Left Ventricular Enlargement
Gregory Kicska, MD, PhD
DIFFERENTIAL DIAGNOSIS
Common
Heart Failure
Aortic Regurgitation
Mitral Regurgitation
Acute Myocardial Infarction
Less Common
Patent Ductus Arteriosus
Coarctation of Aorta
Idiopathic Dilated Cardiomyopathy
Hypertrophic Cardiomyopathy
Amyloidosis
Rare but Important
Athlete’s Heart
Pregnancy-induced Dilated Cardiomyopathy
Alcohol-induced Dilated Cardiomyopathy
ESSENTIAL INFORMATION
Key Differential Diagnosis Issues
Determination of LV chamber enlargement
Radiographic
Normal cardiothoracic ratio < 0.5 on PA and < 0.6 on AP at deep inspiration
Leftward and downward displacement of left heart border
LV extending 2 cm posterior to IVC border (Hoffman-Rigler sign) on lateral view
Cross sectional
LV volume is best measured qualitatively, not quantitatively, when only axial planes are available
Reliable measurements require double oblique planes, usually short axis
Normal internal LV diameter at base is 3.9-5.3 cm for females and 4.2-5.9 cm for males
2-dimensional Simpson rule of discs in short axis or 3D auto-segmented are most reproducible
Less reliable: Biplane method of Simpson rule and area length rule
Volume > 130 mL in females and > 200 mL in males is highly specific for pathologic enlargement
Determination of LV wall thickness
End-diastolic wall thickness > 1.2 cm is pathologic
LV mass > 104 gm/m2 in females or 119 gm/m2 in males is specific for pathology
Pitfalls
Radiographic LV enlargement may be mimicked by pericardial effusion, poor lateral positioning, or pericardial fat pad
Misidentification of end diastole most frequent cause of erroneous left ventricular size measurement
Cardiac volume may be affected by pre-imaging administration of β blockers or nitroglycerin
Helpful Clues for Common Diagnoses
Heart Failure
Ischemic cardiomyopathy most common etiology, followed by diabetes and hypertension
EF < 40%
Multivessel coronary artery calcifications or stenosis
Evidence of prior infarct, subendocardial fat
If retrospective gated CT or MR performed, myocardium can be evaluated for evidence of hibernation
Subendocardial or transmural delayed enhancement present in coronary artery distribution indicates ischemia
If delayed enhancement excludes subendocardial layer, nonischemic etiologies should be considered
Aortic Regurgitation
Bicuspid valve or calcified aortic valve
Incomplete coaptation of cusps during diastole
Regurgitant jet present on bright-blood MR
Mitral Regurgitation
Mitral valve calcifications
Dilated left atrium
Isolated right upper lobe edema is rare manifestation resulting from regurgitant jet
Acute Myocardial Infarction
Enlarged cardiac silhouette compared to recent prior
Supporting clinical information, troponin leak, ECG changes, or typical chest pain
Helpful Clues for Less Common Diagnoses
Patent Ductus Arteriosus
Initially, enlarged main pulmonary arteries; later, LV, LA, and ascending aortic enlargement
LV enlargement with dilated ascending aorta in absence of valvular disease
Best seen in gated CT or 3D MRA
MR Qp:Qs ratio < 1:1
Coarctation of Aorta
Associated with bicuspid valve
Hemodynamic narrowing represented by dilated intercostal collaterals
Not to be confused with pseudocoarctation, a tortuous arch without hemodynamic narrowing
Undiagnosed cases in adults often occur when narrowing distal to left subclavian take-off
Idiopathic Dilated Cardiomyopathy
Age often < 60 years
Diagnosis of exclusion
Significant coronary artery occlusion or myocarditis to be excluded
MR delayed enhancement present in approximately 40% of cases, most commonly mid-myocardial
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