Cardiology
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The usual surgical treatment of tricuspid endocarditis is valve replacement or valve excision alone without valve replacement. 'Vegetectomy', i.e. local excision of the vegetation and leaflet repair, has been previously described and can be applied to cases with well-circumscribed vegetations and little or no valve damage. A case of tricuspid valve endocarditis successfully managed by surgical excision of the vegetation is reported.
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Cardiopulmonary exercise testing refers to the noninvasive measurement of respiratory gas exchange and air flow, together with heart rate, blood pressure, and the electrocardiogram. These data, obtained during an incremental exercise test, can be used to derive the aerobic capacity or VO2max, which is an objective measure of the severity of chronic cardiac and circulatory failure, as well as to predict the maximum cardiac output response to exercise. The additional monitoring of minute ventilation and arterial oxygen saturation can be used to distinguish ventilatory from cardiac or circulatory causes of exertional dyspnea. Finally, this information serves as an objective measure of functional capacity which can be monitored over time to assess the natural history of disease as well as its response to medical therapy.
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In order to study the influence of sudden left ventricular pressure rise on the calibrated apexcardiogram, 181 acute aortic occlusions were performed during systole in 7 dog experiments. For each beat preceding (CO) an occlusion and each occlusion (OC), peak systolic amplitude of left ventricular pressure (CO: 118.5 +/- 17.8 mm Hg; OC: 205.8 +/- 38.7 mm Hg) and apexcardiogram (CO: 48.8 +/- 16.7 mm Hg; OC: 63.0 +/- 25.8 mm Hg) were measured. ⋯ Significant correlations were found: between surface ratios and pressure gradient of pressure (r = 0.80, p less than 0.001) and of apexcardiogram (r = 0.79, p less than 0.001); between surface ratios of pressure and surface of apexcardiogram (r = 0.52, p less than 0.001). The data suggest that during isovolumic systole, the time integral of the left ventricular pressure and its change during the ejection phase define to a large extent the general shape and size of the apexcardiogram.
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beta-Adrenergic blockade represents a major pharmacologic advance. These drugs bind to membrane adrenergic receptors interfering with the effects of endogenous catecholamines. ⋯ The drugs have varying pharmacodynamic properties that may modify certain side effects: beta 1-selectivity, partial agonism, alpha-adrenergic blocking activity, membrane stabilization, and varying pharmacokinetic characteristics. The drugs have been shown to be relatively safe and useful for a wide variety of cardiovascular and noncardiovascular disease states, and their wide spectrum of therapeutic activity illustrates the importance of the sympathetic nervous system in the pathophysiology of medical illness.
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A number of conventional and newer antiarrhythmic agents are available for the treatment and prophylaxis of ventricular tachycardia and sudden death. Using a multifaceted approach of programmed electrical stimulation studies, drug level determinations, exercise tolerance testing, and 24-hour ambulatory electrocardiographic monitoring, the physician can identify those patients who require therapy and then predict the likelihood of efficacy with each antiarrhythmic agent. ⋯ Serious adverse reactions necessitate a change in antiarrhythmic therapy, as opposed to lowering drug dosage to an ineffective level. The unacceptably high incidence of sudden death due to electrical instability can be reversed only by a rigorous and dedicated long-term approach to the management of serious ventricular arrhythmias.