Verapamil in multifocal atrial tachycardia. Hemodynamic and respiratory changes.

The hemodynamic and gas exchange alterations resulting from treatment of multifocal atrial tachycardia (MAT) with intravenous verapamil were monitored in 13 critically ill patients. Administration of verapamil (mean dose 12.9 +/- 1.0 mg) produced immediate if usually transient reduction in heart rate. Stroke volume index rose, but no significant changes in cardiac index, blood pressure, or pulmonary artery or capillary wedge pressures were demonstrated. Verapamil appeared to increase pulmonary venous admixture. Oxygen transport, however, did not decrease significantly. Verapamil is generally beneficial in the treatment of MAT, but its utility may be limited in many patients by its tendency to aggravate pre-existing arterial hypoxemia.