Case 2:  Pulmonary Regurgitation in an Adult Repaired Tetralogy of Fallot

Submitted by
James Lambert MBBS¹, Paaladinesh Thavendiranathan MD^1 
1Toronto General Hospital, University of Toronto, Toronto, Ontario, Canada

History

• A 21 year old female with history of Tetralogy of Fallot (ToF) repaired at the age of 10 years was seen in clinic.
• Repair was performed with an RVOT patch enlargement and pulmonary valve repair with creation of a monocusp from autologous tissue.
• Patient was asymptomatic but underwent regular screening with transthoracic echocardiography (TTE) and cardiac MRI.

How severe is the pulmonic regurgitation?

Figure 1

Figure 2

Finding

• Parasternal RVOT view demonstrated the created monocusp to be thickened and restricted in systole and diastole (top left).
• Colour Doppler across the pulmonary valve (top right) showed extensive colour regurgitant jet during diastole, this colour Doppler had a ”to-and-fro” motion and was noted to be pan-diastolic.
• The right ventricle was imaged with an RV modified apical four chamber view (center). The right ventricle was noted to be severely enlarged.
• Doppler profile of the pulmonary valve (bottom left) showed a regurgitant jet which was dense and triangular with a pressure half time of 66ms which was concerning for severe pulmonary regurgitation (PR).
• A 3D colour Doppler full volume image (bottom right) was post processed with the jet shown in three orthogonal planes in mid-diastole. The dimensions of the regurgitation is obvious from this reconstruction with the jets filling most of the proximal RVOT. The ratio of the jet width to the PV annulus approaches 1.0 which is also suggestive of severe regurgitation.
• The PR index (A/B) of regurgitant (PR) duration to the diastolic time can be estimated from the Doppler profile across the pulmonary valve (bottom left), in this patient the regurgitation duration is similar to the diastolic duration with a PR index approaching 1.0 (<0.77). This value is not suggestive of severe PR, however is potentially limited by factors relating to RV diastolic function and compliance in a patient with longstanding RV dilatation. The patient is also noted to be tachycardic which may disproportionately affect diastolic duration.

Figure 3

Finding

• Quantitation of the PR was performed with volumetric assessment of the RVOT and LVOT stroke volumes (SV)
• SV_RVOT was calculated from the RVOT Doppler profile (Figure 2A) and diameter (Figure 2B) using the continuity equation; which gave a value of 125mL
• SV_LVOT was calculated from the LVOT Doppler profile (Figure 2C) and the LVOT diameter measurement (Figure 2D); which with the continuity equation gave a value of 57mL
• The regurgitant volume (Rvol) was calculated by subtracting the SV_LVOT from the SV_RVOT (under the assumption there was no significant regurgitation of the aortic valve). This is calculated as 68mL
• The regurgitant fraction can then be calculated by dividing the Rvol by the SV_RVOT to give a fraction of 0.54 (54%)
• These findings confirmed that the PR is severe.

Discussion

• This case illustrates the assessment of significant PR, the most common cause of which in adult patients is repaired ToF.
• These patients are often asymptomatic despite enlarged RVs and the threshold for surgical referral to an adult congenital surgeon for asymptomatic PR is not well established. Many centers use cardiac MRI due to its superior capacity for assessing right ventricular volume and function. MRI performed in this patient revealed an RV end diastolic volume of 144mL/m² (moderately dilated) with an RV ejection fraction of 52% (normal).
• The complexity of re-do cardiac surgery in otherwise asymptomatic young patients necessitates an accurate assessment of the severity of the valve lesion.
• The pulmonary valve is an often neglected valve in adult echocardiography, however with some attention to detail and the appropriate acquisition of Doppler information, quantitation can easily be performed. The pulmonary valve is often easily assessed and imaged with TTE given its anterior location.

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