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Biomedical subjects

H Ikram

Publications and source records attributed to H Ikram.

At least 145 records · Page 8Linked to original sources
PubMed1985

Hypertension in hypothyroidism: arterial pressure and hormone relationships.

To investigate the regulation of arterial pressure and vasoactive hormones in hypothyroidism associated with hypertension, we measured intra-arterial pressure and hourly venous hormones (renin, angiotensin II, aldosterone, catecholamines and cortisol) for 24 hours in five hypertensive patients with primary hypothyroidism before commencing treatment, and again after three to six months of thyroxine replacement therapy. Arterial pressure fell significantly after thyroxine replacement in four patients. Thyroxine treatment was associated with a fall in plasma norepinephrine levels together with a decline in slopes of norepinephrine/arterial pressure regression lines which suggests that the sympathetic system may contribute to the hypertension in hypothyroidism. Variability of heart rate, blood pressure and plasma norepinephrine fell with thyroxine replacement consistent with impaired damping of swings in sympathetic activity in the untreated state. Reciprocal changes in arterial pressure and renin-angiotensin-aldosterone system activity suggested that this system was not the mediator of hypertension in hypothyroidism.

Adult↗
PubMed1985

The nature and prognosis of thyrotoxic heart disease.

Thirty-two patients with uncomplicated hyperthyroidism were compared to 17 patients deemed to be suffering from pure thyrotoxic cardiac failure, other heart disease having been excluded. The thyrotoxic failure group were older and had clinically and biochemically milder endocrinal abnormalities for a longer time. Haemodynamic studies at rest and exercise showed that the thyrotoxic failure patients had no functional cardiac reserve. Their response to propranolol indicated that myocardial function was dependent on beta-adrenergic activity. Following specific anti-thyroid medication cardiac function returned to normal in the majority of cases with cardiac failure. This study shows that hyperthyroidism by itself can cause a reversible cardiomyopathy.

Adult↗
PubMed1984

Syncope in aortic valvular stenosis.

Simultaneous, continuous ambulatory recordings of systemic and pulmonary arterial pressure and heart rate were made in four patients with aortic valvular stenosis (AS) to explore the mechanisms of syncope in the disorder. When compared with six normal volunteers, patients with AS showed a subnormal systemic arterial pressure response to graded submaximal exercise. Three near-syncopal episodes, occurring during abrupt symptom-limited exercise, were associated with simultaneous acute falls in systemic and pulmonary arterial pressure in the absence of cardiac arrhythmia. Acute reflex peripheral arterial and venous vasodilatation, which may be mediated by the effects of sudden changes in left-ventricular pressure on ventricular baroreceptor activity, plays a central role in the exertion-induced syncope of aortic stenosis.

Adolescent↗
PubMed1984

Bipolar oesophageal electrocardiography and pacing in a coronary care unit.

This paper describes our experience with bipolar oesophageal electrocardiography in a coronary care unit. Twenty-two patients with tachycardia were studied to clarify the nature of their tachycardia. The treatment of supraventricular tachycardia by rapid atrial pacing via the same electrode was assessed in eight patients. The equipment required and diagnostic and therapeutic applications of oesophageal electrocardiography in this setting are discussed.

Acute Disease↗
PubMed1984

Blood-pressure response to moderate sodium restriction and to potassium supplementation in mild essential hypertension.

To determine whether moderate restriction of dietary sodium content or supplementation of potassium intake reduces blood-pressure in patients with mild essential hypertension, twelve patients were put on three different diets--a control diet (180 mmol sodium/day), a sodium restricted diet (80 mmol/day). Each diet was taken for at least 4 weeks and the sequence of the regimens was randomised. At the completion of each regimen intra-arterial pressure was recorded continuously, and vasoactive hormones were measured hourly, for 24 h, under standardised conditions, in hospital. Compared with the control diet, sodium restriction was associated with lower blood-pressure readings in seven patients, higher levels in five, and an overall reduction in mean pressures of only 4.0/3.0 mm Hg (not significant). Individual differences in blood-pressure between these two diets correlated closely with concomitant differences in plasma renin activity (r = 0.75). Potassium supplementation also resulted in variable changes in arterial pressure, and the mean difference in pressure recordings (0.1/0.8 mm Hg) was insignificant. The results show that moderate restriction of sodium intake or supplementation of dietary potassium has variable effects on arterial pressure in individuals with mild essential hypertension, and that overall the blood-pressure changes induced are very small. Responsiveness of the renin-angiotensin system may limit the fall in blood-pressure induced by sodium restriction.

Adult↗
PubMed1984

The use of intravenous disopyramide for the conversion of supraventricular tachyarrhythmias.

A study of the efficacy of intravenous disopyramide in the conversion of supraventricular tachyarrhythmias to sinus rhythm was undertaken in a group of 23 patients with a variety of cardiological diagnoses. An intravenous bolus (2 mg/kg) followed, where appropriate, by an infusion (0.4 mg/kg) resulted in an overall conversion rate of 63% (43% in atrial fibrillation, 50% in atrial flutter, 89% in atrial tachycardias). Serious cardiotoxic side effects occurred in 15%. The study shows that such a regime is useful in a selected group of patients provided certain precautions are observed.

Adolescent↗
PubMed1984

Campylobacter jejuni myocarditis.

A case of Campylobacter jejuni (C. jejuni) myocarditis in a young man is described. C. jejuni was isolated from the patient's stools and he developed specific antibodies to this organism. Tests for other etiological agents (Salmonella, Shigella, Brucella abortus, beta-hemolytic streptococcus Group A, Treponema pallidum and coxsackievirus B) proved negative.

Adult↗
PubMed1984

Enalapril in heart failure.

Serum MK-422 and plasma angiotensin converting enzyme activity were measured during the introduction of enalapril therapy in eight patients with heart failure. In a second study of 16 patients, we recorded exercise tolerance, clinical status and haemodynamics before and after 12 weeks of placebo or enalapril treatment. Increasing doses of enalapril gave step-wise increments in serum MK-422. Plasma converting enzyme activity remained low for at least 24 h after each dose of enalapril (5, 10 and 20 mg). Compared to placebo patients (n = 8), those receiving enalapril (n = 8) tended to improve their exercise performance and clinical status, and showed a fall in right heart pressures after 12 weeks of treatment.

Aged↗
PubMed1984

Continuous recording of pulmonary artery pressure in unrestricted subjects.

Continuous ambulatory pulmonary artery pressures were recorded using a conventional No 5 French Goodale-Lubin filled catheter linked to the Oxford Medilog system of a portable transducer-perfusion unit and miniaturised recorder. Data retrieval and analysis were performed using a PB2 Medilog playback unit linked to a PDP 11 computer system. The total system has a frequency response linear to 8 Hz allowing accurate pressure recording over the full range of heart rates. Ten recordings in 10 patients yielded artefact free data for 80% or more of the recorded period. This inexpensive reliable method allows pulmonary artery pressures to be recorded in unrestricted subjects.

Aged↗
PubMed1984

Hormone and blood pressure relationships in primary aldosteronism.

We used continuous intra-arterial pressure monitoring and hourly venous hormone sampling over 24 hours in 5 patients with primary aldosteronism to study blood pressure and hormone regulation. Three patients were restudied under identical conditions of controlled diet electrolyte intake and body posture 3-7 months after removal of the aldosterone-secreting adrenal tumor. Prior to surgery there was no positive relationship of arterial pressure to renin or to aldosterone. Norepinephrine fluctuations showed positive correlations with arterial pressure but these 2 indices were more closely related after surgery. Plasma aldosterone levels paralleled those of cortisol both before and after cure of primary aldosteronism. Aldosterone/cortisol regression lines were steeper before surgery, and norepinephrine/renin regression lines were steepened in the post-operation studies. Our findings indicate that in established primary aldosteronism, fluctuations in arterial pressure are regulated in part by the sympathetic nervous system: the pattern of aldosterone secretion is controlled mainly by ACTH: aldosterone responsiveness to endogenous ACTH is enhanced: and sympathetic modulation of renin release in inhibited.

Adenoma↗
PubMed1983

A method for coupling cytomegalovirus antigens to aldehyde-fixed erythrocytes for use in passive hemagglutination.

A method for coupling cytomegalovirus (CMV) antigens to aldehyde-fixed erythrocytes for use in a passive hemagglutination assay for antibody to CMV is described. This method uses acid buffer instead of tannic acid for coupling CMV-complement fixation (CF) antigen to the stabilized cells. The coated cells are stable for at least 6 mth at -70 degrees C and for 5 days at 4 degrees C. This provides an inexpensive reagent having a sensitivity for anti-CMV detection which compares favorably with that of the CF test and enzyme immunoassay.

Antibodies, Viral↗
PubMed1983

Cardiovascular changes in chronic hemodialysis patients.

Coronary angiography and left ventricular (LV) hemodynamic studies were performed after dialysis in 32 home dialysis patients (20 men) aged 49.8 +/- 8.0 years. They had been on hemodialysis for 1 to 47 months and were being considered for renal transplantation. The controls were 11 normotensive patients (6 men) aged 46.1 +/- 11 years without coronary artery disease (CAD). Ten (31%) patients had significant CAD (5 single vessel, 3 double vessel, 2 triple vessel). Cardiac index (4.57 +/- 1.3 l/min/m2), LV mass (140 +/- 43 g/m2), mean aortic pressure (103 +/- 20 mm Hg), and LV stroke work index (72 +/- 30 g X m/m2) were significantly elevated while stroke index, heart rate, LV ejection fraction, maximum dP/dT, LV end-diastolic volume and LV end-diastolic pressure were normal. The hemodynamic changes did not correlate with the time on maintenance dialysis nor with the duration of treatment for hypertension. Patients with CAD had higher LV mass and mean aortic pressure than those without CAD. The cardiac changes are thought to result from a combination of pressure and volume loads and anemia.

Adult↗
PubMed1983

Arterial pressure and hormone relationships in phaeochromocytoma.

To investigate the regulation of arterial pressure and vasoactive hormones in phaeochromocytoma, we measured intra-arterial pressure and hourly venous hormones (renin, angiotensin II, aldosterone, catecholamines and cortisol) for 24 h in two patients before and three months after removal of a catecholamine-secreting tumour. Before surgery, plasma catecholamines, renin and angiotensin II levels showed a weak inverse correlation with arterial pressure, whereas after surgery norepinephrine-blood pressure correlations were close and positive. Heart rate and arterial pressure fluctuations were reciprocal during short-term recordings but were parallel after removal of the tumour. Renin, angiotensin II and aldosterone levels, initially elevated, fell into the normal range after surgery. Circulating norepinephrine correlated in a positive fashion with renin before and after operation. Slopes of log renin (or angiotensin II)/aldosterone, and log cortisol/ aldosterone regression lines were steeper in the initial study compared to the second. We conclude that arterial pressure fluctuations measured hourly are not determined by concurrent levels of catecholamines or angiotensin II in phaeochromocytoma, although we surmise that minute-by-minute changes in blood pressure are catecholamine-related. Renin release is, at least in part, controlled by circulating catecholamines. Aldosterone responsiveness to angiotensin II and to ACTH is enhanced in phaeochromocytoma.

Adrenal Gland Neoplasms↗
PubMed1983

Cytomegalovirus (CMV) antibody in male homosexuals: a source for CMV immune globulin.

Male homosexuals have been found to have an extraordinarily high prevalence, and high titers, of antibodies to cytomegalovirus (CMV), as determined by complement-fixation and passive hemagglutination tests. These findings support other data suggesting that CMV may be sexually transmitted. The high titers of CMV antibody found in this population suggest that the homosexual population may be a valuable source of plasma for preparations of CMV immune globulins. CMV immune globulins may be useful in passive immunoprophylaxis or immunotherapy in immunosuppressed patients.

Antibodies, Viral↗
PubMed1983

Haemodynamic, hormonal, and electrolyte effects of enalapril in heart failure.

Enalapril, the new converting enzyme inhibitor, was administered to eight patients with heart failure (NYHA Functional Class II to IV) during standardised and intensive haemodynamic, hormone, and electrolyte monitoring. The first dose (5 mg) of enalapril induced a fall in plasma angiotensin II and noradrenaline levels, and prolonged decrements in systemic vascular resistance, arterial pressure, heart rate, and right heart pressures. Maximum haemodynamic effects were evident four to eight hours after the first dose, with return to baseline by 24 hours. Plasma angiotensin II levels, however, were still suppressed at 24 hours. The magnitude of haemodynamic response was related closely to baseline (pre-enalapril) activity of the renin-angiotensin system and the sympathetic system. Enalapril treatment over three days induced a positive cumulative balance of sodium and potassium, and a small increase in plasma potassium. Urine aldosterone excretion decreased in a stepwise fashion. Continued enalapril administration for four to eight weeks resulted in improved clinical status (NYHA Functional Class) and exercise tolerance in patients who initially were most severely incapacitated, but little change was observed in healthier subjects. We conclude that in heart failure, enalapril is a long acting converting enzyme inhibitor with clear cut beneficial haemodynamic effects in the short term. Long term controlled studies of enalapril in heart failure are warranted.

Aged↗