A possible mechanism for "tachyphylaxis' to prazosin in heart failure.
Explore the source record for details and available documents.
Biomedical subjects
Publications and source records attributed to H Ikram.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
Eight patients with primary hepatocellular carcinoma (PHC) whose blood was positive for hepatitis B surface antigen (HBsAg) received treatment with cyclophosphamide, adriamycin, and 5-fluorouracil. In 4 cases, a rise in serum HBsAg titer occurred after chemotherapy. In 2 cases involving drug-related leukopenia, the rise in HBsAg titer was marked and associated with a sharp rise in the serum transaminase level (SGOT), up to 1700 in 1 case. Lower-dosage chemotherapy was safely resumed after SGOT had returned to pretreatment levels. No evidence of immunodeficiency after chemotherapy was revealed by in vitro testing of lymphocyte and granulocyte function, percentage of circulating T-cells, and immunoglobulin and complement levels. All 8 cases were negative for e antigen (eAg) and 4 were anti-positive. In 3 of 4 cases, anti-e became negative after chemotherapy, but all remained eAg negative. The negative eAg tests in these cases of PHC suggest they are not highly infectious, in spite of increased HBsAg titers in blood following chemotherapy.
The administration of beta-receptor blocking drugs and antiarrhythmic drugs in close proximity may result in hemodynamic, electrophysiologic, or pharmacokinetic interactions. We examined the hemodynamic and electrophysiologic effects of 0.20 mg/kg intravenous metoprolol followed by a 15-minute infusion of 0.75 mg/kg/min tocainide. In the six patients sutided, metoprolol produced a fall in cardiac rate and output which was not further altered by tocainide. Both drugs decreased peak left ventricular (LV) dP/dt, ejection fraction, and mean Vcf. There was no change in LV end-diastolic pressure or echo dimension and in clinical ill effects. In eight patients without sinus A-V nodal disease electrophysiologic studies showed mild depression of A-V conduction by metoprolol. Tocainide depressed sinus node function and shortened the functional refractory period of the His-Purkinje system. There were no clinical sequelae. However, three patients with preexisting electrophysiologic abnormalities developed asystole. There was no evidence of pharmacokinetic interaction. It is concluded that metoprolol and tocainide can be given concurrently with reasonable safety to cardiac patients without electrophysiologic abnormalities.
1. Since important interrelationships between haemodynamic and hormone indices are possible in cardiac failure, measurements of cardiac output, mean pulmonary artery pressure, plasma renin activity, angiotensin II and aldosterone were carried out before and during acute and chronic frusemide therapy in patients with oedematous heart failure who had been given digoxin. 2. Cardiac output fell significantly 90 min after acute frusemide infection, then returned to baseline. Mean pulmonary artery pressure declined steadily throughout the 4 h of observation. 3. These haemodynamic changes occurred in the absence of major hormonal fluctuations and related presumably to direct vascular and diuretic actions of frusemide. 4. With more chronic (8-10 days) oral frusemide therapy, reciprocal changes between haemodynamic and hormone indices were observed. As the diuretic response to frusemide diminished, cardiac output and pulmonary artery pressure declined whereas the renin-angiotensin system was activated. Statistically significant inverse correlations were observed between these haemodynamic and hormone indices. 5. In both acute and chronic phases of the study, fluctuations in aldosterone levels were regulated by the renin-angiotensin system whereas ACTH, plasma potassium and plasma sodium played, at best, supportive roles.
A continuous multistage bicycle ergometer test was performed on 50 patients with coronary artery disease. Selective cinecoronary angiography and left ventriculography were performed within a week of the test in all patients. Overall, 62% had a positive ischemic response, defined as 1 mm or greater depression of the ST segment. Patients with 75% or greater stenosis in any vessel and those with triple-vessel involvement had a higher incidence of positive tests. Those with low systolic ejection fractions and areas of asynergy had fewer positive tests than patients with normal ejection fractions and normal or minimal segmental wall motion abnormalities. The level of exercise, location of arterial disease and the presence of collateral blood supply to the diseased vessels did not appear to influence the sensitivity of the exercise stress test.
The indirect arterial blood pressure in 50 cases of catheter-proven aortic stenosis without significant incompetence was examined. Defining the upper limit of normal blood pressure as 140/90mmHg, 14 percent had borderline, 18 percent had mild and 8 percent had severe hypertension. There was a significant positive correlation of systolic and diastolic blood pressure with age; ie pressures rose with age. The rate of increase was virtually identical with that of the normal population except for those over 70. Hypertension interferes with reliable clinical and haemodynamic quantitation of the valve lesion. The two lesions summate to increase the systolic burden on left ventricle.
1 The pharmacokinetics of two different sustained-release oral procainamide preparations were studied in ten hospital patients with normal blood ureas and no clinical evidence of heart failure. Each patient received either one or other preparation at 12 hourly intervals for four doses. Frequent blood sampling enabled close monitoring of blood levels. 2 Results showed that both preparations were essentially similar in their pharmacokinetics. Both effectively double the half-life of conventional oral procainamide to 6.5 h and are suitable as prophylactic preparations. One patient developed toxic levels, thought to be related to her metabolic status of being a very slow acetylator. To avoid toxicity pre-therapy assessment of a patient's cardiac and renal function and acetylator status is advised.
Acebutolol ('Sectral'), a cardioselective beta-blocking drug, was administered intravenously in a dose of 25 mg to 10 patients with congestive cardiomyopathy. All of them were in a stable condition on antifailure regimens. The drug resulted in a statistically significant decline in left ventricular contractility as judged by peak left ventricular dP/dT and the contractility index. The mean aortic blood pressure also fell. There was a significant increase in end-diastolic and end-systolic left ventricular volumes. Mean values for heart rate, ejection fraction, left ventricular stroke work index, and cardiac output also fell, but the results were not statistically significant. Left ventricular distensibility as judged by the slope of the diastolic pressure-volume relation also improved significantly. A reduction in myocardial energy requirements, improved compliance, and lowering of arterial pressure would be haemodynamically advantageous. However, further cardiac dilatation and reduction contractility--the basic defects in congestive cardiomyopathy--could lead to further deterioration.
Explore the source record for details and available documents.
Explore the source record for details and available documents.
HBsAg/adw was purified from 2.6 liters of pooled plasma from a single chimpanzee carrier by polyethylene glycol (PEG) precipitation followed by isopycnic and rate zonal centrifugation. The different morphological populatilons of HBsAg separated in the final rate zonal centrifugation step were combined into seven pools: two fractions rich in filaments and Dane particles, two pools composed of filaments and 20--28-nm spheres, and three fractions containing mostly 20--28-nm spheres. The purified preparations of HBsAg analyzed for normal serum protein contaminants revealed albumin and traces of IgG. The same samples analyzed after Tween-80 treatment, revealed enhanced quantitites of the previous two contaminants, and in addition, transferrin, traces of alpha2-macroglobulin, IgM, and complement (C3/C3c). The residual contaminants were mostly removed by further purification and fractionation after detergent treatment using zone convection electrofocusing and rate zonal centrifugation. Our findings indicate that conventional purification techniques will not provide preparations of HBsAg free of traces of serum protein contaminants. Many of these are released only by detergent treatments and subsequent purification. It is not yet clear whether detergents release these contaminants from the interior of the particles or from firm association or incorporation within the membranes.
Explore the source record for details and available documents.
A right ventricular artificial demand pacemaker was implanted into a 59-year-old man with supra-Hisian complete heart block. His postoperative course was complicated by Staphylococcal aureus septicemia, which was controlled with antibiotics. A year later, S. aureus was again isolated from the blood. Echocardiography showed thickening of the tricuspid valve leaflet and multiple echoes in the right atrium. Autopsy findings included tricuspid leaflet thickening and an overlying right atrial thrombus. The echocardiogram is thus useful in localizing an infected valve in bacterial endocarditis and in demonstrating the presence of the thrombus.
Haemodynamic studies were performed in 10 patients with uncomplicated thyrotoxicosis and seven with thyrotoxic cardiac failure. The cardiac output of those with uncomplicated hyperthyroidism was higher than normal at rest. After 2 mg of intravenous propranolol there was a 13% fall but the level was still higher than normal. In patients with thyrotoxic cardiac failure the resting cardiac output was normal, but it fell after propranolol by 30% to subnormal levels. In both groups there was an increase in right heart pressures and fall in the rate of increase in arterial pressure, which indicated a decrease in myocardial contractility. These results indicate that increased autonomic activity is a compensatory phenomenon in hyperthyroid heart failure and that its abolition by beta-blocking drugs has a deleterious effect on cardiac function. They are therefore contraindicated in patients with thyrotoxic heart failure.
A special-purpose calculator is described which computes the left ventricular ejection fraction and end-diastolic volume (and thus stroke and end-systolic volumes) from single-plane cineangiocardiograms. A pair of manual callipers is used to convert the length information of angiographic projections into digital form for processing by the calculator. Volumes are estimated by means of a first order numerical integration method assuming circular cross-section. The angiograms of 42 patients were analysed using both the calculator and a conventional method. The results of the 2 methods correlated very closely (r = 0.99) with a slope within 1% of unity. The calculator is suggested as a practical and cheaper alternative to computer-based systems.
Explore the source record for details and available documents.