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Biomedical subjects

F M Fouad

Publications and source records attributed to F M Fouad.

At least 55 records · Page 3Linked to original sources
PubMed1984

Assessment of parasympathetic control of heart rate by a noninvasive method.

The degree of parasympathetic control of heart rate was assessed by the abolition of respiratory sinus arrhythmia with atropine. Peak-to-peak variations in heart periods (VHP) before atropine injection correlated significantly (r = 0.90, P less than 0.001) with parasympathetic control, indicating that VHP alone may be used as a noninvasive indicator of the parasympathetic control of heart rate. Pharmacologic blockade of beta-adrenergic supply in a separate group of normal volunteers did not alter the relationship between VHP and parasympathetic control, indicating that the condition of the experiment (complete rest in a quiet atmosphere) allows the use of VHP alone without pharmacologic interventions to characterize the vagal control of heart rate in humans.

Animals↗
PubMed1983

Determinants of left ventricular hypertrophy and function in hypertensive patients. An echocardiographic study.

Hypertensive patients present a wide spectrum of echocardiographic alterations. A review of these changes in 74 patients (37 untreated and 37 treated) revealed left ventricular hypertrophy in 43 (58 percent). There was no significant difference between treated and untreated patients in regard to either the prevalence of left ventricular hypertrophy or of its various subtypes [concentric left ventricular hypertrophy in 15 (20.3 percent), asymmetric septal hypertrophy in 16 (21.6 percent), and combined left ventricular hypertrophy and dilation in 12 (16.2 percent)]. None of the patients who showed asymmetric septal hypertrophy had abnormal motion of the mitral valve. Cardiac performance as judged by left ventricular percent shortening was related inversely to end-systolic stress (p less than 0.001) and positively to the ratio of end-systolic pressure/end-systolic volume (an index of myocardial contractility) (p less than 0.01). Multiple regression analysis showed an increased dependence on afterload (end-systolic stress), when left ventricular hypertrophy developed and especially when it was associated with left ventricular dilation.

Adolescent↗
PubMed1983

Predictive value of angiotensin II antagonists in renovascular hypertension.

An angiotensin II antagonist, sarcosine-1, threonine-8 angiotensin II ( [Sar1, Thr8] A II), was infused preoperatively in 14 patients with renal artery stenosis. Postoperative graft patency was documented by renal flow scan in 13 patients. One of these required antihypertensive therapy immediately after surgery, while the other 12 had a significant BP reduction in the first postoperative week (141 +/- 3.7 to 110 +/- 1.6 mm Hg). With longer follow-up, six patients remained normotensive (group 1), while the other six had "residual hypertension" (group 2). There was no significant difference between the two groups as regards age, preoperative BP level, plasma renin activity, blood volume, or response to [Sar1, Thr8] A II. In contrast, clinical signs were most helpful in predicting response to surgery. "Cured" patients had shorter duration of hypertension (less than one year) than patients with residual hypertension, and less impairment of renal excretory function; three patients in group 2 but none in group 1 had a history of malignant hypertension. The decision to operate remains a multifactorial evaluation and cannot be based on results of any single test alone.

Adult↗
PubMed1983

Reversal of left ventricular hypertrophy with captopril: heterogeneity of response among hypertensive patients.

Reversal of left ventricular hypertrophy (LVH) has been reported not to occur with all antihypertensive agents. Moreover, a dissociation between blood pressure response to medical therapy and reversal of ventricular hypertrophy has been previously observed. To evaluate the effects of captopril we studied the electrocardiographic (ECG) changes in 26 severe hypertensive patients who received the drug for more than one year. In 14 patients with normal pretreatment ECG, captopril controlled blood pressure effectively [132 +/- 2.9 (SE) to 104 +/- 3.9 mmHg, p less than 0.001], but had no effect on ECG voltage. In 12 patients with pretreatment LVH, two different response patterns were observed despite similar blood pressure control (144 +/- 4.9 to 102 +/- 3.1 mmHg and 148 +/- 7.3 to 109 +/- 7.3 mmHg, p less than 0.001 for both): seven had complete normalization of ECG while five had residual LVH pattern. No significant difference was found between the latter two groups in regard to age, sex, weight, etiology of hypertension, pretreatment ECG voltage, blood pressure, plasma renin activity, duration of treatment and duration of maintained blood pressure control. The reversal of LVH pattern occurred early (between 12 to 16 months) with no overall correlation between lowering of blood pressure and ECG voltage changes. The heterogeneity of response observed in this study suggests that factors other than blood pressure control modify the reversal of cardiac hypertrophy by antihypertensive therapy.

Blood Pressure Determination↗
PubMed1983

The changing clinical spectrum of primary aldosteronism.

In a prospective study of 80 patients with primary aldosteronism (70 with adenoma and 10 with hyperplasia), "refractory" hypertension, hyperkinetic circulation, and hypovolemia were frequent occurrences. We found that measurements of serum potassium concentration and plasma renin activity were inadequate screening tests because of high rates of false-positive and false-negative results. The demonstration of excessive aldosterone production after three days of salt loading provided the best sensitivity (96 percent) and specificity (93 percent) in identifying patients with primary aldosteronism. Severe, persistent hypokalemia, increased plasma 18-hydroxycorticosterone values, and an anomalous postural decrease in the plasma aldosterone concentration, when present, provided the best indicators of the presence of an adenoma. Of three localizing procedures (selective adrenal venography, adrenal computed tomographic scan, and adrenal venous sampling for plasma aldosterone concentration) the measurement of adrenal venous plasma aldosterone concentration yielded 100 percent accuracy. These results indicate a wider clinical spectrum in primary aldosteronism than previously described. They also show that nonsuppressible aldosterone production is its most important diagnostic hallmark and the single best diagnostic screening procedure, and that adrenal venous sampling for plasma aldosterone concentration remains the most precise technique for identification and localization of tumors.

Adenoma↗
PubMed1983

Membranous glomerulopathy associated with captopril therapy.

Two cases of nephrotic syndrome and biopsy-proved membranous glomerulopathy (membranous glomerulonephritis) were encountered during captopril treatment of 53 hypertensive subjects in our institution. Both patients had impaired renal function before treatment and were treated with 600 mg per day. Discontinuation of captopril led to transient partial remission of proteinuria but was followed by a recurrent, fluctuating course over one year later. Repeat biopsies, eight and 12 months after discontinuation of the drug, demonstrated persistent subepithelial deposits in the glomerular basement membrane. There has been a decline in glomerular filtration rate since discontinuation of the drug, apparently due to arterionephrosclerosis. These studies suggest that glomerular basement membrane deposits in captopril-associated membranous glomerulonephritis are not readily reversible and may be associated with persistent proteinuria, contrary to some previous reports.

Basement Membrane↗
PubMed1983

Predictive value of angiotensin II blockade with (sarcosine-1, threonine-8) angiotensin II in renovascular hypertension.

Administration of an angiotensin II antagonist, (sarcosine-1, threonine-8) angiotensin II, was used to diagnose renovascular hypertension in 22 patients before renal revascularization or nephrectomy. Positive and negative responses to infusion occurred in 12 and 10 patients, respectively. Postoperatively, hypertension was cured in 13 patients, improved in 6 and unchanged in 3. The over-all accuracy of the infusion test in predicting the outcome of surgical therapy was 59 per cent, the false positive rate was 8.3 per cent and the false negative rate was 80 per cent. A similar high incidence of false negative results has been observed with differential renal vein plasma renin assays. The most accurate prediction of the blood pressure response to surgical therapy is obtained by considering multiple factors rather than a single test.

Adolescent↗
PubMed1983

Changes in plasma protein profiles in serum and in liver DNA synthesis of rats following administration of alpha-amanitin, phalloidin and/or carbon tetrachloride.

The aim of the present study is to investigate the capacity of damaged rat liver cells to respond to a second inflammation by a change in plasma protein profile, while the first inflammatory process is in progress. Quantitation of these effects would be useful, especially in situations where patients are suffering from complications due to emergence of a new pathological factor. We therefore studied the effect of phalloidin on rat livers already made necrotic by oral intubation of CCl4. Our data showed that a decrease in acute-phase response does not necessarily always imply healing, but may also be indicative of a second pathological complication.

Amanitins↗
PubMed1983

Plasma protein determination as a clinical probe for liver injury in rats induced by thioacetamide, alloxan or ixoten.

As a result of traumata, cancer or chemical poisoning the level of acute-phase proteins released by the liver undergoes a significant change which can be measured by two-dimensional immunoelectrophoresis. To investigate whether inflammatory reactions following chemical poisoning, tissue necrosis or other treatments result in an uniform change of the plasma protein profile, we examined quantitatively the change in plasma protein profile in the following model situations: 1) alloxan-induced diabetes in rats, 2) thioacetamide-induced liver cirrhosis and 3) ixoten-induced blocking of DNA synthesis in rat liver. Even though the three agents used in the present study or their metabolites directly interacted with liver cells, they did not evoke a uniform change of the plasma protein profile.

Animals↗
PubMed1983

Cardiac and haemodynamic effects of enalapril.

The haemodynamic effects of enalapril were evaluated by sequential radionuclide studies in 10 patients followed for three to seven months. The pattern of response was remarkably similar to that of angiotensin antagonists and other oral converting enzyme inhibitors; it consisted of a reduction in peripheral resistance, minimal blood volume changes and no significant increase in either cardiac output or heart rate. The haemodynamic and neurohumoral responses to upright tilt remained normal, despite the lack of supine tachycardia in response to peripheral vasodilation. The pattern of response suggests that the haemodynamic effects of enalapril resulted from interference with angiotensin II (AII) generation rather than from a direct drug effect. Serial echocardiographic studies showed a significant regression in left ventricular (LV) hypertrophy in six out of seven hypertensive patients followed sequentially for three to seven months. Ventricular performance was well preserved despite the reduction in ventricular mass, as indicated by maintenance of the normal relationship of LV fractional shortening (% Sh) to LV end-systolic stress.

Animals↗
PubMed1983

Can the heart initiate some forms of hypertension?

An active role for the heart in the initiation of hypertension can be postulated in two different sets of conditions. 1) Activation of pressor reflexes from the ventricles, coronary arteries, or aorta has been shown to produce substantial rises of arterial pressure; experience with postcoronary bypass hypertension suggests that these reflexes could be responsible for some types of paroxysmal hypertension. 2) Increased cardiac action caused by either neural or humoral factors can initiate a rise in cardiac output and blood pressure; sustained hypertension could be produced experimentally in conscious dogs by electrical stimulation of the stellate ganglion or by continuous infusion of dobutamine in the left coronary artery. Evidence suggesting that this could occur in humans was derived from a study of the relationship of cardiac output to cardiopulmonary volume in essential hypertension.

Animals↗
PubMed1982

Long-term control of congestive heart failure with captopril.

The long-term effects of captopril therapy were assessed by sequential hemodynamic studies over a 6 month period in 19 patients with resistant congestive heart failure. Initial improvement during the first week of therapy was noted only in 11 and was marked by significant (p less than 0.005) increases in cardiac output and stroke volume, slowing of heart rate, and reduction of total peripheral resistance. Of the remaining eight patients, seven improved subsequently with maintained therapy so that by the end of 3 months of treatment only one patient failed to respond significantly. The hemodynamic index that reflected response most consistently was the shortening in pulmonary mean transit time. Simultaneously with clinical improvement there was a reduction in cardiopulmonary volume that reflected a reduction in pulmonary congestion and probably systemic vasodilation. Associated with these hemodynamic changes there was an increase in plasma renin activity and a significant reduction in plasma aldosterone, but these changes did not differ significantly between patients who responded markedly and those who responded moderately to converting enzyme inhibition. These results suggest that the response of congestive heart failure to captopril can occur gradually. Improvement was related to peripheral hemodynamic changes which led to a reduction in both total peripheral resistance and cardiopulmonary volume. The reduction in the plasma aldosterone/renin activity ratio was an effective marker of compliance.

Adult↗
PubMed1982

Relation of cardiovascular response to the hypotensive effect of metoprolol.

The influence of cardioselective beta blockade on systemic hemodynamics and cardiac performance was assessed in 17 essential hypertensive patients treated with metoprolol (50 to 100 mg twice daily) for 1 month. Eleven patients had a significant reduction of mean arterial pressure (less than 10 mm Hg); the other six patients did not show significant blood pressure change. There was no difference in response of heart rate or cardiac output between the two groups [-14 +/- 1.6 (SE) vs. -9.5 +/- 2.08 bpm, NS, and -0.55 +/- 0.39 vs. 0.80 +/- 0.35 L/min, NS, respectively]. Mean transit time was significantly prolonged in both groups (1.9 +/- 0.56 vs. 1 +/- 0.53 seconds, NS), and changes in ejection fraction in the two groups were not significant. The only significant difference between the two groups was in the response of total peripheral resistance (-1.4 +/- 3.04 vs. +10.2 +/- 3.77 U . m2, p less than 0.05). The reduction in heart rate correlated significantly with control heart rate (r = -0.71, p less than 0.001) and the decreased in cardiac output correlated significantly (r = -0.77, p less than 0.001) and the decrease in cardiac output correlated significantly (r = -0.77, p less than 0.001) with the initial cardiac output. The changes in mean arterial pressure did not correlate with changes in cardiac output (r = 0.116). On the other hand, there was a significant correlation of 0.68 (p less than 0.01) between the changes in mean arterial pressure and the changes in total peripheral resistance. Changes in plasma renin activity (PRA) were not significant in the nonresponders (1.8 +/- 0.9 to 0.6 +/- 0.2 ng/ml, NS), and the reduction of plasma renin activity was significant in the group of responders (5.5 +/- 2.4 to 1.7 +/- 0.8 ng/ml, p less than 0.05). However, there was no correlation between the changes of mean arterial pressure and either initial PRA or the change in PRA. As regards plasma catecholamines (measured in nine patients), there was a tendency to reduction in both responders and nonresponders (411 +/- 84 to 319 +/- 67 ng/L and 562 +/- 141 to 388 +/- 166, respectively); but changes did not reach statistical significance in both groups. It was concluded that metoprolol reduces cardiac output by slowing heart rate; this reduction of cardiac output was not related to decreased cardiac performance. The mechanism of blood pressure reduction seems to be related to the response of systemic resistance to the diminution in cardiac output and not to the decrease in cardiac output per se, inasmuch as the latter occurred in both responders and nonresponders.

Adult↗
PubMed1982

Long-term captopril therapy in congestive heart failure: serial hemodynamic and echocardiographic changes.

Ten patients with refractory congestive heart failure (CHF) were followed serially for systemic hemodynamic (radionuclide techniques) and M-mode echocardiographic changes during long-term captopril therapy with optimum doses. After 1 week of maintenance captopril therapy, all patients were clinically improved. This was associated with a significant (p less than 0.05) reduction of total blood volume (-6 +/- 2% N), mean blood pressure (-9 +/- 3 mm Hg), and peak systolic left ventricular wall stress (-50 +/- 19 X 10(3) dynes/cm2). At the end of 2 months of maintained therapy, mean blood pressure reduction was -12 +/- 4 mm Hg (p less than 0.05); further hemodynamic improvement was manifested by a significant shortening of pulmonary mean transit time (-3.7 +2- 1.33 seconds, p less than 0.05). Echocardiographic data revealed an increase in end-diastolic septal wall thickness (+0.13 +/- 0.05, p less than 0.05) and left ventricular posterior wall thickness (+0.13 +/- 0.03, p less than 0.05), and further reduction in peak systolic stress (-84 +/- 23 X 10(3) dynes/cm2, p less than 0.05). The present study indicates the importance of measuring peak systolic wall stress in the follow-up of CHF patients. Moreover, we found that for functional circulatory evaluation during vasodilator therapy, the radionuclide first-pass methods were more helpful than both M-mode echocardiography and radionuclide gated blood pool techniques.

Adult↗
PubMed1982

Reversal of left ventricular hypertrophy in hypertensive patients treated with methyldopa. Lack of association with blood pressure control.

Ten patients with essential hypertension and left ventricular hypertrophy were treated with relatively small doses of methyldopa (500 to 750 mg/day) added to long-term diuretic therapy. Sequential M mode echocardiography showed significant reduction in left ventricular mass 36 weeks after addition of methyldopa in four patients (359 +/- 77 [standard error of the mean] to 235 +/- 63 g) although blood pressure was not significantly altered by the added treatment. In three of these patients, reduction of left ventricular mass was observed as early as 12 weeks of treatment (384 to 262 g). Neither left ventricular mass to left ventricular volume ratio nor fractional shortening was significantly altered by reduction in left ventricular mass (3.21 +/- 0.26 to 2.74 +/- 0.24 and 0.42 +/- 0.03 to 0.44 +/- 0.02, respectively). There was no apparent relation in these patients between changes in blood pressure and changes in left ventricular mass. Thus, reversal of cardiac hypertrophy with antihypertensive treatment is possible in human beings; however, it seems to depend on other factors besides blood pressure control.

Adult↗