The objective was to assess the diagnostic utility and feasibility of using a 3-10MHz, 8 French, 90cm intracardiac echocardiography (ICE) catheter (Acuson AcuNav®) to evaluate cardiac structures and function in conscious horses sedated with xylazine.
Ten apparently healthy horses (458-619kg) from the Texas A&M university teaching herd underwent a physical exam, transthoracic echocardiography (TTE) and ICE through a 10 French right jugular introducer placed in the proximal 1/3 of the neck. A continuous ECG was recorded during the procedure using simultaneous ECG telemetry. Three positions are described with the associated 2D, pulse wave Doppler (PW), continuous wave Doppler (CW), color Doppler (CD) and M-mode imaging planes standardized by referencing the intracardiac positions and common landmarks. The positions were confirmed with simultaneous TTE.
The 1st position (cranial right atrium) allowed visualization of the right atrium, right ventricle, tricuspid valve, cranial and caudal vena cava in long-axis. Alignment was adequate for CD, CW and PW evaluation of the tricuspid valve for assessment of regurgitation and inflow. Clockwise rotation allowed visualization of the aortic valve and ascending aorta in long axis, and the pulmonic valve in short axis with adequate CD evaluation. Posterioflexion provided adequate alignment for transaortic PW and CW. The 2nd position (mid right atrium) allowed visualization of the left ventricular outflow tract, aortic valve and left atrium in long-axis. The depth of the imaging plane resulted in suboptimal CD evaluation. Anteroflexion and counterclockwise rotation allowed visualization of the mitral valve, interatrial septum, foramen ovale, left atrium, pulmonary veins and associated ostia in long-axis. CD evaluation was adequate. The 3rdposition (right ventricle) allowed visualization of the mitral valve, interventricular septum and left ventricle in long and short-axis. A diagnostic M-mode of the left ventricle was possible from this positon.
The procedure was well tolerated with only mild, intermittent ventricular and supraventricular arrhythmias that resolved with ICE catheter repositioning.
We conclude that ICE is feasible, safe, and allows for acquisition of repeatable diagnostic imaging planes in conscious, sedated horses. It could potentially be useful in clinical situations where TTE may be technically difficult to perform or poorly tolerated in horses.
Veterinary Cardiology Resident
Texas A&M University
Dr. Boutet received his DVM from the Atlantic Veterinary College at the University of Prince Edward Island. He completed a rotating internship at Michigan Veterinary Specialists before finishing a two year fellowship at the Texas Institute for Preclinical Studies with a focus on minimally invasive procedures. He is currently finishing his Cardiology residency at the Texas A&M university. His professional interests include diagnostic imaging, congenital diseases and interventional cardiology.
Thursday, June 14
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Saturday, June 16
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