Diastolic dysfunction of stunned myocardium

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.