Hypoplastic left heart syndrome


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Hypoplastic left heart syndrome

Cardiovascular system

Vascular disorders

Arterial disease

Angina pectoris

Stable angina

Unstable angina

Myocardial infarction

Prinzmetal angina

Coronary steal syndrome

Peripheral artery disease

Subclavian steal syndrome


Aortic dissection


Behcet's disease

Kawasaki disease


Hypertensive emergency

Renal artery stenosis

Coarctation of the aorta

Cushing syndrome

Conn syndrome


Polycystic kidney disease


Orthostatic hypotension


Familial hypercholesterolemia



Chronic venous insufficiency


Deep vein thrombosis




Vascular tumors

Human herpesvirus 8 (Kaposi sarcoma)


Congenital heart defects

Truncus arteriosus

Transposition of the great vessels

Total anomalous pulmonary venous return

Tetralogy of Fallot

Hypoplastic left heart syndrome

Patent ductus arteriosus

Ventricular septal defect

Coarctation of the aorta

Atrial septal defect

Cardiac arrhythmias

Atrial flutter

Atrial fibrillation

Premature atrial contraction

Atrioventricular nodal reentrant tachycardia (AVNRT)

Wolff-Parkinson-White syndrome

Ventricular tachycardia

Brugada syndrome

Premature ventricular contraction

Long QT syndrome and Torsade de pointes

Ventricular fibrillation

Atrioventricular block

Bundle branch block

Pulseless electrical activity

Valvular disorders

Tricuspid valve disease

Pulmonary valve disease

Mitral valve disease

Aortic valve disease


Dilated cardiomyopathy

Restrictive cardiomyopathy

Hypertrophic cardiomyopathy

Heart failure

Heart failure

Cor pulmonale

Cardiac infections



Rheumatic heart disease

Pericardial disorders

Pericarditis and pericardial effusion

Cardiac tamponade

Dressler syndrome

Cardiac tumors

Cardiac tumors

Cardiovascular system pathology review

Acyanotic congenital heart defects: Pathology review

Cyanotic congenital heart defects: Pathology review

Atherosclerosis and arteriosclerosis: Pathology review

Coronary artery disease: Pathology review

Peripheral artery disease: Pathology review

Valvular heart disease: Pathology review

Cardiomyopathies: Pathology review

Heart failure: Pathology review

Supraventricular arrhythmias: Pathology review

Ventricular arrhythmias: Pathology review

Heart blocks: Pathology review

Aortic dissections and aneurysms: Pathology review

Pericardial disease: Pathology review

Endocarditis: Pathology review

Hypertension: Pathology review

Shock: Pathology review

Vasculitis: Pathology review

Cardiac and vascular tumors: Pathology review

Dyslipidemias: Pathology review


Hypoplastic left heart syndrome


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Hypoplastic left heart syndrome

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Content Reviewers

Rishi Desai, MD, MPH


Tanner Marshall, MS

Vincent Waldman, PhD

Hypo means “beneath” or “under,” and plasia means “molding” or “formation,” so hypoplastic means “under form” or in this case, “underdeveloped.” Therefore, hypoplastic left heart syndrome means that the left side of the heart doesn’t fully develop.

Hypoplastic left heart syndrome, or HLHS, is a congenital heart defect that affects the left side of the heart; it specifically affects the left ventricle and ascending aorta. Also, the aortic valve and mitral valve might be either too small to allow enough blood to flow through, or they might be absent altogether, which is called atresia. The exact mechanism that causes HLHS isn’t known, but one popular theory is that there might be some other primary congenital heart defect that reduces the blood flow through the LV and outflow tract during fetal development, so that part of the heart does not grow and develop normally. This said, HLHS is also often associated with other congenital heart defects, and in particular, with an atrial septal defect, which is an opening between the left and right atria. In fact, not only do these babies usually have this defect, they essentially need it to survive after birth. This is in addition to a patent ductus arteriosus, or PDA, a blood vessel that connects the aorta to the pulmonary artery, which usually closes within a few days after birth.

Let’s switch to a more simplified version of the heart to see what happens with blood flow. So, right here you have the atrial septal defect connecting the left and right atria, and the ductus arteriosus, which connects the aorta to the pulmonary artery. This is a really underdeveloped left ventricle and a smallish aortic and mitral valve.


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  2. "Harrison's Principles of Internal Medicine, Twentieth Edition (Vol.1 & Vol.2)" McGraw-Hill Education / Medical (2018)
  3. "Pathophysiology of Disease: An Introduction to Clinical Medicine 8E" McGraw-Hill Education / Medical (2018)
  4. "Hypoplastic left heart syndrome: from comfort care to long-term survival" Pediatric Research (2016)
  5. "Current Therapy for Hypoplastic Left Heart Syndrome and Related Single Ventricle Lesions" Circulation (2016)
  6. "Opciones quirúrgicas actuales y sus resultados en neonatos con síndrome de corazón izquierdo hipoplásico" Anales de Pediatría (2019)

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