Enhancement of regional myocardial efficiency and persistence of perfusion, oxidative, and functional reserve with paired pacing of stunned myocardium.
Key result
In dogs with stunned myocardium, paired pacing significantly increased regional myocardial perfusion, improved systolic function (percent wall thickening from 14% to 30%), and nearly doubled MVO2 (P<0.05).
Why the study?
Does paired pacing improve regional myocardial efficiency and function in a canine model of stunned myocardium?
Population
12 anesthetized, closed-chest dogs subjected to 15 minutes of left anterior descending coronary artery…
Comparison
Paired pacing (an inotropic stimulus) vs Baseline state 1 hour after reperfusion
Design
Preclinical
Follow-up
Acute
Authors
Discussion
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Implication
May enhance efficiency in canine stunned myocardium; hypothesis-generating and should not change clinical practice.
Key Points
- To determine the interrelation between perfusion, oxidative metabolism, and function in stunned myocardium and to define its regional efficiency and reserve capacity during inotropic stimulation.
- Twelve anesthetized, closed-chest dogs underwent 15 minutes of left anterior descending coronary artery occlusion followed by reperfusion.
- Myocardial perfusion (radiolabeled microspheres), oxygen consumption (positron emission tomography with 1-11C-acetate), and function (two-dimensional echocardiography) were assessed 1 hour postreperfusion and during paired pacing.
- At 1 hour postreperfusion, stunned regions displayed near-normal perfusion (0.57 ± 0.13 mL/g/min; 81 ± 13% of remote) and oxygen consumption (1.72 ± 0.7 μmol/g/min; 71 ± 27% of remote) but marked dyskinesis (wall thickening: 14 ± 20%), reflecting poor efficiency.
- Paired pacing improved systolic wall thickening to 30 ± 15% (echo score decreased from 2.6 ± 0.7 to 1.4 ± 0.7) and increased oxygen consumption to 3.41 ± 1.82 μmol/g/min (P < 0.05 for each paired measurement), nearly normalizing regional myocardial efficiency.
Structured PICO
Does paired pacing improve regional myocardial efficiency and function in a canine model of stunned myocardium?
P
Population
12 anesthetized, closed-chest dogs subjected to 15 minutes of LAD occlusion followed by reperfusion to evaluate stunned myocardium.
I
Intervention
Paired pacing (an inotropic stimulus)
C
Comparator
Baseline state 1 hour after reperfusion (stunned myocardium without paired pacing)
O
Outcome
Regional myocardial perfusion, myocardial oxygen consumption (MVO2), and myocardial function (systolic wall thickening)surrogate
Main Result
p-value: p=< .05
In a canine model of myocardial stunning, paired pacing improved systolic function, oxidative metabolism, and regional myocardial efficiency, demonstrating considerable reserve capacity in reperfused myocardium.
Cite This Study
Bergmann et al. (1994) studied Stunned myocardium (n=12). Paired pacing vs. Baseline (1 hour after reperfusion) was evaluated on Regional myocardial efficiency, perfusion, oxidative metabolism, and function (p=< .05). In dogs with stunned myocardium, paired pacing significantly increased regional myocardial perfusion, improved systolic function (percent wall thickening from 14% to 30%), and nearly doubled MVO2 (P<0.05).