Morphology of the sinus node in human and mouse hearts with isomerism of the atrial appendages.

BACKGROUND--The location of the sinus node is known to be at best abnormal, or at worst unknown, in patients with isomerism of the morphologically left atrial appendage. In contrast, the sinus node is known to be an excellent histological marker of the morphologically right appendage, being duplicated in those with right isomerism. The aim of the study was to investigate this condition further in fetal human and mouse hearts. METHODS--Serial histological sections of the area anticipated to contain the sinus node were studied in hearts with isomerism of the atrial appendages taken from 14 human fetuses and 13 iv/iv mice, using 12 mouse hearts with normally arranged or mirror imaged atrial chambers for controls. RESULTS--All hearts with isomerism of the right appendages (two human and four mouse) had bilateral sinus nodes. The cases with isomerism of the left appendages (12 human and nine mouse) showed absence of a recognisable sinus node except in four cases (19%) in which a small remnant of the node was found. In three of these cases, it was related postero-inferiorly to the superior cavoatrial junction. CONCLUSIONS--The concept of isomerism of the atrial appendages is endorsed by findings on the morphology of the sinus node, this being the most reliable histological criterion for existence of a morphologically right atrium. A small proportion of hearts with left isomerism had a structure resembling the sinus node, but it was hypoplastic and displaced postero-inferiorly, distant from its expected position had the hearts possessed an incompletely formed morphologically right appendage.

[1]  A. Cook,et al.  Disposition of the atrioventricular conduction tissues in the heart with isomerism of the atrial appendages: its relation to congenital complete heart block. , 1992, Journal of the American College of Cardiology.

[2]  S. Ho,et al.  Abnormal Laterality and Congenital Cardiac Anomalies: Relations of Visceral and Cardiac Morphologies in the iv/iv Mouse , 1992, Circulation.

[3]  J. Icardo,et al.  Spectrum of Heart Malformations in Mice With Situs Solitus, Situs Inversus, and Associated Visceral Heterotaxy , 1991, Circulation.

[4]  A. Cook,et al.  Isomerism of the atrial appendages in the fetus. , 1991, Pediatric pathology.

[5]  J. Icardo.  Development of the Outflow Tract , 1990, Annals of the New York Academy of Sciences.

[6]  F. Santini,et al.  Segmental situs in congenital heart disease: a fundamental concept. , 1990, Giornale italiano di cardiologia.

[7]  A. Takao,et al.  Characteristics and natural history of abnormal atrial rhythms in left isomerism. , 1990, The American journal of cardiology.

[8]  W. Devine,et al.  The determination of atrial arrangement by examination of appendage morphology in 1842 heart specimens. , 1988, British heart journal.

[9]  F. Macartney,et al.  Cardiac rhythm in atrial isomerism. , 1987, The American journal of cardiology.

[10]  R. Anderson,et al.  Conduction tissue anomalies in absence of the right superior caval vein. , 1985, International journal of cardiology.

[11]  W. Paulus,et al.  Increased Regional Myocardial Stiffness of the Left Ventricle During Pacing‐induced Angina in Man , 1983, Circulation.

[12]  F. Macartney,et al.  Morphological considerations pertaining to recognition of atrial isomerism. Consequences for sequential chamber localisation. , 1980, British heart journal.

[13]  K. R. Anderson,et al.  The Cardiac Conduction System in Situs Ambiguus , 1979, Circulation.

[14]  K. R. Anderson,et al.  Location and vascular supply of sinus node in human heart. , 1979, British heart journal.

[15]  S. Ho,et al.  Histological study of the cardiac conducting system as a routine procedure. , 1977, Medical laboratory sciences.

[16]  W. M. Layton.  Random determination of a developmental process: reversal of normal visceral asymmetry in the mouse. , 1976, The Journal of heredity.

[17]  V. Rose,et al.  Syndromes of asplenia and polysplenia. A review of cardiac and non-cardiac malformations in 60 cases withspecial reference to diagnosis and prognosis. , 1975, British heart journal.

[18]  M. Laks,et al.  Sinus node function; evaluation in patients with and without sinus node disease. , 1975, Archives of internal medicine.

[19]  M. Taylor,et al.  Reconstruction of the human sinoatrial node , 1967, The Anatomical record.

[20]  Van Mierop Lh,et al.  Isomerism of the cardiac atria in the asplenia syndrome. , 1962 .

[21]  T. N. James,et al.  Anatomy of the human sinus node , 1961, The Anatomical record.

[22]  R. van Praagh,et al.  Atrial isomerism in the heterotaxy syndromes with asplenia, or polysplenia, or normally formed spleen: an erroneous concept. , 1990, The American journal of cardiology.

[23]  W. M. Layton.  Heart malformations in mice homozygous for a gene causing situs inversus. , 1978, Birth defects original article series.

[24]  Layton Wm.  Heart malformations in mice homozygous for a gene causing situs inversus. , 1978 .

[25]  M. Lev,et al.  The conduction system of the mouse heart. , 1973, Acta Anatomica.

[26]  L. V. van Mierop,et al.  Isomerism of the cardiac atria in the asplenia syndrome. , 1962, Laboratory investigation; a journal of technical methods and pathology.

[27]  K. Hummel,et al.  VISCERAL INVERSION AND ASSOCIATED ANOMALIES IN THE MOUSE , 1959 .