Ultrasonic backscatter and collagen in normal ventricular myocardium

Area of Science:

• Cardiovascular Ultrasound
• Biomaterials Science
• Cardiac Pathology

Background:

• Integrated ultrasonic backscatter (IUB) is a promising non-invasive method for assessing myocardial collagen content.
• Previous research suggests a correlation between IUB and collagen deposition in fibrotic heart tissue.

Purpose of the Study:

• To measure IUB in the right and left ventricles of normal canine and human hearts.
• To evaluate the impact of formalin fixation on IUB measurements.

Main Methods:

• Utilized a 2.25 MHz transducer to acquire radio frequency backscatter signals from excised hearts.
• Digitized, squared, and integrated backscatter signals, excluding specular reflections.
• Assayed excised myocardial segments for hydroxyproline to quantify collagen content.

Main Results:

• Right ventricles exhibited significantly higher IUB than left ventricles in freshly excised canine hearts (-60.4 vs -66.9 dB, p < .001).
• Right ventricles also showed higher collagen content than left ventricles (4.40 vs 3.58 µg/mg dry weight, p < .005).
• Similar trends were observed in human hearts, though correlations between IUB and collagen content were not significant (r = .28-.32).

Conclusions:

• Regional differences in myocardial structure influence IUB measurements.
• Formalin fixation may alter ultrasonic backscatter properties, necessitating careful consideration in research.
• IUB shows potential for characterizing myocardial tissue, but direct correlation with collagen requires further investigation.