Live 3D echo guidance of catheter-based endomyocardial injection

Abstract

Local delivery of therapeutic agents into the myocardium is limited by suboptimal imaging. We evaluated the feasibility and accuracy of live 3D echo to guide left ventricular endomyocardial injection. An intramyocardial injection catheter was positioned in the left ventricle in five healthy Yorkshire pigs using fluoroscopy. All other catheter manipulations were performed with live biplane and 3D echo guidance. In each animal, a total of 12 endomyocardial injections (volume, 50-100 microl) of echo contrast mixed with blue tissue dye were performed. Four injections, 10 mm apart, were directed to three myocardial target zones: the anterior septum at the mitral valve level (zone 1); the posterolateral wall between the heads of the papillary muscles (zone 2); and the apex (zone 3). The injections were aimed to form a transverse line in zones 1 and 2 and an inverted triangular pyramid in zone 3. The animals were sacrificed, the hearts were inspected and the left ventricular endocardium was examined to create a map of injection marks. Success, defined as a visible injection of tissue dye, was 95%, and accuracy, defined as an injection into the target zone, was 83%. There was no significant difference in accuracy between the zones. Live 3D echo can successfully guide endomyocardial injections by accurately targeting specific myocardial zones, verifying catheter apposition and, when combined with echo contrast, providing real-time visualization of injectate deposition.