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Biomedical subjects

M H Frick

Publications and source records attributed to M H Frick.

At least 109 records · Page 6Linked to original sources
PubMed1978

Effect of beta-blockade by metoprolol on global and regional left ventricular myocardial perfusion in coronary heart disease.

Utilizing semiselective 133Xenon injections and gamma camera recording, global and regional left ventricular myocardial perfusion were recorded under the influence of beta-blockade by metoprolol in 9 patients with angiographically proven coronary artery disease. Metoprolol reduced the rate--pressure variable in every patient, the mean reduction amounting to 24% (P less than 0.01). With one exception, the global left ventricular myocardial flow followed the change in the rate-pressure variable. No significant differences were detected in the flow responses of areas distal to only moderate coronary obstructions (less than 75%) and areas distal to significant (less than 75%) obstructions. The same was true when areas of asynergic contractions were compared with areas of normal contractions, or when areas supplied by collaterals were compared with areas devoid of collateral vessels. It is concluded that the reduction in myocardial flow after metoprolol is due to the reduction of the myocardial oxygen consumption, and no redistribution of flow occurs.

Adult↗
PubMed1977

Regional myocardial perfusion abnormalities on xenon-133 imaging in patients with angina pectoris and normal coronary arteries.

With use of semiselective xenon-133 injections and gamma camera recording, myocardial scintigrams were obtained in a series of 20 patients with angina pectoris, abnormal exercise electrocardiograms and normal coronary arteries. Ten patients (Group I) exhibited localized perfusion defects and the other 10 (Group II) a hjemogenous uptake of the tracer. Group I was characterized by more past myocardial infarctions and, most significantly, by male preponderance (P less than 0.001). Computer analysis of regional xenon-133 washout curves revealed that every patient in Group I had a reduced flow rate in the area of the perfusion defect (P less than 0.001). A comparison of this group with 26 patients with similarly abnormal scintigrams but coronary arterial obstruction revealed that myocardial perfusion was 16 to 18 percent greater in the group with normal coronary arteries. In three patients of this group, myocardial perfusion rates were not augmented by atrial pacing in contrast to the response in patients with coronary arterial obstruction. The data demonstrated localized perfusion abnormalities in half of the patients with angina pectoris and normal coronary arteries and constitute evidence that a metabolic disorder is not the sole mechanism for ischemia in this syndrome.

Adult↗
PubMed1977

Effect of cardioselective beta-blockade by metoprolol on the phasic myocardial blood content and epi/endocardial ratio.

Using I131-albumin labelling of plasma and a special biopsy cutting device, the blood content of the subendocardium and subepicardium was determined in guinea pig hearts. Measurements were done both in untreated animals and after intravenous administration of metoprolol, a new cardioselective beta-blocking compound. The data were compared with results obtained with propranolol and practolol. Metoprolol decreased the blood content less than propranolol. Practolol in a small dose even increased the blood content in the subendocardium in end-systole. The heart rate decreased by about the same magnitude after all the compounds tested, suggesting that the cardioselectivity of metoprolol was the likely explanation for its differing response from propranolol.

Animals↗
PubMed1976

Combined alpha- and beta-adrenoceptor blockade with labetalol in hypertension.

The antihypertensive effect of labetalol, a new alpha- and beta-adrenoceptor inhibiting agent, was studied in 20 patients in a double-blind crossover trial. A dose of 300 mg daily reduced blood pressure only moderately in the supine position, though in the sitting and standing positions the effect was more pronounced. A dose of 600 mg daily produced statistically significant and clinically relevant reductions in blood pressure in all positions studied. The effect on heart rate was small and of significance only in reducing the heart rate increment due to a change in posture. Side effects were mild: only one patient complained of postural dizziness with the higher dose. We conclude that labetalol is useful in the treatment of mild and moderately severe hypertension.

Adult↗
PubMed1976

Genetic variation in serum low density lipoproteins and lipid levels in man.

Combined data from 10 different populations indicate that the serum cholesterol and triglyceride levels are higher in Ag(x-) than in Ag(x+) individuals. Although the differences were relatively small, they became more pronounced with increasing age. The Ag(x) antigen, which is associated with the serum low density lipoprotein, is genetically controlled and the present study therefore has revealed a small but significant effect of a single autosomal locus on lipids implicated in the pathogenesis of atherosclerosis. No explanation of the higher cholesterol and triglyceride levels in Ag(x-) than in Ag(x+) persons is apparent.

Age Factors↗
PubMed1976

Genetic lipoprotein variation and lipid levels in man.

Analyses of 12 population samples have revealed that the total serum cholesterol level is significantly higher in Lp(a +) than in Lp(a -) individuals. The difference is more pronounced in middle-aged and other people than in young persons, and the difference between Lp(a +) and Lp(a -) individuals is larger when LDL cholesterol rather than total serum cholesterol is considered. Lp(a -) individuals have a significantly higher triglyceride level than Lp(a +) individuals. The Lp(a) variation is genetically controlled. Thus, the present study has revealed a small but significant effect of a single, autosomal locus on lipids implicated in atherosclerosis. An association between the phenotype Lp(a +) and coronary heart disease has been demonstrated previously.

Adolescent↗
PubMed1976

Lp(a) lipoprotein/pre-beta1-lipoprotein, serum lipids and atherosclerotic disease.

With appropriate electrophoretic techniques and fresh serum samples, the Lp(a) lipoprotein/pre-beta1-lipoprotein is demonstrable as a distinct zone in the area between beta-lipoprotein and ordinary pre-beta-lipoprotein, when sera which are strongly positive with respect to the Lp(a) antigen are analyzed. The Lp(a) lipoprotein is a genetically determined normal serum component. The phenotype Lp(a+) was found significantly more frequently in two series of patients with coronary heart disease (CHD) than in appropriate controls. The frequency difference between patients and controls was particularly pronounced for the Finnish samples studied, 55% of the patients having the phenotype Lp(a+), as opposed to only 31% of the healthy controls. As judged from electrophoresis strips, hibh concentrations of Lp(a) lipoprotein/pre-beta1-lipoprotein were positively correlated with coronary score as determined by angiography. This correlation was highly significant. Total serum cholesterol value was slightly higher in Lp(a+) than in Lp(a-) persons from two of the four population samples studied, but no statistically significant difference was found. Serum triglyceride levels exhibited a statistically insignificant trend towards higher values in Lp(a-) than in Lp(a+) individuals, in three of the four samples tested. The strong association between the phenotype Lp(a+) and CHD, as well as the correlation between high amounts of Lp(a) lipoprotein/pre-beta1-lipoprotein and coronary score on one hand, and the weak correlation between presence of Lp(a) lipoprotein/pre-beta1-lipoprotein and lipid values on the other, make it highly unlikely that the increased frequency of the Lp(a+) phenotype in CHD patients merely reflects an over-all increase of the intravascular pool of LDL and/or VLDL reflected in increased serum levels of cholesterol and/or triglycerides. By the same token, it is unlikely that the insignificant effect on lipid values can, on its own, explain the correlation between Lp(a) phenotype and CHD.

Adolescent↗
PubMed1976

Analysis of coronary collaterals in ischaemic heart disease by angiography during pacing induced ischaemia.

Studies were made using ordinary selective coronary angiography and angiography during ischaemia produced by right atrial pacing, on a series of 41 patients with ischaemic heart disease, to examine the response of the collaterals to the ischaemia stimulus. Regional myocardial perfusion was determined under the same circumstances by measuring regional 133Xenon washout curves. No collaterals were found in 8 patients, none of whom demonstrated collaterals when angiography was repeated during ischaemia. Eleven of the 33 patients with prepacing collaterals (33%) responded to ischaemia with an increase in the collaterals, 16 patients (49%) showed no change, 5 patients (15%) showed a decrease in the collaterals, and one patient exhibited a bidirectional change. Regional myocardial perfusion responses closely paralleled the angiographic changes, yielding suggestive evidence that the collaterals were intimately involved in the enhancement of the flow. Despite different collateral and flow responses to ischaemia, the data on exercise tolerance, left ventricular end-diastolic pressure, ejection fraction, prevalence of left ventricular asynergy, and the topographic relation between synergy and collaterals, were largely similar. The data show that in some patients the collateral circulation reacts to ischaemia by enhancement, but the functional significance of this response is obscure.

Adult↗
PubMed1976

An appraisal of symptom relief after coronary bypass grafting.

Subjective symptomatic improvement is experienced by 90% of patients after coronary bypass surgery. Objective exercise testing reduces this incidence to 70%. An analysis of the multifactorial genesis of pain relief based on data of non-randomized trials reveals that graft patency plays a dominant but not unique role in causing improved symptomatology. In a number of cases, intra-operative myocardial infarctions seem to explain the pain relief but may also have opposite effects. Changes in left ventricular function operate bidirectionally but data on this variable in relation to changes in symptomatology are not amenable for detailed analysis. Progression in native vessel lesions apparently opposes pain relief and has its greatest impact in connection with graft closure. Residual post-operative angina is evidently related also to incomplete revascularization.

Angina Pectoris↗
PubMed1976

Double-blind titrated-dose comparison of metoprolol and propranolol in the treatment of angina pectoris.

The effectiveness of metoprolol in relieving angina pectoris was compared with that of propranolol at equipotent dosages in a series of 20 patients. Before double-blind periods propranolol was given in gradually increased dosages to obtain a maximal effect for each individual patient. The responses were monitored using subjective assessment based on attack rate and nitroglycerin consumption, as well as objective maximal exercise testing. Both compounds significantly increased the exercise tolerance on a bicycle ergometer, and relieved angina as assessed subjectively. No significant differences were found between the responses to metoprolol and propranolol. The mean increase in exercise tolerance amounted to 36% with metoprolol. Biochemical monitoring revealed no harmful effects. Two cases of rebound phenomenon were observed at the transition from metoprolol to placebo. It was concluded that metoprolol is a useful new cardio-selective beta-blocking compound equipotent to propranolol in the treatment of angina pectoris.

Adult↗
PubMed1976

Radiologically detected collaterals and regional myocardial flow responses to ischaemia in ischaemic heart disease.

By employing 133 Xenon injections and a gamma camera recording of the initial uptake and subsequent disappearance of the tracer, regional myocardial perfusion rates were determined in 38 patients with ischaemic heart disease. Areas supplied by collaterals and areas devoid of them were analyzed separately. In addition to determining basal flow rates, the regional perfusion was studied by repeated 133Xenon scintigrams during pacing-induced ischaemia. The data were grouped and analyzed according to the visual assessment of collateral response as observed in the angiograms performed under the same circumstances. Eleven patients who did not have collaterals on their angiograms were excluded, as were three patients in whom the collaterals were supplying segments distal to only subtotal obstructions leaving 24 patients to the study proper. Angiographic appraisal disclosed two different responses to ischaemia: ten patients exhibited an increase in the collateral pattern (responders) and 14 patients showed no change or reduction in the collaterals (nonresponders). The prepacing grading of the collaterals was similar in the subgroups. Under basal conditions the regional myocardial flow rates in areas supplied by collaterals or devoid of them were roughly similar. Upon ischaemia the greatest regional flow increment occurred in the responders. The data demonstrate a reasonable agreement between the visual assessment of collateral response to ischaemia and a change in the regional perfusion. The data further indicate that similar collateral patterns observed by routine coronary angiography are not functionally equipotent.

Adult↗
PubMed1975

Changes in native coronary arteries after coronary bypass surgery. Role of graft patency, serum lipids and hypertension.

Sixty-seven patients were studied by coronary angiography early (mean 3 weeks) and late (mean 13 months) after coronary bypass surgery to assess changes in the native coronary vessels. Among the 208 nongrafted arteries progression of disease was found in 2.9 percent. In arteries that were normal before operation, the rate was 0.7 percent; in those with luminal obstructions the rate was 7.6 percent (P less than 0.05). Progression of disease occurred in 6 of the 67 patients (8.9 percent). In five bypassed arteries (5 percent), progression of disease occurred at or near the anastomotic site; in this subset the procedure was classified a technical failure. Progression of disease distal to graft insertion occurred in 2.4 percent of cases. The greatest incidence of progression took place proximal to graft insertion, in 24.2 percent of the grafted arteries. This rate differed significantly from the rate in non-grafted arteries (P less than 0.001) and in distal segments of grafted arteries (P less than 0.001). If the grafts were patent in the late control study, the progression of disease proximally occurred at a rate of 24 percent; if they were occluded, the rate was 25 percent. The data on timing of graft occlusion suggested that graft patency was related to the proximal progression. The prevalence of hyperlipidemia or hypertension did not correlate with progression of disease in any group.

Adult↗
PubMed1975

Further studies of Lp(a) lipoprotein/pre- beta1-lipoprotein in patients with coronary heart disease.

The present study of 100 patients (46 of whom were included in a previous study) with suspected or proven coronary heart disease (CHD) confirms that Lp(a) lipoprotein and pre-beta1-lipoprotein are closely related, if not identical, and that Lp(a) lipoprotein/pre-beta-lipoprotein occurs more frequently in patients with CHD than in healthy people. Analysis of this lipoprotein component may have predictive value with respect to CHD.

Adult↗