Right ventricular tachycardia—arrhythmogenic right ventricular cardiomyopathy or idiopathic?

Hans Kottkamp* and Gerhard Hindricks

Department of Electrophysiology, University of Leipzig—Heart Center Cardiology, Struempellstrasse 39, D-04289 Leipzig, Germany

* Corresponding author. Tel.: +49-341-865-1413; fax: +49-341-865-1460
E-mail address: kotth{at}medizin.uni-leipzig.de

EditorialEditorial

See doi:10.1016/S1095-668X(02)00654-1for the article to which this editorial refers.

The majority of right ventricular tachycardias exhibit a left bundle branch block pattern with an inferior axis. The classical differential diagnosis is either idiopathic right ventricular outflow tract tachycardia or arrhythmogenic right ventricular dysplasia/cardiomyopathy. Recently, the entity of right ventricular outflow tract tachycardia has been extended to outflow tract tachycardias with potential origins in the right ventricular outflow tract, the left ventricular outflow tract or the aortic sinus of valsalva.1,2 Especially the R/S transition in the precordial leads of the 12-lead surface ECG has been useful to differentiate between a left or right-sided origin, with the classical left bundle branch block pattern indicating to the right side and a premature transition at V1 to V3 indicating more towards the left side or the aortic sinus. In some cases, the definite origin may only be defined periinterventionally. In general, right ventricular outflow tract tachycardia occurs in the absence of structural heart disease and has a favorable prognosis.3 In some studies, however, structural abnormalities have been described using magnetic resonance imaging.4 Clinical manifestations include nonsustained or sustained ventricular tachycardias that are related to physical exercise in a significant portion of the cases.

Arrhythmogenic right ventricular cardiomyopathy is characterized pathologically by fibro-fatty replacement of the right ventricularmyocardium.5,6 Although segmental right ventricular disease is most commonly seen, evolution to a more diffuse right ventricular involvement and also left ventricular abnormalities have been described. Clinical manifestations include depolarization/repolarization abnormalities in the right precordial ECG leads, structural abnormalities of the right (and rarely left) ventricle, ventricular tachycardias and presentation with sudden cardiac death, and a family history of the disease. Criteria for diagnosis of arrhythmogenic right ventricular dysplasia include global and/or regional dysfunction, histologic tissue characteristics, repolarization and depolarization/conduction abnormalities, arrhythmias and a family history.5,7 The fulfillment of the diagnosis of right ventricular dysplasia has been proposed by the presence of two so-called major criteria, one major plus two minor criteria, or four minor criteria. Theoretically, the definite diagnosis of right ventricular dysplasia is based on the histological demonstration of transmural fibro-fatty replacement of right ventricular myocardium at either necroscopy or surgery. Obviously, the clinical value with respect to findings at necroscopy or surgery as diagnostic criteria is very limited and, in addition, assessment of the diagnosis based on right ventricular endomyocardial biopsy specimens is also inherently difficult for several reasons.5–7 In clinical praxis, the histological demonstration of transmural fibro-fatty replacement therefore does not play a major role.

The study by O'Donnell et al.8 in this issue of the European Heart Journal addresses clinical and electrophysiological differences between patients with arrhythmogenic right ventricular dysplasia and right ventricular outflow tract tachycardia. The study presents important data because the clinical problem is analyzed comprehensively with clinical data, electrocardiographic data, echo data, magnetic resonance imaging data, invasive electrophysiologic data as well as results of catheter ablation including a relatively long follow-up period. Needless to say that the proposed major and minor criteria were applied for differentiation between the two clinical entities by the authors. Interestingly, a mean number of only 1.2 major criteria was found in the patient group with arrhythmogenic right ventricular cardiomyopathy. The higher mean number of 3.0 minor criteria was therefore necessary for the diagnosis emphasizing the puzzle-like steps in reaching the diagnosis of arrhythmogenic right ventricular cardiomyopathy. The value of magnetic resonance imaging is critically highlighted in the present study with 54% of the patients with idiopathic right ventricular tachycardia showing some structural abnormalities. In contrast, no structural abnormalities were found using echocardiography or right ventricular cine angiography in the idiopathic patient group.

Among the key information of the present study is the reported data from the invasive electrophysiological studies.8 A first criterion for differentiation was the mode of induction, with 82% of the cardiomyopathy patients being inducible with critically timed extrastimuli versus only 3% in the idiopathic group indicating the reentrant mechanism of the ventricular tachycardias in the majority of patients with arrhythmogenic right ventricular cardiomyopathy. Secondly, the electrophysiologic study revealed a range of one to six morphologies of inducible ventricular tachycardias (mean 1.8), with 71% of the patients having more than one morphology. In contrast, the patients with idiopathic ventricular tachycardia all had only one morphology. The presence of more than one morphology in the cardiomyopathy group is best explained by the broader arrhythmogenic substrate allowing the perpetuation of more than one reentrant circuit or at least the presence of more than one exit site. The third invasive criterion of fragmented potentials also relates to the substrate created by the fibro-fatty myocardial replacement in arrhythmogenic right ventricular cardiomyopathy with the creation of zones of slow and/or zigzag conduction. The direct electrogram recordings during the electrophysiologic study revealed fragmented potentials in 82% of the cardiomyopathy patients and, therefore, were much more sensitive than the surface ECG correlate, i.e. the epsilon potentials, that were found in only 30% of the cardiomyopathy patients. In addition, the specificity of fragmented potentials remained high since fragmented potentials could only be detected in a single patient (3%) in the idiopathic group.

Overall, the study by O'Donnell comprehensively describes the differences between patients with idiopathic right ventricular outflow tract tachycardia and arrhythmogenic right ventricular cardiomyopathy from a clinical point of view. This also includes the possibility of re-grouping a patient with suspected idiopathic ventricular tachycardia towards the cardiomyopathy group after inducing additional ventricular tachycardia morphologies and the recording of fragmented potentials during the invasive electrophysiologic study. In the individual patient, such a re-grouping is not academical, given the striking differences in therapy, i.e. catheter ablation versus implantable defibrillator, and also in prognosis.

References

  1. Callans D, Menz V, Schwartzman D et al. Repetitive monomorphic tachycardia from the left ventricular outflow tract: electrocardiographic patterns consistent with a left ventricular site of origin. J Am Coll Cardiol. 1997;29:1023–1027.[CrossRef][Medline]
  2. Kanagaratnam L, Tomassoni G, Schweikert R et al. Ventricular tachycardias arising from the aortic sinus of valsalva: an under-recognized variant of left outflow tract ventricular tachycardia. J Am Coll Cardiol. 2001;37:1408–1414.[CrossRef][Medline]
  3. Wilber DJ, Baerman J, Olshansky B et al. Adenosine-sensitive ventricular tachycardia. Clincial characteristics and response to catheter ablation. Circulation. 1993;87:126–134.[Abstract]
  4. Carlson MD, White RD, Trohman RG et al. Right ventricular outflow tract tachycardia: detection of previously unrecognized anatomic abnormalities using cine magnetic resonance imaging. J Am Coll Cardiol. 1994;24:720–727.[Medline]
  5. McKenna WJ, Thiene G, Nava A et al. Diagnosis of arrhythmogenic right ventricular dysplasia/cardiomyopathy. Br Heart J. 1994;71:215–218.[Medline]
  6. Gemayel C, Pelliccia A, Thompson PD. Arrhythmogenic right ventricular cardiomyopathy. J Am Coll Cardiol. 2001;38:1773–1781.[CrossRef][Medline]
  7. Corrada D, Fontaine G, Marcus FI et al. Arrhythmogenic right ventricular dysplasia/cardiomyopathy: need for an international registry. Circulation. 2000;101:E101–E106.[Medline]
  8. O'Donnell, D, Cox, D, Bourke, J. et al. Clinical and electrophysiological differences between patients with arrhythmogenic right ventricular dysplasia and right ventricular outflow tract tachycardia. Eur Heart J2003;24:801–810..

Related articles in EHJ:

Clinical and electrophysiological differences between patients with arrhythmogenic right ventricular dysplasia and right ventricular outflow tract tachycardia
D. O'Donnell, D. Cox, J. Bourke, L. Mitchell, and S. Furniss
EHJ 2003 24: 801-810. [Abstract] [Full Text]  




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