Familial bundle branch block

J. M. Combrink, M.B., Ch.B., M.Med. (Int.) Pret.* W. II. Davis, B.Sc., M.B., Ch.B., M.Med. (I&.) Pret.* 11. W. Snyman, M.B., Ch.B. (Rand), M.D. (Gron.)**

Pretoria, South Africa

V arious forms of familial heart disease are on record. Morquio, in 1901,

reported on 5 brothers with atrioventricu- lar conduction disturbances. In 1903, Osler’ described a family with slow pulse rates and Stokes-Adams attacks. Aylward,2 in 1928, described 2 sisters who had total atrioventricular block. Wallgren and Win- blad,3 in 1938, investigated a family in which 2 out of 5 siblings had congenital heart disease; one had a complete heart block, whereas the father and the other members showed evidence of conduction disturbances. In a family with complete heart block observed by Wendkos and Study,a in 1947, it was noted that the parents also had conduction disturbances. Various degrees of atrioventricular con- duction disturbances with familial inci- dence have been described by Stephan, Fulton, and Canabal and Dighiero.6 Fa- milial cardiomegaly has been described b,. Evans’; and Paulley and associates* submitted a well-documented report on 3 affected siblings with pathologic simi- larity at necropsy. Battersby and Glennerg described a sibship of which 5 members had an identical cardiomyopathy, some with conduction defects.

We recently had the opportunity of investigating another type of conduction

disturbance, in which all 4 siblings of a family revealed varying degrees of right bundle branch block. No other evidence of disease could be found.

Case reports The 4 children were brought for investigation by

the father shortly after the death of his wife. His wife’s parents had both died suddenly in their early

Fig. 1. Standard Lead I with phonorardiogram (bottom tvare) revealing systolic murmur.

From the Department of Internal Medicine, I:niversity of Pretoria, Pretoria, South Africa. Received for publication Feb. 16, 1962. *Assistant Physician. **Professor of Internal Medicine. and Director, Cardiac Group, University of Pretoria. (The Cardiac Group is sup-

ported by the Council for Scientific and Industrial Research.)

397

398 Combrink, Davis, and Snyman

g.“-.-T-!~-.-...-.. -. _

Fig. 2. Electrocardiographic tracings of the 4 siblings, revealing right bundle branch block.

Familial bmdle branch block 399

thirties; one of her brothers has heart trouble desig- nated as a conduction disturbance, another brother has dextrocardia, and the other 3 siblings are ap- parently normal. His wife had died during an attack of heart block at the age of 35 years. Her record, which was obtaiued subsequently, revealed that she had been seen at an antenatal clinic-6 years prior to her death. Xt that time the pulse rate had been 80 per minute, the blood pressure was 130/90 mm. Hg, and nothing abnormal was detected. Minor ailments without cardiovascular involve- ment were recorded subsequently. A year before her death she had been hospitalized while in a Stokes-.‘idams attack; the electrocardiogram re- \~ealed total atrioventricular dissociation with L probable complete right bundle branch block. .4 roentgenogram revealed that the size and con- Jiguration of the heart were normal. Approximately II year later she died in a Stokes-Adams attack. .Z necropsy was not performed.

The 4 siblings (B. B., a 12-year-old girl; M. B., an 11 -year-old girl; C. B., a h-year-old girl; and P. B., a -I-year-old boy) \vere subjectively healthy, and, on questioning, had no symptoms referable to the cardiovascular system. On examination, the pulse rates and blood pressures were normal in all 4. They all had a mid-systolic, Grade l-2, ejection murmur at the base of the heart to the left of the sternum. In some, tised splitting, and in others, fairly wide splitting, could be heard over the second intercostal space to the left of the sternum. (See Fig. 1,) The rest of the physical examination re- vealed no abnormality in general build, systems,

or organs. The electrocardiogrclms of the 4 siblings (Fig. 2)

re\,ealed mild to Fross right bundle branch block. In C. B., the tnrclng was only suggestive of right bundle branch block.

The physical examination and the electrocardio- gram of the father, who ~vas 36 ).ears old, revealed no abnormality (Fig. 3).

The electrocardiogram of the mother obtained a )-car previous to her death revealed total atrio- ventricular dissociation and probable right bundle branch block (Fig. 4).

lioentgenograms of the 4 siblings indicated no abnormalit)-.

The eldest child (B. K. 1 ver)- williugly submitted to a cardiac catheterization of the right side of the heart, during which no evidence of abnormal pres- sures or shunts could be elicited.

Discussion

The mother and 4 young siblings of this family revealed an almost identical condurtion defect: right bundle branch i~locl; was common to all, with the mother developing a complete atrioventrirular dissociation. This is apparentI\- a very rare observation, since we could find no report of a similar group. The basis of the abnormality can as yet be only a matter of conjecture. No history or findings suggestive of a rheumatic process, a viral

myocarditis, or an ischemic process are at hand. Apparently, the abnormality is restricted to a section of the conducting system in which a genetic defect may be

Fig. 3. Electrocardiographic tracing of the father, showing normal picture.

Fig. 1. Electrocardiographic tracing of mother, revealing total atrioventricular dissociation and right bundle branch block.

400 Combrink, Davis, and Snyman

present, either as a structural fault in the conducting bundle or possibly merely as a biochemical enzyme derangement in the fibers of the right bundle branch.

Follow-up studies of the children, who are being kept under observation, might throw a more revealing light on this in- triguing familial abnormality.

Summary

A description is given of a mother who died at the age of 35 years, and of 4 young siblings, all of whom revealed right bundle branch block as an isolated finding.

REFERENCES

1. Osler, W.: On the so-called Stokes-Adams dis- ease, Lancet 2516, 1903.

Am. Heart 3. September, 1962

2. Aylward, R. I>.: Congenital heart-block, Brit. M. J. 1:943, 1928.

3. Wallgren, A., and Winblad, S.: Cougenital heart-block, Acta paediat. 20:17.5, 1937.

4. Wendkos, M. II., and Study, R. S.: Familial congenital complete I\-\: heart block. .\M. HEART J. 34:138,1947.

5. Stephan, E.: Familial ;~uri~~~lo~entricular block (in French), birch. mal. cocur 54:333, 1961.

6. Canabal, E. J., and Dighiero, J.: ‘Bradicardia familiar congenita por bloqueo auriculoven- trirulsr com&to (enfermednd de Morquio), Rev. awent. cardiol. 1850.1951.

7. Evans, “NT.: Familial cardiomegaly, Brit. Heart J. 11:68, 1949.

8. f’aulley, J. I?:., Jones, K., Green, II:. I’. I)., and Kane. E. P.: Mvocnrdial toxoulasmosis;. Brit. Heart J. 18~55, 14.56.

9. Battersby, E. J., and Glenner, G. G.: Familial cardiomyopathy, .qm. J. Med. 30:382, 1961.