Title: Acute Changes in LV Function as Assessed by Strain and Myocardial Performance Index (MPI) in Post Tricuspid Shunts Following Closure
Authors: Lakshmi Sadasivan Pillai, Kothandam Sivakumar
DOI: https://dx.doi.org/10.18535/jmscr/v5i6.34
Abstract
Background: Hemodynamically significant left to right shunts, once closed, decreases the left ventricular (LV) preload and increases the after load by isolating the low resistance pulmonary circulation from LV outflow circulation. The simultaneous reduction in the LV preload and increase in after load may lead to LV systolic dysfunction. We present our assessment of changes in LV function following closure of significant post tricuspid left to right shunts.
Materials and Methods: This is a prospective study conducted in a tertiary care Pediatric cardiology centre. Patients with post tricuspid shunts who underwent surgery /device closure during the period from march 2016 to November 2016 were included in the study. Patients with Ventricular septald effect VSD) and Patent ductus arteriosus (PDA) with significant left to right shunt as shown by left atrial and left ventricular dilatation on echocardiography were included in the study. Patients with other associated diseases and complex heart diseases were excluded from the study.
Echocardiography for assessment of LV volume and function, strain imaging, and assessment of MPI was done on the day prior to surgery/ device closure. The imaging was repeated one day after intervention and seven days after surgery. All analysis was done in Epic 7 (philips) echocardiography machine by single operator.
Results: A total of 24 patients,19 with PDA and 5 with VSD were included in the study. Mean age was 16.04± 12.08 months and mean body surface area was 0.408± 0.105. Average size of PDA was 4.58 ± 1.1mm and average size of VSD was 6.2 ±1.09mm. Mean QP/QS was 2.22 ±0.743. All patients with PDA underwent device closure and all patients with VSD had surgical closure except one which was closed with a device. All patients had normal baseline ejection fraction (EF). There was a statistically significant reduction in LV ejection fraction post procedure. 13 { 54.2%} Patients had a significant fall in LV ejection fraction post procedure.{defined as more than or equal to 10% fall from the baseline or EF post procedure less than 50%.}.This included 11 patients {57.8%} with PDA closed with device and 2{40%} VSD closed surgically. There was no significant difference in pre procedural ejection fraction between the two groups. There was a statistically significant reduction in LVEDVI, longitudinal and circumferential strain of LV, LA size and LVEF post procedure .There was no significant change in LV end systolic volume index post procedure. There was a statistically significant increase in LV MPI post procedure.
On comparison of the group with significant reduction in LVEF post procedure with the group with preserved LVEF , we were not able to identify any significant parameters contributing to the reduction in LVEF post procedure.
Conclusion: Acute reduction in LV volume on closure of post tricuspid shunts associates with large left to right shunts and is likely to cause an acute reduction in end diastolic fibre length. Decrease in end diastolic volume can lead to a decrease in ejection fraction by volume unloading. There is also an element of after load mismatch due to removal of shunt which can also account for acute reduction in LV function.
