Increased cardiac work provides a link between systemic hypertension and heart failure

Area of Science:

• Cardiovascular Research
• Animal Models of Disease
• Cardiac Physiology

Background:

• The spontaneously hypertensive rat (SHR) is a widely used model for human hypertensive heart disease.
• Progression to heart failure in SHRs has been poorly understood due to a lack of longitudinal data.
• Understanding these mechanisms is crucial for developing effective treatments for heart failure.

Purpose of the Study:

• To longitudinally assess cardiac structure and function in SHRs using MRI.
• To compare cardiac indices in SHRs with Wistar-Kyoto (WKY) controls over time.
• To elucidate the mechanisms underlying the transition to heart failure in SHRs.

Main Methods:

• Longitudinal magnetic resonance imaging (MRI) was used to quantify left ventricular mass, volume, and cardiac work.
• SHRs and WKY controls were studied from 3 to 21 months of age.
• Cardiac output, ejection fraction, and stroke work were analyzed.

Main Results:

• SHRs exhibited lower ejection fraction but maintained cardiac output compared to WKY controls across all ages.
• At 21 months, SHRs showed significantly elevated stroke work and cardiac minute work.
• SHRs developed a higher left ventricular mass to body mass ratio, indicating hypertrophy.

Conclusions:

• SHRs demonstrate impaired systolic function and compensatory hypertrophy, maintaining cardiac output.
• Increased cardiac work at later stages, coupled with fibrosis and cell death, likely drives heart failure progression.
• This study provides critical longitudinal data on the mechanisms of heart failure in the SHR model.