Hemiblocks Revisited

The trifascicular nature of the intraventricular conduction system and the concept of trifascicular block and hemiblock were described by Rosenbaum and his coworkers in 1968. Since then, anatomic, pathological, electrophysiological, and clinical studies have confirmed the original description and scarce advances have been developed on the subject. In the present study, we attempt to review and redefine reliable criteria for the electrocardiographic and vectorcardiographic diagnosis of left anterior and posterior hemiblock. One of the most important problems related to hemiblocks is that they may simulate or conceal the electrocardiographic signs of myocardial infarction or myocardial ischemia and may mask or simulate ventricular hypertrophy. Illustrative examples of these associations are shown to help the interpretation of electrocardiograms. The incidence and prevalence of the hemiblocks is presented based on studies performed in hospital patients and general populations. One of the most common causes of hemiblocks is coronary artery disease, and there is a particularly frequent association between anteroseptal myocardial infarction and left anterior hemiblock. The second most important cause is arterial hypertension, followed by cardiomyopathies and Lev and Lenègre diseases. The hemiblocks may also occur in aortic heart disease and congenital cardiopathies. Left anterior hemiblock is more common in men and increases in frequency with advancing age. Evidence is presented regarding the relationship of spontaneous closure of ventricular septal defects, which may explain the finding of this and other conduction defects in young populations. Isolated left anterior hemiblock is a relatively frequent finding in subjects devoid of evidence of structural heart disease. Conversely, isolated left posterior hemiblock is a very rare finding; its prognostic significance is unknown and is commonly associated with right bundle-branch block. The most remarkable feature of this association is that the prognosis is much more serious with a great propensity to develop complete atrioventricular block and Adams-Stoke seizures.

[1]  Barry J Maron,et al.  Contemporary definitions and classification of the cardiomyopathies: an American Heart Association Scientific Statement from the Council on Clinical Cardiology, Heart Failure and Transplantation Committee; Quality of Care and Outcomes Research and Functional Genomics and Translational Biology Interd , 2006, Circulation.

[2]  Jeroen J. Bax,et al.  Prognostic significance of left anterior hemiblock in patients with suspected coronary artery disease. , 2005, Journal of the American College of Cardiology.

[3]  R. Macalpin,et al.  In search of left septal fascicular block. , 2002, American heart journal.

[4]  S Tawara,et al.  The conduction system of the mammalian heart : an anatomico-histological study of the atrioventricular bundle and the Purkinje fibers , 2000 .

[5]  P. Chiale,et al.  Cierre espontáneo de la comunicación interventricular: una causa ignorada de trastornos de la conducción auriculoventricular e intraventricular , 1996 .

[6]  M. Elizari,et al.  Intraventricular conduction disturbances in civilian flying personnel: left anterior hemiblock. , 1992, Aviation, space, and environmental medicine.

[7]  P. Froom,et al.  Left anterior hemiblock in otherwise healthy pilots. , 1988, Aviation, space, and environmental medicine.

[8]  S. Rabkin,et al.  Natural history of marked left axis deviation (left anterior hemiblock). , 1979, The American journal of cardiology.

[9]  H. Uhley The concept of trifascicular intraventricular conduction: historical aspects and influence on contemporary cardiology. , 1979, The American journal of cardiology.

[10]  U. Goldbourt,et al.  Intraventricular conduction disturbances: a review of prevalence, etiology, and progression for ten years within a stable population of Israeli adult males. , 1978, American heart journal.

[11]  M. Dubois,et al.  Prognostic significance of left anterior hemiblock with right bundle branch block in mass screening , 1978 .

[12]  P. Denes,et al.  Chronic right bundle branch block and left posterior hemiblock. Clinical, electrophysiologic and prognostic observations. , 1975, The American journal of cardiology.

[13]  K. Rosen,et al.  Surgical Bifascicular Block , 1975, Circulation.

[14]  P. Rizzon,et al.  Left posterior hemiblock in acute myocardial infarction. , 1975, British heart journal.

[15]  K. Yano,et al.  Left axis deviation and left anterior hemiblock among 8,000 Japanese-American men. , 1975, The American journal of cardiology.

[16]  W. Gersony,et al.  Postoperative left anterior hemiblock and right bundle branch block following repair of tetralogy of Fallot. Clinical and etiologic considerations. , 1975, Circulation.

[17]  P. Rizzon,et al.  Intraventricular conduction defects in acute myocardial infarction. , 1974, British heart journal.

[18]  M. Elizari,et al.  Left Anterior Hemiblock Obscuring the Diagnosis of Right Bundle Branch Block , 1973, Circulation.

[19]  C. B. Mullins,et al.  Ventricular conduction blocks and sudden death in acute myocardial infarction. Potential indications for pacing. , 1973, The New England journal of medicine.

[20]  T. N. James,et al.  Normal Blood Supply to the Human His Bundle and Proximal Bundle Branches , 1973, Circulation.

[21]  D. Kincaid,et al.  Significance of isolated left anterior hemiblock and left axis deviation during acute myocardial infarction. , 1972, The American journal of cardiology.

[22]  T. Rowland,et al.  Surgically Induced Right Bundle‐Branch Block with Left Anterior Hemiblock: An Ominous Sign in Postoperative Tetralogy of Fallot , 1972, Circulation.

[23]  H. Kulbertus,et al.  Histopathological examination of concept of left hemiblock. , 1972, British heart journal.

[24]  S. Weinberg,et al.  The incidence and mortality of intraventricular conduction defects in acute myocardial infarction. , 1972, The American journal of cardiology.

[25]  A. Castellanos,et al.  Diagnosis of left anterior hemiblock in the presence of inferior wall myocardial infarction. , 1971, Chest.

[26]  L. Ostrander,et al.  Left axis deviation: prevalence, associated conditions, and prognosis. An epidemiologic study. , 1971, Annals of internal medicine.

[27]  M. B. Rosenbaum,et al.  Right Bundle‐Branch Block and Left Anterior Fascicular Block (Left Anterior Hemiblock) Following Tricuspid Valve Replacement , 1970, Circulation.

[28]  H. Marriott,et al.  Hemiblock in acute myocardial infarction. , 1970, Chest.

[29]  Julie H. Campbell,et al.  The Conduction System , 1986 .

[30]  F. de Pádua,et al.  Left median hemiblock-a chimera? , 1978, Advances in cardiology.

[31]  A. J. Dunning,et al.  Bundle branch block in acute myocardial infarction. , 1978, European journal of cardiology.

[32]  T. Niki,et al.  Prominent anterior QRS force as a manifestation of left septal fascicular block. , 1978, Journal of electrocardiology.

[33]  A. Benchimol,et al.  Coexisting left anterior hemiblock and inferior wall myocardial infarction. Vectorcardiographic features. , 1972, The American journal of cardiology.

[34]  J. Titus,et al.  The vasculature of the human atrioventricular conduction system. , 1972, Mayo Clinic proceedings.

[35]  P. W. Seavey,et al.  Left axis deviation. An electrocardiographic mortality study. , 1971, Transactions of the Association of Life Insurance Medical Directors of America.

[36]  M. Rosenbaum CHAGASIC MYOCARDIOPATHY. , 1964, Progress in cardiovascular diseases.