Complete A-V block and phrenic paralysis complicating surgical closure of ventricular septal defect--a case report

The incidence of post-surgical complete A-V block has come down from 16% in the 50's to less than 1% with improvement in technique. Of these, 14% are transient and attributable to post-operative oedema and haemorrhage at the site of block. Permanent damage manifests early, or as late as 15 years, and in these, the risk of sudden death is a reality. Phrenic paralysis has been attributed to inadvertent pinching, cutting, traction on the phrenic nerve, and has been noticed after pericardiectomy, Blalock-Hanlon operation, Mustard repair, performance of a Blalock-Taussig shunt or closure of ASD. It has also been noted to result from hypothermic injury following iced saline slush application for topical hypothermia the so called "Frost Bitten Phrenics". The entity is commoner than appreciated, although its actual incidence has not been properly worked out. It can be unilateral or bilateral. Patients are mostly asymptomatic, the post-operative X-Ray chest revealing the defect. Uninhibited movement of the costal margin away from the midline on the side of paralysis gives clinical clue (Hoover's Sign), and is confirmed by fluoroscopy which shows paradoxic diaphragmatic movement on sudden sniffing (Keinbock's Phenomenon).