Combined flow-based imaging assessment of optimal cardiac resynchronization therapy pacing vector: a case report

Abstract

Background: There are still many pendent issues about the effective evaluation of cardiac resynchronization therapy impact on functional mitral regurgitation. In order to reduce the intrinsic difficulties of quantification of functional mitral regurgitation itself, an automatic quantification of real-time three-dimensional full-volume color Doppler transthoracic echocardiography was proposed as a new, rapid, and accurate method for the assessment of functional mitral regurgitation severity. Recent studies suggested that images of left ventricle flow by echo-particle imaging velocimetry could be a useful marker of synchrony. 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. We describe a case in which the two technologies are used in combination during acute echocardiographic optimization of left pacing vector in a 63-year-old man, Caucasian, who showed worsening heart failure symptoms a few days after an implant, and the effect of the device's optimization at 6-month follow-up.

Discussion: The degree of realignment of hemodynamic forces, with quantitative analysis of the orientation of blood flow momentum (φ), can represent improvement of fluid dynamics synchrony of the left ventricle, and explain, with a new deterministic parameter, the effects of cardiac resynchronization therapy on functional mitral regurgitation. Real-time three-dimensional color flow Doppler quantification is feasible and accurate for measurement of mitral inflow, left ventricular outflow stroke volumes, and functional mitral regurgitation severity.

Conclusion: This clinical case offers an innovative and accurate approach for acute echocardiographic optimization of left pacing vector. It shows clinical utility of combined three-dimensional full-volume color Doppler transthoracic echocardiography/echo-particle imaging velocimetry assessment to increase response to cardiac resynchronization therapy, in terms of reduction of functional mitral regurgitation, improving fluid dynamics synchrony of the left ventricle.

Keywords: Cardiac resynchronization therapy; Echo-PIV; Full-volume color Doppler echocardiography; Mitral regurgitation; Three-dimensional echocardiography.

Fig. 1

a Twelve-lead electrocardiogram showing the wide native QRS complex (145 ms) with first-degree atrioventricular block (PR 280 ms). b Two-dimensional color transthoracic echocardiogram apical four-chamber view. AV atrioventricular, CRT cardiac resynchronization therapy, ECG electrocardiogram, ICD implantable cardioverter defibrillator, LBBB left bundle branch block, M male, NO ISCH. DCM non-ischemic dilated cardiomyopathy, NYHA New York Heart Association, TTE transthoracic echocardiogram

Fig. 2

Left anterior oblique chest X-ray view displaying the left ventricular quadripolar lead (arrow)

Fig. 3

Quantitative analysis (to compare with the results of analysis represented in Fig. 7) by echo-particle imaging velocimetry of the orientation angle (φ) of the global hemodynamic forces exchanged between blood and surrounding tissues during acute study (post-cardiac resynchronization therapy 13-day follow-up). Left: Two-dimensional transthoracic echocardiogram high-temporal resolution contrast echocardiographies are performed by three-chamber apical view approach during acute study of different setting (a, b, c, d). Right: Changes in electrical activation settings modify the orientation of intraventricular forces during acute study. The intraventricular forces were predominantly transverse and not aligned along the LVaxis (a₁) as quantified by the large value of their mean angle φ (φ = 55.6°). A first setting option (CRT ON, VV delay 0 ms) changed the orientation of intraventricular forces (b₁) reducing the angle (φ = 45°), and increasing the delay (CRT ON, VV delay − 30 ms) improved the alignment (c₁) reducing the angle (φ = 40.3°). The sequential biventricular activation with delay − 50 ms (d₁) provided the best alignment of intraventricular forces (φ = 38.8°). CRT cardiac resynchronization therapy, F.U. follow-up, PIV particle imaging velocimetry, VV interventricular, TTE transthoracic echocardiogram

Fig. 4

Quantitative analysis (to compare with the results of analysis represented in Fig. 6), of functional mitral regurgitation by three-dimensional full-volume color Doppler transthoracic echocardiography: acute study (post-cardiac resynchronization therapy 13-day follow-up). Left: Setting cardiac resynchronization therapy OFF. Right: Setting cardiac resynchronization therapy ON with interventricular delay 0 ms. a, c Automated anatomy detection of the left ventricular endocardial border, mitral annulus, left ventricular outflow, and placement of three-dimensional hemispheric flow sampling planes in the mitral annulus (white arrow) and left ventricular outflow (yellow arrow). b, d Flow-time curve derived from automatic flow volume aggregation at each frame in the cardiac cycle and the automated calculation of the mitral (In SV), aortic (Out SV) stroke volume, regurgitant volume, regurgitation fraction (RF), and cardiac output (CO), with mean value, in three cardiac cycles, respectively. AVG mean value, CRT cardiac resynchronization therapy, F.U. follow-up, REG VOL regurgitant volume, TTE transthoracic echocardiogram, VV interventricular

Fig. 5

Left side: a Dilated left ventricle with an end-systolic volume of 380 ml, and an ejection fraction of 4.8% as was measured by the modified Simpson’s method pre-implant. b Pulsed wave Doppler mitral inflow pattern showing advanced diastolic dysfunction (deceleration time (DT) of early filling velocity, 165 ms). Right side: c Dilated left ventricle with reduced end-systolic volume of 288 ml and improved ejection fraction of 26.6% as was measured by the modified Simpson’s method post-implant at 6-month follow-up. d Pulsed wave Doppler mitral inflow pattern showing impaired relaxation. CRT cardiac resynchronization therapy, EF ejection fraction, ESV end-systolic volume, F.U. follow-up, LV left ventricle, PW pulsed wave

Fig. 6

Quantitative analysis (to compare with the results of analysis represented in Fig. 4), of functional mitral regurgitation by three-dimensional full-volume color Doppler transthoracic echocardiography: at 6-month follow-up setting cardiac resynchronization therapy ON interventricular delay − 50 ms. a Automated anatomy detection of the left ventricular endocardial border, mitral annulus, left ventricular outflow, and placement of three-dimensional hemispheric flow sampling planes in the mitral annulus (white arrow) and left ventricular outflow (yellow arrow). b Flow-time curve derived from automatic flow volume aggregation at each frame in the cardiac cycle and the automated calculation of the mitral (In SV), aortic (Out SV) stroke volume, regurgitant volume, regurgitation fraction (RF), and cardiac output (CO), with mean value, in three cardiac cycles, respectively. AVG mean value, CRT cardiac resynchronization therapy, F.U. follow-up, REG VOL regurgitant volume, VV interventricular

Fig. 7

Quantitative analysis (to compare with the results of analysis represented in Fig. 3), by echo-particle imaging velocimetry of the orientation angle (φ) of the global hemodynamic forces exchanged between blood and surrounding tissues during acute study (post-cardiac resynchronization therapy 6-month follow-up). a Two-dimensional transthoracic echocardiogram high-temporal resolution contrast echocardiography is performed by three-chamber apical view approach (see Additional file 10: Video S10 interventricular − 50 ms SONOVUE 6-month follow-up). b The polar histogram showed with setting interventricular delay − 50 ms the most aligned intraventricular forces that were partially dominated by the longitudinal path of pressure gradient (lower φ, value 43.1°). CRT cardiac resynchronization therapy, F.U. follow-up, PIV particle imaging velocimetry, TTE transthoracic echocardiogram, VV interventricular