Myocardial Perfusion in Hypoplastic Left Heart Syndrome.

Area of Science:

• Cardiology
• Pediatric Cardiology
• Cardiovascular Imaging

Background:

• The coronary microcirculation of the systemic right ventricle in hypoplastic left heart syndrome (HLHS) is poorly understood.
• HLHS patients in Fontan circulation may have unique pathophysiological characteristics affecting the systemic right ventricle's coronary microcirculation.

Purpose of the Study:

• To quantify myocardial blood flow (MBF) using cardiac magnetic resonance imaging (CMR) in HLHS patients.
• To evaluate determinants of microvascular coronary dysfunction and myocardial ischemia in HLHS.

Main Methods:

• 119 HLHS patients and 34 controls underwent CMR approximately 1.8 years post-total cavopulmonary connection (TCPC).
• Assessed right ventricular volumes and function, myocardial perfusion, fibrosis, and late gadolinium enhancement (LGE) in four HLHS subtypes.
• Quantified resting and hyperemic MBF; estimated coronary conductance from MBF and aortic pressure.

Main Results:

• HLHS patients had lower hyperemic MBF than controls (1.89 vs. 2.70 mL/g/min; P<0.001).
• Risk factors for reduced hyperemic MBF included specific HLHS subtypes, LGE, RV diastolic dysfunction, and older age at TCPC.
• Coronary conductance correlated negatively with systemic oxygen saturation (r=-0.29; P=0.02); LGE frequency increased with age at TCPC.

Conclusions:

• Young HLHS patients exhibit distinct coronary microcirculation differences compared to controls.
• Identified HLHS-specific risk factors for microvascular dysfunction.
• Early relief of cyanosis via TCPC may benefit HLHS patients.