Why the study?
Does dual stimulation from pacing and walking affect cardiac function in goats following cardiomyoplasty?
Does dual stimulation from pacing and walking affect cardiac function in goats following cardiomyoplasty?
In a goat model of cardiomyoplasty, dual stimulation from pacing and walking caused erratic muscle contractions and impaired ventricular filling.
May caution against combined pacing and ambulation in cardiomyoplasty; leaves open optimal stimulation protocols for translational research.
Following cardiomyoplasty, the latissimus dorsi (LD) muscle contracts in response to both pacemaker and central nervous system (CNS) derived action potentials. To evaluate the effect of this dual stimulation on cardiac function, six goats (56 kg to 80 kg) underwent treadmill tests 4 to 5 months after surgery. Sonomicrometer crystals were used to measure changes in the left ventricular short-axis dimension (LVSAD) and regional length changes in the LD muscle. Pacing mediated stimulation resulted in 17 +/- 4% fractional shortening of the muscle pedicle lasting 400 +/- 17 msec. Walking at speeds of 0.8 and 2.4 km/hr produced muscle contractions of variable duration and intensity. LVSAD was decreased by both pacing (14%) and walking (up to 10%). Pacing in combination with walking caused erratic muscle contractions with concomitant changes in LVSAD suggestive of impaired ventricular filling. No arrhythmias were noted during exercise.
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Irié et al. (1991) studied this question.
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