Two cases with drug refractory ectopic atrial tachycardia are described. A map-guided partial resection of the right atrium (RA) was done after preoperative endocardial catheter mapping hadshown well-defined areas of fractionated RA potentials. Intraoperatively, there were no aneurysmal formations present as described by other authors. Histopathologic examination of the resected tissue showed atrial myocarditis in both patients. Postoperative right ventricular myocardial biopsies revealed no inflammatory tissue. A minor elevation of antibodies against echoviruses was found in one case. Postoperative electrophysiologic studies were negative. We conclude: focal RA myocarditis without concomitant ventricular myocarditis may represent one cause of drug-resistant ectopic atrial tachycardia. Map-guided surgical intervention may cure the diseas

FROMER, M.

GENTON, C.

GOY, JJ

KAPPENBERGER, L.

SCHLAEPFER, J.

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European Heart Journal (1990) 11, 566-571Is there an isolated arrhythmogenic right atrialmyocarditis?M. FROMER, C. GENTON,* J. SCHLAEPFER, JJ. GOY, L. KAPPENBERGERDivision of Cardiology, Medical Clinic, University Hospital, Lausanne and the * Institute of Pathology,University of Lausanne, SwitzerlandKEY WORDS: Atrial myocarditis, atrial tachycardia, endocardial resection.Two cases with drug refractory ectopic atrial tachycardia are described. A map-guided partial resection of theright atrium (RA) was done after preoperative endocardial catheter mapping hadshown well-defined areas offractionated RA potentials. Intraoperatively, there were no aneurysmal formations present as described byother authors. Histopathologic examination of the resected tissue showed atrial myocarditis in both patients.Postoperative right ventricular myocardial biopsies revealed no inflammatory tissue. A minor elevation ofantibodies against echoviruses was found in one case. Postoperative electrophysiologic studies were negative.We conclude: focal RA myocarditis without concomitant ventricular myocarditis may represent one cause ofdrug-resistant ectopic atrial tachycardia. Map-guided surgical intervention may cure the disease.IntroductionThe anatomic substrate of ectopic atrial tachy-cardia (AT) is rarely evaluated as the investigationof the underlying disease requires a surgicalapproach. Successful surgical resection wasreported by a few groups'1"3'. Olsson el a/.'1'described an aneurysmal formation of the atrialtissue close to the right atrial appendix. Wyndhamet al.m reported in 1980 a case with patchy fibrosis ofthe right atrium close to the appendix, an increase ofconnective tissue and mononuclear cell infiltration.The same group reported later surgical experiencewith eight cases, however, the results of histologicexamination were not given'31. In our report of twocases we describe the occurrence of ectopic right ATwithout aneurysmal formation, however with well-defined inflammation of the right atrium in theabsence of concomitant myocarditis of the rightventricle. We hypothesize that myocarditis of theright atrium may be responsible for recurrentectopic AT resistant to antiarrhythmic drug regi-mens, and map-guided resection of the abnormalarea may cure the disease.Submitted for publication on 9 August 1989, and in revised form26 September 1989.Martin Fromer is recipient of a SCORE grant #3.750-87 from theSwiss National Foundation of Sciences.Address for Correspondence M. Fromer, MD. Division ofCardiology, Centre Hospitalier Universitaire Vaudois, CHUV, 1011Ljusanne. Switzerland.CaselA 20-year-old male was referred for electro-physiologic evaluation of a 1 -year history of highlysymptomatic, drug-resistant supraventriculartachycardia. Clinical and echocardiographic exam-ination showed no associated cardiomyopathy.Standard techniques for electrophysiologic evalu-ation were used'4'. An atrial tachycardia with acycle length of 300 ms and 2:1 atrioventricularconduction was present (see Fig. 1). Endocardialcatheter mapping showed areas of abnormal electri-cal activity with fractionated potentials in thepostero-lateral regions of the mid right atrium (Fig.2). This area was considered to be responsible forthe AT. This finding together with the patient'shistory motivated an attempt at surgical resection.Intraoperative epicardial mapping confirmed thepresence of an ectopic right sided AT originating inthe infero-posterior areas of the right atrium. Thepostoperative course was unremarkable and theatrial Jachycardia did not reoccur.Case 2A 27-year-old male has been referred for theevaluation of a 5-year history of drug-resistantsupraventricular tachycardia. Drug trials withdisopyramide, verapamil, beta blockers, flecainideand propafenone were not effective. Clinical andechocardiographic evaluation disclosed no cardio-vascular abnormality. The electrophysiologic study0195-668X 90 060566 + 06 $03.00 0 © 1990 The European Society of CardiologyFocal RA myocarditis 567SCHCFigure 1 12-lead standard electrocardiogram of patient 1 show-ing an atrial tachycardia with 2:1 atrioventricular conduction.Paper speed 25 mm s"'.showed an atrial tachycardia (Fig. 3) and largezones of fractionated potentials (Fig. 4) in the mid-right atrium. The same findings were reproducibleduring a second electrophysiologic study done pre-operativelyand motivated the surgical intervention.Epicardial mapping confirmed the presence of rightsided AT. Intra-operatively, large zones with frag-mented potentials were found around the appendixand anterolateral segments of the right atrium. Alarge resection including all areas of fragmentedpotentials was done and replaced with a pericardialpatch. After this the AT was no longer inducible.Results of histologic examinationCASE 1Six specimens were given for histologic examin-ation. The largest measuring 2x1x0-5 cm, thesmallest 1 -5 x 0-7 x 0-2 cm. Histologically, a moder-ate inflammatory infiltrate was found in the myo-cardium and endocardium. This focally confluentinfiltrate was essentially lymphocytic, there were noeosinophilic leucocytes nor giant cells. Obviouslydamaged myocytes with vacuolization were present(Fig. 5). In some areas, granulation tissue with thebeginning of fibrosis was present. There were nomural thrombi. These findings are consistent with amoderate, diffuse lymphocytic myocarditis withgranulation tissue and fibrosis. Eight days later,right ventricular endomyocardial biopsies wereobtained from the lateral wall and septum. Examin-ation of multiple sections of the six specimenssuggested an increased interstitial cellularity butimmunohistochemical staining for polymorpho-nuclear leucocytes and lymphocytes were negative.The specimens were therefore considered torepresent normal myocardium.568 M. Fromer tta\.MRAH B E -SCH.C.Figure 2 Representative illustration of local recordings of right atrial electrocardiograms inpatient 1 dunng atrial tachycardia with 2:1 AV-conduction. Arrows indicate nght atrial potentialswith abnormal low amplitude. Note for comparison the normal right atrial potentials (HRA) withrapid rise of the intnnsic deflection and high amplitude of the local electrocardiogram and shorterduration of the signal. I, aVF, V1 and V6 represent standard surface electrocardiographic leads.Other abbreviations: HRA = high right atrium, MRA = mid right atnum, HBE = His bundleelectrocardiogram, including low right atrial depolarization. Paper speed 100 mm s~'.V * » •Figure 3 12-lead electrocardiagrams of patient 2 showing ectopicright atnal tachycardia with 1:1 conduction. Paper speed at left25mms ', at right 50mm s ' .Focal RA myocarditis 569l t 774aVF—4r ~ V ^ 4/ J^-MRAHRAK.P.Figure 4 Local recordings of right atnal electrocardiograms in patient 2 during right atnaltachycardia with 1:1 conduction. Arrows indicate abnormal fragmented nght atrial potentialsas discussed in Fig. 2. For abbreviations see Fig. 2.Figure 5 Confluent lymphocytic infiltrate of myocardium and endocardium accompanied byobvious vacuolization of myocytes and beginning fibrosis. Haematoxylin and eosin x 250.CASE 2 endocardium showed oedema and an essentiallyThe resected part of the right atrium measured lymphocytic infiltrate which was also present in the6 x 3-5 cm and comprised the appendix, which myocardial interstitium. There was focal vacuoliz-appeared slightly dilated. Microscopically the ation and necrosis of myocytes (Fig. 6), sometimes570 M. Fromer eta\.figure o hocal and connuent lymptiocytic lntiltrates in trie myocardium with vacuolizationand focal necrosis of myocytes, some of which show large hypcrchromatic nuclei. Haematoxylinand eosin x 250.accompanied by small haemorrhages. There wasalso some degree of interstitial fibrosis. The micro-scopic findings are consistent with a moderate dif-fuse lymphocytic myocarditis with some interstitialfibrosis of unknown origin.DiscussionSeveral reports in the literature have discussedthe diagnostic, therapeutic and electrophysiologicaspects of ectopic (right) atrial tachycardia'1"3-6-71.However, the probable anatomic substrate for thesetachycardias is difficult to investigate. Wyndhamet a/.'21 described the histologic findings of onepatient with ectopic right AT demonstrating mono-nuclear cell infiltration and increased connectivetissue. Olsson et a/.'1' described two patients withectopic AT. In one of those patients three smallaneurysms were seen located between the sinusnode and right atrial appendage. After excisionof this area, sinus rhythm reappeared. Results ofhistologic examination were not given.In the two cases described here, no aneurysmalformations were observed. Histologic examinationshowed a subacute myocarditis in one case and anon-going chronic myocarditis in the other151.Biopsies of the right ventricle showed no con-comitant ventricular myocarditis, however, proofthat the disease was only affecting the right atriumwas unavailable. The etiology of the disease is notclear yet. In case 1 serologic investigations for aviral infection have not been done. In case 2 a mildelevation of antibodies to echoviruses was found. Inboth cases the endocardial catheter mappingshowed large areas in the right atrium with abnor-mal electrical activity. After intra-operative con-firmation of these findings and resection of thoseabnormal zones, the ectopic tachycardia dis-appeared. We therefore conclude that in some caseswith ectopic (right) AT, an isolated myocarditis ofthe atrium may be the anatomic substrate for thearrhythmia. Careful histologic examination of theresected areas may clarify the pathogenesis ofectopic AT in a subgroup of patients. Furtherinvestigations are necessary to clarify whetherthe management of these patients requires anti-inflammatory drug therapy to avoid disseminationof the disease.References[1] Olsson SB, Blomstroem P, Sabel K-G, William-Olsson G.Incessant ectopic atrial tachycardia: successful surgicaltreatment with regression of dilated cardiomyopathy pic-ture. Am J Cardiol 1984; 53: 1465-6.[2] Wyndham CRC, Amsdorf MF, Lcvitsky S et at.Successful surgical excision of focal paroxysmal atrialtachycardia. Circulation 1980,6: 1365-72.Focal RA myocarditis 571[3] Seals AA, Lawrie GM, Magro S el al. Surgical treatmentof right atrial focal tachycardia in adults. J Am Coll Car-diol 1988; 11: 1111-7.[4] Shenasa M, Fromer M, Faugere G el al. Efficacy andsafety of intravenous and oral diltiazem for Wolff-Parkinson-White syndrome. Am J Cardiol 1987; 59:301-6.[5] Aretz HT. Myocarditis: the Dallas criteria. Hum Pathol1987; 18:619-24.[6] Mirowski M, Lau SH, Wit AL el al. Ectopic right atrialrhythms: experimental and clinical data. Am Heart J1971; 81: 666-76.[7] Scheinman MM, Basu D, Hollenberg M. Electrophysio-logic studies in patients with persistent atrial tachy-cardia. Circulation 1974; 50: 266-73.

Is there an isolated arrhythmogenic right atrial myocarditis?

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