Left Heart Obstructive Lesion
Alexander J. Towbin, MD
DIFFERENTIAL DIAGNOSIS
Common
Aortic Coarctation
Hypoplastic Left Heart
Aortic Stenosis
Less Common
Interrupted Aortic Arch
Hypertropic Obstructive Cardiomyopathy
Mitral Valve Stenosis
Rare but Important
Cardiac Rhabdomyomas
Pseudocoarctation
Shone Complex
Cor Triatriatum
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Left ventricular outflow tract obstruction (LVOTO) is common congenital abnormality
Multiple anomalies can cause LVOTO
Causative lesion often at level of aortic valve, mitral valve, aorta, or left ventricle
Presentation depends on severity of lesion
Critical LVOTO presents as ductus arteriosus begins to close
↓ systemic and coronary perfusion, acidosis, end-organ injury, and shock
Prostaglandins help keep ductus open
Less severe LVOTO presents later
Failure to thrive, tachypnea, pulmonary vascular congestion
Helpful Clues for Common Diagnoses
Aortic Coarctation
Stenosis in proximal descending aorta
Usually just beyond origin of left subclavian artery
Stenosis may be discrete or long
5-8% of congenital heart defects (CHD)
2x more common in males
Associations: Turner syndrome, bicuspid aortic valve, ventricular septal defect (VSD)
Severe coarct presents when ductus closes
Mild coarct presents with upper extremity hypertension and ↓ lower extremity pulses
Hypertension is major cause of long-term morbidity
If uncorrected, ˜ 90% die by age 60
Rib notching not usually seen on chest x-ray (CXR) until after age 6
Treatment options: Surgical repair, angioplasty, or stent placement
Hypoplastic Left Heart
Abnormal development of left heart leading to LVOTO
Usually includes hypoplasia of left ventricle (LV), aorta, and aortic arch, as well as atresia of aortic and mitral valves
LV does not extend to cardiac apex
Accounts for up to 3.8% of CHD
70% occur in males
Systemic blood flow is dependent on patent ductus arteriosus (PDA)
Atrial septal defect (ASD) is required
Left-to-right shunt decompresses pulmonary circulation
CXR with cardiomegaly and ↑ vascularity
Can be diagnosed in utero
2 major surgical treatment options: Transplant or staged palliation
Staged palliation: Norwood procedure (near birth), bidirectional Glenn (6-8 months), and Fontan (18-48 months)
Aortic Stenosis
Can be valvular, subaortic, or supravalvular
Valvular aortic stenosis is most common
Accounts for 3-6% of CHD
4x more common in males
˜ 20% have associated cardiac anomaly
Severity related to degree of obstruction
10-15% present before age 1
Infants can present with congestive heart failure and cardiogenic shock
Patients > 1 year are often asymptomatic
Older children can present with early fatigue, chest pain, syncope, or systolic ejection murmur
CXR can be normal or show cardiomegaly, vascular congestion, and poststenotic dilation of ascending aorta
Treatment: Surgery or catheterization
Subaortic stenosis can be discrete or diffuse
Discrete form is caused by thin fibromuscular membrane
Membrane arises from ventricular septum and extends to mitral valve
Other cardiac anomalies in ˜ 30% of patients
Discrete form is due to abnormal shear forces during contraction
Diffuse form is less frequent
In diffuse form, stenosis extends along ventricular septum
Supravalvular is least common (< 10%)
Narrowing of aortic root at or above sinotubular ridge
Frequently seen in Williams syndrome
Association: Pulmonary artery stenosis
Helpful Clues for Less Common Diagnoses
Interrupted Aortic Arch
Discontinuity of aorta
Accounts for 1% of CHD
Associations: DiGeorge syndrome and 22q11 deletion
3 types: Isolated, simple, and complex
Isolated: No other cardiac anomalies
Simple: Associated with VSD and PDA
Complex: Associated with complex CHD
Hypertropic Obstructive Cardiomyopathy
Most common hereditary cardiac disorder
Asymmetric septal hypertrophy → LVOTO
Can present with sudden death
Mitral Valve Stenosis
If acquired, due to rheumatic heart disease
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