Determination of sensed and paced atrial-ventricular delay in cardiac resynchronization therapy.

BACKGROUND: Optimization of atrial-ventricular delay (AVD) during atrial sensing (SAVD) and pacing (PAVD) provides the most effective cardiac resynchronization therapy (CRT). We demonstrate a novel electrocardiographic methodology for quantifying electrical synchrony and optimizing SAVD/PAVD. METHODS: We studied 40 CRT patients with LV activation delay. Atrial-sensed to RV-sensed (As-RVs) and atrial-paced to RV-sensed (Ap-RVs) intervals were measured from intracardiac electrograms (IEGM). LV-only pacing was performed over a range of SAVD/PAVD settings. Electrical dyssynchrony (cardiac resynchronization index; CRI) was measured at each setting using a multilead ECG system placed over the anterior and posterior torso. Biventricular pacing, which included multiple interventricular delays, was also conducted in a subset of 10 patients. RESULTS: When paced LV-only, peak CRI was similar (93 ± 5% vs. 92 ± 5%) during atrial sensing or pacing but optimal PAVD was 61 ± 31 ms greater than optimal SAVD. The difference between As-RVs and Ap-RVs intervals on IEGMs (62 ± 31 ms) was nearly identical. The slope of the correlation line (0.98) and the correlation coefficient r (0.99) comparing the 2 methods of assessing SAVD-PAVD offset were nearly 1 and the y-intercept (0.63 ms) was near 0. During simultaneous biventricular (BiV) pacing at short AVD, SAVD and PAVD programming did not affect CRI, but CRI was significantly (p < .05) lower during atrial sensing at long AVD. CONCLUSIONS: A novel methodology for measuring electrical dyssynchrony was used to determine electrically optimal SAVD/PAVD during LV-only pacing. When BiV pacing, shorter AVDs produce better electrical synchrony.

Two Sudden and Unexpected Deaths of Patients with Schizophrenia Associated with Intramuscular Injections of Antipsychotics and Practice Guidelines to Limit the Use of High Doses of Intramuscular Antipsychotics.

Intravenous haloperidol has been associated with torsades de pointes (TdP). These two sudden deaths were probable adverse drug reactions (ADRs) following intramuscular (IM) antipsychotics. The autopsies described lack of heart pathology and were highly compatible with the possibility of TdP in the absence of risk factors other than the accumulation of antipsychotics with a high serum peak after the last injection, leading to death within hours. The first case was a 27-year-old African-American male with schizophrenia but no medical issues. His death was probably caused by repeated IM haloperidol injections of 10 mg (totaling 35 mg in 2 days). The second case involves a 42-year-old African-American female with metabolic syndrome. Her probable cause of death was the last ziprasidone IM injection of 20 mg in addition to (1) three extra haloperidol doses (2 hours before the ziprasidone injection, 5 mg oral haloperidol; approximately 21 hours earlier, 5 mg oral haloperidol; and 2 days prior, one 10 mg IM haloperidol injection), (2) 10 mg/day of scheduled oral haloperidol for 6 days before death, and (3) a long-acting paliperidone injection of 156 mg 18 days before death. The study of haloperidol glucuronidation and its impairment in some African-Americans is urgently recommended.