Impact of rapid ventricular pacing during TAVI on microvascular tissue perfusion

Rapid ventricular pacing (RVP) is an established technique to temporarily reduce left ventricular output during transcatheter aortic valve implantation (TAVI). The purpose of this study was to evaluate the impact of RVP on microvascular tissue perfusion (MTP) in patients undergoing TAVI.

We studied 42 patients (mean age 81.8 ± 6.9 years, n = 18 females. EuroSCORE 33 ± 12 %) during TAVI. MTP was analyzed using Sidestream-Darkfield imaging, of the sublingual microvasculature. Microvascular flow index (MFI) was continuously measured in small (10-25 μm)- and medium (26-50 μm)-sized vessels, starting 10 s before and ending 12 s after RVP. Further, perfused capillary density, total vessel density and the proportion of perfused vessels were assessed. After a mean RVP duration of 14.3 s (range 6-29), mean arterial pressure decreased from 68 ± 05 to 40 ± 7 mmHg (p < 0.001). This was associated with a significant decrease of MFI in small- and medium-sized vessels from 2.29 ± 0.64 and 2.36 ± 0.6 to 0.87 ± 0.66 (p < 0.001) and 1.0 ± 0.83 (p < 0.001), respectively. MFI remained significantly below baseline values (small: 1.75 ± 0.8, p = 0.001 vs. baseline; medium: 1.77 ± 0.85; p = 0.005 vs. baseline) at 12 s after end of RVP.

The study demonstrates a time-dependent effect of RVP on microflow, leading to 50 and 25 % of baseline at 8 and 18 s of RVP, respectively. In a substantial proportion of patients, RVP is associated with microcirculatory arrest and a delayed recovery of microflow. Although the impact of these findings on outcome is yet unclear, TAVI operators should be aware of the potentially adverse effects of even short periods of RVP.