Impaired left ventricular postischemic function and metabolism in chronic right ventricular hypertrophy

Area of Science:

• Cardiovascular Physiology
• Cardiac Surgery
• Pediatric Cardiology

Background:

• Chronic right ventricular hypertrophy (RVH) is known to alter left ventricular diastolic properties.
• However, its effects on left ventricular systolic function, especially under ischemic conditions, remain less understood.

Purpose of the Study:

• To investigate the impact of chronic pressure overload-induced RVH on left ventricular systolic function.
• To assess changes in left ventricular systolic function before and after reversible hypothermic global ischemia in a porcine model.

Main Methods:

• RVH was induced in newborn piglets via pulmonary artery banding (PAB).
• At two months, both PAB and control groups underwent 2 hours of hypothermic global ischemia followed by 1 hour of reperfusion.
• Left ventricular systolic function was evaluated using end-systolic pressure-volume relationship (Emax) measured by a conductance catheter.

Main Results:

• The PAB group showed a significant decrease in Emax post-ischemia (4.7 to 2.97 mm Hg/ml), unlike the control group (4.1 to 4.1 mm Hg/ml).
• The PAB group experienced significant reductions in ATP and phosphocreatine (CP) levels during ischemia.
• CP recovery was notably impaired in the PAB group post-reperfusion compared to controls.

Conclusions:

• Chronic RVH significantly compromises left ventricular systolic function following ischemic insult.
• RVH leads to impaired myocardial energy metabolism (ATP and CP depletion) during ischemia, hindering recovery.