Journal of the American College of Cardiology
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J. Am. Coll. Cardiol. · Aug 1987
Case ReportsHyperkalemia-induced failure of atrial capture during dual-chamber cardiac pacing.
This report describes hyperkalemia-induced failure of atrial capture associated with preservation of ventricular pacing in a patient with a dual-chamber (DDD) pacemaker. This differential effect on atrial and ventricular excitability during cardiac pacing correlates with the well known clinical and experimental observation that the atrial myocardium is more sensitive to hyperkalemia than is the ventricular myocardium.
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J. Am. Coll. Cardiol. · Aug 1987
Surgical management of subaortic obstruction in single left ventricle and tricuspid atresia.
Subaortic obstruction caused by either a restrictive bulboventricular foramen in single left ventricle with an outflow chamber or by a restrictive ventricular septal defect in tricuspid atresia with transposition of the great arteries can lead to a hypertrophied, noncompliant ventricle and excessive pulmonary blood flow. This combination is disadvantageous to potential Fontan procedure candidates because they are dependent on good ventricular function and low pulmonary vascular resistance for survival. The results of surgical procedures to directly or indirectly relieve significant subaortic obstruction (gradient greater than 30 mm Hg) in 24 patients, 16 with single left ventricle and 8 with tricuspid atresia, were reviewed. ⋯ These data show that: Surgical relief of established subaortic obstruction in patients with single left ventricle and tricuspid atresia carries a high mortality rate, especially if the subaortic gradient is greater than 75 mm Hg. The best procedure appears to be the pulmonary artery to ascending aorta anastomosis. A clearer understanding of the factors leading to the development of significant subaortic obstruction is necessary to prevent it or to devise improved therapeutic strategies.