Pacemaker‐mediated endless loop tachicardia is usually caused by a P wave displaced from the physiologic position preceding a QRS complex to a time of atrial channel sensitivity after the QRS. Five cases are described of endless loop tachycardia starting after a normally‐timed P wave, either spontaneous and preceding a ventricular stimulus or a P wave produced by an atrial channel stimulus followed by a ventricular stimulus and QRS complex. In each instance, the atrial refractory interval (ARI) was shorter than the retrograde conduction time. In four of the cases, prolongation of the atrial refractory interval after the ventricular event ended the tachycardias. In the fifth, in which the pulse generator could not be so programmed, the ventricular inhibited mode was required.
SummaryWhile the last 20 years have seen a decrease in the number of cardiac surgical procedures performed in the United States, there has not been a commensurate decrease in the number of cardiac surgical programs. The result has been growth of lower-volume programs, which face disproportionate challenges across several important areas. Even though cardiac surgery consolidation seems to be a logical next step in markets where duplication of services exists, this rarely happens. Providence St. Joseph Health consolidated a moderate-sized cardiac surgery program into a nearby higher-volume center in order to better distribute limited resources, improve operational performance, and deliver better outcomes. An effort of this magnitude requires extensive planning, taking note of the risks and impact to patients and clinical teams alike.
. An unusual mechanism for recurrent, wide QRS complex supraventricular tachycardia is described in this report. A 25‐year‐old man with normal PR and QRS intervals during sinus rhythm was shown to have preexcitation with a left bundle branch block pattern during tachycardia and during atrial pacing. Electrophysiologic studies demonstrated slow and decremental conduction properties in an accessory “bystander” AV pathway utilized for antegrade conduction during AV nodal reciprocating tachycardia. The differential diagnosis of this tachycardia is discussed in detail.
