Pressure-flow relations across the normal mitral valve.

The stenotic mitral valve area is a major determinant of the atrioventricular pressure-flow relation, and mean atrioventricular pressure gradient is proportionate to the square of mean flow rate. In the absence of obstruction, this relation is linear. The effect of the normal mitral valve area on this pressure-flow relation has not been previously examined. Pulsed Doppler studies of transmitral flow were performed simultaneously with thermodilution cardiac outputs in 25 patients in sinus rhythm and with no valvular disease. Mean flow rate was determined as thermodilution stroke volume/diastolic filling period measured by Doppler. Several instantaneous pressure gradients were estimated from multiple velocity measurements using the modified Bernoulli equation and were plotted against time. Mean pressure gradient was estimated by dividing the area under the pressure-time curve by the diastolic filling period. Average and standard deviation of mean flow rate and pressure gradient was 223 +/- 70 ml/s and 1.4 +/- 0.8 mm Hg, respectively. There was an excellent linear correlation between these 2 parameters (r = 0.91, SEE = 30 ml/s). This confirms the linear relation of mean pressure gradient to mean flow rate in the absence of obstruction. The excellent correlation, obtained without considerations of individual variations of valve area, suggests that this relation is independent of valve area, under normal physiologic conditions.

Papilloedema secondary to acute purulent sinusitis.

Upper respiratory tract infections and sinusitis are common, but intracranial complications of sinusitis are rare in children and are often clinically unremarkable. Papilloedema secondary to purulent sinusitis is a complication previously not reported. We report two cases to highlight atypical manifestations of sinusitis in children.

Association between childhood rhabdomyosarcoma and maternal history of stillbirths.

A case/control study of childhood rhabdomyosarcoma (RMS) was conducted utilizing information from birth records. Cases among Connecticut residents age 19 and younger diagnosed between 1960 and 1988 were identified from the Connecticut Tumor Registry files. Connecticut birth certificates were located for 103 of the 130 cases identified. A random sample of control birth certificates was frequency-matched to the cases by year of birth, sex, and ethnic origin, with a control:case ratio of 2:1. Information abstracted from birth certificates included birth weight, length of pregnancy, plurality, birth order, mother's prior stillbirths, mother's age, father's age, and father's occupation. Data were analyzed by conditional logistic regression. The major finding was an association between RMS and the mother having had one prior stillbirth or more (odds ratio = 3.7; 95% confidence interval = 1.5 to 8.9). Particularly noteworthy was the observation that 6 mothers of cases, but no mothers of controls, had had 2 or more prior stillbirths. The trend for increasing risk of RMS with increasing number of mother's prior stillbirths was highly significant (p = 0.0004). This association suggests that RMS and a class of stillbirths share a common etiologic factor. This factor may be genetic or may involve in utero exposure to an exogenous or endogenous agent.