Page 41 - Journal of Structural Heart Disease Volume 3, Issue 6

197 Case Report
Figure 6. Twelve-lead electrocardiograms. Panel A. Electrocardiogram prior to pacemaker placement, demonstrating atrial brillation with an incomplete right bundle branch block pattern, with normal axis and nonspeci c ST-T segment abnormalities seen inferolat- erally. Panel B. Electrocardiogram after dual-chamber pacemaker placement, demonstrating an atrioventricular paced rhythm and a paced ventricular morphology with an indeterminate axis and atypical left bundle branch morphology (no broad R waves noted in lateral leads). Pseudofusion (thick arrow) was intermittently noted, revealing the patient’s native QRS morphology and fusion (thin arrow).
Video 3. Two-dimensional transesophageal echocardiogra- phy of the mitral valve as seen in Figure 2C after percutane- ous mitral valve repair. View supplemental video at https://doi. org/10.12945/j.jshd.2017.033.17.vid.03.
right ventricular apex is the standard pacing site for dual-chamber pacemakers, several studies report detrimental e ects of electrical dyssynchrony from RV pacing, including exacerbation of valvular dys- function and heart failure [3, 4].
In this case, invasive hemodynamics obtained during PMVR demonstrated worsening of functional MR from septal dyssynchrony induced by RV apical pacing. The association between MR and right ven- tricular apical pacing has been described in many
Video 4. Three-dimensional transesophageal echocardiog- raphy of the mitral valve as seen in Figure 2D after percutane- ous mitral valve repair. View supplemental video at https://doi. org/10.12945/j.jshd.2017.033.17.vid.04.
clinical scenarios ranging from acute severe MR im- mediately following pacemaker implantation to slow progression of MR in the setting of chronic right ven- tricular apical pacing [4-6].
The mechanism of MR with RV pacing is derived from intraventricular dyssynchrony. Pacing from the right ventricular apex induces an iatrogenic form of left bundle branch block as depolarization spreads from the apex to the base, as demonstrated by the patient’s electrocardiograms before and after du-
Nguyen H. L. et al.
Worsening MR from V-Paced Septal Dyssynchrony