Isolated dextrocardia and congenital heart blocking.

To our knowledge, isolated dextrocardia in association with congenital complete atrioventricular heart block has not been previously reported. We report such a case, elaborate on the possible pathogenesis, and present our experience with management.

Case report

A 32-year-old previously healthy female presented with a two-month history of fatigue and dyspnea on exertion, without evidence of palpitation, chest pain, presyncope, or syncope. The family history was unremarkable for any cardiovascular disease or arrhythmia, congenital defects, or syndromes; her mother had no rheumatologic symptoms during pregnancy.

On physical examination, the patient was hemodynamically stable, with a heart rate of 45 beats per minute. Physical examination of the heart exam revealed a loud holosystolic murmur radiating to both carotids. Electrocardiography, peformed with different positioning of the leads, revealed dextrocardia and complete atrioventricular block (Fig. 1, A and B). Transthoracic echocardiography showed no structural cardiac defects except for dextrocardia and evidence of situs inversus. Abdominal radiography confirmed situs inversus.

Figure 1

32-year-old female with dextrocardia and congenital heart blocking. Prepacemaker electrocardiogram. A. The leads are placed to the right. B. The precordial leads are placed to the left. Notice the R wave progression in the precordial leads versus the poor progression seen in B. Evident are the right axis deviation and the complete heart block with prolonged PR interval. Also note the inverted P waves in leads I and AV, L indicating dextrocardia. Notice in B the low voltage seen in V4, V5, V6.

Hematologic studies (including complete blood counts), erythrocyte sedimentation rate, serum electrolytes, renal tests, and liver function tests were normal. Rheumatologic tests for antinuclear antibodies (ANA), anti-dsDNA antibodies, anticyclic citrullinated peptide antibodies (anti-CCP), RA Latex, anti-Ro/SSA, and anti-La/SSB were negative. Rheumatologic workup of the mother was negative for the anti-Ro/SSA and anti-La/SSB antibodies but was slightly positive for ANA (1:80). However, the patient’s mother did not have any signs or symptoms for systemic lupus erythematous. The patients was thus diagnosed with congenital complete atrioventricular block and isolated dextrocardia. She underwent insertion of a dual-chamber pacemaker in the right atrium and right ventricle. The rhythm was paced following insertion (Fig. 1, C and D). Chest radiography after pacemaker insertion revealed no complications, and the leads were in place (Fig. 2).

Figure 1

32-year-old female with dextrocardia and congenital heart blocking. Post-pacemaker insertion. C. This electrocardiogram shows the leads placed to the right. D. This EKG has been recorded with leads to left. The rhythm is now paced, with dextrocardia noted.

Figure 2

32-year-old female with dextrocardia and congenital heart blocking. Chest X-ray (anteroposterior [A] and lateral [B]) reveal dextrocardia (cardiac apex to the right) with gastric gas bubble and the aortic arch on the right side. Pacemaker leads are noted in right atrium and right ventricle.

Discussion

Congenital heart block is highly associated with maternal connective-tissue disease. Pregnant women testing positive for anti-Ro/SSA and anti-La/SSB, whether symptomatic or not, are at increased risk of having a child born with congenital heart block, with an estimated prevalence of 2–5% and a recurrence rate up to 17–19% (1). However, our patient’s mother tested negative for anti-Ro and anti-La antibodies and had no evidence of rheumatologic symptoms.

Antibodies targeted against the endogenous retrovirus (ERV)-3 during pregnancy were found in high titers in infants diagnosed with congenital heart block. Silent viral infections have also been implicated in the pathogenesis of congenital heart block (2). Whether our patient had such evidence of viral infections or related autoantibodies during pregnancy cannot be fully ruled out. Several cardiac defects are associated with congenital heart block including ventricular septal defect (VSD), endocardial cushion defect, patent ductus arteriosis (PDA), mitral incompetence, patent foramen ovale (PFO), coarctation of the aorta, transposition of the great vessels, and Ebstein’s anomaly (3). However, our patient did not show any of these anomalies on echocardiography.

Dextrocardia is often associated with structural cardiac anomalies such as single ventricle, double-outlet double-inlet ventricle, tricuspid atresia, pulmonary stenosis, interventricular defects, and transposition of the great vessels. Dextrocardia has mainly been associated with arrhythmias such as the sick sinus syndrome, but rarely with second- or third-degree atrioventricular block (4). To our knowledge, isolated dextrocardia with congenital complete atrioventricular block has not been previously reported, and a possible underlying association between the two entities remains to be evaluated.

Successful management with dual-chamber pacemaker implantation has been reported in several cases where atrioventricular blocks were associated with dextrocardia along with cardiac anomalies (5). Our patient likewise underwent successful pacemaker implantation, although she exhibited isolated dextrocardia without other cardiac anomalies. Further research is warranted to outline the underlying pathogenesis of such cases.

Acknowledgments

The authors of this manuscript have certified that they comply with the Principles of Ethical Publishing in the International Journal of Cardiology (6).