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Diastolic dysfunction of stunned myocardium
T Ehring1, R Schulz, J D Schipke
1Dept. of Pathophysiology, University of Essen Medical School, FRG.
Insights
This study measured cardiac function in dogs after blocked blood flow was restored. Diastolic function, specifically isovolumic diastole and filling phases, showed distinct changes during and after reperfusion.
Area of Science:
- Cardiology
- Myocardial reperfusion injury
Background:
- Prolonged systolic dysfunction after reperfusion is well-documented.
- Diastolic function changes during reperfusion are less understood.
- Previous studies have not separated isovolumic diastole from the filling phase.
Purpose of the Study:
- To separately assess systolic (Vsys), isovolumic diastolic (Viso), and filling phase (Vfill) velocities.
- To evaluate post-ejection thickening (Pejt) as a marker of left ventricular asynchrony.
- To characterize regional myocardial function during coronary artery occlusion and reperfusion.
Main Methods:
- Measurements in 12 anesthetized dogs under control, 15-minute left circumflex coronary artery occlusion (CAO), and reperfusion conditions (10 min, 4 hr, 8 hr).
- Determination of Vsys, Viso, Vfill, and Pejt of anterior and posterior myocardium.
- Monitoring of heart rate and left ventricular pressure.
Main Results:
- Anterior wall function remained unchanged.
- Posterior wall showed systolic thinning during CAO.
- Systolic wall excursion (Vsys) recovered gradually during reperfusion.
- Isovolumic diastolic (Viso) and filling phase (Vfill) velocities changed significantly during CAO and showed distinct recovery patterns post-reperfusion.
Conclusions:
- Regional diastolic function is significantly altered during and after myocardial ischemia and reperfusion.
- Separate analysis of isovolumic diastole and filling phase provides a more detailed understanding of post-reperfusion cardiac mechanics.
- These findings highlight the importance of assessing diastolic function in managing myocardial reperfusion injury.
Abstract:
The prolonged regional contractile failure of reperfused myocardium has usually been characterized in terms of systolic function, while only few reports on its diastolic function are available. None of these studies considered changes in the isovolumic diastole and the subsequent filling phase separately. Therefore, in the present study, the velocities of wall excursion during systole (Vsys), isovolumic diastole (Viso) and filling phase (Vfill) were determined in 12 anesthetized dogs. Additionally, post-ejection thickening (Pejt), a marker of left ventricular asynchrony, was determined. Measurements were performed under control conditions, during a 15 minute left circumflex (LCX) coronary artery occlusion (CAO) and at 10 minutes, 4 and 8 hours reperfusion. Heart rate, left ventricular pressure, and Vsys, Viso, Vfill, and Pejt of the anterior myocardium remained unchanged throughout the experiments. During CAO, systolic wall-thickening of the posterior wall was reversed to systolic wall-thinning. Upon reperfusion, Vsys started to recover (2.5 +/- 3.2 mm/s at 10 minutes) and gradually improved over 8 hours of reperfusion (4.6 +/- 3.2 mm/s at 4 hours, 6.4 +/- 1.5 mm/s at 8 hours). Viso became positive during CAO (9.4 +/- 7.1 mm/s vs. -5.6 +/- 3.9 mm/s under control conditions) and was unchanged at 10 minutes reperfusion (7.9 +/- 5.2 mm/s). After 4 hours and 8 hours of reperfusion, Viso recovered to 1.2 +/- 9.2 mm/s and -0.3 +/- 10.7 mm/s, respectively. Vfill also became positive during CAO (1.5 +/- 6.2 mm/s vs. -18 +/- 8.7 mm/s under control conditions). There was a quick recovery of Vfill (-9.4 +/- 7.5 mm/s) with the onset of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)