The Possible Relationship Between Patent Foramen Ovale and Decompression Sickness:.
DEFENCE AND CIVIL INST OF ENVIRONMENTALMEDICINE DOWNSVIEW (ONTARIO)
Pagination or Media Count:
A patent foramen ovale PFO is a small opening between the right and left cardiac atria, a persisting remnant of a physiologic communication present in the fetal heart. This normally closes after birth, but remains patent through to adulthood in up to a third of normal adults. A patent PFO is a potential conduit for blood clot resulting in a stroke, or venous gas bubbles during decompression, resulting in type II neurologic decompression sickness. There has been considerable controversy about the significance of a PFO as a possible mechanism for type II decompression sickness. Despite the high prevalence of PFO in the general population and the relatively common occurrence of venous gas bubbles in diving and altitude exposures, the incidence of type II DCS in diving or with altitude exposure is low. This paper reviews the literature with respect to the potential for right-to-left embolization through a PFO, relation of PFO to DCS, screening techniques for PFO, and treatment options. The literature supports a relationship between the presence and size of PFO and cryptogenic stroke stroke, generally in younger individuals with no other identifiable risk factors. The weight of evidence also favours an increased relative risk of type II DCS with a PFO, although the absolute increase in risk accrued is small. The gold standard for PFO screening is a trans-esophageal echocardiographic TEE and colour flow study, but trans-cranial Doppler TCD with contrast is a promising technique with good accuracy compared with TEE.
- Medicine and Medical Research
- Stress Physiology