Latissimus dorsi muscle blood flow during synchronized contraction: implications for cardiomyoplasty.
BACKGROUND
Damage in latissimus dorsi muscle flaps has been reported after clinical and experimental cardiomyoplasty, and an ischemic origin has been suggested.


METHODS
In situ, preconditioned latissimus dorsi muscles in 5 sheep were stimulated in either 1:1 (muscle: heart) or 1:2 synchrony with the systolic phase of the cardiac cycle, using a burst duration of either 21% or 35% of the cycle. Thoracodorsal artery blood flow and thoracodorsal venous lactate concentrations were measured before and immediately after a 3-minute period of stimulation.


RESULTS
The exercise-induced augmentation of thoracodorsal artery blood flow was significantly (p < 0.05) less with a 1:2 regimen than a 1:1 regimen, for both a 21% (88%; 95% confidence interval [CI], 55.6% to 127.3% versus 138.9%; CI, 97.6% to 188.8%) and 35% burst duration (123.2%; CI, 84.7% to 169.9% versus 167.0; CI, 120.8% to 222.6%). After cessation of stimulation, reactive hyperaemia was observed in 3 of 5 animals with 1:1 21% burst stimulation, and in 5 of 5 animals with a 35% burst duration, but was not seen after 1:2 regimens. A significant (p < 0.01) increase in thoracodorsal venous lactate levels was present after 1:1 35% burst stimulation (34.9%; CI, 9.9% to 65.6%), but lactate levels tended to fall when a 1:2 ratio was used (15.9%; CI, -3.2% to 31.5%; p < 0.1).


CONCLUSIONS
One-to-one stimulation regimens may be detrimental to latissimus dorsi blood flow, and an adaptive, rather than fixed, burst duration may be preferable. These findings have important implications for the cardiomyoplasty procedure.
van Doorn
C A
CA
Department of Cardiothoracic Surgery, Wythenshawe Hospital, Manchester, United Kingdom.
Bhabra
M S
MS
Hopkinson
D N
DN
Barman
D
D
Cranley
J J
JJ
Hooper
T L
TL
D000818:Animals; D018421:Cardiomyoplasty / Q000379:methods*; D016001:Confidence Intervals; D007773:Lactates / Q000097:blood; D008297:Male; D009119:Muscle Contraction / Q000502:physiology*; D018482:Muscle, Skeletal / Q000098:blood supply*; D010805:Physical Conditioning, Animal / Q000502:physiology; D012039:Regional Blood Flow; D012756:Sheep
D007773:Lactates