Darija Mahović

Lakušić Lakušić

Valentina Slivnjak

English

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Acta Clin Croat,  Vol. 48,  No. 3,  2009 99Acta Clin Croat 2010; 49:99-100 Letter to the EditorASHMAN PHENOMENON: AN OFTEN UNRECOGNIZED ENTITY IN DAILY CLINICAL PRACTICENenad Lakušić1, Darija Mahović2and Valentina Slivnjak11Department of Cardiology, Hospital for Medical Rehabilitation, Krapinske Toplice; 2University Department of Neurology, Zagreb University Hospital Center, Zagreb, CroatiaCorrespondence to Nenad Lakušić, MD, PhD, Department of Cardiology, Hospital for Medical Rehabilitation, Gajeva 2, HR-49217 Krapinske Toplice, Croatia E-mail: nenad.lakusic@post.htnet.hrDear Editor,We decided to reply with this letter regarding the entity that is often unrecognized in daily clinical practice. Ashman phenomenon is an aberrant ventricular conduction most frequently seen during atrial fi bril-lation. Th is phenomenon is an intraventricular con-duction abnormality caused by a change in the heart rate. Ashman beat is typically seen when a relatively long cycle is followed by a relatively short cycle1. Th e beat with a short cycle often has right bundle-branch block (RBBB) morphology (Fig. 1a). Th is phenom-enon may cause diagnostic confusion with premature ventricular complexes (PVCs) (Fig. 1b), and a series of consecutive aberrantly conducted supraventricular impulses may be mistaken for ventricular tachycardia (Fig. 1c). Th e pathophysiology of Ashman phenomenon de-pends on the relative refractory period of the conduc-tion tissues and the heart rate. Th e duration of the refractory period of the heart muscle is proportional to the R-R interval of the preceding cycle. A longer cycle will prolong the ensuing refractory period, and if a shorter cycle follows the beat terminating the cycle is likely to be conducted with aberrancy. Th e refrac-tory period of the right bundle-branch is longer than the left one and it will still be in the refractory pe-riod when supraventricular impulse reaches the His-Purkinje system resulting in a complex with RBBB2,3. Ashman phenomenon is principally diagnosed by a 12-lead surface electrocardiogram (ECG). Rarely, in diffi  cult cases, invasive electrophysiological studies will be required to establish the source of an arrhyth-mia whether supraventricular or ventricular4.For daily use, useful criteria to establish the diag-nosis of Ashman phenomenon are those described by Fisch5: 1) relatively long cycle immediately preceding the cycle terminated by the aberrant QRS complex; 2) RBBB-form aberrancy with normal orientation of the initial QRS vector, a series of wide QRS supraven-tricular beats is possible; 3) irregular coupling of aber-rant QRS complexes; and 4) lack of fully compensa-tory pause. Clinically, Ashman phenomenon by itself is asymp-tomatic and does not require any specifi c treatment. Finally, although Ashman phenomenon has been known for more than sixty years now1, it still often stays unrecognized, or misdiagnosed as PVCs. Un-derstanding Ashman phenomenon is useful and nec-essary in daily clinical practice because, for example, in 24-hour Holter ECG records we can fi nd even several thousand wide QRS complexes caused by Ashman phenomenon. It usually occurs with atrial fi brillation, and atrial fi brillation is the most common sustained cardiac rhythm disturbance, increasing in prevalence with age6. Furthermore, not only the cardiologists, but often physicians of diff erent profi les such as neu-rologists, anesthesiologists, general practitioners, etc. see it and treat it. Book Acta 1-2010.indb   99 14.6.2010   9:23:10N. Lakušić et al. Ashman phenomenon100 Acta Clin Croat,  Vol. 49,  No. 1,  2010In conclusion, it is important to notice that in a pa-tient with atrial fi brillation and wide QRS complexes with RBBB morphology, Ashman phenomenon must be considered to avoid further unnecessary diagnostic and, more important, therapeutic procedures.References1. KENNEDY LB, LEEFE W, LESLIE BR. Th e Ashman phenomenon. J La State Med Soc 2004;156:159-62.2. NAVE C, NARDI S, GAUDINO M, CURCIO N, CIRILLO T, IACONO A. Th e electrophysiological basis of aber-rant intraventricular conduction during atrial fi brillation. Cardiologia 1996;41:1193-8.3. SCHAMROTH L, JACOBS ML. A study in intracardiac conduction with special reference to the Ashman phenom-enon. Heart Lung 1982;11:381-2.4. QUAAL S, SCHAMROTH L. Aberrant ventricular con-duction during atrial fi brillation. Heart Lung 1985;14:101.5. FISCH C. Electrocardiography of arrhythmias. From deduc-tive analysis to laboratory confi rmation – twenty-fi ve years of progress. J Am Coll Cardiol 1983;1:306-16.6. FUSTER V, RYDÉN LE, CANNOM DS, CRIJNS HJ, CURTIS AB, ELLENBOGEN KA, et al. ask Force on Practice Guidelines, American College of Cardiology/Amer-ican Heart Association; Committee for Practice Guidelines, European Society of Cardiology; European Heart Rhythm Association; Heart Rhythm Society. ACC/AHA/ESC 2006 guidelines for the management of patients with atrial fi brilla-tion – executive summary: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines and the European Society of Cardiology Committee for Practice Guidelines (Writing Committee to Revise the 2001 Guidelines for the Management of Patients with Atrial Fibrillation). Eur Heart J 2006;27:1979-2030.Fig. 1. Holter ECG records in Ashman phenomenon: (A) atrial fi brillation with aberrant conduction – Ashman phe-nomenon (4th beat); (B) the same patient – note the ECG morphology diff erence between ventricular ectopic beat (4th beat) and aberrant conduction – Ashman phenomenon (8th and 9th beats); (C) aberrant conduction run – Ashman phe-nomenon (6th, 7th and 8th beats).ABCBook Acta 1-2010.indb   100 14.6.2010   9:23:10

Ashman Phenomenon: An Often Unrecognized Entity in Daily Clinical Practice

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