Subendocardial burn injury causes ST segment depression in bullfrog heart mimicking electrocardiographic change in subendocardial myocardial infarction

Q: What is the clinical evidence from this study?

Population: Non-ST segment elevation myocardial infarction (NSTEMI) / Subendocardial myocardial infarction (n=13). Intervention: Subendocardial burn injury vs. Baseline (before burn injury) and Subepicardial burn injury. Primary outcome: ST segment depression.

Q: What does this research mean for the field?

Subendocardial burn injury in the bullfrog ventricle induces ST segment depression, replicating the electrocardiographic changes characteristic of human subendocardial myocardial infarction. Novelty: ClaimNovelty.METHODOLOGICAL. Consensus alignment: ConsensusAlignment.NEUTRAL.

Kanata SEGAWA; Kinari Kawamura; Kurumi Sugawara; Hiroyuki Sonobe; Junko Shida; Itsuro Kazama

doi:10.1292/jvms.26-0327

January 1, 2026Journal of Veterinary Medical ScienceOpen Access

Subendocardial burn injury causes ST segment depression in bullfrog heart mimicking electrocardiographic change in subendocardial myocardial infarction

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Key result

Subendocardial burn injury induces ~490 mV ST depression in bullfrogs, mimicking NSTEMI changes.

n=13

Why the study?

Electrocardiographic changes in subendocardial myocardial infarction, specifically ST segment depression, require experimental replication to understand underlying injury currents.

Does subendocardial burn injury produce ST segment depression in adult bullfrog hearts?

Key Points

To determine whether inducing targeted burn injury to the subendocardial surface of the bullfrog heart ventricle reproduces the ST segment depression characteristic of subendocardial myocardial infarction.
Studied 13 anesthetized adult bullfrogs (450–550 g) with surgically exposed hearts undergoing direct electrocardiogram recording.
Induced subepicardial thermal injury using a glass capillary tube heated to over 600 °C (n=5) or subendocardial thermal injury via a myocardial wall-penetrating 22-gauge needle with a coiled tip heated to over 600 °C (n=8).
Evaluated histological changes using Masson's trichrome staining and quantified ST segment deviations using the onset of the QRS complex as the baseline reference.
Subendocardial burn injury generated marked ST segment depression of 490 ± 29.2 mV (n=8) from the isoelectric baseline.
Subepicardial burn injury induced marked ST segment elevation of 571 ± 63.3 mV (n=5) relative to baseline.
Histological analysis with Masson's trichrome confirmed localized subendocardial damage characterized by thick layers containing fibrous material, edema, and atrophic muscle with fibrous degeneration.

Structured PICO

Does subendocardial burn injury produce ST segment depression in adult bullfrog hearts?

P

Population

13 adult bullfrogs weighing 450-550 g were used as an experimental animal model to evaluate electrocardiographic changes associated with subendocardial myocardial infarction.

I

Intervention

Subendocardial burn injury induced by a heated 22-gauge stainless steel needle with a coiled tip (heated >600 °C) applied to the endocardial surface of the ventricle

C

Comparator

Pre-injury baseline state and subepicardial burn injury (induced by a heated glass capillary tube on the epicardial surface)

O

Outcome

Electrocardiographic ST segment deviation (depression or elevation) from the isoelectric linesurrogate

Main Result

Absolute Event Rate: 490% vs 0%

A bullfrog heart model of subendocardial burn injury successfully replicates the ST segment depression characteristic of subendocardial myocardial infarction, offering a simple model for studying NSTEMI electrophysiology.

Implication

Subendocardial bullfrog injury reproduces NSTEMI-like ST depression; hypothesis-generating for ischemia models, does not alter clinical practice.

Abstract

Non-ST segment elevation myocardial infarction (NSTEMI) is caused by partial occlusion of a coronary artery due to atherosclerotic plaque disruption and superimposed thrombus formation. Common electrocardiographic findings in NSTEMI include permanent ST segment depression, indicative of subendocardial myocardial infarction. In our earlier research, we simulated the ST segment elevation observed in human ischemic heart disease by inducing subepicardial burn injuries in the bullfrog heart ventricle. In the present study, we successfully replicated ST segment depression, similar to that observed in patients with subendocardial myocardial infarction, by inducing burn injuries on the subendocardial surface of the frog heart ventricle, as confirmed by histological examination. The currents of injury generated by the damaged endocardium were thought to be responsible for this electrocardiographic change.

Discussion

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Cite This Study

SEGAWA et al. (2026) studied Non-ST segment elevation myocardial infarction (NSTEMI) / Subendocardial myocardial infarction (n=13). Subendocardial burn injury vs. Baseline (before burn injury) and Subepicardial burn injury was evaluated on ST segment depression. Inducing a subendocardial burn injury in the bullfrog heart ventricle caused a marked ST segment depression of 490 ± 29.2 mV, successfully mimicking electrocardiographic changes seen in NSTEMI.

synapsesocial.com/papers/6ad0fce415427f6a840403a7 https://doi.org/10.1292/jvms.26-0327

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Subendocardial burn injury causes ST segment depression in bullfrog heart mimicking electrocardiographic change in subendocardial myocardial infarction

Key Points

Structured PICO

Main Result

Implication

Abstract

Discussion

Cite This Study

Subendocardial burn injury causes ST segment depression in bullfrog heart mimicking electrocardiographic change in subendocardial myocardial infarction

Key Points

Structured PICO

Main Result

Implication

Abstract

Discussion

Cite This Study

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