Fontaine, Guy

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HISTORY OF CARDIOLOGYCardiology Journal2009, Vol. 16, No. 3, pp. 294–296Copyright © 2009 Via MedicaISSN 1897–5593294 www.cardiologyjournal.orgôThe serendipitous discovery of fulguration(high energy DC ablation)The patient involved in the first fulguration wasa 47 year-old man who had experienced a myocar-dial infarction ten years previously. This had beenlong forgotten until he experienced an abrupt syn-cope, followed quickly by a second episode. In lightof these episodes, an electrophysiological explora-tion was performed in 1979 with the intention ofhighlighting a probable disorder of atrio-ventricu-lar conduction. This disorder was presumed to belocated below or inside the His bundle because thePR interval was not lenghtened. Apart from someextra-systoles, there were no disorders of intra-ventricular conduction resulting from the oldmyocardial infarction.The insertion of an endocavitary explorationcatheter identified a good His bundle potential as-sociated with a normal HV interval of 40 ms. Ho-wever, despite meticulous exploration by means ofmoving the electrodes on the atrio-ventricular junc-tion, it was impossible to obtain the 2nd Hisian po-tential which could have documented a disorder ofconduction located in the trunk of the His bundle.Such an interruption of conduction could have thenled to a period of heart standstill and would haveexplained the symptoms.During the second part of the study, while fol-lowing a well-planned protocol, a dynamic study ofatrio-ventricular conduction was done by program-med stimulation delivered on the atrium, whichshowed normal effective and functional refractoryperiods of atrio-ventricular conduction in the ante-rograde direction. At this point of the examination,the conduction system was cleared of any suspicion.However, in accordance with the regular electro-physiological study protocol used at that time, theatrial catheter was moved into the ventricle to prac-tice a programmed ventricular stimulation in orderto study retrograde conduction as well. It was notcompletely impossible that apparently normal an-terograde conduction could have been revealed byan abnormal retrograde conduction (the reverse ofwhat one generally observes).By principle, this programmed ventricular sti-mulation created an extra-stimulus increasingly clo-ser to the basic stimulations in order to trigger anartificial ventricular extra-systole applied progres-sively closer to the top of the ‘T’-wave of the pre-ceding QRS complexes, which were already of‘extra-systolic’ type, having been induced by ven-tricular stimulation. However, during this protocol,an episode of ventricular tachycardia was obviouslyinduced by the stimulation. We then used a shortperiod of fast stimulation to stop the ventriculartachycardia at once, as is routinely done. But inste-ad of stopping, the tachycardia accelerated. This isa known event which can itself be stopped by ano-ther burst of even faster stimulation, but in thiscase, the tachycardia had taken an extremely fastrate associated with hemodynamic failure promp-tly leading to loss of consciousness.Although impressive, this was not completelyexceptional. It had been known since the methodsof programmed stimulation were introduced bya team of famous doctors in Amsterdam in 1972 thatit was indeed possible to trigger an episode of ven-tricular tachycardia in the chronic phase after my-ocardial infarction. It was therefore possible toexplain the syncopes of the patient as due to spon-taneously recurring episodes of fast ventricular ta-chycardia with cerebral hypoxia, and not to a disor-der of atrio-ventricular conduction!It wasn’t possible to discuss this reasoning inmore detail because the tachycardia had quicklytransformed into ventricular fibrillation. This issometimes experienced in the electrophysiologylab, and is always something for which suitablemeasures must be taken as soon as possible, suchas applying a defibrillation shock. At present, whenone practices an electrophysiological exploration atthe Institute of Cardiology in the Salpetrière Ho-spital on a patient of this type, one always takes theprecaution of placing two self-adhesive electrodesof defibrillation on the patient, one anterior and oneposterior, both connected to a defibrillator withwhich such an incident can be quickly controlled.Indeed, as soon as ventricular fibrillation is authen-ticated on the electrocardiography and as soon as thepatient has lost consciousness, the doctor or thenurse nearest the defibrillator can easily and immedia-tely deliver a shock which restores normal sinusrhythm at once. But in those days, such electrodesdid not yet exist. Then, in the event of syncope, onehad to quickly grab the ‘emergency reanimation cart’,seize the manual electrodes, dab a good quantity ofconducting paste onto the active metal plaque andapply them manually to the thorax of the patient.295Guy Fontaine, The serendipitous discovery of fulguration (high energy DC ablation)www.cardiologyjournal.orgIt was impossible to know exactly what hadoccurred, but the fact was that when the first shockwas applied and the spot (which had been driven offthe screen) returned to view, it was obvious thatthe patient was still in ventricular fibrillation. Yetat first, this was something relatively banal, as it isknown that the threshold of defibrillation is varia-ble and that it is necessary in certain cases to applya second shock to correct this rhythm disorder. Thedefibrillator was thus reloaded and a second shockapplied, but when the spot quickly returned to thescreen once more, it showed the patient was stillin ventricular fibrillation. This was a situation en-countered rarely in practice, but known to be po-ssible. Under these conditions, the energy was in-creased. In fact, the maximal energy was used,which caused the defibrillator to take a noticeablylonger time to reload. Once reloaded, a third shockwas applied, the effect of which was exactly thesame as that of the preceding two. The heart stillremained in ventricular fibrillation. One could ima-gine that concern seized the operator because it wasknown that defibrillation became increasingly moredifficult to correct as time passed.The defibrillator was reloaded again with thesame negative result. The fourth shock, and eventhe fifth, remained ineffective, even though thedefibrillator functioned perfectly well, causing thepatient to ‘jump’ with each discharge. At that point,it had become necessary to make instant decisionsbecause the situation had turned life-threatening.It was necessary to improvise hastily by tearingoff the sterile fields, pushing back the radiology ap-paratus, applying a larger amount of paste to theelectrodes and tightening the thorax between them.Then a sixth shock was given. This time, when thespot returned to the screen, ventricular fibrillationhad disappeared. But after a moment of surprise, itwas evident that the small round waves which ap-peared on the screen were not QRS complexes flat-tened by the effect of the shock on the electrocar-diography amplifiers, but indeed authentic P-wavesnot followed by the expected QRS complexes. It be-came evident that there did not exist either a junc-tional escape or spontaneous ventricular rhythm,and that the patient remained inert. He was now incardiac standstill with a complete ’solemn’ atrio-ventricular block.Very quickly, the ventricular catheter wasmoved to the ventricle and connected to the stimu-lator. After a few seconds, the patient made someconvulsions, opened his eyes and gradually retur-ned to consciousness. After a few more minutes ofstimulation, he was able to answer the questions ofthe nurses more coherently, and everyone was re-assured.Yet that was not the end of it, because eachtime the stimulation was stopped, the electrocar-diogram showed only P-waves, not followed by thenormal ventricular complexes. They seemed some-times to be followed by a QRS complex with a we-akened, widened and sometimes fragmented Hispotential. After approximately one and a half hoursof waiting, the patient was put back into His bedunder electronic monitoring, with a catheter con-nected to an external stimulator fixed upon histhigh. He would remain there for nearly a week, atthe end of which the complete atrio-ventricularblock was as ‘solemn’ as during its first appearan-ce. A pacemaker was implanted, which would bechanged several times over the subsequent years.At present, the patient is with his seventh deviceand continues to carry out a normal life!This entire incident, which could have easilyturned into a catastrophe, was at first difficult to un-derstand. Why had a complete atrio-ventricularblock occurred during a series of external electricshocks, followed by a delayed but acceptable reco-very? To this question, there was no clear answerin the literature of the time, especially consideringthe beginning of electrophysiological explorationwhich proved that the patient had a normal atrio-ventricular conduction. In addition, this completeblock with absolutely no ‘ventricular escape beats’was also in itself surprising.At first, it was impossible to understand theelectrical phenomenon that led to this surprisingevent. But, I remembered from having read severaldetective novels that a very important aspect ofa police investigation is to reconstitute the environ-ment of a crime at the place where it occurred. So,I gathered all the personnel who had attended theevent and asked each of them to describe exactly whathappened from their point of view. The only intere-sting item that emerged from this reconstitutionwas that one nurse said that she had heard a spark!A spark? That point immediately attracted myattention and I asked what she meant by the word‘spark’. She said that ‘spark’ was the common termreferring to an ‘electric spark’ that can sometimesbe observed during the use of electrical apparatus.This was intriguing! How could a spark have occur-red in such an environment?The answer came several years later, proba-bly when I was manipulating catheters and connec-tor leads, the same equipment which was used du-ring the initial event.The ‘spark’ could have burst near one of theelectrodes of defibrillation during the last shock.This spark occurred when the electrodes were cor-rectly applied against the thorax with a large quan-tity of conducting jelly. In this case, it was known296Cardiology Journal 2009, Vol. 16, No. 3www.cardiologyjournal.orgôthat the current runs out between the broad surfa-ces of the two electrodes of defibrillation to coverthe ventricular mass in near totality, thus allowingfor an effective defibrillation. But how, under the-se conditions, could a spark have been possible?The explanation lies in the particular environ-ment in which the incident occurred. The proximalpart of the endocavitary United States CatheterInstrument Company (USCI) catheter, pushed upby right femoral way, was connected to the electro-physiology amplifiers, while passing by a connectionbox assembled on a metal bar, located behind thehead of the patient. A significant space was presentbetween the proximal male part of the USCI cathe-ter and the connecting box. However, it was foundby chance that an interconnection cable made inFrance by a company called L’Electronique Appli-quée, especially designed on my request to connectendocardial catheters to external stimulators fortemporary pacing, could provide the explanation!The same equipment proved suitable to connect thejunction box to the USCI catheter. On this side eve-rything functioned correctly, except that becauseof the differences between inches and centimetersthe male part of the USCI catheter was not goingdeep enough inside the female part of the intercon-necting wire. This was sufficient to ensure a goodelectrical contact, but unfortunately left nearly oneand a half centimeters of the metal connector of thecatheter outside the connection and therefore expo-sed to any external contact (Fig. 1).I realized that when the sterile fields had beenwithdrawn, the catheter was of course not discon-nected and the exposed part of the connector displa-ced during the emergency move of the surgicalfields came into electrical contact with the pasteoverflowing from one of the defibrillation electro-des. It happened that this connector was preciselyconnected to the intra-cardiac electrode exactlylocated on the His bundle. Part of the electric fieldintended for defibrillation could have been diver-ted through the paste towards the exposed con-nector, which had led to the creation of a spark andhad explained the leakage of the current in the di-rection of the electrode placed on the His bundle.It is now well known that energies from a fewjoules to a few tens of joules are sufficient to defi-nitively deteriorate atrio-ventricular conduction.The absence of escape rhythm can be also expla-ined by the fact that the his bundle and itsbranches are more sensitive to current than thenormal myocardium.All of this is now clear, but the credit goesto one of us (Dr. Jacques Vedel) who was to writeabout it in an important scientific publication whichwould not pass unnoticed. Indeed, at that time, sur-gical methods were used to interrupt atrio-ventri-cular conduction, but when these methods werecarried out on a purely anatomical basis, even inopen heart surgery, they were not always assuredof success. One knows now that the anatomicallocation of the His bundle can be located on the leftside of the interventricular septum in certain cases.In such a case, it is necessary to approach the hisbundle from the left part of the heart, which is po-ssible, but more difficult, because the catheter mustbe introduced through the femoral artery and mustcross the aortic valves with counter-current toreach the critical zone.It was thus interesting to exploit the possibili-ties of the use of an electric current to obtain a vo-luntary interruption of atrio-ventricular conductionamong patients with incessant supraventriculararrhythmias resistant to anti-arrhythmic drugs, andthose who had a myocardium unable to tolerateopen heart surgery.Guy FontaineHôpital de la SalpetrièreInstitut de Cardiologie, Unité de rythmologie47 Bld de l’Hôpital, 75013 Paris, Francee-mail: g.fontaine@psl.aphp.frThe spark that was heard by thenurse from the electrophysiology labExternal defibrillatingelectrodesFigure 1. The mechanism of accidental His bundleablation.

The serendipitous discovery of fulguration (high energy DC ablation)

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The serendipitous discovery of fulguration (high energy DC ablation)

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