PVCs can occur naturally in most otherwise-healthy adults, so measuring the characteristics of a given person's HRT can offer a non-invasive way to evaluate certain aspects of their cardiac or autonomic function without applying artificial external stimuli.
[citation needed] The measured values of HRT parameters have been shown to be a statistically significant prediction of the probability of dying from cardiac disease after a patient suffers a myocardial infarction.
They proceeded to test this hypothesis using 24-hour electrocardiogram (Holter monitor) recordings from one hundred survivors of heart attacks with frequent PVCs.
This results in a pulse (blood pressure) weaker than expected and triggers normal homeostatic mechanisms that try to compensate by constricting arteries and increasing heart rate (the turbulence onset part of HRT).
The compensatory constriction of the arteries and increased heart rate can cause blood pressure to overshoot normal values, triggering the opposite baroreflex.
The exact quantitative contribution of the parasympathetic and sympathetic nervous flow to the heart to HRT is unknown.
Whether the single beat blood pressure increase after a compensatory pause occurs in both normal and compromised hearts as well is at present uncertain.