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Biomedical subjects

D V Unverferth

Publications and source records attributed to D V Unverferth.

116 records · Page 7Linked to original sources
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The hemodynamic effects of ibopamine, a dopamine congener, in patients with congestive heart failure.

Ten patients with congestive heart failure underwent noninvasive and invasive hemodynamic testing before and sequentially after the administration of ibopamine to determine the cardiovascular effects of this oral dopamine congener. Single doses of 200, 400 and 600 mg were administered to all patients and 5 repeated doses of 200 or 400 mg were studied in 8. Hemodynamic effects occurred as early as 30 minutes and lasted up to 4 hours after dosing. In general, ibopamine elicited statistically significant dose-related increases in cardiac output and reductions in the derived resistance of the systemic and pulmonary circulations. A biphasic response in central and peripheral pressures was observed; up to 1 hour after administration, ibopamine elevated mean right and left atrial pressures and pulmonary and systemic arterial pressures with a significant reduction of these measurements beyond 1 hour. It did not alter heart rate. Repeated doses qualitatively affected hemodynamics similar to the initial dose and did not appear to be accompanied by short-term tolerance. While oral ibopamine elicits some favorable hemodynamic effects in humans with cardiac failure, the biphasic hemodynamic response is generally undesirable in the majority of these patients.

Adult↗
PubMedDate not supplied

The dopamine congener, ibopamine, in congestive heart failure.

The hemodynamic effects of the dopamine congener, ibopamine, were investigated in nine patients with chronic congestive heart failure. A placebo-controlled design was utilized. Placebo and ibopamine in doses of 100, 200, and 300 mg were given orally as a single dose to each patient on 4 successive days. Dopamine at 1, 2, 4, and 6 micrograms/kg/min intravenously, was used as an internal standard. Ibopamine did not significantly change heart rate, systemic and pulmonary arterial pressures, pulmonary capillary wedge pressure, or mean right atrial pressure. Significant decreases of systemic arterial resistance (19%) and total pulmonary arterial resistance (21%), and significant increases of cardiac index (20%) and stroke volume index (16%) were elicited by ibopamine at doses of 200 and 300 mg. Peak effects occurred at 1 to 2 h with a duration of action of less than 4 h. The 2 changes were comparable with those obtained by dopamine 2-4 micrograms/kg/min. Except for mild changes at 30 min postdosing, the inotropic indices of the systolic time intervals were not altered significantly by ibopamine. Ibopamine elicits significant hemodynamic effects in patients with chronic congestive heart failure; in large part, these effects appear to be mediated through vasodilatory properties rather than direct positive inotropy.

Adult↗
PubMedDate not supplied

Electrophysiological effects of cyclic GMP on canine cardiac Purkinje fibers.

The effect of cyclic 3'5'-guanosine monophosphate (8-bromo-cGMP) on action potential characteristics was investigated. Standard microelectrode techniques were used to study the effects of 8-bromo-cGMP on canine cardiac Purkinje fibers in vitro. Canine Purkinje fiber tissue preparations were exposed to increasing concentrations of 8-bromo-cGMP (10(-6), 10(-5), 10(-4) M). The action potential duration at 50% (APD50) and 90% (APD90) repolarization, resting membrane potential (RMP), action potential amplitude (APA), rate of rise of phase 0 (Vmax), spontaneous rate (SR), escape time (ET), and effective refractory period (ERP) did not change at these concentrations of 8-bromo-cGMP. The effect of 8-bromo-cGMP on isoproterenol (10(-7) M) treated Purkinje fibers was tested. Predictably, isoproterenol shortened APD and ERP and increased SR. APD or ERP shortening was not affected by 8-bromo-cGMP, but the increase in SR produced by isoproterenol was prevented. Eleven of sixteen Purkinje fiber preparations treated with isoproterenol alone became spontaneously arrhythmic, whereas none of six treated with 8-bromo-cGMP and isoproterenol became arrhythmic (p less than 0.05). Slow-response action potentials elicited by potassium depolarization and catecholamines were abbreviated and eventually abolished by 8-bromo-cGMP. In conclusion, 8-bromo-cGMP has no effect on action potential characteristics in normally polarized canine Purkinje fibers but depressed slow response action potentials. The effects of isoproterenol on SR are antagonized and the production of arrhythmias in this model are prevented by 8-bromo-cGMP.

Action Potentials↗
PubMedDate not supplied

Regional hemodynamic effects of clonidine in congestive heart failure.

Regional and central hemodynamic variables were ascertained in 10 patients with congestive heart failure before and after the oral administration of clonidine. Following the 0.2 mg dose, renal, hepatic, and limb blood flow remained unaltered, whereas a reduction was noted in heart rate (10%), mean systemic (14%), and pulmonary capillary wedge pressures (27%). Cardiac index and systemic vascular resistance fell slightly, however the changes were not statistically significant. Higher dose clonidine (0.4 mg) elicited similar regional hemodynamic effects whereas systemic vascular resistance significantly diminished (21%) and cardiac index remained unchanged. In congestive heart failure, the central antihypertensive agent, clonidine, effects a significant reduction in preload (left ventricular filling pressure) and afterload (systemic blood pressure) without markedly altering other central and regional hemodynamic variables.

Adult↗
PubMedDate not supplied

Reiter's aortitis with pericardial fluid, heart block and neurologic manifestations.

A man who presented with Reiter's triad and keratoderma blenorrhagicum followed by cardiac manifestations is reported. He developed mild aortic insufficiency, A-V block and pericardial effusion. Painful ophthalmoplegia occurred 5 months later with exacerbation of the cardiac complications as corticosteroids were being tapered. Retreatment with high dose corticosteroids resulted in a remarkable remission of the neurologic complications and stabilization of his cardiac manifestations now maintained for 3 years.

Adrenal Cortex Hormones↗
PubMedDate not supplied

The relationship between drug-induced changes in central and regional hemodynamics in congestive heart failure.

Sixty-one patients with moderate to severe congestive heart failure underwent simultaneous central and regional hemodynamic measurements before and after the intravenous or oral administration of one of a number of vasoactive agents including nitroglycerin, nitroprusside, isosorbide dinitrate, hydralazine, prazosin, clonidine, indoramin, and nifedipine. The relationship between changes in cardiac output and concomitant changes in regional (limb, hepatic, and renal) blood flow was determined and analyzed. For the entire population, the aforementioned vasoactive drugs (as a group) effected changes in regional blood flow which correlated poorly with changes in cardiac output; the correlation coefficient (r) between changes in cardiac output and limb blood flow was 0.16 (p = NS), hepatic blood flow 0.04 (p = NS), and renal blood flow 0.42 (p less than 0.05). When individual drugs were analyzed, only hydralazine's alterations in renal blood flow corresponded to simultaneous changes in cardiac output (r = 0.81, r2 = 0.65, p less than 0.05). The results of this study well demonstrate the complex pathophysiologic mechanisms which determine the distribution of blood flow in congestive heart failure, and the wide individual variability of hemodynamic responses to most vasoactive agents.

Adult↗
PubMedDate not supplied

Human myocardial morphologic and functional changes in the first 24 hours after doxorubicin administration.

The purpose of this study was to document early structural changes in the human heart after the initial administration of doxorubicin. Endomyocardial biopsies were performed at baseline and at 4 and 24 hours after doxorubicin administration to 13 patients. Morphometric analysis of electron micrographs (x 31,200) quantitated mitochondrial and tubular sizes (sarcoplasmic reticulum and T tubules). The mitochondrial size increased from 0.25 +/- 0.01 mu 2 (mean +/- SE) at baseline to 0.27 +/- 0.03 mu 2 (not significant [NS]) at 4 hours and 0.30 +/- 0.03 mu 2 (NS) at 24 hours. The tubular size increased from 2.24 +/- 0.13 x 10(4) nm2 at baseline to 2.60 +/- 0.26 x 10(4) nm2 (P less than 0.05) at 4 hours and 2.46 +/- 0.29 x 10(4) nm2 (NS) at 24 hours. Micrographs analyzed for nuclear changes showed nucleolar contraction and segregation of granular and fibrillar components. These changes were noted in five of ten patients at 4 hours and in eight of 13 patients at 24 hours. Serial echocardiographic and systolic time interval determinations of left ventricular function demonstrated a significant improvement at both 4 and 24 hours. In conclusion, doxorubicin has its most significant effect on tubular structures. Left ventricular function improved during this time despite these findings.

Adult↗