Cardiology
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In five patients with postural hypotension (disturbed sympathetic vasomotor control) the effect of intravenous and oral administration of dihydroergotamin (DHE) has been studied. The therapeutic effect of oral administration of DHE has also been compared to the effect of treatment with an antigravity suit. Following intravenous administration of DHE, systemic and central venous pressure increased in all cases. ⋯ In the legs which were deprived of sympathetic tone intravenous administration of DHE caused constriction of resistance vessels. In the intact forearm there was a decrease of tone in the resistance vessels. The results indicate that DHE - apart from its well-known venoconstrictive effect - also may constrict resistance vessels when they are subjected to a low sympathetic nervous outflow.
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In anesthetized dogs, initially breathing spontaneously, the effects of intermittent positive pressure ventilation (IPPV), thoractomy and pericardiectomy on cardiac function, pericardial-ventricular relationships and cardiopulmonary volumes were evaluated. After IPPV stroke volume and work decreased. After thoracotomy there was no further change in cardiac output or work. ⋯ In the ventilated open-chest dog the effects of IPPV are greater than those of thoracotomy, and the extent of the effects is related to the level of IPPV. With moderate IPPV and adequate ventilation, the systemic hypotension, marked decreases in cardiac output and reduction of heart volumes reported by previous investigators can be avoided. The removal of the pericardium does not appear to have any deleterious effect in the normal dog.