Differing autonomic response to dobutamine in the presence and absence of ischemia: implications for the autonomic contribution to positive inotropic intervention.

Although it is well recognized that dobutamine is a powerful positive inotropic agent mediating increased myocardial contractility through direct beta-adrenergic stimulation, the mechanism of its overall circulatory effects appears more complex than that which may be ascribed solely to this direct action on the myocardium. Previous investigations have implied that reflex alterations in autonomic balance may contribute significantly to the response to this agent, but direct evidence describing such a response has not been reported. The objective of this investigation was to assess changes in autonomic tone induced by dobutamine in the presence and absence of ischemia through the measurement of heart rate variability in patients undergoing dobutamine stress echocardiography. Of 25 consecutive patients undergoing dobutamine stress echocardiography, 16 were found to have unequivocal evidence for or against the presence of ischemia during dobutamine infusion. Heart rate data from these 16 patients were submitted for spectral analysis of heart rate variability and quantification of parasympathetically governed high-frequency heart rate variability and sympathetically influenced low-frequency heart rate variability. Of the 16 patients nine were not found to have evidence for ischemia (group 1), and seven were found to have echocardiographic findings consistent with dobutamine-induced ischemia (group 2). The two groups significantly differed (p = 0.04) in the change in parasympathetic tone associated with dobutamine with a significant (p = 0.04) increase in parasympathetic tone in group 1 and a numeric decrease in group 2. A significant (p = 0.04) decrease in sympathetic tone was noted in group 1 as reflected by low-frequency heart rate variability with a numeric increase in this measure in group 2.(ABSTRACT TRUNCATED AT 250 WORDS)

Linewidth instabilities in narrow-linewidth flashlamppumped dye laser oscillators.

Linewidth instabilities in double-longitudinal-mode (250 MHz

A maternal death associated with prostaglandin E2.

A maternal death following prostaglandin E2 (PGE2) administration is reported. It is suggested that prostaglandin may not be safer than other methods of uterine evacuation for late abortion and fetal death.

Etopic pregnancy causing massive rectal bleeding.

A case of severe rectal bleeding due to an ectopic pregnancy in the wall of the cecum is reported. The usual preoperative studies for rectal bleeding were performed but did not yield a definitive diagnosis. At laparotomy the right side of the uterus was found to be adherent to the cecum.