CASE 17542 Published on 14.12.2021

Hypoplastic Left Heart Syndrome (HLHS)



Case Type

Clinical Cases


Dr. Mohit Khandelwal MBBS. MD.

Department of Radiology, Khetan Diagnostic Centre, Jaipur, India


6 days, male

Area of Interest Arteries / Aorta, Cardiac, Cardiovascular system ; Imaging Technique CT, CT-Angiography
Clinical History

6-day old male neonate presented with cyanosis within 24 hr of birth, respiratory distress, irritability, poor feeding. Examination revealed tachypnea, tachycardia, crepts in bilateral lungs, abnormal cardiac auscultation. -

Imaging Findings

Hypoplastic aortic root, ascending aorta (AA), and arch of aorta (AOA) with normal-sized Descending aorta (Fig1). Hypoplastic left ventricle (LV) and ventricular septal defect (VSD) (Fig 2) seen. Normal left arterio- ventricular communication (Fig 3).  Long tubular Patent ductus arteriosus (PDA) between AOA, distal to left subclavian artery origin and Left Pulmonary Artery (LPA) (Fig 4). Dilated main pulmonary artery (MPA) is seen towards left side of AA and shows absence of normal crossover (Fig 5). Dilated MPA, Right Pulmonary Artery (RPA) and LPA are seen (pulmonary arterial hypertension changes) (Fig 6).  Dilated Right atrium(RA) with Atrial septal defect (ASD) seen (Fig 7). Dilated and hypertrophied right ventricle(RV) with normal right arterio- ventricular communication (Fig 8). All the pulmonary veins draining into left atrium(LA). Superior vena cava (SVC) and inferior vena cava (IVC) draining into RA. IVC and hepatic veins are dilated.


HLHS is a complex congenital cardiac malformation which if left untreated is, invariably fatal. [1,2]. It is characterized by hypoplasia/aplasia of left-sided heart structures with normal right-sided heart structures and normal ventriculo-arterial concordance. The exact aetiology is not fully known, however, it is believed to be caused by multiple errors during the early stages of cardiogenesis. 

During intrauterine fetal development, hypoplastic left-sided cardiac structures i.e. Mitral valve (MV), LV, and aortic valve (AV) cause hypoplasia of aortic root and AA leading to reduced blood flow into AA during systole. However, the presence of PDA allows retrograde perfusion of coronary arteries and upper body region during diastole. Thus in intrauterine life, the fetus thrives well. 

However, during extrauterine life, LA is not able to pump adequate blood through stenotic MV, which leads to pulmonary venous outflow obstruction and a typical feature of neonate with congestive cardiac failure. ASD allows left to right shunting of blood which may be restrictive or non-restrictive depending upon the size of ASD. A restrictive pattern of ASD is more common than no restrictive pattern. AV stenosis coupled with LV hypoplasia leads to reduced flow into AA during systole. The right-sided heart then receives as well as supplies all the blood. However, it cannot provide an adequate amount of oxygenated blood (neither functionally nor physiologically) for adequate perfusion, resulting in systemic and coronary ischemia, which causes cyanosis, acidosis, and death if left untreated. [3] PDA is critical and maintained by prostaglandin e and hypoventilation.

Echocardiocardiography is the investigation of choice antenatally (most reliably ~22 weeks) as well as postnatally. It is the most common congenital cardiac malformation detected in fetal life. [4] 

The incidence is between 1.7-6.7: 10, 000 live births [5]. CT scan allows direct visualization of vessel anatomy and malformation [6] and provides valuable information for pre-operative planning, however, is less commonly performed due to its inability to assess function, valves, and radiation safety issues. 

Treatment is mainly surgical and includes Norwood procedure [7] bidirectional cavopulmonary anastomosis or Hemi-Fontan procedure.

Take-Home Message

Nowadays CT pulmonary angiography is being done for pre-operative evaluation of congenital cardiac anomalies. HLHS is seen to be associated with other cardiac anomalies. Therefore, its recognition is imperative for the radiologist and cardiac surgeon for proper treatment planning and hence surgical correction is equally important for the overall success of surgery.  

Written informed patient consent for publication has been obtained.

Differential Diagnosis List
Hypoplastic left heart syndrome
Infantile aortic coarctation
Interrupted aortic arch
Final Diagnosis
Hypoplastic left heart syndrome
Case information
DOI: 10.35100/eurorad/case.17542
ISSN: 1563-4086