Left Ventricular Fibrosis and Systolic Hypertension Persist in a Repaired Aortic Coarctation Model

Surgically induced aortic coarctation in a neonatal porcine model allows for longitudinal assessment of cardiovascular changes

Noncritical aortic coarctation (COA) typically presents beyond early childhood with hypertension. Correction of COA does not ensure a return to normal cardiovascular health, but the mechanisms are poorly understood. Therefore, we developed a porcine COA model to study the secondary cardiovascular changes. Eight male neonatal piglets (4 sham, 4 COA) underwent left posterolateral thoracotomy with descending aorta (DAO) mobilization. COA was created via a 1-cm longitudinal DAO incision with suture closure, plication, and placement and an 8-mm external band. All animals had cardiac catheterization at 6 (11-13 kg), 12 (26-31 kg), and 20 (67-70 kg) wk of age. Aortic luminal diameters were similar along the thoracic aorta, except for the COA region [6.4 mm COA vs. 17.3 mm sham at 20 wk (P < 0.001)]. Collateral flow could be seen as early as 6 wk. COA peak systolic pressure gradient was 20 mmHg at 6 wk and persisted through 20 wk increasing to 40 mmHg with dobutamine. Pulse pressures distal to the COA were diminished at 12 and 20 wk. This model addresses many limitations of prior COA models including neonatal creation at an expected anatomic position with intimal injury and vessel sizes similar to humans.NEW & NOTEWORTHY A neonatal model of aortic coarctation was developed in a porcine model using a readily reproducible method of aortic plication and external wrap placement. This model addresses the limitations of existing models including neonatal stenosis creation, appropriate anatomic location of the stenosis, and intimal injury creation and mimics human somatic growth. Pigs met American Heart Association (AHA) criteria for consideration of intervention, and the stenoses were graded as moderate to severe.

Impact of left ventricular hemodynamic forces in adult patients with treated aortic coarctation and preserved left ventricular systolic function

BACKGROUND

The LV myocardial strain and hemodynamic forces (HDFs) are innovative markers of LV function. Aortic coarctation is safely repaired in infancy; however, mortality and morbidity remain increased in later life. The study investigated the role of left ventricular myocardial deformation and HDFs in asymptomatic patients who underwent successful aortic coarctation repair.

METHODS

Clinical and echocardiographic data were analyzed from 42 repaired CoA, 32 ± 20 years after surgery, 2D echocardiographic global longitudinal strain (GLS), circumferential strain (GCS) and HDFs were determined. CoA patients were compared with 42 patients affected by blood hypertension and 84 healthy controls; all matched for age and gender.

RESULTS

All groups had normal LV ejection fraction (LVEF), dimensions, and volumes. CoA patients showed a significantly higher rate of LV mass indexed (p < .001) and left atrial volumes indexed (p < .001). LV myocardial and endocardial global longitudinal and circumferential strain were decreased in CoA patients (p < .001, p < .001; p = .032 and p < .001, respectively). HDF parameters such as LV longitudinal force, LV systolic longitudinal force and LV impulse (LVim) were uniformly reduced (p = .006, p = .001, and p = .001, respectively). LV myocardial strain and HDF parameter values were independently associated with hospitalization for heart failure on univariable Cox regression analysis.

CONCLUSION

Despite preserved LVEF, patients with CoA had lower LV myocardial strain and HDF parameters values, independently associated with hospitalization for heart failure.

RNA sequencing analyses in infants patients with coarctation of the aorta

BACKGROUND

Coarctation of the aorta (CoA) is a serious innate heart disease. Although surgery results are generally good, some complications such as recoarctation and aortic aneurysm or persistent hypertension were serious threats to patient's health. To better understand the pathology of CoA and its underlying molecular mechanism is particularly important for early diagnosis and preventing the occurrence of its complications. However, the mechanisms of CoA remain unclear, especially for infants.

METHODS

RNA sequencing (RNA-seq) was used to identify the differentially expressed genes (DEGs) in vascular tissues of 12 patients with CoA and 10 normal participants form 3- to 34-month-old infants. The characteristic of DEGs were validated by quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and immunochemical staining (IHC) in vessels of patients with CoA and normal infants.

RESULTS

A total of 2491 DEGs with the false discovery rate less than 0.05(> 1.5-fold, P < 0.05 change) were identified, including 443 upregulated genes and 2048 downregulated genes. The Gene Ontology enrichment analysis showed that 26 out of the 2491 DEGs identified were associated with cardiovascular diseases. These 26 genes were mainly associated with extracellular matrix (ECM) and smooth muscle cells (SMCs) differentiation. Three DEGs, that is, CNN1 (calponin), α-actinin1 and myosin heavy chain 11 MYH11, were validated using qRT-PCR and Western blot analysis. In addition, immunochemical staining showed that calponin and MYH11 were highly expressed on the surface and in the deep layers of the thickened intima respectively.

CONCLUSION

This study comprehensively characterized the CoA transcriptome. Migration of extracellular matrix (ECM) and smooth muscle cells (SMCs) to the subendothelial space may be the major characteristic of CoA in infants.

Aortic Coarctation

Aortic coarctation is a discrete narrowing of the thoracic aorta. In addition to anatomic obstruction, it can be considered an aortopathy with abnormal vascular properties characterized by stiffness and impaired relaxation. There are surgical and transcatheter techniques to address the obstruction but, despite relief, patients with aortic coarctation are at risk for hypertension, aortic complications, and abnormalities with left ventricular performance. This review covers the etiology, pathophysiology, diagnosis, and management of adults with aortic coarctation, with emphasis on multimodality imaging characteristics and lifelong surveillance to identify long-term complications.