Researchers Refine Gold Standard for Assessing Heart Function
Feb. 10, 2025 - Researchers from UC Irvine and University of Wisconsin have conducted a valuable study of the current volume calibration methods used to measure heart function. Their findings, published in the Journal of Heart and Lung Transplantation, direct implications for clinicians treating patients with cardiac disease.
The study focused on understanding how different methods of volume calibration impact the accuracy of right ventricular (RV) pressure-volume (PV) loops, which are important for evaluating right heart performance, particularly in conditions like pulmonary hypertension. “These PV loops help assess metrics such as ventricular contractility, afterload (the resistance the heart works against), and ventricular-vascular coupling (how the heart and blood vessels interact),” said UCI biomedical engineering graduate student Christopher Lechuga, a co-first author of the paper.
The researchers compared two calibration methods: cardiac MRI (CMR), a noninvasive imaging method considered the gold standard, and hypertonic saline (HS) injection, an alternative that involves injecting a salt solution to measure internal heart volumes.
The findings revealed that the hypertonic saline injection calibration overestimated RV volumes, leading to an underestimation of the heart's pumping efficiency. Despite this, both methods produced similar results for RV-vascular interaction metrics like ventricular contractility, arterial afterload and coupling, even during exercise. This suggests that while hypertonic saline may not be as accurate for absolute volume measurements, it is still reliable for evaluating changes in right heart function and coupling during physical exertion.
Lechuga says the research has important implications for clinical practice. “In cases where cardiac MRI is unavailable or impractical, hypertonic saline provides a viable alternative for monitoring heart performance, especially during exercise testing. By validating this alternative, we aim to make advanced heart function assessments more accessible without compromising the accuracy of key functional metrics.”
Following the publication of the study, a cardiologist and professor at the Medical University of South Carolina wrote an editorial to the journal praising the work as providing a meaningful refinement of the current approach. “It is daunting to attempt to refine a gold standard particularly one as complex as PV loop analysis of the RV,” wrote Dr. Brian Houston. “The authors are to be congratulated on such elegant work.”
Others involved in the research include UCI Professor Naomi Chesler and University of Wisconsin researchers Dr. Farhan Raza and Oliver Wieben.
– Lori Brandt
