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Biomedical subjects

H C Smith

Publications and source records attributed to H C Smith.

At least 163 records · Page 9Linked to original sources
PubMed1982

Right Ventricular endomyocardial biopsy: clinicopathologic correlates in 100 consecutive patients.

The first 100 consecutive patients to undergo right ventricular endomyocardial biopsy at the Mayo Clinic were divided retrospectively into five groups, depending on the prebiopsy clinical diagnosis, and the biopsies were review histologically in a single-blind format. Group 1 consisted of 34 patients with a diagnosis of unexplained congestive heart failure and a dilated heart; of these, 4 (12%) had active myocarditis by biopsy. Of the six patients in group 2 with a clinical diagnosis of myocarditis, only one (17%) had biopsy evidence of inflammation, but two (33%) had changes that, in the clinical setting, were suggestive of cardiomyopathy. Group 3 consisted of 27 patients with dysrhythmia, syncope, or cardiac arrest but without congestive heart failure; of these, 4 (15%) had active myocarditis by biopsy, and 8 (30%) had changes that, with the clinical history, were consistent with cardiomyopathy. Group 4 included 19 patients with unexplained congestive heart failure and a nondilated heart; 4 (21%) had cardiac amyloid on biopsy. Group 5 was a diverse group of 14 patients with possible cardiac involvement by a known systemic disease; myocardial disease was documented by biopsy in 7 (50%). On the basis of these findings, we recommend endomyocardial biopsy (1) in patients with dilated cardiomyopathy in whom myocarditis is suspected, (2) in patients with the clinical diagnosis of active myocarditis in whom tissue documentation is indicated before treatment with anti-inflammatory or immunosuppressive drugs, (3) in patients with clinically unexplained life-threatening dysrhythmias in whom myocarditis or cardiomyopathy may be present, and (4) in patients with apparent hypertrophic or restrictive cardiomyopathy in whom cardiac amyloid may be present.

Adolescent↗
PubMed1982

Results of surgical treatment of ascending aortic dissections occurring late after cardiac operation.

Seven patients (one woman) have been seen with ascending aortic dissections at a mean of 8.8 years (6 months to 20 years) after cardiac operation. Previous cardiac operations included saphenous vein coronary artery bypass grafts (CAB) (two), aortic valve replacement (AVR) (one), aortic valvulotomy (one), AVR plus CAB (two), and patch closure of a ventricular septal defect and repair of a perforated aortic cusp (one). During the initial operation, three of seven patients had dilatation of the ascending aorta. Five of seven patients were hypertensive at the time of diagnosis of dissection. Six patients were managed by operation. A composite prosthetic aortic valve and ascending aortic graft with implantation of coronary ostia and saphenous vein grafts was utilized in three patients. In three the repair was by graft replacement of the ascending aorta alone. Five of six patients survived repair and were asymptomatic at discharge. Subsequent problems resulting from distal, descending thoracic, or abdominal aortic extension of the dissection were frequent and necessitated fenestration (one patient) or a graft replacement of the infrarenal aorta (one patient). We conclude that patients may be predisposed to aortic dissection occurring late after cardiac operation, possibly related to prior aortic valvular disease or systemic arterial hypertension. Operative repair is feasible and relatively safe. Follow-up for potential complications of distal aortic problems seems indicated. Techniques of operative repair in these patients are emphasized.

Adult↗
PubMed1981

Coronary artery disease in twins.

In two pairs of monozygotic twins with coronary artery disease who were studied by coronary angiography, there were striking similarities in the clinical course, response to exercise, and distribution of coronary artery disease. Though it is difficult to distinguish between heredity as an independent risk factor and the other major risk factors, the similarities in each twin pair may be best explained by identical heredity.

Adult↗
PubMed1981

Coronary artery thrombosis in patients with unstable angina.

This report describes the clinical course, coronary artery anatomy, and ventricular function of 16 patients in whom coronary artery thrombosis was detected at the time of cardiac catheterisation. All patients had an unstable clinical course in which accelerated angina occurred a mean of four weeks (range four days to 12 weeks) before catheterisation, and four patients had recent subendocardial myocardial infarction. In all patients severe coronary artery disease was documented at catheterisation. Fifteen patients had segmental wall motion abnormalities involving the left ventricular wall that was supplied by the coronary artery in which there was thrombus. Three patterns of coronary artery thrombus were noted: (1) Thrombus proximal to high-grade coronary artery stenosis; (2) thrombus distal to high-grade coronary artery stenosis; and (3) thrombus in segments of the arterial tree in which there was no high-grade coronary artery stenosis. Though the precise cause of the coronary artery thrombosis in our patients is unknown, it may have been a result of stasis, a ruptured atherosclerotic plaque, or coronary spasm. The common clinical course with unstable angina of acute onset suggests the possibility that the thrombus may have been responsible for the abrupt change in clinical condition or may have been a contributing factor in the patients' course.

Aged↗
PubMed1981

Radionuclide measurement of left ventricular volume.

Count rates observed at end-diastole and end-systole in the region of the left ventricle on gated radionuclide angiograms were correlated with corresponding estimates by biplane contrast angiography of left ventricular volumes in 37 patients. When count rates were normalized for number of cardiac cycles processed, time per frame, isotope decay, and count rate observed in venous blood after equilibrium, there was a strong correlation between normalized left ventricular count rate and contrast angiographic volume, whether the venous sample was counted in a well counter or with the use of the same gamma camera. The latter technique was judged easier and more accurate. The derived regression equations yielded a good estimate of ventricular volume from left ventricular count rates when prospectively compared with contrast angiographic volumes in a further 17 patients. Interobserver variability of both the radionuclide and the contrast angiographic estimate of the left ventricular volume was similar. Changes in left ventricular stroke volume induced by sublingual administration of nitroglycerin as measured by the radionuclide method correlated reasonably with corresponding changes in stroke volume measured by the dye-dilution method. It is concluded that left ventricular volumes obtained noninvasively by the radionuclide technique were accurate and were subject to the same interobserver variability as the contrast angiographic technique.

Cardiac Output↗
PubMed1981

The unpredictable progression of symptomatic coronary artery disease: a serial clinical-angiographic analysis.

To determine whether risk factors or angiographic features could be correlated with progression of coronary artery disease, we independently analyzed serial coronary angiograms in 65 symptomatic patients for progression without knowledge of their respective risk factors. An important design feature of this study was that observer variability of coronary lesion assessment was objectively evaluated and taken into account in defining progression of coronary artery disease. The reproducibility of lesion assessment varied with the severity of stenosis: moderate stenoses had the greatest intraobserver and interobserver variability. At initial study, 337 partial and 68 complete occlusions were identified. Of the 337 partial occlusions at risk of progression, 73 (22%) progressed; 13 (3.2%) of the initial lesions regressed. In the 65 patients with persistent or increasing angina, progression occurred in 51 (78%) over a mean period of 24 months. Apart from the tendency of high-grade stenosis( greater than or equal to 98%) to progress to complete occlusion, no measured clinical, laboratory, or angiographic variable showed any significant effect on progression to coronary artery disease, in this selected group of symptomatic patients these same risk factors did not predict its progression. We believe that (1) and definition of progression should incorporate the factor of observer variability and (2) therapeutic measures designed to influence progression of coronary artery disease should take into account this apparently unpredictable progression.

Aged↗
PubMed1981

Percutaneous transluminal coronary angioplasty: initial Mayo Clinic experience.

Percutaneous transluminal coronary angioplasty is a promising new method of treatment for patients with coronary artery disease. Inflation of a balloon located at the tip of a catheter is used to dilate stenoses. In the first year of the use of percutaneous transluminal coronary angioplasty at the Mayo Clinic, it was applied in 34 selected patients whose severe angina pectoris was related to a single, high-grade coronary artery stenosis. Successful dilation (stenosis opened by 40% or more of the normal luminal diameter) was achieved in 22 patients (65% of the total). Early postangioplasty assessment indicated relief of angina in all of these patients except for one patient who demonstrated coronary spasm that was responsive to medication. Median hospital stay was 3 days. Failure of percutaneous transluminal coronary angioplasty in the remaining 12 patients was usually due to an inability to manipulate the balloon catheter across the stenotic segment. Eleven of these patients had saphenous vein bypass graft surgery, as planned, immediately after the attempted angioplasty. There have been no deaths, but three patients sustained a transmural myocardial infarction. This initial experience with percutaneous transluminal coronary angioplasty indicates that it is a relatively safe and a frequently effective method of relieving coronary stenosis in selected patients with symptomatic coronary artery disease.

Angina Pectoris↗
PubMed1981

Mural thrombus in left ventricular aneurysm: incidence, role of angiography, and relation between anticoagulation and embolization.

One hundred consecutive patients undergoing left ventricular aneurysmectomy were reviewed to determine the incidence of associated mural thrombus, the accuracy of angiography in detecting thrombus, and any effect of anticoagulant therapy on the incidence of thrombus and embolism. Thrombus was present in 48% of cases and was located in antero-apical aneurysms in all but two cases. Angiography resulted in correct diagnosis of thrombus with a sensitivity of only 31% and a predictive accuracy of 54%. Presence of mural thrombus correlated inversely with duration of anticoagulant therapy. Embolism occurred in 5% of patients with left ventricular aneurysm.

Adult↗
PubMed1980

Use of the cardiac-catheterization laboratory in a defined population.

We evaluated trends in the use of the cardiac-catheterization laboratory from 1973 through 1977 in a well-circumscribed population in southeastern Minnesota. A total of 346 patients (248 male and 98 female patients) underwent coronary arteriography, left ventriculography, or cardiac catheterization, and there were 369 visits to the catheterization laboratory. The total number of catheterization-laboratory visits per 10,000 population increased from 4.3 in 1973 to 11.5 in 1977. According to individual category, the rates for coronary arteriography increased more than fourfold during the five-year period, whereas the rates for cardiac catheterization period, whereas the rates for cardiac catheterization showed no substantial change. On the basis of the 1977 rate for all visits to the catheterization laboratory and under conditions similar to those in this community, a population of approximately 230,000 would be required to ensure use of a catheterization laboratory at the suggested minimum level of 300 adult examinations per year.

Angiography↗
PubMed1980

Binding of reverse T3 to hepatic nuclear protein.

The study was undertaken to examine the potential intrinsic biological activity of reverse T3 by comparing its binding to nuclear protein in vitro with that of other iodothyronines. Nuclear protein was extracted from normal pig liver using methods described for rat tissues. At 25 degrees 30% of the added 125I rT3 was specifically bound to the nuclear protein. The order of potency in displacing 125I rT3 was rT3 > 3'5'T2 > T4 > T3 > 3,3'T2 > 3,5T2. This contrasted with the order of potency in displacing 125I T3 which was T3 > T4 > 3,3'T2 > 3,5T2 > rT3 > 3'5'T2. This difference in the hierarchy of iodothyronine binding is consistent with binding of these radioligands to different components of the nuclear protein extract. These experiments demonstrate separate binding components of nuclear protein for T3 and rT3 in a thyroid hormone responsive tissue and may be relevant to the mechanism of action of thyroid hormones.

Animals↗
PubMed1980

Binding of endogenous iodothyronines to isolated liver cell nuclei.

The metabolic role of a number of the metabolites of T4 is unknown. Hence, these iodothyronines, now known to be present in human serum, were tested for their ability to displace [125I]T3 from specific binding sites in isolated pig liver nuclei. Compared with T3 (1.0), the molar inhibition ratios of the analogs tested were: triiodothyroacetic acid, 4.4; T4 6.2; 3.3'-diiodothyronine, 56; 3,5-diiodothyronine, 245; rT3, 264; and 3',5'-diiodothyronine, 60,000. In isolated pig liver nuclei, the Ka for T3 was 1.73 +/- 0.21 X 10(9) M-1 and that for T4 was 0.17 +/- 0.06 X 10(9) M-1. Nuclei stored in liquid nitrogen for up to 8 weeks leaked bound [125I]T3 into the supernatant during the incubation period. No loss of bound [125I]T3 was observed with freshly prepared nuclei. The data indicate that, with the exception of T3 and T4, iodothyronines derived from T4 are unlikely to modulate the interaction of T3 with its receptor unless their perireceptor concentration is significantly greater than their serum concentration.

Animals↗