Biomedical subjects
Publications and source records attributed to I A Brooksby.
The following is a case report of a farmer with documented aortic valve disease who developed bacterial endocarditis secondary to Streptococcus equinus. This is a rare pathogen in man and its acquisition in this case may be related to the subject's occupation.
Over 30 months 9292 consecutive patients admitted to nine coronary care units with suspected myocardial infarction were considered for admission to a randomised double blind study comparing the effect on mortality of nifedipine 10 mg four times a day with that of placebo. Among the 4801 patients excluded from the study the overall one month fatality rate was 18.2% and the one month fatality rate in those with definite myocardial infarction 26.8%. A total of 4491 patients fulfilled the entry criteria and were randomly allocated to nifedipine or placebo immediately after assessment in the coronary care unit. Roughly 64% of patients in both treatment groups sustained an acute myocardial infarction. The overall one month fatality rates were 6.3% in the placebo treated group and 6.7% in the nifedipine treated group. Most of the deaths occurred in patients with an in hospital diagnosis of myocardial infarction, and their one month fatality rates were 9.3% for the placebo group and 10.2% for the nifedipine group. These differences were not statistically significant. Subgroup analysis also did not suggest any particular group of patients with suspected acute myocardial infarction who might benefit from early nifedipine treatment in the dose studied.
Optical Mark Reader forms have been used by the Cardiac Department at St Thomas's Hospital for six years to store clinical and haemodynamic data by computer. Forms are completed by clinical staff in outpatients and also for those patients undergoing cardiac catheterisation. Three documents are used to record the symptoms and signs at the clinical consultation, the results of relevant investigations, and the important findings at cardiac catheterisation. These documents are fed into a computer and data from them, together with a limited quantity of types information, are used to produce full clinical reports for our colleagues and the case notes. There reports have saved much secretarial and medical time. A variety of analyses is available for research and management purposes.
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.
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.
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.
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.
Left ventricular endomyocardial biopsies have been obtained from patients with cardiomyopathy and hypertrophy due to aortic valve disease. These biopsies have been examined by electron microscopy and the ultrastructural abnormalities compared. In congestive cardiomyopathy no specific abnormalities were found although myofibrillary degeneration and membrane-bound vacuoles were more commonly present. Crossing of whole groups of sarcomeres was found only in asymmetric septal hypertrophy, but was not present in all cases. Amyloid deposits were demonstrated easily by electron microscopy in patients with restrictive cardiomyopathy. In the patients with hypertrophy due to aortic valve disease, no specific features were found and ultrastructural abnormalities did not differentiate between normal and impaired left ventricular functions.
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.
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Cardiac tissue obtained by left-ventricular endomyocardial biopsy from patients with valvular heart-disease was assayed for marker enzyme activities of subcellular organelles and these were correlated with left ventricular function as assessed by haemodynamic studies. In patients with poor left ventricular function, calcium-dependent adenosine-triphosphatase (A.T.P.ase) activity, predominantly localised to the myofibrils, was strikingly reduced. Activity of lactate dehydrongenase, a cytosol enzyme, was significantly increased in tissue from patients with poor left ventricular function. The activity of enzymes associated with sarcolemma (5'-nucleotidase), mitochondria (glutamate dehydrogenase and monoamine oxidase), microsomes (neutral alpha-glucosidase), and lysosomes (acid phosphatase, N-acetyl-beta-glucosaminidase) was no different in patients with good or poor left ventricular function. It is suggested that reduced myofibrillary A.T.P.ase concentration is the biochemical basis for the impaired ventricular function.
Pulsus alternans was studied hemodynamically in 5 patients with calcific aortic stenosis. Left ventricular function was assessed by angiographic volume analysis and by force-velocity analysis. All cases showed alternation of max and min dP/dt and kVmax. Inconsistent factors were an alternating left ventricular enddiastolic pressure, alternating left ventricular enddiastolic volume, alternating left ventricular endsystolic volume, ejection fraction, enddiastolic wall stress and wall stiffness. All cases had a high ventricular mass, but the critical value of ventricular mass or the ratio of mass to left ventricular enddiastolic volume were also inconsistent. Pulses alternans is primarily due to alternating contractility.
The usually recommended treatment for anomalous origin of a left coronary artery from the pulmonary artery is proximal ligation of the anomalous artery with a saphenous vein bypass graft to restore aortocoronary continuity. In an adult patient with large collateral vessels and with the left coronary artery arising from the back of the pulmonary artery, the technical surgical problems associated with this procedure are formidable. Closure of the orifice of the anomalous left coronary artery from inside the pulmonary artery is suggested as the treatment of choice in such a case.
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