How does left ventricular (LV) dysfunction occur in congenital diaphragmatic hernia (CDH)?

Left Ventricular Dysfunction in Congenital Diaphragmatic Hernia (CDH)

Left ventricular dysfunction in congenital diaphragmatic hernia occurs due to a combination of structural abnormalities, ventricular interdependence, and pulmonary hypertension, making it a critical determinant of mortality in CDH patients. 1

Pathophysiological Mechanisms of LV Dysfunction in CDH

Structural and Developmental Factors

• CDH is characterized by marked lung hypoplasia with pulmonary hypertension (PH) and impaired cardiac performance, with severe PH being a critical determinant of survival 2
• LV systolic and diastolic dysfunction and small LV size are complicating pathologies in CDH that contribute to poor outcomes 2
• The presence of abdominal organs in the chest cavity during prenatal development not only causes pulmonary hypoplasia but also affects cardiac development 2

Ventricular Interdependence

• Right ventricular (RV) dysfunction due to pulmonary hypertension creates mechanical stress on the left ventricle through ventricular interdependence 3
• LV longitudinal strain correlates significantly with RV longitudinal strain in CDH cases, demonstrating the interdependence between the ventricles 3
• Global impairment of both RV and LV systolic function is present in newborn infants with CDH 3

Pulmonary Hypertension and Hemodynamic Effects

• Severe pulmonary hypertension complicates the course of most infants with CDH, with high prevalence (63%) and mortality (45%) 2
• Pulmonary hypertension increases right ventricular afterload, which shifts the interventricular septum toward the left ventricle, compromising LV filling and function 2
• When pulmonary vascular resistance (PVR) is lowered with vasodilators in the presence of an abnormal LV that cannot respond to increased stroke volume, pulmonary venous hypertension and pulmonary edema may worsen 2

Clinical Implications and Management

Impact on Outcomes

• Left ventricular dysfunction is an independent determinant of severity and clinical outcome in CDH 1
• The adjusted risk of death (hazard ratio) for cases with LV dysfunction was 1.96 (95% CI, 1.29-2.98) and for cases with combined RV and LV dysfunction was 2.27 (95% CI, 1.77-2.92) 1
• Decreased LV cardiac output is more strongly associated with the need for extracorporeal life support (ECLS) than severity of pulmonary hypertension or RV dysfunction 4

Treatment Considerations

• PAH-specific drug therapies should be used cautiously in newborns with CDH and PH due to the complicating LV pathology 2
• Some patients with CDH and severe LV dysfunction may benefit from augmenting the ability of the RV to maintain cardiac output through enhancement of right-to-left ductal shunting with prostaglandin E1 infusion 2
• Intravenous milrinone is reasonable in infants with persistent pulmonary hypertension of the newborn (PPHN) and signs of LV dysfunction 2

Monitoring and Assessment

• Early echocardiographic assessment of ventricular function within the first 48 hours of life is crucial for risk stratification in CDH patients 5
• Speckle tracking echocardiography can be used to assess ventricular mechanics and synchrony in infants with CDH 3
• Left ventricular cardiac index (LVCI) is a reliable predictor of ECLS need in neonates with CDH, with significantly decreased LVCI (1.33 L/min/m² vs 1.80 L/min/m²) observed in patients requiring ECLS 4

Clinical Pitfalls and Considerations

• Failure of inhaled nitric oxide (iNO) to cause sustained improvement in newborns with CDH may be due partly to the complicating LV pathology 2
• iNO therapy should not be used routinely in CDH; its use should be limited to patients with suprasystemic PVR with right-to-left shunting across the oval foramen causing critical preductal hypoxemia and after optimal lung inflation and adequate LV performance are established 2
• Even in "low-risk" CDH cases, early left ventricular dysfunction and severe pulmonary hypertension are independent predictors of adverse outcomes 6
• Mechanical dispersion (asynchrony) in the left ventricle correlates with LV dysfunction in CDH, suggesting that dyssynchrony may contribute to poor cardiac performance 3