Discussion

Permanent pacing therapy has been performed in paediatric patients since the late 1960s. Although transvenous lead implantation has been recently advocated for children, epicardial route remains the most popular approach in small babies due to vascular access limitations, or complicated intracardiac anatomies. Stimulation is rarely uneventful and complications are usually lead-related. This case report illustrates how the commonly occurring lead fracture concealed the rarely reported and potentially fatal coronary compression, misleading initial clinical management. Retrospectively, the patient presented ventricular fibrillation secondary to the compression of the left anterior descending coronary artery and was resuscitated by the external electric shock. Chest compressions fractured the lead afterward. Upon admission, lead failure was logically incriminated in the mechanism of the cardiac arrest leading to extreme bradycardia followed by shockable ventricular arrhythmia. Surgery was precipitated. Diagnostic coronarography was performed based on three arguments: coronary reimplantation history, automated external defibrillator tracings confirming lead good functioning at the time of ventricular fibrillation, and the rapidly favourable neurologic evolution incompatible with prolonged cardiac arrest as seen in ventricular fibrillation after lead dysfunction.

Coronary compression is a recognised mechanical complication of epicardial pacing but it is underdiagnosed. ^{Reference Mah, Prakash, Porras, Fynn-Thompson, DeWitt and Banka7} The incidence is not well defined with only few reported cases. ^{Reference Brenner, Gaines, Cordier, Reiner, Haney and Gundry3–Reference Carreras, Duncan, Djurdjev and Campbell6} An incidence of 5.5% was recently reported by Mah et al. ^{Reference Mah, Prakash, Porras, Fynn-Thompson, DeWitt and Banka7} Clinical presentations vary from coronary compression in asymptomatic subjects to post-mortem diagnosis. None of the recognised diagnostic tools is perfect for assessment. ^{Reference Carreras, Duncan, Djurdjev and Campbell6,Reference Mah, Prakash, Porras, Fynn-Thompson, DeWitt and Banka7} Chest radiography is a good surveillance tool as it can detect early suspicious patterns of leads implanted within the pericardium (Fig 3). Cine CT-scan can identify dynamic compression but must be confirmed by catheter angiography and myocardial scintigraphy, especially when surgery is being considered. ^{Reference Mah, Prakash, Porras, Fynn-Thompson, DeWitt and Banka7} Lead placement is challenging as a mismatch between limited lead length and somatic growth must be avoided. The risk factors are not well established but placement of the excess lead in the anterior pericardium or around the ventricles has been associated with an increased risk. ^{Reference Takeuchi and Tomizawa8,Reference Alhuzaimi, Roy and Duncan9} Janík et al recently published a forensic report on how an epicardial pacing wire retained in place for almost three decades led to the sudden cardiac death of a young adult. ^{Reference Janík, Hejna, Straka, Krajčovič and Novomeský10} Clinicians must be aware that active surveillance needs to be continued even for abandoned non-functioning leads and prophylactic pacing systems placed within the pericardium. Lead removal should be considered whenever suspicious patterns are diagnosed or suspected.