Heart rate changes during the Valsalva maneuver in patients with isolated aortic insufficiency

To determine the possible relationship between left ventricular dilatation and heart rate changes provoked by the Valsalva maneuver (Valsava ratio), we studied 9 patients with isolated chronic aortic insufficiency. Left ventricular systolic function was assessed by two dimensional echocardiography and cardiac catheterization. All patients were asymptomatic (functional class I of the New York Heart Association). The left ventricular internal diameters and volumes were significantly increased in all patients. The asymptomatic patients had either normal or slightly depressed ejection fraction (EF>0.40). The Valsalva ratio of these asymptomatic patients showed no significant correlation with the left ventricular volumes or with the left ventricular ejection fraction. In other words, parasympathetic heart rate control, as expressed by the Valsalva ratio, was normal in the asymptomatic patients with left ventricular dilatation and preserved left ventricular ejection fraction. Therefore, left ventricular dilatation may not be the major mechanism responsible for the abnormal parasympathetic heart rate control of patients with acquired heart disease.

Heart rate changes during the Valsalva maneuver in patients with isolated aortic insufficiency.

To determine the possible relationship between left ventricular dilatation and heart rate changes provoked by the Valsalva maneuver (Valsalva ratio), we studied 9 patients with isolated chronic aortic insufficiency. Left ventricular systolic function was assessed by two-dimensional echocardiography and cardiac catheterization. All patients were asymptomatic (functional class I of the New York Heart Association). The left ventricular internal diameters and volumes were significantly increased in all patients. The asymptomatic patients had either normal or slightly depressed ejection fraction (EF > 0.40). The Valsalva ratio of these asymptomatic patients showed no significant correlation with the left ventricular volumes or with the left ventricular ejection fraction. In other words, parasympathetic heart rate control, as expressed by the Valsalva ratio, was normal in the asymptomatic patients with left ventricular dilatation and preserved left ventricular ejection fraction. Therefore, left ventricular dilatation may not be the major mechanism responsible for the abnormal parasympathetic heart rate control of patients with acquired heart disease.

Dexamethasone-prepared Escherichia coli-induced disseminated intravascular coagulation. Animal model.

We have developed a new model of disseminated intravascular coagulation in rats based on the induction of immunosuppression by prolonged high-dose dexamethasone treatment. Most models of disseminated intravascular coagulation are based on the generalized Shwartzman reaction, which is observed characteristically in experimental animals after two separate inoculations of bacterial endotoxins. These produce massive deposition of thrombi in the microcirculation and significant hemorrhagic and ischemic phenomena. We have demonstrated that the administration of glucocorticosteroids at the specific doses and intervals can adequately replace the first (preparatory) injection of endotoxin. For this reason, we have attempted to experimentally simulate a frequent clinical situation, such as sepsis secondary to peritonitis, by intraperitoneal inoculation of Escherichia coli and hog gastric mucin into rats pretreated with dexamethasone. This inoculation was equivalent to the second injection of endotoxin in the Shwartzman model (triggering inoculation). A typical picture of disseminated intravascular coagulation induced by bacterial endotoxins developed, as demonstrated by the anatomopathologic, microbiologic, and hematologic studies performed. These results were then compared to those obtained in rats treated exclusively with dexamethasone or given, in addition, an effective antibiotic therapy.