Atrial and ventricular septal changes in ethanol vapour exposed chick embryos.

OBJECTIVE: To study the effects of ethanol vapour exposure on development of atrial and ventricular septa of chick embryo. METHODS: The experimental study was conducted at the College of Physicians and Surgeons, Islamabad, from 2006 to 2007. The experimental and control groups were further divided into three subgroups based on the day of sacrifice. The experimental group was exposed to ethanol vapours produced in a specially-designed vapour chamber and then compared with age-matched controls. RESULTS: There were 90 eggs in each of the two groups. The development of inter-ventricular septum completed at day 7 of development in chick embryo. Ethanol vapour exposure produced a small discontinuity at day 10 of development in a chick embryo which may be labelled as ventricular septal defect since ventricular development is completed by day 7. Interatrial septum formed till day 7 with small perforations which persisted till hatching. CONCLUSIONS: Ethanol vapour exposure may lead to ventricular septal defect.

Leftward bulging of atrial septum is provoked by nitroglycerin and by sustained valsalva strain.

BACKGROUND: The motion of the interatrial septum primum (septum) is dependent on the interatrial pressure relation, normally with slightly higher pressure in the left atrium and the septum bulging toward the right atrium. The aim of this study was to explore the physiologic mechanisms that reverse interatrial pressures and provoke leftward bulging of septum (LBA). The hypothesis was that both left ventricular unloading with nitroglycerin and sustained Valsalva strain would independently provoke LBA and that their combination would further intensify the effect. METHODS: Prospectively collected transesophageal echocardiography recordings from 13 patients with obstructive sleep apnea were retrospectively analyzed for the presence or absence of LBA during resting respiration and during Valsalva strain. In each condition, LBA beats were counted at time points before and after nitroglycerin spray had been administered, which enabled a comparison of the independent effects and the combined effect of the nitroglycerin and the Valsalva maneuver. An LBA beat was defined as a heartbeat displaying any LBA during the cardiac cycle. RESULTS: Nitroglycerin increased the proportion of LBA beats significantly during resting respiration, from 21 ± 27% to 54 ± 43% (P = .008). During Valsalva strain, the proportion increased with nitroglycerin spray from 48 ± 21% to 80 ± 17% (P = .001). After nitroglycerin administration, LBA occurred in at least three beats during strain in all Valsalva periods. CONCLUSIONS: Unloading of the left ventricle by nitroglycerin administration and by sustained Valsalva strain independently provoked LBA. The combination of these two interventions further intensified the effect.