Demand dynamic cardiomyoplasty: mechanograms prove incomplete transformation of the rested latissimus dorsi.
BACKGROUND
In dynamic cardiomyoplasty, standard stimulation produces high fatigue resistance but also undesirable dynamic characteristics of the latissimus dorsi (LD). Based on results of intermittent stimulation in animals we introduced demand stimulation, a lighter regimen of LD activity-rest stimulation, and the mechanogram, a noninvasive method to determine the contractile characteristics of LD wrap.


METHODS
Surgery and standard stimulation was according to the technique of Carpentier and Chachques, demand stimulation and LD wrap mechanogram were as we previously described. The LD contraction is synchronized to heart systole by mechanogram and echocardiography, and extent of transformation by tetanic fusion frequency analysis. A total of 22 patients were studied to date. Data for the 8 subjects who attained 6-month follow-up are reported. Four of them were lightly stimulated from the conditioning period, whereas 4 others were converted to light and then demand stimulation after years of standard stimulation. Patients were followed up with respect to survival, functional class, hospital admission rate, medication used, cardiopulmonary exercise testing, and LD wrap mechanography.


RESULTS
Latissimus dorsi wrap slowness reverses by the activity-rest regimen, even after years of standard stimulation (Tetanic fusion frequency of 11 +/- 2 Hz after standard stimulation vs 30 +/- 3 Hz after demand regimen, p < 0.0001). After demand dynamic cardiomyoplasty there are no deaths. Quality of life is substantially improved with significant reduction of heart failure symptoms (New York Heart Association class: preoperative 3.0 +/- 0.0, post-demand dynamic cardiomyoplasty 1.5 +/- 0.2, p < 0.0001). In the subgroup of patients lightly stimulated from LD conditioning, exercise capacity tends to increase over preoperative values more than 2 years after operation (VO2 max: preoperative 12.3 +/- 0.7 vs 16.6 +/- 1.7 post-demand dynamic cardiomyoplasty, p = 0.05).


CONCLUSIONS
Demand stimulation and mechanography of the LD wrap are safe procedures that could offer long-term benefits of dynamic cardiomyoplasty to patients with pharmacologically intractable heart failure.
Department of Biomedical Sciences, and Institute of Cardiovascular Surgery, University of Padua, Italy. bam@civ.bio.unipd.it
U
U
Carraro
M
M
Barbiero
G
G
Docali
A
A
Cotogni
G
G
Rigatelli
D
D
Casarotto
C
C
Muneretto
D000328:Adult; D002311:Cardiomyopathy, Dilated / Q000601:surgery*; D018421:Cardiomyoplasty / Q000379:methods*; D004558:Electric Stimulation; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D008297:Male; D008875:Middle Aged; D009119:Muscle Contraction; D019739:Skeletal Muscle Ventricle / Q000502:physiology*