Effects of red rest and prazosin in congestive heart failure

Hemodynamic effects at rest and during exercise in long-term treatment with prazosin in chronic congestive heart failure

The long-term effects of prazosin in chronic congestive heart failure were studied in 10 patients (New York Heart Association class III-IV) in a double-blind cross-over study. Patients with systolic blood pressure greater than 120 mmHg and left ventricular filling pressure greater than 15 mmHg were included. Prazosin lowered the arteriovenous oxygen difference both at rest and during exercise (p less than 0.05), increased cardiac index (p less than 0.01) and reduced right atrial pressure and systemic vascular resistance (p less than 0.05) during exercise. Left ventricular filling pressure was also reduced, but not significantly, during exercise. Our data show that prazosin has beneficial long-term effects during exercise in patients with chronic congestive heart failure.

Effects of isosorbide dinitrate on electrocardiography, hemodynamics, and ventilation in patients with exercise-induced elevation of pulmonary artery wedge pressure

BACKGROUND

The mechanisms underlying exertional hyperpnea in patients with coronary artery disease and transient left ventricular dysfunction are still not fully understood.

HYPOTHESIS

The study was undertaken to investigate whether the ventilatory response to exercise reflects the effects of acute medical treatment of exercise-induced left ventricular dysfunction, and to evaluate mechanisms relevant to excessive exertional ventilation.

METHODS

In 11 male patients, aged 65.2 +/- 6.0 years, all with pulmonary artery wedge pressure (PAWP) > 25 mmHg and ST depression > 2 mm during moderate supine exercise, ventilation (V), oxygen uptake (VO2), hemodynamics, electrocardiogram (ECG), and arterial and mixed venous blood gases were examined during supine rest and exercise, before and at hourly intervals after peroral intake of 30 mg isosorbide dinitrate (ISDN). Six similar patients were examined with the same protocol without ISDN administration and comprised a control group.

RESULTS

Before administration of ISDN, exercise PAWP was 35.3 +/- 5.9 mmHg, ECG showed 2.77 +/- 1.06 mm ST depression, and V/VO2 was 31.8 +/- 4.8 l/l. One h after ISDN administration, exercise mean PAWP was 11.0 +/- 2.5 mmHg (p < 0.001), ST depression 0.59 +/- 0.8 mm (p < 0.001), whereas V/VO2 was unchanged, 30.1 +/- 5.3 l/l. Two h later, PAWP remained reduced and there were only minor ST depressions, while V/VO2 remained high. Exercise cardiac index (CI) and mixed venous oxygen tension (PvO2), initially 4.7 +/- 0.67 l/min/m2 and 3.54 +/- 0.35 kPa, respectively, remained at the same low level throughout the study. In the six nontreated patients, there were no significant changes in ST depression, exercise PAWP, or exertional ventilation.

CONCLUSION

Isosorbide dinitrate treatment markedly improved exercise-induced left heart dysfunction, whereas excessive ventilatory response was unaffected, even after 3 h. Thus, measurements of the exercise hyperpnea did not properly reflect effective reduction of myocardial ischemia.

Short-term effects of eating on vasoactive hormones and haemodynamics in patients with heart failure

OBJECTIVES

To investigate if eating can influence the measurements of vasoactive hormones or their relationship to important haemodynamic variables.

DESIGN

Haemodynamic variables and plasma concentrations of atrial natriuretic peptide (ANP), arginine vasopressin and angiotensin enzyme (ACE) activity were measured. During the 24-h study period the patients ate ordinary hospital meals and thus were studied both in the absorptive and post-absorptive phases.

SETTING

Two university hospitals in Sweden participated in the study.

SUBJECTS

Ten patients with heart failure, due to ischaemic heart disease.

INTERVENTION

Eating.

MAIN OUTCOME MEASURES

Change in haemodynamic variables and plasma concentrations of vasoactive hormones related to eating.

RESULTS

After a meal (absorptive phase) pulmonary capillary wedge pressure and plasma concentrations of ANP were significantly lower compared to the postabsorptive phase, 13 +/- 1.7 vs. 16 +/- 1.9 mmHg and 57 +/- 9.5 vs. 72 +/- 12.2 pmol l-1, respectively. The relationship between ANP and its main predictor, pulmonary capillary wedge pressure, was not altered during the study period. Plasma concentration of arginine vasopressin, ACE activity and mean right atrial pressure decreased with time and the cardiac index increased with time over the study period.

CONCLUSIONS

A meal may significantly influence plasma concentrations of ANP. Studies on vasodilator treatment and its interactions with ANP should take account of these basal fluctuations. The present data confirm previous reports on haemodynamic improvement during the first 24 h of supine cardiac catheterization in patients with heart failure, and add new information about decreasing concentrations of arginine vasopressin and ACE.

Acute hemodynamic, hormonal and electrolyte effects of ramipril in severe congestive heart failure

The response to ramipril, 10 and 20 mg on consecutive days, in 9 patients with severe (New York Heart Association functional class III or IV) chronic congestive heart failure was measured. Hemodynamic cannulae were placed more than 2 days before ramipril administration to ensure a stable baseline. Dietary sodium (40 mmol daily) and potassium (80 mmol daily) were constant before and during the study, and maintenance doses of digoxin and furosemide (80 to 1,000 mg daily) were continued unchanged. Ramipril induced pronounced, sustained decreases in angiotensin converting enzyme activity, angiotensin II and aldosterone levels, and a reciprocal increase in plasma renin activity. Plasma catecholamines, antidiuretic hormone and cortisol levels were not altered. Urinary sodium and potassium excretion diminished, plasma sodium decreased and plasma potassium increased. Plasma urea and creatinine levels increased. Ramipril treatment resulted in a decrease in systemic arterial pressure that was sustained for 24 hours, a decrease in heart rate and an increase in cardiac index, but little change in pulmonary artery pressure or right atrial pressure. Three patients were drowsy after ramipril administration, and 1 patient had a marked, temporary reduction in urine output. It was concluded that ramipril is a potent, long-acting angiotensin converting-enzyme inhibitor that is likely to be beneficial in patients with severe cardiac failure.

Comparative hemodynamic and clinical effects of long-term treatment with prazosin and captopril for severe chronic congestive heart failure secondary to coronary artery disease or idiopathic dilated cardiomyopathy

Short- and long-term hemodynamic and clinical responses to sequential therapy with prazosin (15 mg/day for 3 to 12 weeks) and captopril (75 to 300 mg/day for 2 to 15 weeks) were compared in 22 patients with severe chronic congestive heart failure. First doses of prazosin produced marked increases in cardiac index and stroke volume index (p less than 0.01), but these effects were lost during long-term treatment. First doses of captopril produced only modest increases in both variables, but these persisted without attenuation during prolonged therapy. Both drugs produced immediate decreases in left ventricular filling pressure, mean arterial pressure, mean right atrial pressure and systemic vascular resistance; these changes became significantly attenuated (p less than 0.01) with prazosin but not with captopril. At the end of treatment, stroke volume index was significantly higher and right and left ventricular filling pressures were significantly lower with captopril than with prazosin (p less than 0.05 to 0.01). Only 8 of the 22 patients (36%) treated with prazosin benefited clinically, whereas 14 of 19 patients (74%) treated with captopril felt that they had improved (p less than 0.05). These differences could not have been predicted by comparing responses to first doses of the 2 drugs. These findings indicate that the choice of 1 vasodilator drug over another in patients with congestive heart failure should be based on studies that compare their long-term rather than short-term hemodynamic and clinical effects.

Role of the renin-angiotensin system in the development of hemodynamic and clinical tolerance to long-term prazosin therapy in patients with severe chronic heart failure

Right heart catheterization was performed before and during long-term therapy with prazosin in 27 patients with severe chronic heart failure who underwent serial hemodynamic studies during 3 to 12 weeks of treatment with the drug. Doses of digoxin and furosemide remained constant during the trial; in addition, 11 of the 27 patients were assigned to concomitant therapy with spironolactone, while the remaining 16 patients did not receive the aldosterone antagonist. First doses of prazosin produced marked increases in cardiac index and marked decreases in mean arterial pressure, left ventricular filling pressure and systemic vascular resistance in both groups of patients (all p less than 0.01), but these effects became rapidly attenuated (p less than 0.01) in both groups after 48 hours and remained attenuated during long-term therapy. After 3 to 12 weeks, values for cardiac index returned to pretreatment levels and did not decrease when the drug was withdrawn; values for mean arterial pressure, left ventricular filling pressure and systemic vascular resistance remained significantly decreased (although attenuated) after 3 to 12 weeks (p less than 0.01) and increased to pretreatment values when the drug was withdrawn. The magnitude and time course of these responses were not altered by concomitant therapy with spironolactone. Complete loss of hemodynamic efficacy (prazosin tolerance) was noted in 14 (58%) of the 24 patients who underwent long-term hemodynamic study and was not accompanied by long-term changes in plasma renin activity or body weight. These data indicate that prazosin produces long-term hemodynamic and clinical benefits in only 30 to 40% of patients with severe chronic heart failure and do not support a role for the renin-angiotensin system in the development of tolerance to alpha-adrenergic blockade. This low response rate explains why most randomized double-blind trials of prazosin in heart failure have not been able to demonstrate a significant difference between patients treated with placebo and those receiving active drug.

The immediate haemodynamic and electrophysiological response to prenalterol during fixed rate pacing in patients with chronic ischaemic heart disease

The immediate haemodynamic and electrophysiologic effects of intravenous prenalterol 2.5-75 micrograms/kg in patients with coronary heart disease without clinical heart failure were investigated during fixed rate atrial pacing. Right ventricular peak dP/dt increased pronounced and serum concentration dependent after prenalterol concomitant with an increase in stroke volume and a moderate decrease in peripheral vascular resistance. The effects on haemodynamics after prenalterol were thus serum concentration dependent but with marked interindividual variation. AV nodal conduction velocity increased significantly. It is concluded that prenalterol possess pronounced inotropic properties. The haemodynamic response to prenalterol intravenously is to a lesser degree dependent on the chronotropic effects of the drug and it is often unpredictable.

Stability and inter-relationships of hormone, haemodynamic and electrolyte levels in heart failure in man

Relationships between clinical status, haemodynamic measurements, hormone and biochemical indices, and maintenance diuretic dose in patients with chronic cardiac failure, are not clear. This study assessed such relationships and their stability under standardized conditions in 21 hospitalized patients. The daily maintenance dose of frusemide correlated closely and in a positive fashion with plasma levels of renin activity, angiotensin II and aldosterone (P less than 0.001), and to a lesser extent with plasma noradrenaline. Although there was some overlap, patients most incapacitated by their heart failure had the highest circulating levels of renin activity, angiotensin II, aldosterone and noradrenaline. Plasma aldosterone correlated closely with concomitant angiotensin II levels (r = 0.70, P less than 0.001) but not with its other secretagogues ACTH (as reflected by plasma cortisol) or plasma potassium. Close positive correlations between angiotensin II and plasma levels of urea and creatinine (P less than 0.01) were observed. Both renin and angiotensin II showed positive relationships with right heart pressures, but were inversely related to cardiac index and arterial pressure. These results show close relationships between clinical and haemodynamic indices on one hand, and hormones on the other. The renin-angiotensin system appears to be the primary regulator of aldosterone under these conditions, and its activity relates closely to haemodynamic measurements and to the degree of azotaemia.

Acute and long-term response to enalapril in congestive failure

Enalapril, a novel long acting angiotensin converting enzyme (ACE) inhibitor, was given orally to 12 patients with chronic heart failure (NYHA functional class III and IV) and cardiomegaly. The optimal dose averaged 17 mg given once-daily. Heart rate, systemic arterial blood pressure, pulmonary arterial pressure, right and left ventricular filling pressures and cardiac index were monitored during dose efficacy titration. Eleven patients were recatheterised 3 months later. After stabilisation of cardiac filling pressures, all patients had left ventricular filling pressures in excess of 20 mmHg. Enalapril increased cardiac index acutely by 34% but at 12 weeks follow-up, cardiac index was not different from control levels. Left ventricular filling pressure was reduced acutely by 36% and by 41% at 3 months. Heart rate, systemic arterial and right atrial pressures and plasma concentrations of aldosterone were reduced during the observation period. ACE activity was inhibited at the time of peak haemodynamic effect from 25.3 +/- 9.8 to 4.9 +/- 3.4 U/ml (P less than 0.01). Renin was markedly elevated. These changes were accompanied by marked and sustained clinical improvement and subjective well-being.