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Biomedical subjects

H Smulyan

Publications and source records attributed to H Smulyan.

At least 19 recordsLinked to original sources
PubMed2001

Comparative effects of aging in men and women on the properties of the arterial tree.

OBJECTIVES: We measured the properties of the arterial tree, seeking differences between men and women as they aged. BACKGROUND: There are many differences between men and women, besides menopause, which might account for such disparities. These include body height, heart rate, stroke volume and smaller arterial diameters. Any gender differences in arterial stiffness could influence pulse pressure (PP), now recognized as a cardiovascular risk factor. METHODS: A total of 530 patients (347 men and 183 women) were classified by age into quartiles: < or = 40, 41-47, 48-54 and > or = 55 years. The middle groups represented the menopausal years. Studies included brachial artery blood pressure (BP), aortic pulse wave velocity (PWV), B-mode ultrasonography and wave form analysis of the common carotid artery (CCA), with its conversion to the aortic wave formin. Standard echocardiography provided left ventricular dimensions and flows. Calculated values included CCA compliance and distensibility, systemic compliance, stroke volume and peripheral resistance. RESULTS: At all ages, women had higher heart rates but lower BP than men. Pulse pressure, however, was lower in young women and higher in older women. Measurements influenced by body size, such as CCA diameter, compliance and systemic compliance, were lower in women. Those related to arterial wall properties, such as CCA and aortic distensibility, were the same. Although aortic PWV rose similarly with aging, PWV had more of an influence on PP in women than did mean BP. The reverse was true in men. CONCLUSIONS: Despite lower mean BP and similar arterial distensibilitvy, women develop a higher degree of pulsatility with aging, as compared with men. This is mainly due to their smaller physical characteristics, independent of the role of menopause and its related hormonal changes.

Adult↗
PubMed2001

Heart rate, arterial stiffness, and wave reflections in paced patients.

Elevated heart rate (HR) and pulse pressure (PP) have a cumulative effect on cardiovascular risk, with the exception of HR >/=100 bpm. How an increase in HR may influence the PP level has never been investigated. In 11 patients with pacemaker monitoring, aortic (pulse-wave analysis) and digital (photoplethysmographic device) blood pressure were measured at 3 different levels of HR, together with determinations of carotid dimensions (echo tracking technique), wave reflections (pulse-wave analysis), and aortic pulse-wave velocity. Increased HR is associated with the following: (1) a significant increase of digital systolic, diastolic, and mean blood pressure; (2) a significant reduction of digital and carotid PP, with a more pronounced reduction of the carotid than of the digital PP, resulting in a significant PP amplification; and (3) a reduction in the time required for the backward pressure wave to return toward the heart, without any change of arterial stiffness. Increased HR significantly enhances PP amplification, leading to an increase of peripheral blood pressure without comparable change in central blood pressure. These results are important to consider for a better understanding of cardiovascular risk and the mechanism of white-coat hypertension.

Aged↗
PubMed2000

The diastolic blood pressure in systolic hypertension.

Because antihypertensive therapy is effective in elderly patients with isolated systolic hypertension, attention has been focused on the systolic blood pressure as a predictor of cardiovascular risk. However, it is a normal diastolic pressure that separates patients with isolated systolic hypertension from those with essential hypertension. The normal diastolic and elevated systolic pressures are largely due to age-related stiffening of the aorta. An indistensible aorta causes the pressure pulse to travel faster than normal, where it is quickly reflected off the peripheral resistance. The reflected wave then returns to the central aorta in systole rather than diastole. This augments the systolic pressure further, increasing cardiac work while reducing the diastolic pressure, on which coronary flow is dependent. The potential harm of further reducing the diastolic pressure with antihypertensive therapy, especially in patients with coronary heart disease, underlies the controversial "J curve." By decreasing the blood pressure, all antihypertensive agents improve aortic distensibility, but no agents do so directly; the nitrates come the closest. Such an agent would be useful because any therapeutic increase in aortic distensibility would decrease systolic pressure without greatly reducing diastolic pressure. The problem is complicated by the suspected inaccuracy of the cuff technique in predicting the aortic diastolic pressure. New noninvasive methods to predict the aortic diastolic pressure may help in the future. At present, the combination of a high systolic and normal diastolic pressure-a widened pulse pressure-seems to be the best predictor of cardiovascular risk in patients with hypertension or heart disease. Patients with isolated systolic hypertension should be treated, but marked diastolic hypotension should be avoided.

Aging↗
PubMed1999

Clinical studies and therapeutic trials in systolic hypertension.

A disproportionate increase in SBP over DBP has been recognized for many years as a frequent accompaniment of aging. Initially this was considered to be benign, risk free and potentially dangerous to treat. Study over the years has shown that it is not benign and that antihypertensive therapy can reduce the risks of stroke, myocardial infarction, congestive heart failure and cardiovascular death. Currently, the drugs most widely recommended for this purpose are the thiazide diuretics, long acting dihydropiridine calcium channel antagonists, ACE inhibitors, and beta blocking agents. There may be a special place for nitrates, since these agents are very effective in increasing arterial distensibility--a primary abnormality of the disorder--but a formal study of their effectiveness has not been done. Concern about diastolic hypotension during therapy suggests that treatment to lower the blood pressure in this disorder should be carried out gradually with the aim of reducing the SBP toward normal while avoiding diastolic hypotension.

Adult↗
PubMed1998

Influence of body height on pulsatile arterial hemodynamic data.

OBJECTIVES: This study sought to present evidence that short stature is a hemodynamic liability, which could explain in part the inverse relation between body height and cardiovascular risk. BACKGROUND: Other explanations for the association of short stature with increased cardiovascular risk include advancing age, reduced pulmonary function, genetic factors, poor childhood nutrition and small-caliber coronary arteries. This study adds another factor-the physiologic effects of reduced body height on the arterial tree, which increase left ventricular work and jeopardize myocardial perfusion. METHODS: Four hundred two subjects were studied: 149 with end-stage renal disease and 253 with normal renal function. Measurements included blood pressure, body height, cardiac cycle length, carotid to femoral artery pulse wave velocity, carotid artery pulse waves (by applanation tonometry) and the arrival time of reflected waves. Calculations included the carotid augmentation index, carotid artery compliance and the diastolic to systolic pressure-time ratio (an index of myocardial supply and demand). RESULTS: On linear and stepwise multiple regression, body height correlated with all variables except mean blood pressure. CONCLUSIONS: The early systolic arrival of reflected waves in short people in this group acts to stiffen the aorta and increase the pulsatile effort of the left ventricle, even at the same mean blood pressures. Short stature also induces a faster heart rate, which increases cardiac minute work and shorten diastole. Stiffening lowers the aortic diastolic pressure and, coupled with a shortened diastole, could adversely influence myocardial supply. Although indirect, this evidence supports a physiologic hypothesis for the body height-cardiovascular risk association.

Adolescent↗
PubMed1998

Hormonal response to orthostasis in elderly people with systemic systolic hypertension.

BACKGROUND: Orthostatic hypotension is a common phenomenon in the elderly. Hormonal changes during orthostatic stress have been described in elderly normotensive people and in those with essential hypertension. However, the hormonal response in elderly people who have systolic hypertension during orthostasis has not yet been quantified. METHODS: In this study we investigated 14 non-diabetic men, aged 60 to 75 years, with untreated systolic hypertension who were subjected to 45 degrees passive head-up incline on a tilt table for 15 min. Their hormonal profile and hemodynamic changes were analyzed before and after the stress. RESULTS: In the supine position, plasma levels of norepinephrine, atrial natriuretic peptide and aldosterone were in the normal range, while the plasma renin activity was low. Immediately upon tilt the systolic blood pressure fell but it reverted to baseline values after 15 min of orthostasis. At that time the cardiac output decreased while the systemic vascular resistance and the plasma norepinephrine concentration rose. The atrial natriuretic peptide appeared to fall, and the renin-aldosterone level did not change. CONCLUSION: The physiologic response to orthostatic stress in elderly people with systolic hypertension is comparable to that of elderly normotensive people and those with essential hypertension, i.e. a decrease in cardiac output and an increase in plasma norepinephrine levels. The atrial natriuretic peptide appeared to fall appropriately. The response of the renin-aldosterone system mimicked that in elderly patients with low renin essential isolated hypertension. These observations may have a bearing on the management of elderly people with systolic hypertension who also have orthostatic symptoms; they may not require a different approach from that needed for others of the same age group.

Aged↗
PubMed1997

Systolic blood pressure revisited.

The clinical importance of systolic blood pressure (SBP) needs no emphasis. Its determinants are well known, but recent studies of one of these determinants, arterial distensibility, have led to results that now have clinical relevance. This review summarizes the role of arterial stiffness in ventricular-vascular coupling in the normal circulation and that disordered by aging and hypertension. The discussion defines the unfamiliar terms of compliance, distensibility and modulus and indicates how they are measured. Such measurements have increased our understanding of the parts played by the inhomogeneity of the arterial tree and reflected pressure waves in governing SBP. Elevated SBP is a recognized risk factor for cardiovascular complications among older patients, but when this elevation is due to a stiffened arterial tree, diastolic blood pressure (DBP) is necessarily reduced. Early epidemiologic studies in hypertension required a DBP > or = 90 mm Hg for hospital admission. They therefore excluded persons with high SBP, low DBP and very wide pulse pressure (PP). More recent inclusion of such patients has shown that elevation of SBP and PP is a strong predictor of cardiovascular risk. These considerations point to a possible redefinition of hypertension to include patients with lower DBP and to the inaccuracy but indispensability of the brachial artery pressure as a surrogate for aortic pressure--the pressure the heart sees. Finally, we review the known effects of available antihypertensive drugs on the arterial wall and indicate possible future directions of research stemming from wider understanding of the role of arterial distensibility in hypertension.

Antihypertensive Agents↗
PubMed1997

Pulse pressure: a predictor of long-term cardiovascular mortality in a French male population.

Studies on the usefulness of blood pressure as a prognostic factor in cardiovascular disease have more often involved investigations of the levels of diastolic or systolic blood pressure. However, blood pressure may be divided into two other components: steady (mean pressure) and pulsatile (pulse pressure). In this study, the relationship of pulse pressure to cardiovascular mortality was investigated in 19 083 men 40 to 69 years old who were undergoing a routine systematic health examination and were being followed up after a mean period of 19.5 years. Subjects were divided into four groups according to age (40 to 54 and 55 to 69 years) and mean arterial pressure (<107 and > or =107 mm Hg). Each group was further divided into four subgroups according to the pulse pressure level. A wide pulse pressure (evaluated according to the quartile group or as a continuous quantitative variable) was an independent and significant predictor of all-cause, total cardiovascular, and, especially, coronary mortality in all age and mean pressure groups. No significant association between pulse pressure and cerebrovascular mortality was observed. In conclusion, in a large population of men with a relatively low cardiovascular risk, a wide pulse pressure is a significant independent predictor of all-cause, cardiovascular, and, especially, coronary mortality.

Adult↗
PubMed1994

Baroreflex function during 45-degree passive head-up tilt before and after long-term thiazide therapy in the elderly with systolic systemic hypertension.

The ratio of the 30th to the 15th cardiac cycle duration on an electrocardiogram (30:15 ratio) immediately after active standing from the supine position has been used as one of the markers of baroreflex function. A ratio of < or = 1.0 has been suggested to indicate baroreflex dysfunction. Blood pressure (BP) changes were measured and the 30:15 ratio was calculated after standing and during 45-degree passive head-up tilt from the supine position in 10 nondiabetic men (mean age +/- SE 70.1 +/- 1.05 years, and BP < 150/90 mm Hg). After tilt the decrease in systolic BP (from 132 +/- 4.8 to 117 +/- 6.3 mm Hg; p < 0.001) appeared to be larger than that after standing (from 132 +/- 4.6 to 123 +/- 5.8 mm Hg; p < 0.01), whereas the 30:15 ratios were 0.965 +/- 0.006 and 0.970 +/- 0.014, respectively, which suggested baroreflex dysfunction. Although the mean of the 2 ratios did not differ, the variance appeared to be less during tilting than after standing. Thus, the 45-degree passive head-up tilt appeared to be a better and more uniform inducer of orthostatic stress than active standing. Therefore, 45-degree head-up tilt was used in a group of 10 nondiabetic male patients (aged 70 +/- 1.46 years) with isolated systolic hypertension (systolic BP > 160 mm Hg, diastolic BP of < 90 mm Hg) to assess their baroreflex function. Upon tilting, their systolic BP decreased from 190 +/- 5.5 to 179 +/- 5.8 mm Hg (p < 0.05) and their 30:15 ratio was 0.985 +/- 0.011.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1993

Hemodynamic response to orthostatic stress in the elderly with systolic systemic hypertension before and after long-term thiazide therapy.

The hemodynamic effects of orthostatic stress in elderly subjects with systolic hypertension were studied before and after long-term hydrochlorothiazide therapy (50 mg daily). Sixteen nondiabetic men aged 70 +/- 1 (SE) years participated in the study initially, and 12 completed 1 year of therapy. Patients underwent 45 degrees head-up incline on a tilt table before, after 1 month and after 1 year of therapy. Hemodynamic variables were measured in the following situations: (1) the supine position, (2) immediately after completion of passive 45 degrees head-up position at 0 minute, (3) at 15 minutes in the tilted state while patients performed intermittent foot movements to minimize gravitational pooling and simulate the standing position outside the laboratory, and (4) after returning to the supine position. Systolic and diastolic blood pressure (BP) decreased significantly after 1 month of therapy, and this reduction was maintained up to 1 year in all aforementioned body positions, with the exception of diastolic BP at 0 minute of tilt, which was significant at 1 year only. Before therapy was begun, there was a significant reduction in systolic BP immediately after completion of tilting; however, this was statistically insignificant both at 1 month and 1 year of therapy. Thus, the data may help dispel the concern of exacerbating the hypotensive response to orthostatic stress in patients with systolic hypertension after long-term thiazide diuretic therapy.

Aged↗
PubMed1993

Acute pericardial distension in pigs: effect of fluid conductance on body surface electrocardiogram QRS size.

OBJECTIVES: Pericardial effusion has long been associated with low voltage of the surface electrocardiogram and its clinical utility is well known. The cause of this reduced QRS voltage has usually been attributed to short circuiting of the impulses by the pericardial fluid, but its precise mechanism has not been clearly elucidated. Therefore, we investigated this phenomenon by instilling various fluids with different resistances in increasing volumes into the pericardial space to finally produce acute cardiac tamponade. METHODS: Acute cardiac tamponade was produced 65 times in 25 closed chest pigs with a mean weight of 57(SEM 1.2) kg. A sufficient quantity (mean = 200 ml) of plasma, saline, blood, and blood with varying packed cell volume was introduced into the pericardial space in 60 ml increments to decrease systemic and pulmonary pressures to 50% of control to produce cardiac tamponade. At that point intrapericardial pressure had increased to 15-20 mm Hg. Resistivity values for the instilled fluids are 150 omega-cm for blood, 60 omega-cm for plasma, and 50 omega-cm for saline. RESULTS: Mean limb and precordial lead QRS voltage fell significantly, with no significant differences among these fluids. Electrocardiograph recordings from a unipolar electrode catheter in the right ventricle showed an increase in R wave voltage, but body surface recordings of stimuli introduced into the right atrium via a bipolar electrode catheter showed no amplitude change. CONCLUSIONS: In considering possibilities such as internal shunting of cardiac currents by intrapericardial fluid, distance of the heart from body surface electrodes, and change in cardiac position, the results are best explained by a reduction of cardiac volume and size during cardiac tamponade. This conclusion confirms Brody's hypothesis.

Acute Disease↗
PubMed1993

Diagnosis of right atrial mass lesions by transesophageal and transthoracic echocardiography.

The echocardiographic findings by transesophageal and transthoracic techniques were compared in 16 patients with right atrial mass lesions diagnosed by transesophageal echocardiography. In only 8 of the 16 patients were the masses imaged by transthoracic echocardiography. Masses in the main body of the right atrium (three of five), as well as those associated with indwelling catheters and pacer wires (three of four) were more likely to be imaged by transthoracic echocardiography than masses in the right atrial appendage (zero of three) or in the superior or inferior vena cava (one of three). Associated masses in other cardiac chambers were detected by transthoracic echocardiography in three of six patients. Other features such as size, mobility, and site of attachment of right atrial masses in general were better defined by transesophageal echocardiography. Thus, patients with suspected right atrial masses should be investigated with transesophageal echocardiography.

Adult↗
PubMed1992

An analysis of symptoms in patients with permanent ventricular pacemakers.

The prevalence and severity of symptoms of the "pacemaker syndrome" were investigated in 64 patients with VVI pacemakers and compared, in the same patients, to a series of control symptoms, unrelated to pacemaker function. Symptoms were also compared in patient groups unlikely to have the "pacemaker syndrome" (atrial fibrillation), most likely to have such symptoms (retrograde atrial activation) and in an intermediate group (competitive paced and sinus rhythms). There was a linear relationship between the frequency and severity of "pacemaker" symptoms and control questions in all groups and no preponderance of "pacemaker" symptoms in any group. The study provides an estimate of the number and severity of symptoms in patients with VVI pacemakers, demonstrates the non-specificity of the "pacemaker syndrome" and shows no evidence of a sub-clinical "pacemaker syndrome" in the patients observed.

Aged↗
PubMed1992

Captopril administered every three hours in difficult-to-control hypertension.

The renovascular hypertension of an elderly patient, which was controlled initially with standard-dose therapy with captopril, later responded only to 75 mg given every 3 h without side effects. Changeover to another class of antihypertensives, as is recommended in recalcitrant cases, was not needed. Convenient maintenance therapy with lisinopril (10 mg twice daily) has kept blood pressure under control for a year.

Aged↗