Ventricular structure-function relations in health and disease: Part I. The normal heart

Area of Science:

• Cardiology
• Cardiac Anatomy
• Biomechanical Engineering

Background:

• Cardiac structure-function relationships are key to understanding normal heart dynamics and disease.
• Historical anatomical descriptions of cardiac fibers have varied, leading to ongoing debate.
• The Torrent Guasp model proposes the helical ventricular myocardial band (HVMB) with distinct loops influencing cardiac mechanics.

Purpose of the Study:

• To review the potential role of the helical ventricular myocardial band (HVMB) in explaining cardiac mechanics.
• To analyze the mechanics of isovolumic contraction, ejection, post-ejection interval, rapid filling, torsion, and recoiling.
• To re-evaluate conventional cardiac function terminology in light of the HVMB model.

Main Methods:

• Literature review of anatomical and functional cardiac models.
• Analysis of the helical ventricular myocardial band (HVMB) model proposed by Torrent Guasp.
• Examination of the proposed functional pathways and their mechanical implications during the cardiac cycle.

Main Results:

• The HVMB model comprises an outer basal loop and an inner apical helical loop, creating an apical vortex.
• A ~90-ms hiatus exists during the post-ejection isovolumic interval between descending and ascending segment contractions.
• Compromise of this hiatus by disease impairs the torsion-untwisting relationship and cardiac function.

Conclusions:

• The helical ventricular myocardial band (HVMB) model offers a framework for understanding cardiac mechanics and dynamics.
• The identified hiatus in the post-ejection isovolumic interval is critical for normal cardiac function.
• Disease-related compromise of this interval significantly impacts the interdependence of torsion and untwisting, leading to impaired heart function.