BENGALURU: Ajay (name changed) had walked into a Bengaluru hospital for evaluation of a health complaint. But within hours, the 26-year-old, who had lived with a complex congenital heart condition since childhood, suffered a sudden cardiac arrest and had to be revived by doctors. Further evaluation revealed severe dysfunction of his only functioning heart chamber, prompting doctors to implant a specialised defibrillator to protect him from another potentially fatal cardiac arrest.The patient, who has been under regular cardiac follow-up for years, has a rare form of congenital heart disease with single-ventricle physiology. In his case, the right ventricle is severely underdeveloped, leaving the left ventricle as the main functioning pumping chamber. Doctors said such complex single-ventricle conditions account for less than 5% of congenital heart disease cases.The patient had undergone a palliative bidirectional Glenn procedure in 2004 and continued with periodic follow-ups. A year ago, he had experienced a brief episode of loss of consciousness but recovered spontaneously and was managed conservatively.A few days ago, he presented to the outpatient department of Manipal Hospital, Old Airport Road, for evaluation of an unrelated symptom. Following his initial consultation and assessment, he suddenly went into cardiac arrest. His ECG showed ventricular tachycardia, a potentially life-threatening abnormal rhythm in which the lower chambers of the heart beat extremely rapidly. Doctors immediately delivered an electric shock to his heart and resuscitated him. He was subsequently stabilised and gradually weaned off ventilatory support.An echocardiogram then showed severe dysfunction of his single functioning ventricle, with an ejection fraction of just 15%. This meant that his heart was pumping significantly less blood than normal. Given his cardiac arrest and severely reduced pumping capacity, doctors said he was at high risk of further life-threatening ventricular arrhythmias and required an implantable cardioverter-defibrillator (ICD).However, his unusual cardiac anatomy made a conventional ICD challenging. In a conventional device, a lead is passed through the blood vessels and positioned inside the heart. Doctors said that in a patient with single-ventricle physiology, placing a lead inside the heart can increase the risk of clot formation and stroke.The team therefore opted for a subcutaneous implantable cardioverter-defibrillator (S-ICD), which is implanted beneath the skin and does not require a lead to be placed inside the heart or blood vessels. The device continuously monitors the heart’s electrical activity and can deliver an electric shock when it detects a dangerous rhythm.“In a patient with a single ventricle, implanting a lead inside the heart carries a high risk of stroke. We therefore decided to use a subcutaneous ICD, in which the entire system remains outside the heart and blood vessels, avoiding this risk,” said Dr Anand Shenoy, consultant, interventional cardiology, Manipal Hospital Old Airport Road.Dr Darshan Krishnappa, lead consultant, cardiac electrophysiology, said patients with severely reduced pumping capacity are at higher risk of sudden cardiac arrest and that an ICD can help detect and treat dangerous heart rhythms in appropriately selected patients.The patient successfully underwent S-ICD implantation and was discharged in a stable condition. Given the severity of his underlying heart condition and ventricular dysfunction, he is now being evaluated for a heart transplant.Doctors said the case highlights the challenges of managing patients with complex congenital heart disease into adulthood, particularly those with single-ventricle physiology, and the need to tailor treatment to their individual cardiac anatomy.
