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Biomedical subjects

D J Coltart

Publications and source records attributed to D J Coltart.

At least 109 records · Page 6Linked to original sources
PubMed1977

Influence of lipid concentrations and age on transfer of plasma lipoprotein into human arterial intima.

Transfer of low-density lipoprotein (L.D.L.2) from plasma to arterial intima was studied in 16 patients undergoing arterial surgery. Autologous labelled lipoprotein was used to demonstrate that L.D.L.2 enters the intima from plasma. Net flux of L.D.L.2 appeared to increase with age. Within each age-group the net flux of L.D.L.2 showed a pronounced positive correlation with plasma-L.D.L.-cholesterol concentrations. This may account in part for the association between hypercholesterolaemia and the development of atherosclerosis.

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. III: ultrastructural characteristics of cardiomyopathy and cardiac hypertrophy with good or poor ventricular 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.

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↗
PubMed1976

Enzymic analysis of cardiac biopsy material from patients with valvular heart-disease.

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.

Acid Phosphatase↗
PubMed1976

Haemodynamic effects of beta-blockade in patients with angina pectoris.

The pressure-volume relationship of the intact human ventricle during ischaemia and following the administration of a drug commonly used to treat ischaemic heart disease has been studied. Precise quantitation of the effects of the non-selective beta-adrenergic blocking drug propranolol (0-15 mg/kg body weight) on left ventricular function, segmental wall motion and diastolic pressure-volume relationship in man has been performed. High fidelity left ventricular pressure measurements and simultaneous single-plane angiograms were recorded and volumes calculated by a light-pen computer system. Patients were transvenously atrially paced for constancy of heart rate during drug infusion or paced to angina. In patients with coronary heart disease paced to angina, logarithmic pressure-volume relationship showed change in slope (P greater than 0-05) of the regression line and upward shift in intercept b (+0-25; P greater than 0-001). The diastolic effects of propranolol may include substantial increases in ventricular volumes in those patients with impaired cardiac function. With respect to the intact human ventricle, propranolol may increase diastolic volume for a given level of ventricular pressure. Thus, in a static sense, the ventricle in these patients could be viewed as being more compliant following propranolol administration. However, the fact that the length-tension relationship as measured by the slope of the logarithmic pressure versus volume plot is unaltered by propranolol, suggests that the muscle comprising the ventricle itself exhibits no alteration in its passive elastic properties.

Angina Pectoris↗
PubMed1975

Left atrial myxoma: diagnosis, treatment, and cytological observations.

A patient first seen with cardiac cachexia was found to have a large left atrial myxoma. The diagnosis was first suggested by echocardiographic examination. Cure was achieved by surgery. Light and electron microscopic studies indicate a multipotential mesenchymal cell origin of myxomata.

Cardiac Catheterization↗
PubMed1975

Measurement of stroke volume from pulmonary artery pressure record in man.

Stroke volume was determined from the pulmonary artery pressure record by application of the pulse contour method. Pulmonary artery pressure records were obtained in 17 patients using a high fidelity catheter-tip pressure transducer and simultaneous measurements of cardiac output were obtained from indicator dilution curves. The formula used was SV = KP sa (i plus T s/Td) where Psa is the planimetered area beneath the systolic portion of the pulmonary artery pressure curve. Ts and Td are the durations of systole and diastole, and K is a constant. Stroke volume was altered by isometric handgrip exercise and/or pharmacological agents in 15 patients. Serial measurementswere made in 2 patients in acute pulmonary oedema after myocardial infarction. Comparison of a wide range of values of stroke volume by the pulse contour method with those obtained from dye dilution curves showed a good correlation (r plus 0.97, P smaller than 0.001) regression line y = 1.01 times - 0.47. Measurement of stroke volume from the pulmonary artery pressure contour is a technique of potential value in serial haemodynamic monitoring.

Blood Pressure↗
PubMed1975

Investigation of the safe withdrawal period for propranolol in patients scheduled for open heart surgery.

The time necessary for dissipation of radioactive labelled propranolol and its metabolites and the cardiac effects of this agent in the hearts of patients undergoing open-heart surgery were studied. Isoprenaline produced chronotropic and inotropic responses in atrial muscle in tissue bath studies which were normal 8 to 12 hours after withdrawing propranolol. After the administration of either 25 or 75 muCi of 14C-labelled propranolol, the myocardial tissue concentration declined to insignificant levels between 24 and 28 hours. We conclude that withdrawal of propranolol therapy 24 to 48 hours before cardiac surgery should be acceptable.

Cardiac Surgical Procedures↗
PubMed1975

Left ventricular contraction and relaxation in patients with coronary heart disease.

The relationship of left ventricular relaxation and compliance to the mechanism of elevation of left ventricular enddiastolic pressure during ischemia was investigated. Isovolumic left ventricular contraction, relaxation, and diastolic pressure-volume relationship were studied in controls and in coronary heart disease patients. Patients were studied at similar heart rates during ergometric exercise and pacing. Diastolic aortic, left ventricular systolic, and incisural pressure were not significantly different in both groups at rest, pacing, and exercise. Left ventricular dP/dtmax increased during pacing and exercise in controls (P smaller than 0.05; P smaller than 0.01) and in coronary heart disease patients (P smaller than 0.01 for both); whereas left ventricular dP/dtmin increased only in controls during exercise (P smaller than 0.01). Peak measured velocity of shortening (Vpm) and of lengthening (Vpmr) of the contractile elements was calculated as (dP/dt)/p. Vpm and Vpmr increased in controls during both pacing (P smaller than 0.05; P smaller than 0.02) and exercise (P smaller than 0.01 for both). In coronary heart disease patients Vpm increased during pacing (P smaller than 0.01) while Vpmr did not differ significantly. During exercise both Vpm and Vpmr were unchanged. In patients with coronary heart disease paced to angina, diastolic logarithmic pressure-volume relationship showed change in slope (P smaller than 0.05) of the regression line and upward shift in intercept b (+0.25; P smaller than 0.001). Ischemia produced an impaired contractile state, delayed relaxation and generation of active diastolic tone in the intact ventricle.

Adult↗