Three cases of hypotension and syncope with ventricular pacing: possible role of atrial reflexes.

Hypotension with lightheadedness and near syncope occurred in three patients during effective ventricular pacing. Hemodynamic studies demonstrated a decrease in cardiac output ranging from almost no decrease to 15 percent, presumably related to the loss of effective atrial contraction. The decrease in output was too small to explain by itself the reduced blood pressure, which resulted from paradoxic reduction of total peripheral resistance in one patient and from failure of resistance to increase in two.

Hemodynamics of postmyocardial revascularization hypertension.

The evolution of hemodynamic variables during the development of postcoronary bypass hypertension was investigated with use of serial cardiac output determination (indocyanine green dye) in 17 patients. Seven of the 17 patients remained normotensive (Group I) during the follow-up period of 4 to 6 hours after operation, whereas 10 (Group II) had a steady increase in blood pressure (173/101 mm Hg +/- 5.9/2.