Clinical evaluation of myocardial contractility and its problems

Area of Science:

• Cardiology
• Physiology

Background:

• Assessing myocardial contractility non-invasively is crucial for clinical decision-making.
• Existing indices like ET/PEP and Pd/ICT have limitations in accurately reflecting contractility under varying hemodynamic conditions.

Purpose of the Study:

• To evaluate the clinical applicability and usefulness of non-invasive myocardial contractility indices.
• To identify a more reliable index for assessing contractility, particularly when preload and afterload are altered.

Main Methods:

• Studies in dogs involved altering preload, afterload, and contractility using drugs.
• Evaluation of indices including ET/PEP, Pd/ICT, and a corrected index (Pd/ICT)/(AO/EO).
• Clinical cases involved administering positive inotropic substances and analyzing patients with azotemia and hypertension.

Main Results:

• ET/PEP was influenced by both preload and afterload; Pd/ICT was influenced by afterload.
• The corrected index (Pd/ICT)/(AO/EO) showed a satisfactory correlation with maximal velocity of circumferential fiber shortening (Vmas) even with altered preload/afterload.
• All tested indices changed with positive inotropic agents in clinical cases; (Pd/ICT)/(AO/EO) reflected Frank-Sterling curve changes in azotemic patients.

Conclusions:

• No single non-invasive index is perfect for clinical myocardial contractility assessment.
• The corrected index (Pd/ICT)/(AO/EO) shows promise for improved accuracy.
• A comprehensive evaluation using multiple indices, considering underlying conditions, is recommended for accurate myocardial contractility assessment.