RT-107
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Evaluation of myocardial lesion
after radiofrequency catheter ablation using in-111-antimyosine antibodies: preliminary
results
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X. Vinolas, I. Carrió*, R. Oter,
O. Aslan, M. Ballester, P. Torner, M.C. Varela, A. Bayés de Luna.
Cardiology and Cardiac Surgery Department,
*Nuclear Medicine Department, Hospital de Sant Pau, Barcelona, Spain
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Introduction
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Radiofrequency catheter ablation (RFCA) is nowadays
the first line treatment for most supraventricular tachycardias. The big development of
the technique is due to various factors. First of all, energy application is not painful,
thus general anaesthesia is not needed as it was with DC shocks. Secondly, as we will
explain later, the lesion is well limited and no barotrauma is present. Finally the
success rate in experts groups is near 100% with a very low complication rate (< 5%)
and a mortality very near to 0%.
Myocardial lesion produced by RFCA
Myocardial lesion is created by the RF current (unmodulated alternate current, 500 to
750 Hz) between the distal electrode of a catheter (usually of 4 mm2) and a
large sur-face dissipative electrode (usually located in the left scapular area)1. The power used ranges usually between 1-50 J and
actually automatic temperature control using close loops systems are used routinely, thus
making the energy applied more rationale. Temperature control has almost completely
abolished the carbonisation of catheter tip electrode and the irregular lesion created
when this phenomena occurs. Radiofrequency catheter myocardial lesion is due to a
coagulative-dessecative necrosis produced by the heating of catheter-tissue interface,
with a dimension of the lesion ranging from 0.5 to 1 cm maximum, and very well limited
borders.
A lot of studies have been made evaluating the myo-cardal lesion produced by RF
applications, but most of them are anatomo-pathological animal studies or in vitro studies2. Different approaches have been used to evaluate -
non-invasively - the myocardial lesion produced in vivo by radiofrequency pulses.
Echocardiogram and Holter recordings were performed in a consecutive serie of 250 patients
in our institution. Five pericardial effusions (2%), without any segmentary contractility
abnormalities were observed (unpublished data). No proarrhythmic effect was observed in
Holter and/or clinical follow-up3. Serial
determinations of classical biochemical markers of necrosis (CK, GOT) did not show a
significant increase, thus indicating that the lesion should be small. Recent studies have
demonstrated an increase in a much sensitive marker of myocardial lesion: troponine
levels.
The possibility of a non-invasive evaluation of myocardial lesion created by the RF
pulse application could be useful, because it will allow us to evaluate the follow-up of
the in-vivo lesions and the effect of the differents procedure parameters. Furthermore CK
and troponine levels do not distinguish between diffuse and localized lesions.
Antimyosin monoclonal antibodies
Monoclonal 111 indium-labelled antimyosin monoclonal antibodies are fixed by the
myocardial cells when membrane rupture occurs. This technique is very sensitive and
specific in order to evaluate myocardial membrane cell rupture, and has been used to
diagnose, locate and evaluate the extension for example of myocardial infarctions4-6. Its sensitivity and specificity have pushed some
investigators to use antimyosine antibody to evaluate other non-ischemic cardiopathies in
which more diffuse myocardial necrosis can be present. Several studies have been made to
evaluate its value in myocarditis, dilated cardiomyopathy and heart transplantation
rejection7-9. The fact that antimyosine uptake
evaluation is non-invasive, without side-effects and very sentitive and specific makes it
very attractive.
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Key Words
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Radio frequency catheter ablation of
tachyarrhythmias
myocardial lesion, antimyosine monoclonal antibodies, heart-lung index, echocardiogram, OA
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