Does blood flow through holmium:YAG transmyocardial laser channels?
BACKGROUND
Early reports indicate that transmyocardial laser revascularization improves symptoms in patients with refractory angina. However, there is little experimental evidence of whether blood flow through channels is the mechanism of action.


METHODS
Endocardial channels were made in the distribution of the left anterior descending coronary artery in canine hearts (n = 5) using a holmium:yttrium-aluminum garnet laser. Hearts were excised acutely while perfused in a retrograde fashion from a second dog so that the aortic valve always remained closed. The proximal left anterior descending coronary artery was ligated. To measure direct transmyocardial blood flow, colored microspheres were injected into the left ventricular chamber.


RESULTS
The number of spheres per gram of tissue in the channel region was significantly higher than in the control region (low load, 302.5 +/- 169.0 versus 41.8 +/- 59.4; high load, 208.4 +/- 138.3 versus 5.8 +/- 11.7; both, p < 0.05). However, the estimated regional blood flow through the channels was extremely low (<0.01 mL/g/min. In the chronic setting (n = 4) (2-week survival), no flow as detected through the channels, and the endocardial entry points were closed.


CONCLUSIONS
Transmyocardial blood flow does not appear to occur through channels made with the holmium:yttrium-aluminum garnet laser. It remains to be determined whether this is the case with other types of lasers.
Kohmoto
T
T
Department of Surgery, Columbia University, New York 10032, USA.
Fisher
P E
PE
Gu
A
A
Zhu
S M
SM
Yano
O J
OJ
Spotnitz
H M
HM
Smith
C R
CR
Burkhoff
D
D
D000818:Animals; D003326:Coronary Circulation / Q000528:radiation effects; D004285:Dogs; D006695:Holmium; D053685:Laser Therapy; D008863:Microspheres; D009204:Myocardial Revascularization / Q000379:methods; D009206:Myocardium; D012039:Regional Blood Flow; D015019:Yttrium
D015019:Yttrium; D006695:Holmium