What echo views are used to assess an infracristal ventricular septal defect (VSD)?

Echocardiographic Assessment of Infracristal VSD

The subcostal frontal view is the most reliable and essential echocardiographic window for visualizing infracristal (perimembranous) VSDs, successfully demonstrating the defect in nearly all cases, with parasternal and apical views serving as supplementary approaches. 1

Primary 2D Echocardiographic Views

Subcostal Approach (First-Line)

• The subcostal frontal view is the gold standard for infracristal VSD visualization, successfully imaging the defect in 49 of 50 cases (98%) in validation studies 1
• This view provides optimal visualization of the membranous septum and its relationship to the atrioventricular valves 1
• Deep inspiration during subcostal imaging enhances visualization in adults with suboptimal windows 2

Parasternal Views (Supplementary)

• Parasternal long-axis and short-axis views demonstrate infracristal VSDs in approximately 46% of cases as supplementary windows 1
• These views are particularly useful for assessing the relationship of the defect to the aortic valve and detecting associated aortic valve prolapse 3
• Parasternal views help evaluate for subaortic stenosis, which can develop in association with perimembranous VSDs 3

Apical Views (Adjunctive)

• Apical four-chamber and five-chamber views visualize infracristal VSDs in approximately 22% of cases 1
• These views are less reliable as primary imaging windows but provide complementary information about defect size and hemodynamic impact 1

3D Echocardiographic Protocols

Full-Volume Mode with iCrop (Highest Success Rate)

• 3D full-volume mode with iCrop achieves 100% success rate for obtaining diagnostic-quality en face views of VSDs, making it the preferred 3D protocol 4
• This technique provides anatomically oriented views from the left ventricular perspective, allowing complete assessment of defect circumference and spatial relationships 5, 4

Full-Volume Standard Mode with XYZ Cropping

• Standard full-volume mode with adjustable plane cropping achieves 97% success rate for diagnostic en face views 4
• This approach allows precise measurement of major and minor axis diameters with excellent correlation to surgical measurements (r=0.92 and r=0.91, respectively) 5

Narrow-Sector Live 3D Mode

• Live 3D narrow-sector imaging achieves 94% success rate but is slightly less reliable than full-volume techniques 4
• This real-time approach is useful when full-volume acquisition is limited by patient cooperation or arrhythmias 4

Critical Assessment Parameters

Anatomic Characterization

• Transthoracic echocardiography must document defect location, number of defects, size (major and minor axis diameters), and spatial relationship to the aortic valve and tricuspid valve 3, 6
• 3D en face views from the left ventricular perspective provide superior assessment of defect shape compared to 2D imaging 3, 5

Hemodynamic Evaluation

• Assess left ventricular volume overload through chamber dimensions and interventricular septal motion 1
• Estimate right ventricular systolic pressure from tricuspid regurgitation jet velocity with simultaneous blood pressure measurement 3
• Evaluate for aortic valve prolapse (particularly right coronary cusp) and degree of aortic regurgitation, which occurs commonly with perimembranous VSDs 3

Transesophageal Echocardiography Indications

• TEE becomes necessary when transthoracic windows are inadequate in adults or when precise anatomic delineation is required for interventional closure planning 2
• 3D TEE provides en face views of the ventricular septum that facilitate navigation during percutaneous closure procedures 3
• TEE allows accurate defect sizing through multiplanar reconstruction tools 3

Common Pitfalls to Avoid

• Trabecular and apical muscular VSDs are particularly difficult to visualize with standard 2D imaging; consider adding color Doppler or 3D imaging when clinical suspicion exists despite negative 2D findings 1
• M-mode echocardiography is unreliable for VSD imaging and should not be used as a primary diagnostic modality 7
• Apparent septal dropout on 2D images may mimic a VSD; confirm with color Doppler demonstrating actual shunt flow or use contrast echocardiography 2
• Distinguish residual left ventricle-to-right atrium shunting from tricuspid regurgitation in postoperative patients, as misidentification leads to erroneous diagnosis of pulmonary hypertension 3