Current Knowledge and Recent Advances of Right Ventricular Molecular Biology and Metabolism from Congenital Heart Disease to Chronic Pulmonary Hypertension

Table 1

Main characteristics of healthy phenotypes of fetal and adult right ventricles.

Characteristics	Fetal phenotype	Adult phenotype
Environment
Oxygen environment	Low	High
Main blood circulation	Placental circulation	Systemic circulation
Ductus arteriosus	Opened	Closed
PVR	High	Low
Main vascularized heart regions	Right ventricular free wall, Right side of the IVS	Left ventricular free wall, Left side of the IVS
Systemic ventricle	Right ventricle	Left ventricle
Genetics
Gene pattern expression	β-MHC	α-MHC
Metabolic features
Mitochondrial function	Normal/adapted	Normal/adapted
mROS production	Adapted to heart activity	Adapted to heart activity
Energetic substrates	Carbohydrates	Fatty acids
Hypoxia-induced factors
(i) HIF1α; (ii) VEGF	Expressed	Not expressed
Ca^2+ homeostasis	Immature	Mature
Cellular features
Myocytes diameter	5–7 µm	15–25 µm
Myocytes/nonmyocytes ratio	30%	70%
Sarcomeres	Disoriented	Parallel
Capillary density	Preserved	Preserved
Fibrosis	Absent	Absent

PVR: pulmonary vascular resistance; MHC: myosin heavy chain; mROS: mitochondrial reactive oxygen species; HIF-1α: hypoxia inducible factor 1 alpha; VEGF: vascular endothelial growth factor; Ca²⁺: calcium.