A Structural Breakpoint in the Diastolic-Systolic Interval Ratio at ~135 bpm: Prediction from a Physical Framework of Cardiac Inevitability and Verification Using Public Exercise ECG Data

Abstract

Why must the heart pulsate? Why is its position anatomically central? Many coreobservations in cardiac physiology—from the necessity of pulsation to thearterial-venous topological differentiation—currently lack a unified explanationat the level of physical necessity. Here, we propose a physical framework in whichthe heart emerges as the geometrically predetermined dissipation center of anymulticellular aggregate. From two standard physical principles—the second law ofthermodynamics and Ohm's law—we deduce that injection is centrifugal anddissipation is centripetal, geometrically necessitating a central convergencepoint. This center must differentiate into a pulsatile heart, unilaterallysegregating high-pressure arteries from low-pressure veins. A key, a prioriquantitative prediction follows: a critical heart rate exists beyond which thediastolic self-charging window, upon which the heart's own perfusion depends,collapses disproportionately. We tested this prediction using public gradedexercise ECG data (n=89 healthy adults). A segmented regression analysis detecteda structural breakpoint at approximately 135 beats/min (bootstrap 95% CI: 128-142beats/min), above which the diastolic-systolic decline slope accelerated 3.92-fold.During recovery, the diastolic interval rebounded 2.87 times faster than thesystolic interval, indicating a prioritization of the heart's self-charging window.We further show that this physical framework is consistent with a wide range ofindependent, previously disconnected observations, including cross-speciesembryogenesis timelines, the birth circulatory transition, allometric scaling laws,and the clinical hallmarks of heart failure with preserved ejection fraction(HFpEF). Complete, experimentally accessible falsification conditions are specifiedfor each major deduction, inviting rigorous adjudication.