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Biomedical subjects

V E Smith

Publications and source records attributed to V E Smith.

At least 19 recordsLinked to original sources
PubMed1991

Comparison of ambulatory left ventricular ejection fraction and blood pressure in systemic hypertension in patients with and without increased left ventricular mass.

To evaluate the effects of long-standing systemic hypertension on left ventricular (LV) function during daily activities, ambulatory radionuclide monitoring of LV ejection fraction (EF) and blood pressure was performed during exercise and other structured activities in 31 hypertensive patients. Patients were divided into 3 groups based on the absence of LV hypertrophy (group 1 [n = 16], LV mass 107 +/- 12 g/m2), presence of LV hypertrophy without electrocardiographic changes (group 2 [n = 10], LV mass 141 +/- 8 g/m2) and LV hypertrophy with associated electrocardiographic changes (group 3 [n = 5], LV mass 158 +/- 9 g/m2). The groups were similar with respect to age, baseline medication, treated and untreated blood pressure, resting EF and treadmill exercise time. Patients in group 3 had the longest history of hypertension. Peak filling rate was normal in group 1 (2.9 +/- 0.4 end-diastolic volume/s), but reduced at rest in groups 2 (2.4 +/- 0.4) and 3 (2.1 +/- 0.3). Patients in group 1 had normal EF responses to exercise and mental stress testing, as well as during routine ambulatory activities. Patients in group 2 had a blunted EF response to exercise, and those in group 3 had a significantly abnormal response. Both group 2 and 3 patients demonstrated abnormal EF responses to mental stress, as well as cold pressor testing in association with significant increases in mean arterial pressure and marked reduction in diastolic filling rate. Decreases in EF were also observed during routine patient monitoring in 3 group 3 patients and 4 group 2 patients. These events were associated with significantly increased blood pressure.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1991

Protection from rotavirus reinfection: 2-year prospective study.

To measure protection induced by natural rotavirus infection, 163 infants enrolled in a rotavirus vaccine trial were prospectively followed for 2 years. Serotype 1 rotaviruses were the predominant circulating strains during the study. Over the 2 years of observation, significantly fewer infants infected before enrollment developed a symptomatic reinfection (0 of 21) or any reinfection (4 of 21) compared with previously uninfected infants (P = .0003). Of the 60 infants who developed a primary rotavirus infection in the first year (40 symptomatic, 20 asymptomatic) only 4 were reinfected in the second year compared with 29 of 82 subjects not previously infected (P = .00003). Asymptomatic primary infection appeared to be as protective as symptomatic primary infection. The only symptomatic reinfections occurred in 2 subjects who did not develop rotavirus antibody after the initial detection of rotavirus. An age-related reduction in the ratio of symptomatic to asymptomatic primary rotavirus infection was also detected. In this study, protection against homotypic serotype 1 reinfection appeared to last greater than or equal to 2 years.

Age Factors↗
PubMed1991

Neither awake nor sleep blood pressures better predict target-organ effect.

We sought to assess the strengths of commonly used ambulatory blood pressure (ABP) parameters as predictors of transmitral flow/velocity ratio (E/A) and the dimensions that govern the left ventricular (LV) mass index. ABP, E/A, and LV dimensions were assessed in 47 subjects, with inclusion of 45 in the final data analysis. The results of four weekly (96 h total) ABP studies were averaged for each subject. No single ABP parameter immerged as a "best predictor." Furthermore, casual blood pressures taken at the beginning of the echo examination had predictive strength for LV mass which was similar to that of the ambulatory data. In the present study, neither awake nor sleep ABPs differed significantly with respect to correlations with indices of LV structure.

Adult↗
PubMed1990

Evaluation of WC3 rotavirus vaccine and correlates of protection in healthy infants.

The safety, immunogenicity, and efficacy of WC3 rotavirus vaccine was evaluated in a double-blind, placebo-controlled trial of healthy infants 2-12 months of age; 103 received one dose of vaccine and 103 received placebo. Vaccination appeared to be safe and induced an antibody response (WC3 neutralizing antibody) in 97% of vaccinees. Only 9 (9%) of these, however, produced antibody to human rotavirus serotypes; at least 7 of the 9 were naturally infected before vaccination. Neither the number of symptomatic episodes of rotavirus diarrhea (21 vs 25) nor the number of moderate to severe rotavirus illnesses (9 vs. 15) was significantly different in vaccine or placebo recipients, respectively, during a predominantly serotype 1 rotavirus season. A slight but significant decrease in mean symptom score was detected in vaccine recipients. Despite an overall lack of efficacy, protection could be correlated to previous rotavirus infection, high levels of WC3 neutralizing antibody, and preexisting (maternal) serotype 1 neutralizing antibody with a titer greater than or equal to 30.

Antibodies, Viral↗
PubMed1989

Regression of left ventricular mass is accompanied by improvement in rapid left ventricular filling following antihypertensive therapy with metoprolol.

Left ventricular hypertrophy is associated with abnormal left ventricular diastolic filling in patients with hypertension. To assess the effects of antihypertensive therapy on the heart in nine previously untreated patients with echocardiographically-detected left ventricular hypertrophy, left ventricular mass and rapid left ventricular filling rate were compared before and after 6 months of treatment with metoprolol monotherapy. Metoprolol was given in doses of 100 to 400 mg/day (average dose, 167 mg/day in two divided doses) and significantly reduced both casual, office blood pressure (150/101 to 130/86 mm Hg, p less than 0.01) and 24-hour ambulatory blood pressure (139/91 to 126/79 mm Hg, p less than 0.05 for systolic, p less than 0.01 for diastolic). Following treatment with metoprolol, left ventricular mass index decreased from 135 +/- 20 to 120 +/- 13 gm/m2 (p less than 0.05), while rapid left ventricular filling rate increased from 1.89 +/- 0.24 to 2.09 +/- 0.27 end-diastolic volumes/sec (p less than 0.01). The reduction in left ventricular mass index was secondary to decreased posterior and septal wall thicknesses (13% and 11%, respectively, p less than 0.05 for both), as there were no changes in the left ventricular internal dimensions. Neither resting nor exercise left ventricular ejection fraction changed on metoprolol therapy compared to the baseline values. These data demonstrate that regression of left ventricular hypertrophy in never-previously-treated hypertensive patients is accompanied by improved diastolic performance following beta-adrenergic blocker monotherapy.

Adult↗
PubMed1987

Echocardiographic assessment of left ventricular diastolic performance in hypertensive subjects. Correlation with changes in left ventricular mass.

Left ventricular hypertrophy resulting from hypertension is accompanied by significant morbidity and mortality and in advanced stages may be irreversible. Hence, early detection of cardiac changes in hypertensive patients remains an important diagnostic goal. When the hypertrophy is mild or moderate, parameters of left ventricular diastolic function and measurements of left atrial size may facilitate the distinction between normal variation and pathologic increases in left ventricular mass. We measured left ventricular isovolumic relaxation time (IVRT, the time from aortic valve closure to mitral valve opening) and left atrial dimensions and correlated them to left ventricular mass index measured by M-mode echocardiography and rapid left ventricular filling by radionuclide ventriculography. In 20 subjects with untreated mild essential hypertension, IVRT was prolonged compared to a normotensive age-matched control group (91 +/- 23 vs 65 +/- 13 msec, p less than 0.0001). Left atrial dimension index was increased in patients compared to controls (1.9 +/- 0.4 vs 1.4 +/- 0.5 cm/m2, p less than 0.001), and this increase was related to prolonged IVRT (r = 0.46, p less than 0.001). Abnormal IVRT correlated with both increased left ventricular mass and decreased rapid ventricular filling in the hypertensive subjects. Thus, prolonged IVRT and borderline left atrial dimension may help identify subtle pathologic left ventricular mass increases in hypertensive subjects.

Aging↗
PubMed1986

Improved left ventricular filling accompanies reduced left ventricular mass during therapy of essential hypertension.

Abnormal left ventricular diastolic performance, an early manifestation of hypertension in the heart, may precede the development of left ventricular hypertrophy. To assess effects of antihypertensive therapy on the heart, left ventricular mass (determined by echocardiography) and rapid left ventricular filling rate (determined by radionuclide ventriculography) were compared before and after 6 months of treatment of 16 patients. Nitrendipine (a dihydropyridine calcium channel blocker) was given alone or in combination with either propranolol or hydrochlorothiazide, or both, and significantly reduced blood pressure (156/103 +/- 12/7 to 137/89 +/- 10/6 mm Hg). In 6 of the 16 patients, left ventricular mass decreased by more than 10% (270 +/- 95 to 193 +/- 47 g, p less than 0.01); in the same patients, left ventricular filling rate increased (2.03 +/- 0.35 to 2.30 +/- 0.45 end-diastolic counts/s [EDC/s], p less than 0.01). In the one patient whose left ventricular mass increased (137 to 195 g), left ventricular filling rate decreased from 2.01 to 1.78 EDC/s. In the remaining nine patients who had no change in left ventricular mass, there was no significant changes in left ventricular filling. The changes in ventricular mass and filling could not be related to the extent of change in blood pressure or heart rate. These data suggest that regression of left ventricular mass during antihypertensive therapy with nitrendipine is accompanied by improved diastolic function.

Adult↗
PubMed1986

Effect of the calcium channel blocker nitrendipine on left ventricular mass in patients with hypertension.

Reductions in left ventricular (LV) mass have been reported after antihypertensive therapy with certain sympatholytic agents and converting enzyme inhibitors, but little or no improvement has been noted after vasodilator therapy. In this study we evaluated the effect of the calcium channel blocker nitrendipine on echocardiographic LV mass. During a 12-month period, nitrendipine was used as monotherapy in 30 patients and in combination with propranolol or a diuretic in an additional 28 patients. Nitrendipine monotherapy lowered supine blood pressure from 148/97 to 136/83 mm Hg, but LV mass did not change significantly. Supine blood pressure decreased from 155/103 to 134/86 mm Hg in patients receiving combination therapy but, again, changes in LV mass were not significant. These data suggest that nitrendipine is effective in lowering blood pressure, but this is not associated with a significant decrease in LV mass in patients with mild hypertension.

Adult↗
PubMed1985

Rapid ventricular filling in left ventricular hypertrophy: I. Physiologic hypertrophy.

The effects of endurance training on the diastolic properties of the left ventricle were examined by comparing left ventricular filling rates in 11 male distance runners and 12 age-matched nonathletic control subjects selected to have nearly similar heart rates at rest. Maximal oxygen consumption was 69 +/- 11 ml/kg-min for the athletes and 48 +/- 8 ml/kg X min for the control subjects (p less than 0.001). Left ventricular end-diastolic dimension, posterior wall thickness and mass were determined by echocardiography, and average left ventricular filling rate was determined with a nonimaging scintillation probe. Electrocardiographic voltage was significantly greater in the athlete group than in the control group (sums of the voltages of the S wave in lead V1 and the R wave in lead V5 were 40 +/- 10 and 26 +/- 7 mV, respectively) (p less than 0.001), whereas ejection fraction was similar in the two groups. Despite a modest degree of left ventricular hypertrophy in the athlete group compared with the control group (left ventricular mass index 127 +/- 30 and 82 +/- 13 g/m2, respectively) (p less than 0.001), the average left ventricular filling rate was similar in the two groups (2.53 +/- 0.34 versus 2.38 +/- 0.29 end-diastolic counts/s, p = NS). There was no trend for the athletes with a higher left ventricular mass to exhibit a slower filling rate. These findings demonstrate that unlike pathologic hypertrophy associated with chronic hemodynamic over-loading, physiologic left ventricular hypertrophy is not accompanied by slowed left ventricular diastolic filling.

Adaptation, Physiological↗
PubMed1985

Rapid ventricular filling in left ventricular hypertrophy: II. Pathologic hypertrophy.

To define the extent of left ventricular ejection and filling abnormalities in patients with mild hypertension, a non-imaging nuclear probe was used to generate high resolution time-activity curves in 25 patients with an average systolic blood pressure of 154 +/- 20 mm Hg and diastolic pressure of 98 +/- 8 mm Hg. The hypertensive patients did not meet electrocardiographic criteria for left ventricular hypertrophy, and none had evidence of ischemic or other cardiac disease. Compared with 25 age-matched normal subjects who had average systolic and diastolic pressures of 123 +/- 10 and 79 +/- 8 mm Hg, respectively, the hypertensive patients had a significantly lower ejection rate (2.00 +/- 0.20 versus 2.34 +/- 0.36 end-diastolic counts/s for the control group, p less than 0.05) and ejection fraction (58 +/- 4.9 versus 62 +/- 4.4) (p less than 0.05). The hypertensive patients had a markedly lower average rapid left ventricular filling rate (1.87 +/- 0.32 versus 2.69 +/- 0.41 counts/s for the control group, p less than 0.001). Although there was a modest inverse relation between echocardiographic left ventricular mass index and filling rate in the hypertensive patients (r = -0.59, p less than 0.01), 4 of 12 hypertensive patients with normal left ventricular mass index had a depressed filling rate. All of the hypertensive patients with increased left ventricular mass index had an abnormal left ventricular filling rate (less than 1.89 end-diastolic counts/s).(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1985

Effects of chronic nitrendipine on casual (office) and 24-hour ambulatory blood pressure.

To assess the clinical efficacy of chronic nitrendipine therapy in mild to moderate essential hypertension, we studied blood pressure (BP) and heart rate responses in 22 subjects receiving maintenance nitrendipine therapy. Ten subjects (45%) whose hypertension was controlled with chronic monotherapy had an 11/12 mm Hg decrease in supine BP (P less than 0.05) with a mean (+/- SD) dose of 71 +/- 15 mg/day. The 12 (55%) subjects whose hypertension was not controlled with monotherapy had a comparatively higher baseline BP than the other 10 (156/105 +/- 10/6 compared with 150/98 +/- 15/4 mm Hg; P less than 0.05). Eight of the 10 subjects demonstrating office BP control with chronic nitrendipine monotherapy who also had full-time employment underwent continuous ambulatory BP monitoring before and after maintenance monotherapy. Nitrendipine induced a reduction in the mean 24-hour BP and mean BP at home, but did not reduce the BP during work or while asleep. These data suggest that nitrendipine lowers BP when assessed by casual office methods. The ambulatory BP monitor data demonstrate that the hypotensive response to chronic nitrendipine is modified during work periods, which are generally associated with increased adrenergic activity. Ambulatory BP monitoring may be superior to office (casual) monitoring in the assessment of the overall efficacy of antihypertensive drugs.

Adult↗
PubMed1983

Inotropic and lusitropic abnormalities in the genesis of heart failure.

Cardiac pumping action is governed by two interdependent systems; those that govern contraction and the emptying of the heart (inotropic) and those that control its relaxation and filling (lusitropic). The signs and symptoms of 'heart failure' can be caused by abnormalities of either or both of these systems. Major technological advances in the evaluation of the cardiac patient, especially those that utilize measurements of ventricular volume, coupled with potent new drugs that can modify differently the inotropic and lusitropic properties of the myocardium, make it necessary to understand the role that each plays in the genesis of the clinical syndrome of heart failure.

Blood Pressure↗
PubMed1983

Detection of tricuspid insufficiency by portable nuclear probe monitoring over the liver.

A case is presented in which a portable nuclear scintillation probe was used to detect tricuspid regurgitation. An electrocardiographically-gated scintigraphic collection obtained over the liver was correlated with findings from contrast echocardiography and jugular venous pulse tracings. The nuclear probe may provide a simple means for the detection of tricuspid insufficiency. It remains to be determined if quantification of severity will be possible.

Echocardiography↗