Anatomical observations of the moderator band.

Apical ventricular septal defects are rare pathologies of the ventricular septum. The moderator band, or other large trabeculations, is the major obstacle for the repair of such defects. The aim of our study was to identify and describe variations in the size and anatomy of the moderator band. We studied the right ventricular apical trabeculations in 100 adult human cadavers. Overall, we identified the moderator band in 92% of hearts. In just over two-fifths (42%), the band was a short and thick trabeculation, whereas, in one-eighth (12%), it was long and thick. In just under one-quarter of the hearts (24%), the band was short and thin, whereas it was long and thin in 14% of the hearts. In the remaining eight hearts, we were unable to identify the moderator band. The mean thickness of the band was 4.5 +/-1.8 mm, and its mean length was 16.23 +/- 2.3 mm, ranging from 11.3 to 24.3 mm. According to these measurements, we were able to classify the band as originating less than 45% of the distance from the tricuspid valve to the apex (closer to tricuspid valve), seen in 12 hearts, between 45 and 55% of the distance from the valve to the apex, seen in 45 hearts, and greater than 55% of this distance (closer to the apex), seen in 39 specimens. We present these data that may prove useful in the setting of the surgical repair of apical ventricular septal defects through the right atrium.

Short-term secondhand smoke exposure decreases heart rate variability and increases arrhythmia susceptibility in mice.

Exposure to secondhand smoke (SHS), a major indoor air pollutant, is linked to increased cardiovascular morbidity and mortality, including cardiac arrhythmias. However, the mechanisms underlying the epidemiological findings are not well understood. Impaired cardiac autonomic function, indexed by reduced heart rate variability (HRV), may represent an underlying cause. The present study takes advantage of well-defined short-term SHS exposure (3 days, 6 h/day) on HRV and the susceptibility to arrhythmia in mice. With the use of electrocardiograph telemetry recordings in conscious mice, HRV parameters in the time domain were measured during the night after each day of exposure and 24 h after 3 days of exposure to either SHS or filtered air. The susceptibility to arrhythmia was determined after 3 days of exposure. Exposure to a low concentration of SHS [total suspended particle (TSP), 2.4 +/- 3.2; and nicotine, 0.3 +/- 0.1 mg/m(3)] had no significant effect on HRV parameters. In contrast, the exposure to a higher but still environmentally relevant concentration of SHS (TSP, 30 +/- 1; and nicotine, 5 +/- 1 mg/m(3)) significantly reduced HRV starting after the first day of exposure and continuing 24 h after the last day of exposure. Moreover, the exposed mice showed a significant increase in ventricular arrhythmia susceptibility and atrioventricular block. The data suggest that SHS exposure decreased HRV beyond the exposure period and was associated with an increase in arrhythmia susceptibility. The data provide insights into possible mechanisms underlying documented increases in cardiovascular morbidity and mortality in humans exposed to SHS.