Alterations in regional myocardial function after heterogeneous cardioplegia

Area of Science:

• Cardiovascular Surgery
• Cardiology
• Physiology

Background:

• Coronary stenoses can cause uneven cardioplegic solution delivery during cardiac surgery.
• This heterogeneity may lead to regional myocardial dysfunction despite preserved global heart function.

Purpose of the Study:

• To investigate the functional consequences of heterogeneous cardioplegia on regional myocardial mechanics.
• To assess the impact of hemodynamic manipulations on damaged myocardial regions.

Main Methods:

• Simulated heterogeneous cardioplegia by occluding the circumflex artery during cardioplegic infusion in canine heart bypass preparations.
• Measured regional myocardial function (systolic shortening) using sonomicrometry.
• Evaluated diastolic properties (distensibility, resting length) and response to afterload and volume loading.

Main Results:

• Regional function often diminished despite preserved global function.
• Recovery of regional function showed poor correlation with global measures like stroke work.
• Volume loading improved regional function in damaged areas; afterload did not worsen damage.
• Heterogeneous cardioplegia significantly impaired regional diastolic distensibility and increased resting length.

Conclusions:

• Heterogeneous cardioplegia causes distinct regional changes in both systolic and diastolic myocardial function.
• These localized alterations are often undetectable by assessing global ventricular function alone.
• Precise hemodynamic control is crucial for observing these subtle changes in diastolic properties.