was found with symptoms of cardiac failure and mortality at follow-up, but not with ejection fraction or degree of regurgitation.

Adult↗
PubMed1979

Biopsy evidence of left ventricular myocardial abnormality in patients with mitral-leaflet prolapse and chest pain.

Left ventricular endomyocardial biopsy specimens were obtained at cardiac catheterisation in 11 patients with mitral-leaflet prolapse, chest pain, and normal coronary arteries. Specimens were examined for birefringence before and after contraction induced by adenosine triphosphate and were also subjected to histochemical analysis. Biopsy specimens from a control group of patients with rigorously defined normal left ventricular function and another control group with poor left ventricular function were also studied. Biopsy specimens from patients with mitral-leaflet prolapse showed a markedly subnormal birefringence response to adenosine triphosphate, with the group mean value intermediate between values for controls with normal and poor left ventricular function. Histochemical studies in the prolapse group also revealed an abnormal pattern, particularly for monoamine-oxidase activity. This is further evidence of a cardiomyopathy in this symptomatic subgroup of patients with mitral-leaflet prolapse.

Adenosine↗
PubMed1979

A computerised dichromatic earpiece densitometer for the measurement of cardiac output.

This study assesses a precalibrated dichromatic earpiece densitometer and microprocessor for the measurement of cardiac output by indocyanine green dye dilution. The measured cardiac output is compared with values of cardiac output simultaneously determined using a cuvette densitometer. The microprocessor computation of cardiac output agreed very closely with the cardiac output determined by manual calculation from the same dye dilution curves (standard deviation +/- 1.47%). The reproducibility of the earpiece densitometer (standard deviation +/- 5.2%) was virtually identical to that of the cuvette densitometer (+/- 5.3%). In a comparison of earpiece and cuvette densitometers for 60 measurements of cardiac output following pulmonary arterial injection of dye and for 50 measurements following femoral venous injection of dye, correlation coefficients were 0.83 and 0.78 and the standard deviations of the differences of simultaneous measurements were 7.2% and 8.3% respectively. The instrument offers an accurate reproducible and relatively noninvasive technique for measuring cardiac output.

Cardiac Output↗
PubMed1979

Echocardiographic and exercise evaluation of results of mitral valvotomy operations.

M-mode echocardiography was performed in 54 patients 1 month to 3 years after mitral valvotomy for dominant mitral stenosis. The mitral valve closure index (MVCI), an index previously shown to correlate well with the calculated mitral valve area, was used to diagnose residual mitral stenosis. Using the equation MVCI = 33 MVC--12, 12 patients (22%) were deemed to have mild, 4 (7%) moderate, and 2 (4%) severe residual stenosis. Repeat cardiac catheterisation confirmed the diagnosis in 7 patients. The postoperative mitral valve closure index correlated significantly with patients' subjective symptoms and objective exercise indices. It was higher in patients in whom the posterior mitral leaflet movement became normal after valvotomy, and was lower in patients in whom the anterior mitral leaflet excursions below 14 mm before operation. The mitral valve closure index is a sensitive index for diagnosing residual mitral stenosis after valvotomy.

Adolescent↗
PubMed1979

Sarcoma obstructing right ventricular cavity: clinical, echocardiographic, haemodynamic and angiographic features.

Right atrial hypertension and pericardial effusion developed 2 years after mastectomy for fibrosarcoma. Clinical and echocardiographic features suggested right ventricular tumour. At catheterization the right ventricular cavity was almost obliterated, with an infundibular gradient of 13 mmHg, and biopsy of the mass was attempted. Post-mortem revealed extensive infiltrating and intracavitary right ventricular fibrosarcoma without extracardiac tumour.

Echocardiography↗
PubMed1978

Echocardiographic analysis of posterior mitral leaflet movement in mitral stenosis.

Echocardiographic analysis of the movement of the posterior mitral valve leaflet in 60 patients with lone mitral stenosis, 35 patients with aortic stenosis, and 18 patients with aortic and mitral stenosis showed a spectrum of initial posterior mitral valve leaflet movement in early diastole. The classical anterior movement was seen in 36 out of 60 patients with mitral stenosis (60%), and 8 out of 16 patients with aortic and mitral stenosis (50%). Normal posterior movement was present in all patients with lone aortic stenosis but was also seen in 10 patients (17%) with mitral stenosis and 6 patients (33%) with aortic and mitral stenosis. The remaining patients with mitral stenosis or aortic stenosis and mitral stenosis showed a biphasic type of initial movement. Patients with anterior movement had a mean calculated mitral valve area from cardiac catheterisation significantly smaller than the rest (P less than 0.001), but neither biphasic nor posterior movement excluded severe mitral stenosis. The distinction between patients with mitral stenosis and initial movement of the posterior mitral valve leaflet and patients with left ventricular discompliance is possible when there is sinus rhythm. Late diastolic anterior movement of the posterior mitral valve leaflet during atrial contraction is diagnostic of true mitral stenosis.

Aortic Valve Stenosis↗
PubMed1978

Coronary artery ectasia--a variant of occlusive coronary arteriosclerosis.

In a study of 1000 consecutive coronary arteriograms, 12 patients (all men) had coronary artery ectasia. Ectasia was found most frequently in the circumflex or right coronary artery. Only 1 patient had ectasia in the left anterior descending coronary artery. In 11 patients, ectasia of one artery was associated with severe stenosis or occlusion of other vessels, typical of arteriosclerosis. Histology from an ectatic segment in one of this group showed changes of severe arteriosclerosis with extensive intimal fibrosis and destruction of the media. One patient had a mixed collagen vascular disease. Measurement of coronary sinus flow in 2 patients with coronary artery ectasia showed flows in the range of patients with non-ectatic coronary artery disease. At cardiac surgery flows down the graft to ectatic arteries were in the same range as in grafts to non-ectatic vessels. Patients with coronary artery ectasia should be anticoagulated.

Adult↗
PubMed1978

Coronary artery surgery: indications and recent experience.

The comprehensive experience of coronary artery surgery in a Cardiothoracic Unit over a 31-month period is reviewed. Hospital mortality for elective bypass grafting was 3.9% overall and 2.5% in those with good pre-operative left ventricular function. Major influences on hospital mortality were pre-operative left ventricular function, extent of coronary artery disease and extent of the surgical procedure undertaken in terms of number of aortocoronary grafts inserted, coronary endarterectomy and particularly concomitant valve surgery or aneurysm resection. Follow-up experience shows 74% of grafted patients to be symptom-free and 85% symptomatically improved one year after surgery with 70% symptom-free and 80% improved at two years. Early post-operative deaths appear related to early graft closure and recurrence of symptoms postoperatively to late graft closure or progression of coronary disease in the native circulation. The study provides a guide to the relative risks of coronary artery surgery for symptomatic coronary artery disease and expected symptomatic results in the early follow-up period.

Adult↗
PubMed1978

Pulmonary vein blood flow velocity in pulsus paradoxus.

The effect of inspiration on pulmonary vein blood flow velocity and forward pressure gradient from pulmonary vein to left atrium was studied in seven patients with chronic constrictive pericarditis, five of whom had clinically obvious pulsus paradoxus. Compared to patients without pericardial disease, where inspiration produced no change, patients with pericardial disease showed an inspiratory fall in the forward pressure gradient and forward blood flow velocity in the pulmonary veins on inspiration. The mechanism of pulsus paradoxus in these patients can be explained by incomplete transmission of the inspiratory fall of intrathoracic pressure to the left atrium.

Adult↗
PubMed1977

Systolic and diastolic ventricular function in cardiac amyloidosis. Studies in six cases diagnosed with endomyocardial biopsy.

Five cases of cardiac amyloidosis diagnosed after endomyocardial biopsy are described. Systolic function was normal in three cases as assessed by cardiac index, ejection fraction and maximal velocity of contractile element shortening at zero developed pressure. The diastolic dip and plateau wave form was a characteristic but not an invariable finding. Increased ventricular end-diastolic pressure but normal end-diastolic volume indexes in all cases implied a disorder of diastolic compliance. The diastolic pressure-volume plots suggested a sudden decrease in distensibility after normal early filling of the ventricle. The functional defect did not necessarily differ from that of other diseases of heart muscle. Therefore, hemodynamic data should not be relied upon for diagnostic purposes. Electron microscopy was the most reliable aid in making the diagnosis from the endomyocardial biopsy specimens especially in the presence of fibrosis. It may not be valid to assume a diagnosis of cardiac amyloidosis from the finding of amyloid in other organs.

Adult↗
PubMed1977

Left ventricular endomycardial biopsy. I: description and evaluation of the technique.

The results of left ventricular endomyocardial biopsy by means of a long sheath technique in 154 patients are reported. The risks of left ventricular biopsy are those of left heart catheterisation. In 30 of these patients the results of left and right ventricular biopsy were compared, and in further 10 patients the right ventricle only was biopsied. Biopsy from the left ventricle carries less risk of cardiac perforation, gives a higher incidence of successful biopsy, and with the exception of hypertrophic obstructive cardiomyopathy yields more diagnostic information.

Biopsy↗
PubMed1977

Left ventricular endomyocardial biopsy. II: the value of light microscopy.

Histological sections of left ventricular endomyocardial biopsies have been examined by light microscopy. The biopsies were taken from patients with congestive, hypertrophic, or restrictive cardiomyopathy and from patients with either aortic stenosis or regurgitation. In congestive cardiomyopathy no specific features were found and similar abnormalities were seen in aortic valve disease. In only one of six cases of asymmetric septal hypertrophy were the characteristic histological appearances noted. In four out of five patients with a restrictive type of cardiomyopathy, amyloid was demonstrated. The muscle fibres in aortic stenosis had a greater cross-sectional area than those in aortic regurgitation. A greater degree of fibrosis was present in aortic stenosis than in aortic regurgitation. In aortic stenosis the amount of fibrous tissue was inversely related to function.

Aortic Stenosis, Subvalvular↗
PubMed1977

Enzymic analysis of endomyocardial biopsy specimens from patients with cardiomyopathies.

Myocardial biopsies have been obtained from patients with hypertrophic or congestive cardiomyopathies. Marker enzymes for the principal subcellular organelles of the myocardium were estimated using highly sensitive assay procedures. The results were compared with those obtained in tissue from patients with valvular heart disease with good or poor left ventricular function. Left ventricular myocardial tissue from patients with hypertrophic cardiomyopathy showed essentially normal levels of enzymic activities. In congestive cardiomyopathy, right ventricular tissue showed reduced levels of mitochondrial enzymes with increased levels of lactate dehydrogenase. Left ventricular tissue from patients with congestive cardiomyopathy showed reduced levels of mitochondrial and myofibril enzymes but high levels of lactate dehydrogenase. The reduced levels of myofibril Ca++-activated ATP in congestive cardiomyopathy is similar to that found in patients with impaired left ventricular function secondary to valvular disease. It is suggested that defective mitochondrial function is a characteristic feature of congestive cardiomyopathy and that the increased levels of lactate dehydrogenase reflect a compensatory response.

Cardiomyopathies↗