Abstract
Background and Objective
Oxyhemoglobin (HbO~2~) has been regarded as the primary target chromophore for selective photothermolysis of vascular malformations. In theory, venous lesions might be better treated with wavelengths preferentially absorbed by deoxyhemoglobin (Hb).
Study Design/Materials and Methods
Wavelengthโdependent fluence thresholds for photocoagulation of whole human blood were determined in glass capillary samples with measured oxygen saturation levels. Pulsed dye lasers at 585, 590, 595, 600, 633โnm, a 694โnm ruby laser, a 755โnm alexandrite laser, and a 1,064โnm Nd:Yag laser were used, all with 1.5โ3 milliseconds pulse width and similar exposure spot size.
Results
Selectivity (a lower fluence threshold) for venous blood was maximal at 694โnm, and significant at 595, 600, 633, and 755โnm. At 633โnm, a wavelength with strong relative absorption by metHb, selectivity for venous blood was much less than expected. The Nd:YAG laser at 1,064โnm showed significant selectivity for arterial blood.
Conclusion
Preferential photocoagulation of venous blood is possible at wavelengths with a high Hb/HbO~2~ absorption coefficient ratio. Laserโinduced metHb may also affect wavelengthโdependent selective photothermolysis. Venular malformations such as port wine stains could potentially be treated more selectively with โผ630โ780โnm sources. Nd:YAG laser pulses at 1,064โnm tend to affect arterial more than venous blood. Lasers Surg. Med. 44:152โ157, 2012. ยฉ 2012 Wiley Periodicals, Inc.