IMAGES IN MEDICINE
Real-time myocardial contrast echocardiography for echo-guided alcohol septal ablation

Introduction

Until the early 1990s, surgical myectomy represented the standard treatment for patients with hypertrophic obstructive cardiomyopathy (HOCM) and drug-refractory symptoms. More than one decade ago, alcohol septal ablation (ASA) was introduced as a less invasive alternative therapy for symptomatic HCM patients with obstruction. Alcohol septal ablation is performed through a percutaneous approach, in which 1-3 ml of absolute alcohol is introduced into the septal branch to create a controlled septal infarction of the basal interventricular septum with its subsequent shrinkage and outflow gradient elimination (Figure 1). This procedure results in relief of symptoms, a decrease of pressure gradient and improvement of the left ventricular diastolic function [1-3].
During the procedure, contrast myocardial echocardiography is performed to delineate the area to be infarcted (Figures 2, 3) and to exclude contrast (and subsequently alcohol) injection in remote myocardial regions such as the left ventricular posterior wall or papillary muscles. The optimal septal branch is identified by opacification of the area in the basal septum which is adjacent to the zone of maximal acceleration of the outflow jet and includes the point of coaptation between the septum and the anterior mitral leaflet.
Several studies with echocardiographic monitoring of this procedure have been reported since 1996. Conventional harmonic imaging (CI) that was used in the past has some limitations regarding the presence of tissue harmonics, which results in lower contrast-to-tissue ratio (Figure 2). We demonstrate for the first time a clinical use of real-time myocardial contrast echocardiography with very low mechanical index (MI) for intra-procedural visualization of the target septal area during ASA (Figure 3).
The very low MI means that the bubble destruction by the incident ultrasound is minimal [4]. This technique improves (more than CI) visualization of regional perfusion in the target septal area, thereby defining the area and extent of future necrosis, and also prevents remote complications following induction of necrosis far from the basal interventricular septum. It seems to be likely that better visualization of the perfusion area of the septal branch using real-time contrast echocardiography might improve outcomes of ASA.
Acknowledgments
Supported by grant of the Ministry of Health of the Czech Republic No. 00064203
References
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