What are the causes of left ventricular (LV) dysfunction in neonates?

Causes of Left Ventricular Dysfunction in Neonates

Left ventricular dysfunction in neonates most commonly results from perinatal asphyxia, congenital heart disease (particularly left-sided obstructive lesions and Ebstein's anomaly), cardiomyopathy, and persistent pulmonary hypertension of the newborn (PPHN). 1, 2, 3

Perinatal Asphyxia and Hypoxemia

• Severe perinatal asphyxia is the most frequent acquired cause of transient LV myocardial dysfunction in neonates, presenting with decreased cardiac output, low stroke volume, and hypotension in the majority of affected infants 1
• Hypoxemia causes heterogeneous myocardial injury with longitudinal systolic contraction being more vulnerable than radial contraction, resulting in paradoxical wall motion in mid-posterior and septal segments 4
• Global hypoxemia induces complex regional dysfunction patterns requiring assessment of both long-axis and short-axis function to capture the full extent of injury 4
• LV dysfunction in PPHN occurs through right ventricular-left ventricular interactions, with LV Tei index being the strongest predictor of negative outcomes (cases: 0.3 ± 0.04 versus controls: 0.25 ± 0.02) 3

Congenital Heart Disease

Left-Sided Obstructive Lesions

• Coarctation of the aorta with cardiogenic shock causes severe global LV systolic dysfunction, with preoperative LV myocardial performance index (MPI) reaching 0.81 (±0.22) in isolated coarctation versus normal values of approximately 0.35 5
• Aortic stenosis causes LV diastolic dysfunction through hypertrophy-induced impaired relaxation and decreased compliance, with critical neonatal aortic stenosis associated with increased pulmonary vascular muscularization present in utero 6
• Hypoplastic left heart syndrome with severe atrial septal flow restriction causes profound cyanosis and pulmonary vascular changes that compromise LV filling and function 6
• Mitral stenosis elevates left atrial pressure leading to LV diastolic dysfunction, particularly when combined with LV hypoplasia, endocardial fibroelastosis, or a small noncompliant left atrium 6

Right-Sided Lesions Affecting LV Function

• Ebstein's anomaly and tricuspid valve dysplasia cause LV dysfunction through reduced combined cardiac index (4.2 ± 1.5 L/min/m² versus 6.5 ± 2.2 L/min/m² in controls), impaired LV circumferential strain (-15.4 ± 6.9 versus -26.2 ± 5.8), and increased circumferential dyssynchrony 2
• Circumferential strain dyssynchrony index >0.2 combined with absent pulmonary valve flow predicts 75% mortality, while dyssynchrony index <0.1 is associated with 100% survival 2
• Left atrial enlargement from cardiac dysfunction can compress the left main bronchus leading to atelectasis and further compromise cardiopulmonary function 6

Cardiomyopathy

• Severe cardiomyopathy with left bundle interruption from LV and conduction system involvement carries a poor prognosis 6
• Congenital myopathies rarely cause cardiac involvement, but when present, neonates develop transient heart failure or LV dysfunction, with recessive mutations in TTN and MYH7 associated with early dilated cardiomyopathy and sudden cardiac death 6
• Hypertrophic cardiomyopathy is associated with increased prevalence of preexcitation syndromes that can compromise ventricular function 6

Metabolic and Systemic Causes

• Hypoglycemia causes transient myocardial dysfunction with abnormal LV contractility that normalizes with correction 1
• Septic shock induces myocardial depression with decreased cardiac output and stroke volume 1
• Chronic lung disease of infancy increases LV preload through decreased renal water excretion and increases lung water through LV dysfunction, creating a vicious cycle of worsening cardiac and pulmonary function 6

Iatrogenic Causes

• Medications including cisapride and diphemanil cause heart block associated with QT interval prolongation, which can compromise ventricular filling and function 6
• Digoxin is contraindicated in neonates with Wolff-Parkinson-White syndrome as it can cause cardiovascular collapse in infants and young children 6

Critical Diagnostic Approach

• Echocardiography must be performed immediately in any neonate with cyanosis, respiratory distress, abnormal arterial pulses, cardiac murmur, failure to thrive, or cardiomegaly on chest radiograph 6
• Pulsed Doppler echocardiography allows detection and evaluation of LV myocardial dysfunction and response to therapy in real-time 1
• Strain Doppler echocardiography with assessment of both longitudinal and circumferential strain plus dyssynchrony indices provides superior prognostic information compared to conventional measures 2
• Cardiac evaluation must occur before anesthesia or sedation in any neonate with suspected cardiac involvement, ideally within 3-6 months of the procedure 6