Abstract 19575: Non-invasive Creation of Localized Embryonic Heart Defects via Multiphoton-guided Femtosecond-laser Photoablation
Background: Congenital heart defects (CHD) often originate as focal obstructions within the outflow tract of the embryonic heart. Experimental challenges currently limit the creation of animal models to elucidate pathogenic mechanisms.
Methods: We present a two-photon microscopy guided femtosecond laser photoablation approach to produce localized obstructions within embryonic chick heart. In this study, the effects of right and/or left 4th pharyngeal arch artery (PAA) occlusion in live chick embryos at 3–5 days of incubation (HH20-HH26) were tested. Nonlinear absorption of tightly focused laser pulses drove the nucleation and growth of a bubble within the lumen (Figure A, B), temporarily occluding vessels up to 150 μm in size with flow velocities exceeding 10 cm/s. Subsequent photolysis of aggregated thrombocytes created a stable clot (Figure C). Doppler ultrasonography and histology were used to quantify blood flow redistribution in neighboring PAA vessels.
Results: Occlusion of the right 4th PAA resulted in immediate flow redistribution within the PAA network. The right 6th PAA (future pulmonary artery) diameter increased significantly from 0.13 ± 0.01 to 0.28 ± 0.0017 mm, and peak velocity increased from 5.88 ± 2.51 to 9.3 ± 2.55 cm/s (P<0.05). No significant change in right 3rd PAA diameter or blood velocity occurred. Interestingly, no significant changes in the contralateral PAAs occurred unless both the right and left 4th PAA were occluded simultaneously, in which case both 6th PAA's diameters and flow velocities increased. Cardiac output was unchanged with single 4th PAA ablation and all embryos survived (N = 4), but output was significantly decreased (20.17%) when both 4th PAA were occluded and embryos died after 72 hours.
Conclusions: Femtosecond-laser photoablation is a powerful new technique to complement genetic perturbation to study CHD pathogenesis. Targeted occlusion of embryonic outflow structures may create new clinically relevant CHD models.
- © 2010 by American Heart Association, Inc.