Hogan, John

Isner, Jeffrey M.

Mosseri, Morris

Pickering, Geoffrey

Elsevier - Publisher Connector 

JACC Vol. 17. No. Z 
February 1991'207A 
u E VASOHOTOR POMSE 
I XATXON IN VI 
TO PULSED HOWiIWM : YAG 
seri, Yohn Hogan, Jeffrey 
pital, Tufts University 
Schoo, of Medicine, Boston, 
The Holmium:YAG laser can succesfully ablate 
atherosclerotic tissue but its combination of high 
pulse energy (PE) and short pulse duration ((PD) has 
been associated with the generation of shock waves. To 
determine if this phenomenon contributes to laser- 
induced vasospasm we rabbit aorta, 
isometrically mounted 2.5 grams of tension in 
oxygenated Rreb@s buff he tissue was irradiated 
with a Holmium:YAG laser (2100 nm, 6 Hz, 600~pm fiber) 
using both a free-running (PD 250 microseconds) and Q- 
switched (PD 200 nanoseconds) mode. PE was increased 
from l-136 millijoules and tissue temperature was 
continuously monitored by thermocouple. Energy ablation 
threshold for each mode was determined by light 
microscopy. When PE was in the subablative range there 
was mild vasoconstriction that resolved to complete 
relaxation within 10 set of cessation of laser 
irradiation. The contractil@ force was linearly related 
to PE (r=0.70, pe.001) and tissue temperature 
(r=O.5O,p<.OOl) and was not different between the free- 
running and Q-switched modes (80f21 wa 66f16 mq, p=NS). 
PE there was a distinctly different response 
severe contrection lasting for greater than I 
minutes. The contractile force wss greater in the Q- 
switched than the free-running mode (555f117 vs 260239 
mg, pe.05) and this sustained response onset at lower 
PE in the Q-switched mode (67.513.7 vs lOl+S.S mJ, 
p<.O1?). In neither mode was the tissue temperature 
eleva:ed by more than 3cC. ative doses 
of Holmium:YAG laser marked 
vasoconsrriction with the high peak PE 
associate& with This suggests that 
significant vasospasm, possibly due to shock waves, may 
occur during :dolmium:YBG laser anqioplasty. 
WISTOIBCIC AND GIOG EFFECTS OF A I PULSED 
HO LASER 
co TKKIES 
IN NO OTIC 
Cbdes '8. McKay, Steve Len&s, David Robertson, Bruce 
Weller, ichael hnfford, University of Iowa, Iowa 
City, IA 
Wistologic effects of pulsed Wolmfum-YAG (WC-YAG) lasers 
(2.1 w- energy) delivered by fiberoptic 
not been documented in human coronary 
catheters have 
rteries (CA). 
effects (HISTO) of increasing 
/pulse) were studied first in 
energy doses 
orta strips. 
atherosclerotic (ATHERO n-15) CA 
( 
in 7 
15) or 
cadaveric 
hearts perfused at 
cJ&eter (1.6-2.0 
pressure. 
containing 
The laser 
rzultiple 
concentric optical fibers was advanebd fluo~oscopically 
over a guidewire. pulses of 25Cl US duration at S-8 Hz 
and energy levels from 56-520 /pulse (150-2,000 
mJ/mm*) were delivered in 5 second groups. Quantitative 
angiogrephy (ANGIO) PRE and POST lssfng demonstrated no 
perforations or dissections. 
DIAW) was unchanged in NL but increased significantly in 
ATHERO seAments . 
NL 3.54 3.78 1 2 0 
HISTO included vacuoles. enhanced staininE. and ablated 
tissue Vraters" 0.25-Q.-7 deep. ck o-f changes in 7 
ER.0 
-188 
energy 
was related td enera delivery 
1 fn calcllfic Ho-YAG Isser 
ate herosclerotic pslaque in human 
coronary arteries and has al the 1 effects on 
normal ;?oronary arteri 


Unique vasomotor response to pulsed Holmium: YAG laser irradiation in vitro 

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Unique vasomotor response to pulsed Holmium: YAG laser irradiation in vitro

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