Background: Coronary artery abnormalities are common in patients with Pulmonary atresia with intact ventricular septum (PA/IVS). There is a paucity of data on the effect of modified Blalock- Taussig shunt (mBT) on the single left ventricle (LV) function in PA/IVS. Given the coronary abnormalities, we hypothesized that there will be deterioration of single LV function in patients with PA/IVS compared to patients with Tricuspid atresia (TA) following placement of mBT shunt. Methods: This observational study included patients with single ventricular physiology (PA/ IVS and TA) who underwent mBT shunt placement for securing pulmonary blood flow. Patients who had arch reconstruction, required ECMO, or had pericardial effusion were excluded. Demographic data and echocardiograms were reviewed. All echocardiograms were performed using Philips IE33 and interpreted by a single reader blinded to clinical data. Global systolic endocardial and myocardial longitudinal strain (endoGLS, myoGLS) and average of peak longitudinal strain of 6 LV segments (average endoLS) from the apical 4-chamber view were analyzed offline using vendor-independent software (Tomtec Inc). Between-group comparisons were done using student t-test and Chi-square test as appropriate (SPSS ver. 22). Results: Our cohort consisted of 31 patients of whom 21(68%) patients had PA/IVS and 10 (32%) had TA; 15 (48.4%) were males. The PA/IVS subgroup was younger at the time of mBT shunt placement compared to TA (2.4±3.3 vs. 5.6±4.2 weeks, p=0.05). The mean endoGLS was decreased after mBT shunt placement in patients with PA/IVS compared to patients with Tricuspid atresia (-16.18± 5.27 vs. -20.10± 4.97, p=0.05). The average endoLS measured from 6 segments of the LV was also decreased. The myoGLS, LV ejection fraction, and the LV end systolic, diastolic and stroke volumes before and after placement of mBT shunt were similar in both the groups (Table). Conclusion: Despite similar LV function at baseline between the two groups with single ventricle physiology, LV function revealed significant abnormalities in the PA/IVS group compared to the TA group, after placement of mBT shunt. The subtle impairment in LV function shown by speckle tracking echocardiography could plausibly be related to coronary artery abnormalities in PA/IVS patients. Long term studies are needed to assess if these difference in the LV function persist and contribute to adverse clinical outcomes.

Table

Comparison of demographic and echocardiographic parameters

Table

Comparison of demographic and echocardiographic parameters

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