The difference between initial arteriole and venule damage could be explained by the threefold higher absorption coefficient at 595 nm in (oxygen-poor!) arterioles. In human patients, PWS consist of ectatic venules (characterized by higher absorption), so that these considerations favor the use of 595-nm irradiation for laser photothermolysis. For optimal treatment of PWS it is proposed that t(p) be between 0.1 and 1.5 milliseconds. This is based on a modified relaxation time tau'(d), defined as the time required for heat conduction into the full thickness of the vessel wall, which is assumed to have a thickness DeltaD approximately 0.1D. The corresponding tau'(d) will be a factor of about six smaller than given in the literature. For vessels with D between 30 and 300 mum, tau'(d) ranges from 0.1 to 1.5 milliseconds.

The chick chorioallantoic membrane (CAM) assay was used to determine the photodynamic response (PDR) of blood vessels to Photofrin, 5-aminolevulinic acid (ALA), benzoporphyrin derivative monoacid ring A (BPD-MA) and lutetium texaphyrin (Lutex). The photosensitizers were administered systemically via intraperitoneal injection into the chick embryo. Forward stepwise regression analysis of the PDR results enabled the individual contributions of seven experimental variables to be ranked: drug dose, light dose, fluence rate, drug uptake time, vessel type (whether arterioles or venules), vessel diameter, and embryo age. The order of importance of the variables, the PDR profile, was determined for each photosensitizer. Relative contributions of the experimental variables from this study to the CAM PDR were compared with those from our previous study on PDR of CAM blood vessels following topical application of the same photosensitizers. PDR profiles were interpreted in terms of biophysical and biochemical characteristics of the individual photosensitizers and the variation in their interactions with the delivery/distribution environment.

Elderly, women, and heart failure patients underwent fewer cardiac procedures than lower-risk patients. Physicians should change their attitude toward these groups and use advanced procedures, bearing in mind the patients' needs rather than good procedural outcomes.