Single-beat noninvasive imaging of ventricular endocardial and epicardial activation in patients undergoing CRT

Abstract

Background: Little is known about the effect of cardiac resynchronization therapy (CRT) on endo- and epicardial ventricular activation. Noninvasive imaging of cardiac electrophysiology (NICE) is a novel imaging tool for visualization of both epi- and endocardial ventricular electrical activation.

Methodology/principal findings: NICE was performed in ten patients with congestive heart failure (CHF) undergoing CRT and in ten patients without structural heart disease (control group). NICE is a fusion of data from high-resolution ECG mapping with a model of the patient's individual cardiothoracic anatomy created from magnetic resonance imaging. Beat-to-beat endocardial and epicardial ventricular activation sequences were computed during native rhythm as well as during ventricular pacing using a bidomain theory-based heart model to solve the related inverse problem. During right ventricular (RV) pacing control patients showed a deterioration of the ventricular activation sequence similar to the intrinsic activation pattern of CHF patients. Left ventricular propagation velocities were significantly decreased in CHF patients as compared to the control group (1.6±0.4 versus 2.1±0.5 m/sec; p<0.05). CHF patients showed right-to-left septal activation with the latest activation epicardially in the lateral wall of the left ventricle. Biventricular pacing resulted in a resynchronization of the ventricular activation sequence and in a marked decrease of total LV activation duration as compared to intrinsic conduction and RV pacing (129±16 versus 157±28 and 173±25 ms; both p<0.05).

Conclusions/significance: Endocardial and epicardial ventricular activation can be visualized noninvasively by NICE. Identification of individual ventricular activation properties may help identify responders to CRT and to further improve response to CRT by facilitating a patient-specific lead placement and device programming.

Figure 1. Panel A shows a patient-specific anatomical model obtained from MRI data (two MRI image slides shown as intersection planes) including chest, lungs and the ventricles merged with the inverse calculated electroanatomic activation map (isochrones; color coded).

Panel B shows a butterfly plot of the 65-body surface ECG leads during native sinus rhythm (blue lines) and biventricular pacing (red lines). Panel C shows a root mean square (RMS) plot (sinus rhythm – blue line; biventricular pacing – red line; dotted lines indicate begin/end of the QRS complex).

Figure 2. Color-coded electroanatomic activation map of the right and left ventricle in a control patient (no structural heart disease) during A) intrinsic sinus rhythm (native) and B) right ventricular (RV) pacing.

Red color illustrates earliest activation, blue color illustrates area of late ventricular activation. Head icon indicates point of view.

Figure 3. Color-coded electroanatomic activation map of the right and left ventricle in a CHF patient during A) intrinsic sinus rhythm (native), B) right ventricular (RV) and C) biventricular (biV) pacing.

Red color illustrates earliest activation, blue color illustrates area of late ventricular activation. Head icon indicates point of view.