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Biomedical subjects

H N Neufeld

Publications and source records attributed to H N Neufeld.

At least 37 records · Page 2Linked to original sources
PubMed1986

Two-dimensional echocardiographic analysis of proximal left main coronary artery in humans.

The left main coronary artery (LMCA) was evaluated in 100 consecutive patients (88 men and 12 women; mean age 63 years) with anginal syndrome, all in New York Heart Association classes II and III. Each patient underwent two-dimensional echocardiography (2DE) from the parasternal short-axis and apical four-chamber views. Coronary angiography was subsequently performed within 24 hours. The LMCA was directly measured by 2DE and coronary angiography at its widest point. Each echocardiogram was blindly evaluated for LMCA aneurysm or obstruction. Eight patients (8%) were excluded because of inadequate visualization of the LMCA. The mean 2DE measurement was 4.4 +/- 0.9 mm vs 4.2 +/- 0.8 mm on coronary angiography (r = 0.86). Atherosclerotic aneurysms of the LMCA were correctly diagnosed in two patients by 2DE. LMCA stenosis (greater than 50%) was found in 11 patients on coronary angiography; three of them had ostial or proximal lesions, three had middle lesions, and five had distal lesions. 2DE correctly diagnosed all three ostial lesions, two of three middle lesions, but only two of five distal lesions. In four patients, dense echoes in the LMCA caused a false positive diagnosis. It was concluded that: the LMCA can be visualized and correctly measured by 2DE; atherosclerotic aneurysms can be detected; and 2DE is yet unable to screen patients for LMCA lesions; however, 2DE is a promising method for evaluating proximal and especially ostial LMCA stenosis.

Adult↗
PubMed1986

High-density lipoprotein cholesterol: correlation with biochemical, anthropometric, behavioral, and clinical parameters in 6,500 Israeli men.

Correlations of high-density lipoprotein cholesterol (HDL-C), expressed in either absolute or relative terms, with a series of coronary risk factors and other variables were examined in the Israeli Ischemic Heart Disease Study sample. The Quetelet overweight index showed the highest correlations with HDL-C (r = -0.21) as well as with HDL-C as a percentage of total cholesterol (TC) (HDL/TC; r = -0.28). Additional negative inverse associations were statistically different from zero but small. High-density lipoprotein cholesterol and HDL/TC were significantly reduced in cigarette smokers, and HDL/TC was significantly reduced in men with myocardial infarction or angina pectoris and (albeit marginally) in diabetes mellitus as well. The presence of these diseases correlated poorly with HDL-C (absolute values). The associations of HDL-C and HDL/TC with the Quetelet index persisted after adjustment for cigarette smoking and vice versa. Reported dietary intake failed to explain HDL-C or HDL/TC variability among individuals. The "net" relationship of HDL-C to several variables was examined in a multiple regression analysis. The Quetelet index accounted for 0.21 of a multiple correlation coefficient of 0.28 (i.e., a very small proportion of explained variability). This magnitude is of an order similar to multiple correlations found in our study for total cholesterol, systolic blood pressure, and serum uric acid. It indicates that our knowledge of the determinants of HDL-C in adults is insufficient. The possible roles of several anthropometric and behavioral variables in determining HDL-C levels are considered, as is the possible genetic factor in dictating interindividual HDL-C variability.

Blood Pressure↗
PubMed1986

Correlation between effects of hydralazine on force and on the adenyl cyclase system of ventricular myocardium in dogs and cats.

Hydralazine is a potent arteriolar dilator, which increases cardiac output in patients with heart failure. Previous studies suggested that these beneficial effects might be due in part to a positive inotropic effect. The present study further investigated the effect of hydralazine on myocardial contractility and adenyl cyclase activity. In isolated cat papillary muscles, bath concentrations of hydralazine up to 10(-4) mol X litre-1 did not alter force development, whereas 10(-3) mol X litre-1 hydralazine increased isometric force by 31%. This effect was blocked by 10(-6) mol X litre-1 propranolol and was absent after catecholamine depletion produced by previous reserpine treatment. In canine ventricular myocardium hydralazine in all concentrations used (10(-7) to 10(-3) mol X litre-1) increased control adenyl cyclase activity. This increase was statistically significant in 10(-6) to 10(-3) mol X litre-1 concentrations, reaching a maximum of 69.5% at 10(-4) mol X litre-1. In cat ventricular myocardium 10(-6) to 10(-3) mol X litre-1 hydralazine increased the cyclic AMP production, although to a lesser magnitude than that in canine tissue. Hydralazine 10(-5) mol X litre-1 produced a 37.8% increase, and the maximum effect of 45.2% occurred at 10(-3) mol X litre-1. The positive effects of hydralazine were completely abolished by the addition of propranolol in dogs as well as in cats. Thus the adenyl cyclase stimulation induced by hydralazine is mediated through the beta receptor.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenylyl Cyclases↗
PubMed1986

Calcium antagonists in secondary prevention after acute myocardial infarction: the Secondary Prevention Reinfarction Nifedipine Trial (SPRINT).

SPRINT was a double-blind, randomized placebo controlled multi-centre trial based in Israel, designed to test whether nifedipine 10 mg X 3 daily would reduce morbidity and mortality during 1 year follow-up in 2279 male and female survivors of acute myocardial infarction. 335 patients were adjudged to be trial deviations. 130 (5.7%) of patients died and 105 (4.6%) experienced a non-fatal myocardial reinfarction. Analysis of the results by trial medication is awaited.

Clinical Trials as Topic↗
PubMed1986

High density lipoprotein cholesterol: prognosis after myocardial infarction. The Israeli Ischemic Heart Disease Study.

In people without overt clinical coronary heart disease (CHD), reduced levels of high density lipoprotein cholesterol (HDLC) are a known predictor of a first myocardial infarction (MI), and of death from CHD. Less is known about the role of HDLC in the prognosis of patients with coronary heart disease. In 130 men with electrocardiographic evidence of myocardial infarction examined in the Israeli Ischemic Heart Disease Study in 1963, the relationship of HDLC to prognosis was examined. Approximately 60% (77 men) died between 1963 and 1978. Analysis of mortality by HDLC quartiles revealed the highest rate, 74%, in the bottom HDLC quartile (less than 30 mg/dl). Quartile analysis was also performed for HDLC as a per cent of total cholesterol (PHDL), known as a better predictor of CHD incidence. Mortality was as high as 81% in the bottom quartile (PHDL less than 13%), with a relative mortality risk of 1.71 for subjects in the bottom quartile compared to those in the top quartile (PHDL greater than or equal to 19%). Initial mean PHDL in patients surviving 15 years was significantly higher than in those dying during that time (17.8% versus 16.2%, p less than 0.05). Multivariate analysis, using the Cox proportional hazards model, indicated an association close to conventional statistical significance between HDLC and long-term mortality (p = 0.069). The results are comparable with those reported by the Coronary Drug Project Study. Further investigations of larger cohorts of CHD survivors are needed before firm conclusions about the role of HDLC and the potential for the use of HDLC affecting drugs or lifestyle changes can be drawn.

Adult↗
PubMed1986

Changes in systemic vascular resistance detected by the arterial resistometer: preliminary report of a new method tested during percutaneous transluminal coronary angioplasty.

A recently developed apparatus provides on-line continuous monitoring of systemic vascular resistance (SVR) by means of simple computer analysis of the peripheral arterial waveform. The fundamental equation of this method is Ri = P'/(dP/dt), where dP/dt is the peak dP/dt of the peripheral arterial waveform, P' is the pressure at time of peak dP/dt, and Ri is a resistance index that bears a direct relation to SVR. Eleven patients undergoing percutaneous transluminal coronary angioplasty (PTCA) were studied to evaluate the changes in SVR associated with myocardial ischemia (angina detection). There were 49 balloon inflations, all of which were associated with an increase in Ri (from 38.4 +/- 12 to 81.2 +/- 36 X 10(-3) sec; p less than .01) and a decrease in dP/dt (from 2076 +/- 257 to 1327 +/- 326 mm Hg/sec; p less than .01). In 42 of the balloon inflations these changes were associated with electrocardiographic ST-T changes and in 23 it was also associated with anginal pain. When angina was present, a further increase in Ri (to 97.5 +/- 43 X 10(-3) sec; p less than .01) and a decrease in dP/dt (to 1218 +/- 338 mm Hg/sec; p less than .01) was observed. It was found that myocardial ischemia is associated with an increase in the resistance index and a decrease in dP/dt and can be detected by the resistometer.

Angioplasty, Balloon↗
PubMed1986

Hemodynamic effects of nifedipine in hypertension in the presence of elevated angiotensin-II and beta-adrenergic blockade.

The hemodynamic effects of the slow release form of a calcium channel blocker, nifedipine retard, in essential hypertension patients after angiotensin II (AII) infusion were studied using nuclear ventriculography. Sublingual nifedipine lowered blood pressure that had been acutely raised by an infusion of AII to its baseline level. When used for 4 weeks, nifedipine retard maintained its blood-pressure-lowering effects without a change in heart rate, both when used alone and when used in addition to beta-adrenergic blockers. In the patients with untreated essential hypertension, nifedipine counteracted the lowering effect of AII on left ventricular ejection fraction (LVEF), which was 67.5 +/- 8.9% at recumbency, 61.2 +/- 6.6% (+/- SD) during AII infusion, and 72.1 +/- 7.5% 30 minutes after sublingual nifedipine. These acute effects seem to result from a marked reduction in total peripheral resistance (TPR) and are accompanied by a rise in cardiac index (CI). The TPR, in dynes/sec/cm-5, was 1376.9 +/- 275.8 at recumbency, 2000.7 +/- 358 during AII infusion, and 1228.6 +/- 289 30 minutes after sublingual nifedipine. The corresponding figures for CI in liters/M2 BSA, were 4.02 +/- 0.77, 3.03 +/- 0.64, and 4.32 +/- 0.79. In patients receiving beta-blocker therapy (propranolol or atenolol) with inadequate control of blood pressure, similar results were obtained in LVEF (69.7 +/- 8.87% at recumbency, 63.7 +/- 11.9% during AII infusion, and 72.2 +/- 6.05% 30 minutes after sublingual nifedipine). The initial TPR was much higher than that of untreated essential hypertensive patients. Nevertheless, the increase obtained during AII infusion was counteracted by sublingual nifedipine. CI was decreased by AII.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists↗
PubMed1986

Elevated systolic blood pressure as a predictor of long-term cancer mortality: analysis by site and histologic subtype in 10,000 middle-aged and elderly men.

The association of a casual reading of blood pressure (BP) in 1963 to subsequent 15-year cancer mortality was examined in a cohort of 10,059 middle-aged and elderly men. Systolic BP (SBP), but not diastolic BP, predicted significantly long-term cancer mortality occurring in 369 subjects. The covariate-adjusted relative risk (RR) estimated by Cox's proportional hazard model was 1.10 [95% confidence interval (CI), 1.00-1.21]. In patients aged less than 60 at the beginning of the study, increased cancer mortality was mainly observed in association with SBP of more than 150 mm Hg. In subjects aged 60 or above, the estimated RR was 1.21 (95% CI, 1.03-1.42). Exclusion of 40 men in whom diagnosis made prior to 1963 or death occurred through 1965 did not alter the results. An excess mortality in men who reported pharmacologic treatment for hypertension while under follow-up was fully accountable by their age, BP, and smoking habits. Analysis by site suggested that the association was mainly due to increased mortality from cancer of the digestive and genitourinary organs (estimated RR's, respectively, 1.20 and 1.26; 95% CI's, respectively, 1.03-1.39 and 0.99-1.59). Analysis by histologic subtype suggests an association with adenocarcinoma (RR = 1.19, 95% CI, 1.04-1.37) but not squamous cell or transitional cell carcinomas, myeloma, lymphomas, and leukemias.

Adult↗
PubMed1986

Does complete revascularization by the conventional method truly provide the best possible results? Analysis of results and comparison with revascularization of infarct-prone segments (systematic segmental myocardial revascularization): the Sheba Study.

Myocardial revascularization is usually considered "complete" if all stenosed major coronaries are bypassed. Attempts were made to compare the results of this method with an approach by which each of the following five left ventricular infarct-prone segments is revascularized if ischemic: anteroseptal, anterolateral, posterosuperior, posteroinferior, and diaphragmatic. Two subsets of patients were studied. A total of 366 patients (Group A) who underwent aortacoronary bypass operations from 1980 to 1982 were followed up for a mean of 16.3 (6 to 43) months and were retrospectively divided into two groups: Group A1 (120 patients) had incomplete segmental revascularization (mean of 3.4 grafts per patient) and Group A2 (246 patients) had complete segmental revascularization (4.0 grafts per patient) (p less than 0.0001). Groups A1 and A2 were identical in all clinical and angiographic parameters: unstable angina, 60%; previous myocardial infarction, 70%; left main stenosis, 10%; and ejection fraction less than 30%, 2%. Overall operative mortality was 2.3%. Results in Groups A1 and A2, respectively, were as follows: operative mortality, 5.8% versus 0.8% (p less than 0.005); perioperative myocardial infarction, 6.9% versus 0.8% (p less than 0.0005); 35 month survival rate, 93.3% versus 97.9% (p less than 0.02); total freedom from symptoms, 54.1% versus 68.3% (p less than 0.025). In addition, 151 patients operated on in 1984 (Group B) were studied prospectively with regard to operative mortality and perioperative myocardial infarction, and the results were identical to those in Group A. Compared to conventional complete revascularization, complete segmental revascularization provides better results.

Adult↗
PubMed1986

Myectomy versus myotomy as an adjunct to membranectomy in the surgical repair of discrete and tunnel subaortic stenosis.

The results of membranectomy and deep myectomy in the left ventricular outflow tract were compared to those of membranectomy and myotomy in 42 patients who underwent surgical repair of discrete and tunnel subaortic stenosis. Fifteen consecutive patients (Group A) underwent membranectomy and myotomy, and 27 consecutive patients (Group B) underwent membranectomy and myectomy. Two patients of Group A and nine of Group B had tunnel subaortic stenosis. The preoperative mean (+/- standard deviation) peak systolic gradients across the left ventricular outflow tract in patients with discrete subaortic stenosis types I and II were 64 +/- 29 mm Hg in Group A and 52 +/- 3 mm Hg in Group B (p = not significant). In the patients with tunnel subaortic stenosis the preoperative mean gradients were 97 +/- 74 mm Hg in Group A and 73 +/- 26 mm Hg in Group B (p = not significant). In patients with discrete subaortic stenosis types I and II, postoperative catheterization at a mean follow-up of 21 months revealed residual mean gradients of 29 +/- 24 mm Hg in Group A and 10 +/- 13 mm Hg in Group B (p less than 0.01). In the patients with tunnel subaortic stenosis, the postoperative mean gradients were 25 +/- 7 and 30 +/- 30 mm Hg in Groups A and B, respectively (p = not significant). We conclude that in the surgical management of discrete subaortic stenosis types I and II, deep myectomy (in addition to membranectomy) produces better relief of the left ventricular outflow obstruction than do membranectomy and myotomy. In patients with tunnel subaortic stenosis myectomy is less effective than in the non-tunnel type but still produces acceptable results and may delay radical procedures to a later age.

Adolescent↗
PubMed1985

Total and high density lipoprotein cholesterol in the serum and risk of mortality: evidence of a threshold effect.

The association of serum total and high density lipoprotein cholesterol values with 15 year mortality was examined in a cohort of 10 059 Israeli male civil servants and municipal employees aged 40 and above. In 618 of 1664 deaths in the cohort (37%) coronary heart disease was documented as the cause of death. Risk of mortality was analysed by quintiles. Neither total mortality nor coronary heart disease mortality rose with serum cholesterol concentrations up to 5.6 mmol/1 (216 mg/100 ml), representing 60% of the sample. Rates rose appreciably only in the highest quintile (cholesterol concentration greater than 6.2 mmol/1; greater than 241 mg/100 ml). High density lipoprotein cholesterol was similarly, although inversely, associated with total mortality when expressed as a percentage of total cholesterol. The inverse association of high density lipoprotein cholesterol with coronary heart disease mortality was, in contrast, continuous. These data support the hypothesis that over most of the range of cholesterol values coronary mortality risk and total mortality risk are nearly independent of total cholesterol and most probably independent of low density lipoprotein cholesterol values. In multivariate analysis a low concentration of high density lipoprotein cholesterol appeared to be more predictive of mortality than a high concentration of total cholesterol. The latter was very weakly related to mortality from all causes after multivariate adjustment. It is concluded that the findings of this and other major epidemiological studies support the notion of a "threshold effect." Success in reducing mortality through the pharmacological reduction of serum cholesterol in hypercholesterolaemic patients does not warrant a similar approach in people with average or slightly above average values. These findings appear to provide support for a "high risk strategy" in reducing the risk of coronary heart disease.

Adult↗