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Percutaneous transluminal septal myocardial ablation (PTSMA: the injection of alcohol in a septal perforator branch perfusing the basal septum) has been increasingly used in the last 15 years as an efficacious treatment option for symptomatic patients with hypertrophic obstructive cardiomyopathy.1, 2
This technique aims to reduce the hypertrophied septum through the production of a small myocardial infarction confined to the part of the septum that is involved in the generation of the gradient.3
In most patients obstruction is caused by systolic anterior motion of the mitral valve towards the hypertrophied basal septum. The target of PTSMA is usually the first larger septal branch, that most probably perfuses the basal septum; there is however considerable variety in its size, angiographic morphology and supplying territory as well as potential collateralization with other septal branches.4, 5
Multiple or atypically originating septal branches may further perplex the choice of the correct branch.
Taking these problems into consideration, echocardiographic guidance with echo-contrast-mediated identification of the target septal branch was clearly the most significant improvement of the original technique and has become indispensable to the procedure.6 Before any alcohol injection, an echocardiographic contrast agent is administered through the central lumen of the balloon catheter under real-time transthoracic 2-dimensional echocardiographic and colour Doppler monitoring. Injection into the optimal septal branch will cause an obvious opacification of the septal area next to maximal flow acceleration that involves the point of contact between the mitral valve and the septum during systole. It is evident that myocardial contrast echocardiography can change the interventional strategy by dictating the need to change the target branch or even abandon the procedure if the proper septal branch can not be identified. Alcohol is injected only when the correct target has been proven and its amount depends mainly on the echocardiographically estimated size of the contrasted septal area.7
The advent of myocardial contrast echocardiography during percutaneous septal ablation has been shown to improve the hemodynamic result and decrease the complication risk.6, 8
Use of the proper contrast agent enables better imaging quality, thus ensuring the safety of the procedure, which could be also applied to treat patients with midventricular obstruction or with a previously unsuccessful surgical attempt. 9, 10
The precise identification of the target septal region has permitted injection of less alcohol without compromising the hemodynamic result. 11-13
Levovist® injected after recording of echocardiographic images acquired with injection of Gelafundin® resulted in no further enhancement of the already contrasted basal septal area (Figure). Moreover, there was no further opacification of other myocardial areas apart from those already indicated by Gelafundin®. Gelafundin® remained long enough in view, so that there was enough time to evaluate all echocardiographic views for possible misplacements. Most importantly, there was no arrhythmogenicity during or after Gelafundin® injection.
The authors’ conclusion was that Gelafundin® seems safe and efficacious as a newly introduced intracoronary injected echocardiographic contrast agent for PTSMA.
The presentation by Pfeiffer B, et al. is of great interest, because it proposes a possible solution to a significant problem. Myocardial contrast echocardiography is sine qua non for PTSMA and the choice of the specific contrast agent may have a tremendous impact on the efficacy and safety of the procedure. The ideal contrast agent should offer good contrast imaging with clear pigmentation of the target area, slow capillary runoff that ensures a stable demarcation of the target area, rapid washout (e.g. destruction of bubbles with increased echo gain) in case of possible misplacement, no allergic potential and of course no arhythmogenicity. Levovist® has shown most of these properties, so as to be regarded as the ideal contrast agent for PTSMA. According to own experience, the use of agitated radiographic contrast produces low quality opacification of the target area, with the possibility to miss a possible misplacement, while Sonovue®, a widely used via the intravenous route contrast agent seems to have a very fast runoff when used in the coronary arteries rendering a safe and detailed scrutiny of the contrasted areas extremely doubtful.
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