Left ventricular diastolic pressure-segment length relations and end-diastolic distensibility in dogs with coronary stenoses. An angina physiology model.
Why the study?
Does pacing-induced ischemia alter left ventricular end-diastolic pressure-segment length relations in dogs with coronary stenoses?
Population
Open-chest dogs with critical stenoses on both left anterior descending and circumflex coronary arteries…
Comparison
Ischemia induced by pacing tachycardia for 3… vs Pacing tachycardia in dogs without stenoses.
Design
Preclinical
Authors
Discussion
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Implication
No immediate clinical implications; hypothesis-generating for ischemic diastolic stiffness mechanisms in humans.
Key Points
- To determine whether altered left ventricular end-diastolic distensibility during pacing-induced ischemia is caused by intrinsic myocardial stiffness or extrinsic compression from the right ventricle.
- Open-chest canine model with critical (90% diameter reduction) stenoses of the left anterior descending and circumflex coronary arteries, instrumented with subendocardial ultrasonic crystals.
- Hemodynamics and regional segment lengths were assessed during transient vena caval occlusion before and after 3-minute pacing tachycardia, alongside a non-stenosed control group (N=6).
- In stenosed dogs, pacing tachycardia significantly increased left ventricular end-diastolic pressure (9.3 ± 0.9 to 16.9 ± 1.5 mm Hg, P < 0.001) and the isovolumic relaxation time constant (46 ± 3 to 60 ± 5 msec, P < 0.01), while reducing ischemic fractional shortening (17.6 ± 1.7 to 14.5 ± 1.3%, P < 0.01) with unchanged right ventricular end-diastolic pressure.
- Left ventricular end-diastolic pressure-segment length relationships shifted upward after pacing tachycardia in stenotic hearts during vena caval unloading, whereas non-stenosed controls showed unchanged end-diastolic pressure (9.4 ± 1.8 to 9.8 ± 1.8 mm Hg, NS) and no curve shift.
Structured PICO
Does pacing-induced ischemia alter left ventricular end-diastolic pressure-segment length relations in dogs with coronary stenoses?
P
Population
Open-chest dogs with critical (90% diameter reduction) stenoses on both left anterior descending and circumflex coronary arteries, and a control group of 6 dogs without stenoses.
I
Intervention
Ischemia induced by pacing tachycardia for 3 minutes, with transient vena caval occlusion.
C
Comparator
Pacing tachycardia in dogs without stenoses.
O
Outcome
Left ventricular end-diastolic pressure and myocardial segment length relations.surrogate
In a canine angina physiology model, pacing-induced ischemia causes an upward shift in the left ventricular end-diastolic pressure-segment length relation, supporting the role of persistent myosin-actin interaction in ischemic diastolic abnormalities.
Cite This Study
Momomura et al. (1984) studied this question.