Changes in mechanical dyssynchrony in severe aortic stenosis patients undergoing transcatheter aortic valve replacement

INTRODUCTION

Aortic stenosis (AS) imposes a significant afterload on the left ventricle, but regional manifestations of the overall load may not be uniform, leading to mechanical dyssynchrony. Accordingly, we evaluated the prevalence of dyssynchrony in patients with severe AS at baseline as well as changes after transfemoral aortic valve replacement (TAVR).

METHODS

This study is a retrospective analysis of 225 patients in sinus rhythm who underwent TAVR for severe AS, in whom inter-ventricular and intra-ventricular dyssynchrony were measured at baseline, discharge, 1 month, and 1 year. Inter-ventricular dyssynchrony was defined as the difference between left and right ventricular pre-ejection intervals; intra-ventricular dyssynchrony was defined as the difference between time to peak systolic velocity of the basal septal and lateral segments. Patients were further stratified into those with QRS <120 ms or >120 ms.

RESULTS

At baseline, a quarter of patients met the criterion for significant inter-ventricular dyssynchrony, and a third had evidence of intra-ventricular dyssynchrony. Both decreased after TAVR although only the intra-ventricular dyssynchrony reached statistical significance. The interplay between QRS duration and changes in inter- and intra-ventricular dyssynchrony are also explored.

CONCLUSIONS

In patients with severe AS, there was evidence of mechanical dyssynchrony that is improved post-TAVR. Whether dyssynchrony is clinically and prognostically significant, and if it represents a potential target for additional therapy remains to be studied.

Partial Resuscitative Endovascular Balloon Occlusion of the Aorta in Swine Model of Hemorrhagic Shock

BACKGROUND

Complete resuscitative endovascular balloon occlusion of the aorta (C-REBOA) increases proximal mean arterial pressure (MAP) at the cost of distal organ ischemia, limiting the duration of intervention. We hypothesized that partial aortic occlusion (P-REBOA) would maintain a more physiologic proximal MAP and reduce distal tissue ischemia. We investigated the hemodynamic and physiologic effects of P-REBOA vs C-REBOA.

STUDY DESIGN

Fifteen swine were anesthetized, instrumented, splenectomized, and subjected to rapid 25% blood volume loss. They were randomized to C-REBOA, P-REBOA, or no intervention (controls). Partial REBOA was created by partially inflating an aortic balloon catheter to generate a 50% blood pressure gradient across the balloon. Hemodynamics were recorded and serum makers of ischemia and inflammation were measured. After 90 minutes of treatment, balloons were deflated to evaluate the immediate effects of reperfusion. End organs were histologically examined.

RESULTS

Complete REBOA produced supraphysiologic increases in proximal MAP after hemorrhage compared with more modest augmentation in the P-REBOA group (p < 0.01), with both groups significantly greater than controls (p < 0.01). Less rebound hypotension after balloon deflation was seen in the P-REBOA compared with C-REBOA groups. Complete REBOA resulted in higher serum lactate than both P-REBOA and controls (p < 0.01). Histology revealed early necrosis and disruption of duodenal mucosa in all C-REBOA animals, but none in P-REBOA animals.

CONCLUSIONS

In a porcine hemorrhagic shock model, P-REBOA resulted in more physiologically tolerable hemodynamic and ischemic changes compared with C-REBOA. Additional work is needed to determine whether the benefits associated with P-REBOA can both extend the duration of intervention and increase survival.