Fracture of a temporary pacemaker electrode catheter.

We have reported an instance of fracture of a temporary bipolar electrode catheter with embolization of the distal fragment to the lung. The patient had no untoward effects for 45 days before death. Autopsy revealed no thrombosis proximal or distal to the catheter fragment.

Responses of coronary vessels to adrenergic stimuli.

Coronary responses to adrenergic stimuli were determined in the intact beating heart before and after administration of practolol, 4-(2-hydroxy-3-isopropylaminoproproxy) acetanilide, which in low doses blocks myocardial but not vascular beta receptors. The left circumflex coronary artery of dogs was perfused with arterial blood at constant flow, and coronary perfusion pressure was measured. Before practolol, intracoronary injections of isoproterenol and norepinephrine and electrical stimulation of left cardiac sympathetic nerves caused reductions in perfusion pressure or vasodilatation associated with increases in left ventricular dp/dt, heart rate, and systolic pressure.