INTRODUCTION: Sudden Infant Death Syndrome or SIDS is described as the sudden death of an infant under 1 year of age that remains unexplained after a thorough case investigation, including performance of a complete autopsy, examination of the death scene, and areview of the clinical history. It is therefore a diagnosis of exclusion. It's responsible for 0.05%, or 50 deaths per 100,000 births in the U.S. It's rare during the first month of life, increases to a peak between 2and 4 months of age, and then declines. Although the cause of SIDS is multifactorial, the common setting is that the infantundergoes a period of unstable homeostatic control and is exposed to triggering factors. The hypotheses for the etiology of SIDS are varied but primarily include cardiacarrhythmias, apnea, primary autonomic nervous system instability, behavioral issues, andinfection. This case report focuses on the theory that cardiac arrhythmias play asignificant role in the etiology of SIDS.
CASE PRESENTATION: D.M. is a 6-week-old male who presented with asystolic arrest at 3 weeks of age. After feeding well the baby began crying in a way that the parents had never heard before, and then became limp and blue. The parents took the baby to an emergency room where he was found to be in asystole. The initial arterialblood gas showed a severe combined metabolic and respiratory acidosis. Following cardiopulmonary resuscitation the patient was transferred to our pediatric intensive care unit intubated. The electrocardiogram (ECG) after resuscitation showed normal sinus rhythm with a normal QTc. The following day the patient developed torsades de pointes.Resuscitation included defibrillation, lidocaine, and amiodarone with eventual return to normal rhythm and hemondynamic stability. An echocardiogram after the second arrest showed structurally normal heart, a small patent foramen ovale vs. an atrial septal defect with left to right shunting, no ventricular septal defect, mild to moderate mitral regurgitation and aorticinsufficiency, dilated and hypocontractile left ventricle with estimated shortening fraction of approximately 20% despite inotropic support. He had 12 episodes of tachyarrhythmias, which degenerated into torsades de pointes associated with hypotension and requiring multiple defibrillations, treated with amiodarone, epinephrine, vasopressin, propranolol, lidocaine, flecainide, magnesium and mexiletine. The episodes lasted from 30 mins to 3 hours despite maintaining all electrolytes in the normal range. Rhythm stability was achieved with sotalol and propranolol and patient was discharged after ICD placement.
DISCUSSIONS: SIDS is multifactorial in origin, but its causes remain unknown and the cardiac hypothesis has regained support due to identification in postmortem genetic samples from SIDS cases of mutations in the same ion channel genes that cause inherited and acquired long QT syndrome (LQTS), one in a potassium channel and two in a sodium channel. Malignant LQTS should stimulate an objective assessment widespread neonatal ECG screening when the prevalence of spurious marked QT prolongations (QTc >470 ms) is minimal. Suchscreening could reveal that these major QT prolongations should prompt the early institution of effective preventive therapies and the identification of additional affected family members in order to help reduce the number of sudden deaths among LQTSpatients. This is supported by a prospective study in which a markedly prolonged QTc (>470 ms) was found in 0.7 of 1000, and in 50% of these a LQTS mutation has been identified.42 Nationwide screening programs have been proposed as a cost-effective means in Europe to identify LQTS and thereby prevent some SIDS.
CONCLUSION: The patient was not found to have any channelopathies but there are several channel abnormalities that presently are not identified yet. The studies discussed above suggest that EKG testing in the neonatal period should be suggested as one of the tools of early detection of any Cardiac electrical abnormality.
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