Rapid Pacing for Better Placing: Comparison of Techniques for Precise Deployment of Endografts in the Thoracic Aorta

Abstract

To investigate the safety, efficacy, impact on positioning, and neurocognitive outcomes of 3 conceptually different methods of avoiding the "windsock" effect during thoracic stent-graft placement. A retrospective review was conducted of 70 patients (48 men; mean age 63 years) who underwent elective or emergency stent-graft placement in the thoracic aorta for various pathologies. Twenty-seven patients (18 men; mean age 64+/-12 years) had stent-graft positioning during rapid right ventricular (RV) pacing at 180 to 200 beats per minute. Another 27 patients (18 men; mean age 62+/-12 years) had stent-graft placement under controlled hypotension (<or=45 mmHg) achieved with sodium nitroprusside (3 microg/kg/min). Sixteen patients (12 men; mean age 63+/-14 years) had intermittent cardiac arrest induced by a 0.5-mg/kg adenosine bolus prior to launching the stent-graft. Termination of the endovascular procedure, weaning, and recovery were conducted according to the same routines in all patients. Hemodynamics, landing precision (deviation from planned placement site), cerebral blood flow, and neurocognitive function were compared. Rapid RV pacing (median 12 seconds) was conducted without technical difficulty or delayed recovery in any of the 27 patients. Once rapid pacing ceased, blood pressure recovered within 8 seconds from 22+/-8 mmHg to normal prepacing levels. The level of hypotension was most pronounced in the rapid RV pacing group (20+/-4 mmHg, p<0.001), and the duration of hypotension was also the shortest (20+/-10 seconds, p<0.001) at a pacing rate of 190+/-10 beats per minute. The instantaneous mean flow velocity was lowest (10+/-4 cm/s, p<0.001) and recovery to normal pressure was quickest (within 1 minute) with rapid pacing. Instrumentation for rapid pacing did not prolong the procedure, but shortened it approximately 25 minutes. Moreover, precise positioning at a mean 2+/-2 mm from the predetermined launch site was observed with rapid pacing (p<0.05). There were no differences in postprocedural neurological assessment among groups. Rapid RV pacing is safe in selected patients and in experienced hands. It abbreviates hemodynamic compromise, shortens the endovascular procedure, and may eventually emerge as the preferred method to avoid the windsock effect during stent-grafting. The maneuver, however, requires knowledge of right cardiac anatomy and expertise in selecting patients.