Septal structure and function relationships parallel the left ventricular free wall ascending and descending segments, thereby supporting the helical heart fiber spatial relationships. The oblique fiber orientation may make the septum become the 'lion of right ventricular function'.

Ventricular pacing disrupts the natural sequence of shortening along the myocardial band, and the resultant dyssynchrony impairs LV function.

Background. The purpose of this study was to determine (1) the role of emergency cardiopulmonary bypass (CPB) after prolonged cardiac arrest and failed cardiopulmonary resuscitation, and (2) the use of systemic hyperkalemia during CPB to convert intractable ventricular fibrillation (VF).Methods. Thirty-one pigs (34 ؎ 2 kg) underwent 15 minutes of cardiac arrest after induced VF, followed by 10 minutes of cardiopulmonary resuscitation-advanced life support. Peripheral CPB was used if cardiopulmonary resuscitation failed to restore stable circulation. Damage was assessed by evaluating hemodynamics, biochemical variables (creatine kinase-MB, neuron-specific enolase), neurologic deficit score, and brain magnetic resonance imaging.Results. Cardiopulmonary resuscitation alone was successful in only 19% (6 of 31 pigs). Cardiopulmonary bypass was initiated in 81% of animals (25 of 31 pigs) either for hypotension (5 of 25 pigs) or intractable VF (20 of 25 pigs). Defibrillation was successful in 7 of 20 animals during the first 10 minutes after initiating CPB.

(1) Biventricular pacing disrupts of the natural sequence of shortening of the myocardial band and results in impaired LV function. (2) High septal pacing preserves the sequential shortening pattern of the myocardial band and LV function.

CPB is an effective resuscitative tool to treat prolonged CA but there is limited improvement of neurological function. NHE inhibition augments cardiac and neurological function, but its effect was less pronounced than in other studies.