Ethical issues with implantable defibrillators.
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Death, Sudden, Cardiac↗
Biomedical subjects
G D Veenhuyzen
Publications and source records attributed to G D Veenhuyzen.
Life threatening ventricular arrhythmias with transient or correctable causes.
Traditionally, myocardial ischemia, electrolyte disorders, and proarrhythmic drug reactions have been considered transient and correctable causes of life threatening ventricular tachyarrhythmias. Recent evidence suggests that patients whose ventricular tachyarrhythmias are attributed to these "causes" have a poor outcome. This overview reviews the available literature examining ischemia, electrolyte disorders and pro-arrhythmic drug reactions as potentially reversible causes of ventricular tachycardia (VT) and ventricular fibrillation (VF). While all 3 are undoubtedly involved in the genesis of these tachyarrhythmias, and all 3 deserve particular clinical attention (outlined in the text), difficulties in the identification and/or reversal of their influences exist. Proarrhythmic drug reaction may be a reversible cause of VT/VF, hypokalemia and hypomagnesemia should be considered risk factors for VT/VF, and the role of ischemia is complex. Accordingly, physicians should use extreme caution in attributing life-threatening ventricular tachyarrhythmias to these 3 conditions. Further research is required to identify "truly reversible" causes of VT/VF.
Arrhythmias, Cardiac↗
Prior coronary artery bypass surgery and risk of death among patients with ischemic left ventricular dysfunction.
BACKGROUND: Patients with ischemic LV dysfunction are at high risk of sudden death. However, no benefit from prophylactic defibrillator therapy was observed in a group of patients with LV dysfunction undergoing CABG (CABG Patch trial). Thus, the effect of CABG on future risk of sudden death in patients with LV dysfunction is of considerable interest. METHODS AND RESULTS: Mortality and modes of death in 5410 patients with ischemic LV dysfunction who were enrolled in the Studies of Left Ventricular Dysfunction (SOLVD) trials were evaluated. Outcomes of patients with (n=1870, 35%) versus without (n=3540) history of prior CABG were compared, and stratification by baseline ejection fraction (EF) values (<0.25, 0.25 to 0.30, and >0.30) was performed. Prior CABG was associated with a 25% (95% CI, 15% to 36%) reduction in risk of death and a 46% (95% CI, 30% to 58%) reduction in risk of sudden death independent of EF and severity of heart failure symptoms. As baseline EF declined, absolute reduction in risk of sudden death with prior CABG increased (P<0.01). No alteration in risk of death from progressive heart failure was observed with prior CABG. When these results were applied to a group of patients with LV dysfunction who had not undergone prior surgery (Coronary Artery Surgery Study Registry) predicted annual rates of death (8.2%) and sudden death (2.4%) were similar to those observed in the CABG Patch trial (7.9% and 2.3%, respectively). CONCLUSIONS: In patients with ischemic LV dysfunction, prior CABG is associated with a significant independent reduction in mortality. These results appear to account for the lack of benefit from defibrillator therapy in the CABG Patch trial.
Adult↗