Left ventricular pacing vector selection by novel echo-particle imaging velocimetry analysis for optimization of quadripolar cardiac resynchronization device: a case report

Abstract

Background: The availability of pacing configurations offered by quadripolar left ventricular leads could improve patients' response to cardiac resynchronization therapy; however, the selection of an optimal setting remains a challenge. Echo-particle imaging velocimetry has shown that regional anomalies of synchrony/synergy of the left ventricle are related to the alteration, reduction, or suppression of the physiological intracavitary pressure gradients. These observations are also supported by several numerical models of the left ventricle that have shown the close relationship between wall motion abnormalities, change of intraventricular flow dynamics, and abnormal distribution of forces operating on the ventricular endocardium.

Case presentation: A 73-year-old white man in New York Heart Association III functional class with an ejection fraction of 27.5 % did not improve after 1 month of cardiac resynchronization therapy. Five configurations were tested and settings were defined by optimizing intraventricular flow. After 6 months, he became New York Heart Association II class with left ventricular ejection fraction of 53.2 %.

Conclusions: The abnormal dynamic of pressure gradients during the cardiac cycle, through biohumoral endocrine, autocrine, and paracrine transduction, may lead to structural changes of the myocardial walls with subsequent left ventricular remodeling. The echo-particle imaging velocimetry technique may be useful for elucidating the favorable effects of cardiac resynchronization therapy on intraventricular fluid dynamics and it could be used to identify appropriate pacing setting during acute echocardiographic optimization of left pacing vector.

Keywords: CRT; Case report; Echo-PIV; Fluid dynamics; Quadripolar lead; RT3D-TTE; Vortex.

Fig. 1

Panel a 1a Twelve-lead electrocardiograms of a patient with heart failure pre-cardiac resynchronization therapy demonstrates a QRS duration of 125 ms. 2a Real-time three-dimensional transthoracic echocardiography full volume mode, one beat: very heterogeneous (orange regional pattern) dynamic map of the time minimum volume that looks at a 10 % of heart cycle time window when it moves through the heart cycle, with individual segments reaching end-systole at different times, and relative high Systolic Dyssynchrony Index of 9.6 %. 3a The polar histogram shows the orientation and relative magnitude of blood-induced intraventricular forces which are not properly aligned along the left ventricle axis. 4a Relative magnitude of blood-induced hemodynamic forces which are not properly aligned along the left ventricle axis. Panel b Changes in electrical activation settings modify the orientation, φ, of intraventricular forces during acute study. The setting (A1-can in the top right, arrow) corresponding to the most aligned intraventricular forces is selected. Panel c 1c At follow-up, 12-lead electrocardiograms post-cardiac resynchronization therapy demonstrate a QRS duration of 126 ms. 2c Real-time three-dimensional transthoracic echocardiography full volume mode, one beat: low heterogeneous (orange regional pattern) dynamic map of the time minimum volume that looks at a 10 % of heart cycle time window when it moves through the heart cycle, with individual segments reaching end-systole at similar times, with low Systolic Dyssynchrony Index of 2.3 %. 3c These settings provided a positive response to therapy, which was associated with improved alignment of intraventricular forces. 4c Left ventricle flow was more regular and the associated hemodynamic forces followed the base–apex orientation. CRT cardiac resynchronization therapy, echo-PIV echo-particle imaging velocimetry, EF ejection fraction, EKG electrocardiogram, ESV end-systolic volume, NYHA New York Heart Association, RT3D-TTE real-time three-dimensional transthoracic echocardiography, SDI Systolic Dyssynchrony Index