Adverse impact of univentricular pacing for the patient with functional single ventricle: successful conversion to cardiac resynchronization therapy

Sugimoto A, Takigiku K, Shiraishi S, Takahashi M, Tsuchida M.Surg Case Rep. 2020 May 13;6(1):101. doi: 10.1186/s40792-020-00863-4.PMID: 32405970 Free PMC article.



Background: In a Fontan candidate, univentricular pacing may cause delay in interventricular conduction, which induces asynchronous contraction. Cardiac resynchronization therapy is expected to be an effective mode of therapy in such a case.

Case presentation: A 7-month-old girl, diagnosed with dextrocardia, congenitally corrected transposition of the great artery [situs solitus, L-loop, and L-transposition], ventricular septal defect, infundibular and pulmonary valvular stenosis, and straddling of the tricuspid valve, was considered as a candidate for the Fontan procedure. She had undergone Blalock-Taussig shunt, and epicardial univentricular pacemaker implantation for persistent complete atrioventricular block. She underwent a bidirectional cavopulmonary shunt concomitant with ventricular lead translocation from the morphological left ventricle to the morphological right ventricle. After discharge, ventricular dyssynchrony was noted and cardiac failure persisted. She was converted to cardiac resynchronization therapy (CRT) at 13 months of age. Two-dimensional speckle tracking imaging was used by cardiologists to determine the most suitable pacing site. CRT rapidly corrected the heart failure; thus, she underwent the Fontan procedure after 1.5 years. Five years have passed since the cardiac resynchronization therapy; her interventricular synchrony is maintained well and the level of brain natriuretic peptide remains within normal range.

Conclusion: We describe the successful conversion from single ventricular pacing to CRT, in a case of congenitally corrected transposition of the great artery indicated for the Fontan procedure. The long-term prognosis of cardiac resynchronization therapy is undetermined in the pediatric population; therefore, further follow-up is required.


Fig. 1 Three-dimensional computed tomography before initial palliation. LA, left atrium; mRV, morphological right ventricle; mLV, morphological left ventricle

Fig. 2 a Speckle tracking echocardiography reveals that the difference in time to peak radial strain between both ventricles is 210 ms before CRT (white arrow). b Speckle tracking echocardiography after CRT shows good interventricular synchrony between both ventricles. The peak radial strain between both ventricles is very short (white arrow). CRT, cardiac resynchronization therapy; mLV, morphological left ventricle; mRV, morphological right ventricle


Fig. 3 a Chest radiograph before cardiac resynchronization therapy (CRT). The cardiothoracic ratio is 65%. Atrial leads are placed on the LA and ventricular leads on the mRV. b Chest radiograph post-CRT. The cardiothoracic ratio is reduced to 50%. New ventricular leads are placed on the mLV, and the cathode of the previous mRV pacing lead is re-located to the mRV outflow tract. c Electrocardiogram before CRT. QRS duration is 156 ms. d Electrocardiogram after CRT. QRS duration is shortened to 140 ms. CRT, cardiac resynchronization therapy; LA, left atrium; mRV, morphological right ventricle; mLV, morphological left ventricle