Vasodilator drug therapy in congestive heart failure

Variants of cardiomyopathic heart pathomorphogenesis. comparison of echocardiographic and endomyocardial biopsy findings

The main variants of cardiomyopathies (undifferentiated, dilatational, hypertrophic, and restrictive) were distinguished using a complex pathomorphological analysis of 600 cardiomyopathic hearts detected in 5000 autopsies after cardiovascular death. The main pathomorphological diagnostic criteria for each variant were defined. High diagnostic value of lifetime echocardiographic diagnosis in comparison with myocardial biopsy was shown. The informative value of endomyocardial biopsy in cardiomyopathic heart is higher, if the method is combined with clinical examinations, noninvasive and invasive studies.

The management of heart failure and the scope for new therapies: what role for xamoterol?

1. Current therapy of heart failure leaves much to be desired. Not all patients respond, and many agents lose their effects with time. 2. Newer agents may be effective but toxic, and some which have a beneficial action when given intravenously have proved disappointing when used orally. 3. The value of digoxin in patients in sinus rhythm is open to debate, and diuretics, although useful acutely in reducing fluid overload, do not appear to improve prognosis. 4. Vasodilators increase effort capacity and reduce symptoms, possibly conferring some long-term benefit, and angiotensin converting enzyme (ACE) inhibitors improve symptoms and decrease mortality in a wide range of patients. 5. Positive inotropes may be effective in the short term, but they increase myocardial oxygen demand and show tachyphylaxis with no prognostic benefit. 6. Xamoterol (Corwin, Carwin, Corwil, Xamtol, ICI 118,587) is a partial sympathetic agonist with approximately 50% of the activity of a pure agonist, which provides inotropic support at rest, and protection against excess sympathetic activity on exercise. 7. It is compatible with other therapies and has shown no serious toxicity. 8. It should be considered at present as an adjunct to diuretic and/or ACE inhibitor therapy, although it may be useful alone; its role will become clearer as its effects on mortality are established.

Serial evaluation of left ventricular function in congestive heart failure by measurement of peak aortic blood acceleration

Peak acceleration of blood in the ascending aorta, an index of global systolic left ventricular (LV) function, can be measured noninvasively using a continuous wave Doppler velocimeter applied suprasternally. The feasibility of this approach as a tool for detecting improvement of LV function was studied in 16 patients with congestive heart failure (CHF). Measurements were made daily for 6 consecutive days. The daily variability of peak acceleration examined in 11 normal subjects was +/- 2 m/s/s. In 11 of 16 patients with CHF, peak acceleration increased more than 2 m/s/s by day 6 compared with day 1 (group 1). In 5 of 16 patients, peak acceleration remained unchanged (group 2). In group 1, peak acceleration was 11 +/- 1 m/s/s on day 1 and increased to 16 +/- 1 m/s/s on day 6 (p less than 0.001). In this group, CHF resolved by day 6 in 9 of 11 patients. In group 2, peak acceleration was 9 +/- 1 m/s/s on day 1 and remained unchanged through day 6. In these 5 patients, the signs and symptoms of CHF persisted through day 6. The results suggest that peak acceleration measured noninvasively with continuous wave Doppler can detect improvement of LV function in patients with CHF. The approach provides a simple and reliable bedside means for serial evaluation of LV systolic function.

Analysis of the efficacy of the new cardiotonic agent TA-064

TA-064 is a new cardiotonic agent which is also effective orally, according to investigations conducted in Japan. We analyzed computer-assisted alterations of pressure-volume relationships serially and of indirect myocardial oxygen consumption (MVO2) estimations on line during TA-064 influence in 16 patients with congestive cardiomyopathy: left ventricular function was moderately decreased in seven patients (group A) and drastically decreased in nine (group B). Results showed that TA-064, 8 micrograms/kg/min intravenously, exerted positive inotropic effects in both groups and induced mean maximal delta percentage changes at about 5 minutes of infusion as follows: left ventricular stroke work index +65% and +47%; dP/dtmax +61% and 59%; left ventricular efficiency +62% and 53%; MVO2 +31% and +11% (p less than 0.05). TA-064, 20 mg by mouth induced serum levels (group A = 23.8 +/- 12ng/ml and group B = 26.4 +/- 20 ng/ml) corresponding to the effects with dosages of 1 to 2 ng/kg/min intravenously (p greater than 0.05), thus implying that significant changes in left ventricular function require higher oral dosages. We conclude that TA-064 improves left ventricular function, primarily via a contractility increase, also in group B patients without toxic side effects. On-line indirect MVO2 assessment and analysis of serial pressure-volume relationships helped to provide a more complex definition of the mechanism and efficiency of the cardiotonic agent under study.

Positive inotropic and vasodilator effects of MDL 17,043 in patients with reduced left ventricular performance

To assess the potential positive inotropic properties of the drug MDL 17,043, 10 patients were studied who had impaired left ventricular (LV) performance and who were undergoing diagnostic cardiac catheterization (LV ejection fraction 16 to 46%). MDL 17,043 was given in repeated i.v. doses of 0.5 mg/kg every 15 minutes until a maximal effect was observed or a total dose of 3 mg/kg was attained. Cardiac output increased from 3.5 +/- 1.0 to 5.3 +/- 0.7 liters/min (p less than 0.005); pulmonary artery wedge pressure decreased from 22 +/- 4 to 9 +/- 5 mm Hg (p less than 0.001); and total systemic resistance decreased from 2,335 +/- 1,147 to 1,310 +/- 365 dyne cm-5 (p less than 0.025). Also, maximal LV dP/dt increased from 1,011 +/- 301 to 1,243 +/- 330 mm Hg/s (p less than 0.001). No significant changes in heart rate, systemic blood pressure, routine blood chemistries, complete blood counts or platelet counts were observed. Thus, MDL 17,043 has hemodynamic effects consistent with positive inotropic and vasodilating properties in patients with reduced LV performance. Because this agent is effective orally, further evaluation in patients with overt congestive heart failure is warranted.

The mechanics of ventricular function

The introduction of new pharmacotherapies for long-term treatment of chronic cardiac failure has underscored the need for serial measurement of ventricular function in the ambulatory patient. Management strategies can best be guided by physiologic assessment of the heart's function as a muscular pump that must serve to propel gases to the metabolizing tissues on a moment-to-moment basis.