Assessing drugs for the treatment of heart failure
Article Abstract:
The evaluation of new drugs in the treatment of heart failure poses significant problems to the researcher. There are already some drugs that provide some benefit for the heart failure patient, and it would be unethical to withhold these drugs from patients simply to provide a control group for a clinical trial. Therefore, any new drug under evaluation must not merely provide improvement, it must provide significant improvement over existing drugs. Since some real improvements may not be large enough to reach statistical significance in a clinical trial, it is possible that potentially important drugs may fall from consideration. In patients with heart failure, as in most diseases, treatment has two purposes: to alleviate symptoms and prolong life. When designing a clinical trial of a drug that is believed to prolong the life of the patient with heart failure, it is critical not to ignore the patient's symptoms during this period. However, evaluating the symptoms of patients with heart failure is far from a straightforward proposition. There is no agreement on which tests are the most appropriate. Many tests involve walking, either in a corridor or on a treadmill. But some testing protocols result in a rapid increase in the workload the heart must perform; such tests often end when the patient becomes breathless. Other tests involve a slowly increasing workload; when these tests end, the patient is fatigued but not yet breathless. The design of a clinical trial must carefully consider the differences in the various methods of patient evaluation. The evaluation of death rate is particularly difficult, since a rapidly deteriorating patient may often be removed from the experimental protocol and placed on a standard regimen. The judgement of the individual physician must prevail, but the case-by-case variation in treatment may make statistical analysis extremely difficult. Therefore, the design of the clinical trial must take into account such alterations in treatment. In many cases, the most important problem will be deciding if two drugs are similar, and not which one is better. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Failure of vasodilator infusion to alter pulmonary diffusing capacity in systemic sclerosis
Article Abstract:
Systemic sclerosis (SSc) is a connective tissue disease characterized by sclerosis (hardening) of the skin, gastrointestinal tract, lungs, heart, and kidneys. SSc is often complicated by lung disease, characterized by fibrosis, or fiber-like tissue formation, in the lungs and development of pulmonary hypertension, or increased pressures in the circulation of the lungs. Pulmonary hypertension is one of the main causes of death in SSc patients. Microscopic examination of the lung tissue has revealed thickening of the arterioles and narrowing of the vessel lumina, or inner cavity. SSc is associated with widespread vasospasm, or uncontrolled contraction of the blood vessels, and recurrent pulmonary vasoconstriction may lead to persistent pulmonary hypertension. Patients with SSc do not show the normal increase in lung diffusing capacity when changing from a sitting to a lying position. This may indicate the inability of the blood vessels within the lungs to distend, and may serve as an indicator of pulmonary vascular involvement in SSc patients with apparently normal lung function. The prostaglandin prostacyclin dilates blood vessels and has been shown to reduce pulmonary vascular resistance associated with pulmonary hypertension. Iloprost, an analog of prostacyclin, also dilates blood vessels and reduces pulmonary vascular resistance, but remains in the body for a longer duration as compared with prostacyclin. The ability of iloprost to dilate blood vessels may counteract possible vasospasm and restore the normal response in lung diffusing capacity in SSc patients. The effects of iloprost on lung diffusing capacity when changing from a sitting to a lying position were assessed in 14 patients with SSc. Before treatment, the patients did not show the normal increase in lung diffusing capacity when they went from a sitting to a lying position. Iloprost did not alter lung function or the abnormal response in lung diffusing capacity in these patients. These findings suggest that the defects of lung circulation in patients with SSc are unrelated to vasospasm of the lung blood vessels. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1991
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Long-term beta-blocker vasodilator therapy improves cardiac function in idiopathic dilated cardiomyopathy: a double-blind, randomized study of bucindolol versus placebo
Article Abstract:
Bucindolol is a beta-blocking drug that is capable of dilating blood vessels. The effectiveness of bucindolol in treating congestive heart failure with idiopathic dilated cardiomyopathy was assessed in 14 patients. A comparison group of nine patients was given a placebo, or inert substance. Bucindolol improved symptoms of heart failure and circulatory function, and increased the left ventricular ejection fraction, which is a measure of the contractility of the heart. The beta-blocking agent improved other measures of heart function including cardiac index, left ventricular stroke work index, pulmonary wedge pressure, and heart rate. Patients receiving bucindolol also had increased left ventricular ejection fraction during exercise and improvement in symptoms, as indicated on a questionnaire. However, the length of time patients could exercise on a treadmill and the consumption of oxygen did not change after bucindolol therapy. Patients receiving a placebo did not experience any changes in heart function or symptoms of heart failure at rest or during exercise. Norepinephrine, a natural substance, is released by nerves in excessive amounts during heart failure to maintain heart contraction. The blood levels of norepinephrine were decreased in patients taking bucindolol, but not in patients given a placebo. The results show that bucindolol is well tolerated by patients with heart failure, and treatment with this beta-blocking agent for three months resulted in improvements in heart function, symptoms of heart failure, and norepinephrine levels. (Consumer Summary produced by Reliance Medical Information, Inc.)
Publication Name: American Journal of Medicine
Subject: Health care industry
ISSN: 0002-9343
Year: 1990
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