AIM To compare estimated pressure gradients from routine follow-up cardiovascular phase-contrast magnetic resonance (PC-MR) with those from Doppler echocardiography and invasive catheterization in patients with congenital heart disease (CHD) and pulmonary outflow tract obstruction. METHODS In 75 patients with pulmonary outflow tract obstruction maximal and mean PC-MR gradients were compared t...

A retrospective study of patients attending the emergency department with acute asthma was performed in Bermuda. Climatic data (barometric pressure, rainfall, humidity, and wind strength and direction) were obtained and compared with frequency of exacerbations of asthma. Three factors--namely, relative humidity, average daily temperature, and northeasterly winds--were found to be related to wor...

Studies correlating prosthetic valve gradients determined by continuous wave Doppler echocardiography with gradients obtained by cardiac catheterization have, to date, been limited to patients with mitral and tricuspid prostheses or have compared nonsimultaneous measurements. Simultaneous Doppler and catheter pressure gradients in 36 patients (mean age, 63 +/- 13 years) with 42 prosthetic valve...

Intracranial Pressure Gradients Associated With Experimental Cerebral Embolism • In a series of 20 cats unilateral cerebral oil embolism was followed by the development of clinical signs of increased intracranial pressure. Simultaneous bilateral epidural pressure measurements revealed marked pressure gradients between both cerebral hemispheres. Such local (tissue) pressure gradients possibly in...

We reviewed current literature on the role of seasonal, meteorological, or circadian factors in ruptured cerebral aneurysms. found that aneurysm rupture most frequently occurs winter and spring, less summer. The highest number aneurysms happens morning, between 8 am 12 pm. data regarding meteorological factors' effect risk are conflicting. However, it should be noted changes barometric pressure...

The maximum height of a siphon is generally assumed to be dependent on barometric pressure-about 10 m at sea level. This limit arises because the pressure in a siphon above the upper reservoir level is below the ambient pressure, and when the height of a siphon approaches 10 m, the pressure at the crown of the siphon falls below the vapour pressure of water causing water to boil breaking the co...