Beneficial hemodynamic response of transthoracic cardiac pacing in a 2 kg preterm neonate.

OBJECTIVE: To describe the beneficial hemodynamic effect of transthoracic external pacing compared with epicardial pacing in a 2 kg premature neonate with congenital complete heart block, hydrops and complex congenital heart disease.
METHODS: Transthoracic epicardial pacing was instituted at a rate of 120 beats/min to treat life-threatening bradycardia (HR 50-60 beats/min), hypotension (BP 45/20 mmHg) and severe lactic acidosis (pH 7.18, lactate 7.5 mmol/l) despite significant catecholamine support. Due to the size of the patient, the external pacing electrodes were placed on the back and front of the patient's chest. To achieve ventricular capture, the electric output had to be increased to 140 mA, resulting in symmetric chest movements. RESULT: Transthoracic pacing resulted in an immediate improvement of the cardiovascular status, with an adequate blood pressure (BP 60/25 mmHg) and normalization of acid-base-balance. After the insertion of an epicardial pacemaker (paced rate at 140 beats/min), a significantly lower blood pressure was achieved (BP 50/25 mmHg), indicating an additive effect of the rhythmic chest movements to the blood pressure. Unfortunately, third-degree burns were detected on the patients back 1 day after pacemaker insertion.
CONCLUSION: Transthoracic pacing is a life-saving option in an emergency situation, when maximal pharmacological support fails to maintain adequate cardiac output. It may have some additional beneficial effect on blood pressure generation in these patients. To prevent skin injury, the output used needs to be as low as feasible, and the period of pacing as brief as practicable.