Sorry, no, I should have been more clear: PVR is pulmonary vascular resistance, a function of the "blood pressure" in the pulmonary vascular tree.  When pressure here is increased, blood flow can somewhat "back up" a bit (think of somebody who's really angry and the jugular veins in their neck pop out).  If there is a shunt within the heart, such as an ASD or VSD (atrial or ventricular septal defect) or PFO, then blood could theoretically start to shunt from the R side to the L side (unoxygenated blood being shunted across to mix with the oxygenated blood returned from the lungs on the left side of the heart).

Normally the pressure on the L side of the heart (which is needed to propel blood out into systemic circulation) is higher than on the R, so the presence of a shunt will result in L -> R flow.  If flow from L -> R starts to overwhelm the R heart, and that pressure becomes higher, the shunt can permanently reverse (a very very serious condition known as Eisenmenger's Syndrome.)  This is not seen with just a PFO in isolation, which is usually a comparatively small hole.

Still would be very interested in seeing citations/references documenting that prolonged crying in an infant could lead to a PFO.  We don't typically see higher rates of PFOs in infants who have chronic lung disease that causes pulmonary hypertension.  Also, the hyperventilation that often occurs with crying would likely cause some pulmonary arterial vasodilation because of the decrease in carbon dioxide.  And the echo reports that I often see where the kiddos are "uncooperative" for the exam (usually crying) do not mention increases in R-sided pressure.

I agree with Judy that this kind of conjecture may not be appropriate for using to advise moms "not to let their babies cry."  I would have been horrified as a new mom if someone had told me that if my baby cried for long periods of time, he would be at an increased risk for either having a hemorrhagic stroke as a newborn, or an embolic stroke as an adult because all that crying would have left a hole open in his heart.  There were many times both of my boys screamed non-stop while we were in the car and there was absolutely nothing I could do about it

And I am certainly not one to advocate letting a baby cry! -- my second son was a 34-wkr who had persistent issues with apnea/bradycardia, and when he'd cry hard, he'd then reflux a bit which would trigger audible laryngospasm and a vagal response which would cause significant bradycardia.  The little guy *lived* in a wrap on my chest or attached to my breast on the couch for his first 4 months of life.  Diagnosed at almost 3 with a subtle laryngeal cleft and only now that it's been temporarily repaired can he freely tantrum/cry like any preschooler without having stridor and inhaling his secretions.  So he's finally learning that crying will NOT always get him what he wants. :)

-Sarah Reece-Stremtan (peds anesthesiology fellow in Washington DC)

             ***********************************************

Archives: http://community.lsoft.com/archives/LACTNET.html
To reach list owners: [log in to unmask]
Mail all list management commands to: [log in to unmask]
COMMANDS:
1. To temporarily stop your subscription write in the body of an email: set lactnet nomail
2. To start it again: set lactnet mail
3. To unsubscribe: unsubscribe lactnet
4. To get a comprehensive list of rules and directions: get lactnet welcome