Cardiac flow dynamics may be different in men and women, according to a new study in healthy volunteers. Based on four-dimensional flow MRI, women had higher vorticity along with higher strain in the left ventricle (LV), while men had higher LV kinetic energy, Dr. David R. Rutkowski of the University of Wisconsin in Madison and colleagues found. "The methods and results of this study may be used to further understand the intricate relationship between cardiac function and flow, as it relates to differences between male and female cardiac physiology," Dr. Rutkowski and colleagues write in Radiology: Cardiothoracic Imaging. Four-dimensional MRI makes it possible to analyze cardiac energetics and cardiac work components, the authors note. "Kinetic energy (KE) metrics, in particular, may indicate the amount of energy that is dissipated in blood motion and, therefore, can be used with flow parameters to provide ventricular efficiency indexes" they add. To measure gender differences in ventricular flow dynamics and cardiac strain, the authors looked at 39 men and women aged 20-35. Mean peak systolic blood KE in the LV was 4.76 mJ for the 20 men and 3.36 mJ for the 19 women (P=0.047). Women had significantly higher peak systolic and diastolic vorticity indexes and higher cycle-average vorticity compared with men, and metrics of radial, circumferential and long-axis LV strain were also higher in women. There was a moderate correlation between circumferential systolic and diastolic strain rates and peak systolic and diastolic vorticity Some of the findings could be due to gender differences in LV anatomy and heart rate, the authors note. "Taken together, increased myocardial function in young women compared with men may be a function of lower energy dissipation of the blood in the LV during filling and ejection owing to the greater vortical flow of the blood in the female heart," they add. "These metrics may shed light on sex-dependent changes in myocardial function with age, which may provide a clinical measure of the risk of cardiovascular disease." In an accompanying editorial, Dr. Karen Ordovas of the University of California, San Francisco, writes that the article is "a small hypothesis-generating study applying advanced cardiac MRI to better understand sex difference in cardiac efficiency. However, the data presented in this article can be extremely useful to guide future study designs and to inform important research questions for subsequent clinical studies in the field." Dr. Rutkowski was not available for an interview by press time. —Reuters Staff Source
