Improvement In Cardiac Index Research Articles

Effects of captopril on pulmonary haemodynamics

The effects of oral captopril on pulmonary haemodynamics were studied in two groups of 6 patients, one of subjects with chronic respiratory failure (PaO2 52 +/- 5.1 mmHg, PaCO2 54 +/- 2.1 mmHg), and the others with chronic heart failure and high plasma renin activity. Two potential mechanisms of its actions were assessed, namely inhibition of hypoxic vasoconstriction and inhibition of the possible effects of angiotensin II on the pulmonary circulation. There were significant (p less than 0.05) decreases in mean arterial pressure, pulmonary wedge pressure and in systemic arterial resistance associated with improvement in cardiac index in both groups. In the chronic respiratory failure group there was no change in blood gases, mean pulmonary arterial pressure or pulmonary vascular resistance. An increase in driving pressure (p less than 0.05) indicated that captopril had had no effect on pulmonary haemodynamics. In chronic heart failure, mean pulmonary arterial pressure and pulmonary capillary wedge pressure were decreased by a similar extent, so that driving pressure and pulmonary vascular resistance were not changed. It is concluded that oral captopril did not inhibit hypoxic vasoconstriction, and that it modified pulmonary haemodynamics in chronic heart failure patients with high renin activity only as a consequence of reduction in systemic afterload.

DEVELOPMENTAL STUDY OF AMRINONE DISPOSITION IN INFANTS

Amrinone (AMR) is an orally effective, positive inotropic agent and vasodilator unrelated pharmacologically to other available drugs, including catecholamines and cardiac glycosides. Clinical studies in adult subjects have demonstrated a close relationship between AMR plasma concentrations and improvement in cardiac index. The disposition of AMR was studied in 6 children (3 neonates and 3 infants <12 mo) receiving the drug for pulmonary hypertension which was unresponsive to other vasodilators. Subjects received doses of 1-3 mg/kg AMR iv and elimination kinetics were determined following the last dose. In this population the volume of distribution (1.54±.85 L/kg) and drug clearance rate (.29±.21 L/kg/h) of AMR showed marked inter-individual variability. This was attributable to increases in volume of distribution (r=.78, p<.1) and drug clearance rate (r=.91, p<.02) with age. Elimination half-life was similar in neonates (4.9±3.0 h) and infants (3.7±.8h). Hemodynamic and oxymetric data suggested that AMR produced selective although transient pulmonary vasodilitation in the infants but not in the neonates in this study. This difference in response occurred despite a trend to higher AMR peak serum concentrations in the neonatal group than in older infants (6.4±4.1 μg/ml vs. 3.5±1.8 μg/ml). Important changes in pharmacokinetic and pharmacodynamic properties of AMR occur during the first year of life and will warrant therapeutic drug monitoring of AMR and similar compounds.

The hemodynamic effects of intravenous verapamil in patients on chronic propranolol therapy

Concern exists regarding the negative inotropic and chronotropic effects of verapamil given to patients receiving chronic propranolol therapy. In order to evaluate the safety of combined therapy, the hemodynamic effects of verapamil were investigated in a group of 19 patients on chronic propranolol therapy undergoing cardiac catheterization. Hemodynamic measurements and left ventriculography were performed prior to and 30 minutes after initiation of intravenous administration of verapamil. Verapamil doses varied from 0.025 mg/kg to 0.1 mg/kg intravenous bolus injection followed by an infusion of 0.005 mg/kg/min. Following verapamil administration, systolic, diastolic, and arterial mean pressures and systemic vascular resistance decreased significantly. There was no significant change in left ventricular end-diastolic pressure, mean pulmonary capillary wedge pressure, cardiac index, arteriovenous oxygen difference, heart rate, mean velocity of circumferential fiber shortening (VCF), end-diastolic volume index, end-systolic volume index, stroke volume index, and ejection fraction (EF). Stroke work index decreased significantly. Lack of improvement in cardiac index, VCF, and EF and decrease in stroke work index in spite of constant filling pressure and decreased afterload suggest the additive negative inotropic action of verapamil. The depressant action of propranolol itself was not determined by this study. In spite of the negative inotropic effect of verapamil, it can be administered acutely to patients who have been on propranolol therapy with relative safety if the propranolol has not already produced severe left ventricualr dysfunction, relative hypotension, bradyarrhythmia, or conduction abnormalities.

Acute and long-term hemodynamic effects of oral pirbuterol in patients with chronic severe congestive heart failure: Randomized double-blind trial

In 20 patients with severe congestive heart failure (CHF), we studied the effects of the beta-adrenergic agonist pirbuterol compared to placebo in both an acute double-blind randomized trial and after long-term treatment. Acutely, pirbuterol patients (n = 10) demonstrated a significant rise in cardiac index (2.2 ± 0.14 to 3.2 ± 0.32 L/min/m 2), stroke index (26 ± 2.6 to 35 ± 2.9 ml/beat/m 2), stroke work index (22 ± 2.4 to 30 ± 2.7 gm · m/m 2), and ejection fraction (22 ± 4 to 30 ± 5%). These hemodynamic variables did not significantly change in placebo patients (n = 10). After 3 weeks of pirbuterol therapy, 14 patients (70%) were symptomatically improved and were continued on the drug for another 3 weeks; 13 of 14 patients who were symptomatically improved underwent restudy. Compared to pretreatment baseline, there was continued improvement in cardiac index (2.5 ± 0.16 to 3.2 ± 0.24 L/min/m 2), stroke index (30 ± 2.5 to 38 ± 2.9 ml/beat/m 2), stroke work index (26 ± 2.3 to 35 ± 3.1 gm · m/m 2), and ejection fraction (24 ± 1 to 28 ± 4%). Patients more frequently improved were those with nonischemic cardiomyopathy and those with higher initial ejection fractions. These results demonstrate the acute beneficial effects of oral pirbuterol versus placebo in a double-blind randomized trial. Improvement was maintained during long-term therapy in the majority of CHF patients.

Hemodynamic effect of myocardial revascularization in the impaired ventricle

The hemodynamic effect of myocardial revascularization with saphenous vein grafts (mean 3.3 per patient) was analyzed 1 year after operation in 111 patients. Operations were performed using one continuous period of aortic cross-clamping with hyperkalemic cardioplegia for distal anastomoses in 84% of patients; 16% had arrest with topical and systemic hypothermia for myocardial protection. Group I (N = 18) had normal ventricles (ejection fraction [EF] greater than 50%; left ventricular end-diastolic pressure [LVEDP] less than or equal to 12 torr); Group II (N = 64) had ischemic ventricles (EF greater than 50%, LVEDP greater than 13 torr); and Group III (N = 30) had abnormal ventricles (EF less than 50%, LVEDP greater than 13 torr). Hemodynamic measurements were obtained before and 1 year after operation. Fifteen of 18 patients (83%) in Group I did not show significant hemodynamic changes, but in three EF decreased by greater than or equal to 10% and LVEDP increased by greater than 10% over preoperative levels. In Group II, EF was unchanged or slightly better in 89% (57/64) and worse in seven patients. Improvement in cardiac index (p less than 0.01) and LVEDP (p less than 0.001) was significant. Worsening of EF in 10 of 82 patients in Groups I and II was attributed to graft closure and/or poor myocardial protection. In Group III, significant improvement in cardiac index (p less than 0.001), EF (p less than 0.001), and LVEDP (p less than 0.01) was also noted. A subset of nine patients with EF less than or equal to 35% showed postoperative improvement in 56%. Of the remaining 20 patients with an EF of greater than 35% to less than 50%, half had greater than or equal to 20% improvement in postoperative EF. Operative mortality was 3.3% (1/30) for Group III. Late mortality was 1.5% (1/64) for Group II and 10% (3/29) for Group III. Significant improvement was noted postoperatively in 67% (57/85) of all patients who had preoperative treadmill tests (p less than 0.001). This study shows that myocardial revascularization significantly improved left ventricular performance in most patients with ischemic and abnormal ventricles. Previous studies that fail to show improvement may be related to incomplete revascularization and/or poor myocardial preservation. These data, therefore, justify the need for revascularization of the impaired ventricle.

Relationship between amrinone plasma concentration and cardiac index.

Amrinone was given to 14 patients with congestive heart failure as an intravenous bolus (1 mg/sec) at doses ranging from 0.5 to 3.5 mg/kg. Simultaneous determinations of cardiac index were made by thermodilution and of amrinone plasma concentration by high-performance liquid chromatography. A relationship between improvement in cardiac index and increasing plasma concentrations of amrinone was demonstrated for 13 of the 14 patients. The percentage increase in cardiac index correlated with amrinone plasma concentration (r = 0.81; p less than 0.001). Amrinone was given to four patients as an intravenous bolus dose of 1.5 mg/kg followed by a constant infusion of 10 micrograms/kg/min for 10 hr; simultaneous determinations of cardiac index and circulating levels of amrinone indicated that both declined after the initial rise. The plasma concentration of amrinone remained relatively constant during the infusion at about 1.7 micrograms/ml. In all cases, despite the relatively constant plasma levels there was a decline in cardiac index after about 4 to 5 hr of infusion, although the cardiac index remained above the baseline; during the constant infusion the cardiac index rose again and was maintained at a reasonably constant level for the last 3 hr. Seven patients received oral doses of amrinone of about 3 mg/kg, and simultaneous determinations of cardiac index and plasma concentration showed a relationship between amrinone level and rise in cardiac index (p less than 0.05). In 16 patients after amrinone orally sufficient blood samples were taken to estimate the apparent first-order terminal elimination t 1/2. The t 1/2 as estimated by log-linear regression ranged from about 3 to 15 hr; mean +/- SEM value was 8.3 (+/- 1.1) hr.

Hemodynamics and Echocardiograms Before and After Cardioversion of Atrial Fibrillation to Normal Sinus Rhythm

Hemodynamic and echocardiographic measurements were obtained in 15 patients prior to cardioversion and immediately, one, three, and five hours after cardioversion of atrial fibrillation to normal sinus rhythm. At five hours after cardioversion, there was improvement in cardiac index (P less than 0.005), in stroke index (P less than 0.005), and in stroke work index (P less than 0.025), but no significant change in heart rate, mean pulmonary capillary wedge pressure, left atrial dimemsions (LAD), left ventricular end-diastolic dimensions (LVEDD), or left ventricular end-systolic dimension (LVESD). At follow-up one week to nine months after cardioversion, 10 of the 15 patients (67 percent) remained in normal sinus rhythm. Neither the size of the left atrium, changes in hemodynamics, LAD, LVEDD, or LVESD, nor the presence or amplitude of the A-wave on the mitral valve echogram correlated with the persistence or normal sinus rhythm.

Mitral Valve Replacement with the Modified University of Cape Town (UCT) Prosthesis: Clinical and Hemodynamic Results

Mitral valve replacement with the modified University of Cape Town prosthesis was performed in 42 patients. In 35 the procedure was an isolated one, and the hospital mortality was 6%. The late survival rate was 60%, half of the late deaths being the result of thromboembolism or complications of anticoagulant therapy. The incidence of hemolysis was low, and hemodynamic results demonstrated improvement in cardiac index and lowering of pulmonary artery pressure, pulmonary artery wedge pressure, pulmonary arteriolar resistance, and transvalvular mean gradients. However, the calculated prosthetic valve orifice area was lower than the measured area. Because of complications of thromboembolism, the high incidence of late deaths, and high transvalvular gradients, this prosthetic valve is no longer used in patients requiring mitral valve replacement.

Cardiovascular function in shock. Responses to volume loading and isoproterenol infusion.

Hemodynamic responses to volume loading with infusion of dextran-40 and myocardial stimulation with isoproterenol in 23 patients in shock from hemorrhage, trauma, or sepsis, and 10 healthy controls were studied. Responses of the control were moderate to dextran and marked to isoproterenol. Shock patients were divided into three groups according to the response of the cardiac index to dextran-40: group I, &gt;50% increase; group II, 15 to 50% increase; group III, &lt;15% increase or a decrease. The central venous pressure of patients who responded to dextran (group I) generally rose moderately and that of those who failed to respond (group III) increased without improvement of cardiac index or stroke index, suggesting myocardial failure. Group II showed cardiac improvement at the expense of marked increase in venous pressure, suggesting relative cardiac insufficiency. Group I failed to respond to isoproterenol infusion, indicating that circulatory failure primarily resulted from failure of venous return. All group III patients responded markedly to isoproterenol. It is concluded that a significant number of patients in shock from hemorrhage, trauma, and sepsis exhibit signs of cardiac insufficiency. The ability of these hearts to respond to isoproterenol suggests that depletion or altered metabolism of endogenous catecholamines in part underlies this insufficiency. Further-more, it is suggested that cardiac insufficiency may contribute to the death of a significant number of patients with severe hemorrhagic and septic shock.