Clinical and pathologic comparison of simple left-to-right shunt congenital heart disease and transposition of the great arteries with ventricular septal defect

Management of systemic to pulmonary shunts and elevated pulmonary vascular resistance

Background

Repair of systemic to pulmonary shunts is timed to prevent the development of irreversible pulmonary vascular disease, including in patients with other factors contributing to pulmonary hypertension. This study assessed outcomes of an individualised strategy for managing patients with mild-moderately elevated pulmonary vascular resistance (PVR) deemed borderline eligible for repair.

Methods

A retrospective chart review was conducted of patients with systemic to pulmonary shunts and baseline indexed PVR (PVRi) ≥3 WU·m2 treated at a single centre from 1 January 2005 to 30 September 2019. Data included demographics, World Health Organization functional class (WHO FC), medications and haemodynamic data at baseline and serial follow-up.

Results

30 patients (18 females) met criteria for inclusion. Median age at diagnosis of pulmonary arterial hypertension was 1.3 years (range 0.03-54 years) and at surgery was 4.1 years (range 0.73-56 years). Median follow-up time was 5.8 years (range 0.2-14.6 years) after repair. Most patients received at least one targeted pulmonary arterial therapy prior to repair and the majority (80%) underwent fenestrated shunt closure. There was a significant decrease in mean pulmonary arterial pressure (mPAP) (p<0.01), PVRi (p=0.0001) and PVR/systemic vascular resistance (p<0.01) between baseline and preoperative catheterisation and a decrease in PVRi (p<0.005), mPAP (p=0.0001) and pulmonary to systemic flow ratio (p<0.03) from baseline to most recent catheterisation. WHO FC improved from FC II-III at baseline to FC I post repair in most patients (p<0.003).

Conclusions

In carefully selected patients with systemic to pulmonary shunts and elevated PVR considered borderline for operability, the use of preoperative targeted therapy in conjunction with fenestrated or partial closure of intracardiac shunts is associated with improvement in WHO FC and clinical outcomes.

Epigenetics: novel mechanism of pulmonary hypertension

INTRODUCTION

Epigenetics refers to changes in phenotype and gene expression that occur without alterations in DNA sequence. MicroRNAs are relatively recently discovered negative regulators of gene expression and act at the posttranscriptional level.

METHODS

This review summarizes epigenetic mechanisms of pulmonary hypertension, focusing on microRNAs related to pulmonary hypertension.

RESULTS

There are three major mechanisms of epigenetic regulation, including methylation of CpG islands, modification of histone proteins, and microRNAs. There may be an epigenetic component to pulmonary hypertension. These epigenetic abnormalities can be reversed therapeutically.

CONCLUSIONS

By better integrating network biology with evolving technologies in cell culture and in vivo experimentation, we will better understand epigenetic mechanisms of pulmonary hypertension and identify more diagnostic and therapeutic targets in pulmonary hypertension.