Imaging techniques in cardiac resynchronization therapy

Abstract

Cardiac resynchronization therapy is a high cost therapeutic option with proven efficacy on improving symptoms of ventricular failure and for reducing both hospitalization and mortality. However, a significant number of patients do not respond to cardiac resynchronization therapy that is due to various reasons. Identification of the optimal pacing site is crucial to obtain the best therapeutic result that necessitates careful patient selection. Currently, using echocardiography for mechanical dyssynchrony assessment performs patient selection. Multi-Detector-Row Computed Tomography (MDCT) and Magnetic Resonance Imaging (MRI) are new imaging techniques that may assist the cardiologist in patient selection. These new imaging techniques have the potential to improve the success rate of cardiac resynchronization therapy, due to pre-interventional evaluation of the venous coronary anatomy, to evaluation of the presence of scar tissue, and to improved evaluation of mechanical dyssynchrony. In conclusion, clinical issues associated with heart failure in potential candidates for cardiac resynchronization therapy, and the information regarding this therapy that can be provided by the imaging techniques echocardiography, MDCT, and MRI, are reviewed.

Assessment of the coronary venous system in heart failure patients by blood pool agent enhanced whole-heart MRI

“…Current selection criteria for CRT patients include a QRS complex duration > 120 ms [3,7], NYHA class of HF III-IV and a LV ejection fraction (EF) < 35%. Several studies [7][8][9] suggest that patient selection can be significantly improved by adding functional dyssynchrony of the LV as a criterion. The motion data of the LV for example could be obtained by pre-operative ultrasound (US) [7][8][9][10], computed tomography (CT) [7][8][9]11], magnetic resonance imaging (MRI) [7,9,[12][13][14] or nuclear imaging [15].…”

“…Several studies [7][8][9] suggest that patient selection can be significantly improved by adding functional dyssynchrony of the LV as a criterion. The motion data of the LV for example could be obtained by pre-operative ultrasound (US) [7][8][9][10], computed tomography (CT) [7][8][9]11], magnetic resonance imaging (MRI) [7,9,[12][13][14] or nuclear imaging [15]. Further improvement is expected from consideration of possible LV scar tissue [16] findings as well as its location and likely from pre-operative assessment of the accessibility of the targeted LV pacing location through the venous system for ensuring adequate transvenous pacing of the lateral wall of the LV.…”

“…Quantification of the LV function [9,[12][13][14][17][18][19][20][21][22] as well as assessment of the LV scar [16] can be derived from MRI data, enabling the identification of preferred implantation target sites. The assessment of the course of the coronary veins, however, has not yet been shown in the difficult-to-image heart failure patients but was restricted to mostly volunteer studies or coronary artery disease (CAD) patients scheduled for coronary artery MRI angiography [23][24][25][26][27].…”

Imaging techniques for cardiac strain and deformation: comparison of echocardiography, cardiac magnetic resonance and cardiac computed tomography

“…Strain analysis may provide a reliable and superior method for predicting CRT response [73,74]. Current studies using strain as a parameter for CRT have used echocardiography [75] more than MRI owing to the potential interaction of the devices with the magnetic fields. CCT is already being performed for CRT to examine the status of coronary veins for transvenous CRT LV lead placement.…”

Nonechocardiographic Imaging in Evaluation for Cardiac Resynchronization Therapy

“…This is particularly important as LV lead placement for CRT is technically challenging in dilated ventricles with prominent tortuousity, stenosis, acute angulation of the coronary veins 28,34 , and especially in the 5% of subjects in whom the posterior vein of the LV and the 39% among whom the left marginal vein are absent 35 . In addition, CCT identifies the relationship of the left phrenic neurovascular bundle to the target vein which allows the operator to avoid diaphragmatic stimulation 36 .…”