# Early Diagnosis of Problems Related to the Self-Organization of the Cardiovascular System Based on the Interplay between RR and JT Cardiac Intervals

## TL;DR

This paper explores how the cardiovascular system's self-organization changes during stress tests by analyzing the timing of heart intervals.

## Contribution

A new semi-gauge tool and modified adaptation index are introduced to assess cardiovascular self-organization during stress.

## Key findings

- Interpretable time delays between RR and JT intervals were identified during stress tests.
- The modified adaptation index Ar helps quantify healthy cardiovascular mobilization during recovery.
- A semi-gauge tool was developed to evaluate cardiovascular system self-organization.

## Abstract

The dynamics of the collapse of complexity observable in the performance of the cardiovascular system during the stress test is investigated in this paper. For this purpose, the interplay between the RR and JT cardiac intervals is measured and assessed for each participant. This case study involves a modest sample size of eight individuals with normal and elevated blood pressure. Although it is anticipated that the interaction between the RR and JT intervals is rather complex during the stress test, the existence of interpretable time delays between those cardiac intervals is demonstrated using the time delayed patterns algorithm. The assessment of the cardiovascular mobilization taking place during the stress test is also an integral part of this study. The velocity of adaptation index Ad and the newly formulated modified adaptation index Ar (computed only for the recovery phase) are used to quantify the healthy mobilization of the cardiovascular system for each participant. The time frequency analysis of the difference signal between the RR and JT intervals is used to quantify the collapse of complexity around the load termination point. Finally, a semi-gauge indication tool is constructed to assess the overall goodness of the self-organization of the cardiovascular system during the stress test.