Utility of remote wireless pressure sensing for endovascular leak detection after endovascular thoracic aneurysm repair.

Background: The goal of thoracic endovascular aneurysm repair (TEVAR) is to exclude and depressurize the aneurysm sac. Type I and III endovascular leaks (EL) transmit systemic pressure and represent treatment failures. The significance of type II EL is more controversial. Remote pressure sensing is a novel nonradiographic technology for EL detection and monitoring. However, little experience exists with regard to use in the thoracic aorta. We present our experience with the EndoSure wireless pressure measurement system (CardioMEMS, Atlanta, GA) for monitoring aneurysm sac pulse pressure (ASP) after TEVAR.

Methods: Beginning May 2006, the EndoSure system was routinely implanted in TEVAR patients with suitable anatomy (36 aneurysm patients; 7 chronic dissection patients). The ASP measurements were taken predischarge and at scheduled follow-up visits. Computed tomography angiograms were performed at scheduled follow-up appointments. Data were prospectively maintained in an institutional aortic database.

Results: Through June 2008, 43 patients (34% of TEVARs performed during this interval) underwent implantation. In 10 patients (23%), the device was suboptimally positioned between the endovascular graft and the aortic wall, rather than in an area of thrombus-free lumen, with subsequent transmission of systemic pressure despite no radiographic evidence of EL. In patients with well-positioned sensors, predischarge ASP averaged 43% +/- 22% of systemic. In 2 patients, systemic ASP measurements before discharge prompted imaging, confirming type I EL; both patients were treated successfully with cuff extension. One patient exhibited reduced ASP before discharge but exhibited increased ASP (70% systemic) at 1 month; computed tomography scan confirmed a type I EL. Additional TEVAR sealed the EL and reduced ASP to 39% systemic. For all patients at midterm follow-up, ASP decreased further, averaging 19% +/- 12% systemic (p = 0.019); this correlates with computed tomography imaging demonstrating a 5 mm or greater reduction in aortic diameter in 76% of patients (25 of 33) with follow-up of 6 months or longer. No patients manifested a recurrent type I or type III EL at latest follow-up. The device has also been used to follow 8 patients with type II EL with low ASP.

Conclusions: Implantation of a wireless ASP sensor provides useful information regarding type I and type III EL after TEVAR and permits serial observation of type II EL. This information may guide clinical therapy and improve outcomes. Longer term follow-up will define sensor reliability in postoperative surveillance.