The effects of procainamide on conduction in anisotropic canine ventricular myocardium.
Key result
Procainamide decreased the ratio of longitudinal to transverse conduction velocities from 3.27 to 3.09 (p<0.05) in canine ventricular myocardium at a pacing cycle length of 1000 msec.
Why the study?
Does procainamide alter conduction velocity longitudinal and transverse to fiber orientation in canine ventricular myocardium?
Population
Epicardial strips obtained from areas of uniform fiber orientation from 15 adult mongrel dogs
Comparison
Procainamide vs Control conditions
Design
Preclinical
Authors
Discussion
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Implication
May alter antiarrhythmic interpretation in anisotropic tissue; leaves open translation to human ventricular conduction.
Key Points
- To examine how procainamide affects conduction velocity in ventricular myocardium considering fiber orientation.
- Evaluated procainamide's effects on conduction in epicardial strips from 15 adult mongrel dogs.
- Measured conduction velocity both longitudinal and transverse to fiber orientation at different pacing cycle lengths.
- Analyzed changes in conduction velocity when pacing direction was altered.
- Mean conduction velocity longitudinally decreased from 0.602 m/sec to 0.532 m/sec (p<0.05) with procainamide.
- Mean conduction velocity transversely decreased from 0.186 m/sec to 0.174 m/sec (p<0.05) with procainamide.
- Procainamide resulted in a decrease in the (theta L/T) ratio from 3.27 to 3.09.
Structured PICO
Does procainamide alter conduction velocity longitudinal and transverse to fiber orientation in canine ventricular myocardium?
P
Population
Epicardial strips obtained from areas of uniform fiber orientation from 15 adult mongrel dogs
I
Intervention
Procainamide
C
Comparator
Control conditions (before the addition of procainamide)
O
Outcome
Conduction velocity longitudinal and transverse to fiber orientation, and intracellular potentialssurrogate
Main Result
Absolute Event Rate: 3.09% vs 3.27%
p-value: p=<0.05
Procainamide slows conduction velocity more in the longitudinal than transverse direction in anisotropic canine ventricular myocardium, decreasing the ratio of longitudinal to transverse conduction velocities.
Cite This Study
Kadish et al. (1986) studied Normal ventricular myocardium (in vitro) (n=15). Procainamide vs. Control (before addition of procainamide) was evaluated on Ratio of longitudinal to transverse conduction velocities (theta L/T) at a pacing cycle length of 1000 msec (p=<0.05). Procainamide decreased the ratio of longitudinal to transverse conduction velocities from 3.27 to 3.09 (p<0.05) in canine ventricular myocardium at a pacing cycle length of 1000 msec.