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Biomedical subjects

B Pitt

Publications and source records attributed to B Pitt.

At least 235 records · Page 13Linked to original sources
PubMed1982

Hemodynamic effects of prostaglandin E1 infusion in patients with acute myocardial infarction and left ventricular failure.

Prostaglandin E1 (PGE1) has been shown to limit infarct size, improve coronary blood flow, inhibit platelet aggregation, and reduce both left ventricular (LV) preload and afterload in experimental animals. Its use in the therapy of patients with acute myocardial infarction (AMI) and congestive heart failure (CHF) has not, however, been reported. Five patients with AMI of less than 12 hours' duration and LV dysfunction were studied to assess the hemodynamic effects of IV infusion of PGE1. PGE1 in the concentration of 0.4 microgram/ml was infused at a rate of 0.003 microgram2kg/min (3 ng . kg-1 . min-1) to a maximum rate of 0.021 microgram/kg/min (21 ng . kg-1 . min-1) for a total time of up to 90 minutes. There was an insignificant increase in heart rate, with significant decreases in mean arterial blood pressure and systemic vascular resistance. Pulmonary capillary wedge pressure declined from 21 +/- 3 to 15 +/ 1 mm Hg (p less than 0.05), mean pulmonary artery pressure and pulmonary vascular resistance decreased (p less than 0.05), mean pulmonary artery pressure and pulmonary vascular resistance decreased (p less than 0.05), with increases in cardiac index from 2.38 +/- 0.08 to 2.89 +/- 0.58 L/min/m2 (p less than 0.01) and stroke volume from 51 +/- 17 to 59 +/- 20 ml/beat (p less than 0.05). No major cardiac or extracardiac side effects were encountered during PGE1 infusion. One patient had transient nausea which did not require discontinuation of the drug. PGE1 is an effective vasodilator and deserves further application in therapy for AMI patients with CHF.

Aged↗
PubMed1982

Radionuclide evaluation of postextrasystolic potentiation of left ventricular function induced by atrial and ventricular stimulation.

Postextrasystolic potentiation of left ventricular function induced by ventricular and atrial stimulation was compared in 10 patients using radionuclide ventriculography. After insertion of pacing wires, a preliminary radionuclide ventriculogram was obtained and then ventricular and atrial trigeminy was induced in random order, each with identical R-R coupling intervals, each for 6 to 10 minutes. During the stimulation studies, radionuclide data were acquired in electrocardiographic gated list mode format. Left ventricular ejection fraction and relative end-diastolic and end-systolic volume changes were measured for each reformatted composite sinus, atrial and ventricular premature beat and potentiated beat. The volume changes were normalized to the count-based values obtained for the sinus beat of the appropriate study. Postextrasystolic potentiation induced by either ventricular or atrial stimulation was characterized by similar significant increases in left ventricular ejection fraction (mean +/- standard deviation 7 +/- 3 percent, p less than 0.01 versus 7 +/- 5 percent, p less than 0.01; difference not significant [NS]) and decreases in relative end-systolic volume (-12 +/- 12 percent, p less than 0.01 versus -12 +/- 8 percent, p less than 0.01; NS) but little change in relative end-diastolic volume (+5 +/- 10 percent, NS versus +4 +/- 7 percent, NS; NS). This was despite a longer compensatory pause (1,120 +/- 220 versus 1,050 +/- 190 ms, p less than 0.01) after the ventricular premature beat. It is concluded that there is no difference in the postextrasystolic potentiation induced by atrial or ventricular premature stimulation.

Adult↗
PubMed1982

Long-term intravenous infusion of antiarrhythmic drugs using a totally implanted drug delivery system.

In vitro and in vivo testing was performed to establish the feasibility of a totally implantable pump system to deliver antiarrhythmic agents. In vitro flow characteristics suggested predictable day to day delivery with acceptably small variations in flow with changes in reservoir volume or temperature. During 3 months of in vitro testing, procainamide and bretylium were found suitable for long-term delivery. Delivery of lidocaine was limited by high viscosity and corrosion of steel elements within the pump. The pump was implanted in a subcutaneous pocket in four dogs. Procainamide (0.5 g/ml), delivered at 4 ml/day (70 mg/kg body weight per day), provided a mean steady state drug concentration of 5.3 micrograms/ml. Bretylium (50 mg/ml), delivered at 8 ml/day (13 mg/kg per day), provided a steady state concentration of 0.8 micrograms/ml (range 0.4 to 1.4). Long-term intravenous administration of therapeutic doses of bretylium and procainamide with this delivery system has been demonstrated in dogs and appears to be feasible in human subjects.

Animals↗
PubMed1982

Aortic stenosis associated with systemic lupus erythematosus.

Hemodynamically significant valvular lesions have been rarely reported sequelae of Libman-Sacks endocarditis complicating systemic lupus erythematosus (SLE). Furthermore, embolic phenomena associated with these vegetations have not been clearly documented. We present a report of critical aortic stenosis associated with SLE in a patient who had received corticosteroid treatment for several years. An embolus, histologically identical with the aortic valve vegetation, was found in the left anterior descending artery at necropsy. There was no evidence of rheumatic heart disease, bacterial endocarditis or a bicuspid aortic valve. Recent reports suggest an increased incidence of significant valvular dysfunction in patients with SLE who have received long-term corticosteroid treatment.

Adult↗
PubMed1982

Vascular reactivity and high dietary eicosapentaenoic acid.

Epidemiologic studies suggest that high dietary intake of eicosapentaenoic acid (EPA), a precursor of the trienoic prostaglandins, is associated with a low incidence and reduced extent of myocardial infarction. Vascular reactivity of isolated aortic strips from rats maintained for 3 weeks on a control diet or on a diet supplemented with menhaden fish oil (17% EPA) was examined with norepinephrine, sodium arachidonate, KC1, PGF2 alpha and nitroprusside. Aortic strips from rats fed the fish oil diet were significantly less responsive to the contractile effects of norepinephrine and arachidonate compared to those from control diet rats. Treatment of aortic strips with indomethacin decreased responsiveness to norepinephrine. The magnitude of the decrease was greater in control rats resulting in a similar vascular response between the 2 groups after blockade. Contractions to arachidonate were abolished by indomethacin. There were no differences in vascular responses to KC1, PGF2 alpha and nitroprusside in aortic strips from control diet rats and those from the fish oil diet rats. Aortic strips from the fish oil diet rats contained more EPA than those from the control diet rats. Thus, the contractile effect of norepinephrine in isolated rat aortic strips is normally augmented by intrinsic prostaglandins, and this augmentation is diminished by dietary intake of EPA.

Animals↗
PubMed1982

The determination of the post-test likelihood for coronary disease using Bayes Theorem.

This report describes a method of using Bayes Theorem for determining the post-test likelihood for coronary disease from the exercise test. The pre-test likelihood is determined from the age, sex, and type of chest pain. Discriminant analysis of the amount of S-T depression, maximum pressure rate product and sex of the patient is then used to determine the sensitivity and specificity of the patient's exercise test for coronary artery disease. The post-test likelihood for coronary artery disease can then be calculated using Bayes Theorem. The discriminant function was estimated from a training set of 174 patients. This was then applied to 113 new patients who had both exercise tests and coronary arteriograms. In this new set, 47 patients had a post-test likelihood of 90% or greater for coronary disease. Only one of these patients had normal coronary arteriograms, a predictive accuracy of 98%. Of the 25 patients with a post-test likelihood of 10% or less for coronary disease, four had multivessel disease and four had single vessel disease. The predictive accuracy for the absence of coronary disease was 68%. The predictive accuracy for the exclusion of multivessel disease was 84%. Eight of 10 patients with left main disease had a post-test likelihood for coronary disease of greater than 90%.

Age Factors↗
PubMed1982

Scintigraphic demonstration of ventriculo atrial conduction in the ventricular pacemaker syndrome.

A patient with the sick-sinus syndrome was evaluated because of symptomatic deterioration after insertion of a ventricular demand pacemaker. Clinical features of the ventricular pacemaker syndrome were recognized and confirmed by electrophysiological and hemodynamic studies. Phase analysis--a new technique for detecting patterns of cardiac emptying from gated cardiac blood-pool scintigrams--demonstrated a pattern consistent with 1:1 ventriculo-atrial conduction. Phase analysis of the gated cardiac blood-pool scintigram may be useful in the assessment of patients with ventricular demand pacemakers who complain of fatigue and effort intolerance.

Aged↗
PubMed1981

Oral flecainide acetate for the treatment of ventricular arrhythmias.

The antiarrhythmic efficacy and safety of oral flecainide acetate were assessed during a controlled, short-term dosage-maintenance study. Thirteen patients with chronic ventricular ectopy entered a placebo control period, and 11 with persistent, frequent (greater than 600 per 12 hours) premature ventricular complexes (PVCs) advanced to drug therapy. Of 10 patients completing a trial of different doses, nine responded completely, with a mean PVC suppression of 98,3 per cent. Repetitive PVCs were eliminated. The mean effective dose was 189 mg per 12 hours, and the effective plasma concentration before administration of a dose averaged 635 ng per milliliter. One patient responded partially (68 per cent of PVCs suppressed). Flecainide continued to be effective and well tolerated at the end of a two-week outpatient trial in the nine complete responders, maintaining an average PVC suppression of 94.6 per cent. The PR and QRS intervals were mildly prolonged. The echocardiographic ejection fraction was unchanged during treatment. The elimination half-life was long - 18.8 +/- 3.8 hours. Flecainide thus appears to be a highly effective and well-tolerated antiarrhythmic agent with favorable pharmacokinetics.

Administration, Oral↗
PubMed1981

Hemodynamic effects of intravenous prenalterol in severe heart failure.

Nine patients with chronic severe low output heart failure (radionuclide left ventricular ejection fraction 17 +/- 5 percent [mean +/- standard deviation], left ventricular filling pressure 26 +/- 6 mm Hg, cardiac index 1.9 +/- 0.4 liters/min per m2, left ventricular stroke work index 18 +/- 6 g-m/m2) from various causes were treated with intravenous prenalterol (a new catecholamine-like inotropic agent) in doses of 1,4 and 8 mg. Significant hemodynamic improvement occurred as measured by increased left ventricular ejection fraction (to 26 +/- 4 percent), decreased left ventricular filling pressure (to 21 +/- 8 mm Hg) and increased cardiac index (to 2.4 +/- 0.6 liters/min per m2) and left ventricular stroke work index (to 25 +/- 8 g-m/m2). Significant increases in heart rate (from 87 +/- 18 to 91 +/- 18 beats/min) and mean systemic arterial pressure (from 87 +/- 8 to 92 +/- 7 mm Hg) also occurred. Peak hemodynamic response occurred at various doses. Significant adverse effects associated with prenalterol consisted of increased ventricular ectopic beats in two patients and asymptomatic ventricular tachycardia in two patients. Thus, intravenous prenalterol produces hemodynamic improvement in patients with a chronic severe low output state but may be associated with increased ventricular ectopic activity.

Aged↗