Cardiac Exam for Pulmonary Embolism

Clinical question	Can TTE be used to identify signs suggestive of a pulmonary embolism (PE) in a hemodynamically unstable patient, and guide urgent management decisions?
Patient positioning	Supine or Semi-recumbent (30–45°): Optimal for ICU or ED patients.
Left lateral decubitus: Preferred in stable patients to optimize imaging windows.
Head of bed may be elevated slightly to improve visualization in dyspneic patients.
Supplies needed	No special supplies needed
Probe	Phased Array Transducer
Frequency: 1–5 MHz
Small footprint allows access between ribs
Optimized for deep penetration needed to visualize cardiac structures
Normal findings	Symmetric right and left ventricular size
Normal tricuspid annular plane systolic excursion (TAPSE >1.6 cm)
No septal flattening or bowing toward the left ventricle
Normal inferior vena cava (IVC) size and collapsibility
Absence of right heart thrombus or McConnell’s sign
Sensitivity & specificity	Sensitivity: ~50–60% (higher in massive or submassive PE)
Specificity: ~80–90% for signs of right ventricular dysfunction
Most useful in massive PE or when CT pulmonary angiography (CTPA) is contraindicated or delayed
A normal TTE does not exclude PE
Contraindications	No absolute contraindications
Alternate diagnostic modalities	CT Pulmonary Angiography (CTPA): Gold standard in stable patients
Ventilation-perfusion (V/Q) scan: Useful if CTPA contraindicated (e.g., pregnancy, contrast allergy)
Pulmonary Angiography: Invasive but definitive
D-dimer: Screening tool in low-to-intermediate risk patients
Lower extremity venous ultrasound: May support PE diagnosis if DVT is found

🛑 As per the above, TTE (and TEE which has higher sensitivity & specificity than TEE) is not the gold standard for evaluation for suspected pulmonary embolism, but can be used emergently to guide management when the patient is too hemodynamically unstable to take to CT or a CT scanner is unavailable.

How to perform this exam

Prepare supplies (ultrasound machine, gel, chuck)
Position the patient
- Supine or LLD (left lateral decubitus) position - use pillow under left side if needed to enhance view
Select the probe & preset
- Use phased array (cardiac) probe to minimize rib shadowing
- Select cardiac preset
- Depth ~15–20 cm
- Gain adjusted to optimize contrast between myocardium and blood
Obtain a Parasternal Short-Axis view
- Place probe in the 3rd or 4th left intercostal space, just left of sternum Marker toward patient's left shoulder Visualizes: LV, RV outflow tract, LA, mitral & aortic valves
- Look for "D-sign" (flattened interventricular septum due to RV pressure overload) - shown below
Obtain an Apical 4-Chamber view
- Place probe at the point of maximal impulse (PMI) or under the left nipple line Indicator toward patient's left (standard convention) - often located at 5th intercostal space in the midclavicular line
- Marker pointed toward patient’s left axilla (~3 o’clock position)
- Probe should be angled superiorly and medially toward the base of the heart Optimize so septum is vertical and both ventricles clearly seen Evaluate:
- Fan anteriorly/posteriorly to center the apex and visualize both ventricles and atria
  - Compare RV:LV ratio; >1:1 ratio suggests RV dilation
  - Assess RV free wall motion (McConnell’s sign: akinesia of mid-RV wall with preserved apex)
  - TAPSE with M-mode on lateral tricuspid annulus
IVC Assessment
- Subxiphoid view, angle probe caudally toward liver
- Visualize IVC entering right atrium
- Assess diameter and respiratory variation (a dilated IVC that is dilated >2.1cm AND that does not collapse with respiratory variability can indicate increased right-sided pressures)
Interpret & Document

Relevant Anatomy

Cardiac Echo Landmarks.jpg

Landmarks for basic cardiac views - probe marker to patient’s left in apical 4-chamber view

A4C PE.gif

Labeled apical 4-chamber view showing bowing of the septum, RV:LV ratio > 1:1, McConnell’s sign (GIF from EMRA)

PSA PE.gif

Labeled parasternal short axis view showing RV:LV ratio > 1:1, bowing of the inter ventricular septum towards the LV (GIF from EMRA)