June 1, 1988Journal of Cardiovascular Pharmacology
Evolving Myocardial Infarction in the Rat In Vivo
Key result
Permanent coronary occlusion in rats reduces cardiac output ~41% with rapid wall thinning and necrosis.
Why the study?
Despite low collateral flow in rat hearts, many reports claim pharmacological limitation of infarct size after permanent coronary occlusion, prompting investigation of possible artefacts.
Population
Isolated rat hearts (n=12/group) with permanent coronary occlusion
Comparison
Permanent coronary occlusion at various time points vs sham operated controls
Design
Preclinical experimental study
Follow-up
Up to 48 hours
Authors
Discussion
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Overview
Rat permanent occlusion models risk confounding infarct size claims via staining artefacts; leaves open true pharmacological efficacy pending refined methods.
Structured PICO
P
Population
Rats subjected to permanent coronary occlusion or sham operation, evaluated at multiple time points up to 48 hours to assess cardiac function and infarct evolution.
I
Intervention
Permanent coronary occlusion evaluated at 1, 2, 4, 6, 12, 18, 24, or 48 hours
C
Comparator
Sham operated controls
O
Outcome
Cardiac function (cardiac output), lumen areas, areas of underperfusion, minimum wall thickness, and tissue necrosis (tetrazolium staining and histology)surrogate
Main Result
Absolute Event Rate: 37.7% vs 63.8%
Apparent pharmacological limitation of infarct size in rat models of permanent coronary occlusion may be confounded by artefacts related to tissue remodeling, white cell infiltration, and tetrazolium staining characteristics.
Limitations
- Incorrect designation of tissue as tetrazolium positive within the severely ischaemic zone of underperfusion
- Inappropriately equating the zone of underperfusion to the risk zone
- Possibility that some drugs might affect white cell infiltration, tetrazolium staining characteristics, wall thinning, and tissue remodelling
Cite This Study
Hearse et al. (1988) studied Myocardial infarction. Permanent coronary occlusion vs. Sham operated controls was evaluated on Cardiac output. Permanent coronary occlusion in rats reduced cardiac output to 37.7 ml/min compared to 63.8 ml/min in sham controls, with substantial wall thinning and necrosis developing by 12 hours.