Fetal Cardiac Interventions

Thomas Smith^*

University of British Colombia

Abstract

A novel and developing method, fetal cardiac intervention, or FCI, allows for the treatment of a subset of congenital heart disease in utero. The three most frequently performed FCI are discussed in this review, along with their rationale, selection criteria, technical characteristics, and current outcomes: hypoplastic Left Heart Syndrome (HLHS), fetal aortic stenosis; HLHS with a restrictive or intact atrial septum; and pulmonary atresia with an intact ventricular septum, which raises the risk of RV hypoplasia getting worse.

A novel and developing method, fetal cardiac intervention, or FCI, allows for the treatment of a subset of congenital heart disease in utero. The three most frequently performed FCI are discussed in this review, along with their rationale, selection criteria, technical characteristics, and current outcomes: hypoplastic Left Heart Syndrome (HLHS), fetal aortic stenosis; HLHS with a restrictive or intact atrial septum; and pulmonary atresia with an intact ventricular septum, which raises the risk of RV hypoplasia getting worse.

Left heart syndrome • Fetal aortic stenosis • Pulmonary atresia • Intact atrial septum • Intact ventricular septums

Introduction

A growing number of congenital diseases can now be treated in utero thanks to advances in fetal diagnostics and innovative interventional methods. Spina bifida, congenital diaphragmatic hernia, tumors, and congenital heart diseases are just a few of the many conditions for which fetal interventions have been proposed or carried out. Even though the vast majority of congenital heart diseases can be accurately diagnosed during pregnancy, only a small subset of them are technically feasible for fetal intervention, and a compelling case can be made for this. There are two types of fetal cardiac diseases that might be treated with Fetal Cardiac Intervention (FCI): diseases that get worse during midgestation and/ or late gestation, causing the disease process to progress from mid gestation to birth; or on the other hand infections that convey a high gamble of end in utero as well as are perilous upon entering the world, to such an extent that FCI offers an opportunity to work on in utero and neonatal endurance. This article audits three sores for which ultrasound directed, percutaneous, catheter-based FCI has been per shaped, and ought to be thought of: fetal aortic stenosis and Hypoplastic Left Heart Syndrome (HLHS), which is developing; HLHS with a restrictive or intact atrial septum; and pulmonary atresia with an intact ventricular septum, which raises concerns about RV hypoplasia getting worse [1].

Description

Aortic stenosis in the fetus with developing HLHS

A spectrum of conditions known as HLHS is characterized by a small left heart structure that cannot support systemic circulation and an intact ventricle septum. Atresia of the mitral and/or aortic valves is present in some forms of HLHS, while hypoplastic but patent mitral and aortic valves and an identifiable Left Ventricular (LV) cavity are present in others. Staged single ventricle palliation outcomes for HLHS have steadily improved, but the medium-term survival rate is only 65–70 percent and significant morbidity, such as arrhythmias, neurocognitive impairment, hepatic dysfunction, and Fontan-specific complications (protein-losing enteropathy, plastic bronchitis, etc.) are common [2, 3]. With the coming of fetal echocardiography during the 1980s, which permitted precise mid gestation finding, it was perceived that fetal aortic stenosis is a dynamic sickness during development, which, in a few cases, deteriorates to the mark of HLHS when of birth [4, 5]. Fetal aortic stenosis regular history studies have shown that a subset of patients with HLHS upon entering the world have vulvar aortic stenosis at mid gestation, with a typical estimated or widened Left Ventricle (LV) with systolic brokenness . During gestation, the ongoing LV pressure load and lack of flow through the left heart cause worsening of endocardial and myocardial fibrosis and growth arrest of left heart structures in fetuses with vulvar aortic stenosis [6].

HLHS with unblemished or prohibitive atrial septum

In contrast to fetal aortic stenosis or pulmonary atresia with intact ventricular septum, the justification for FCI in HLHS with an intact or restrictive atrial septum is different. In contrast to fetal aortic stenosis or pulmonary atresia with intact ventricular septum, where the disease progresses in utero, the justifications for FCI in HLHS with an intact or restrictive atrial septum are as follows: to prevent severe hypoxia in the newborn and death; and to stop the lung disease from getting worse, which is often caused by chronic in utero pulmonary venous hypertension. Despite advancements in surgical and medical management, HLHS patients with an intact or restrictive atrial septum continue to represent a subset of single-ventricle patients with extremely high mortality. In HLHS, approximately 6% of patients have an intact atrial septum, while up to 22% have a restrictive atrial septum. A 1-year survival rate of less than 30% remains for patients with HLHS and an intact atrial septum. The fetus and newborn in HLHS need a sufficient foramen ovale to allow pulmonary venous return to exit the left atrium [7]. Upon entering the world, aspiratory vascular obstruction drops and pneumonic blood stream increments intensely. Youngsters with flawless atrial septum create significant haemodynamic unsteadiness, hypoxia and acidosis inside the principal long stretches of life, because of left atrial hypertension, prompting gigantic aspiratory oedema and low cardiovascular result. An open surgical approach, a percutaneous catheter-based approach, and the utilization of Ex Utero Intrapartum Treatment (EXIT) procedures are all options for emergent intervention to open the atrial septum in postpartum management. Strategies vary from institution to institution [8, 9]. Lung disease (often pulmonary lymphangiectasis with the appearance of nutmeg lung) and pulmonary hypertension are at least partially to blame for the high mortality rate in this patient population despite improved prenatal diagnosis and postnatal management techniques. Chronic in utero obstruction of pulmonary venous return leads to pulmonary venous hypertension, which in turn causes the lung disease [10].

Conclusion

Despite the fact that FCI offers the capacity to adjust the illness direction and possibly further develop results in HLHS with unblemished atrial septum, no endurance benefit has been exhibited to date. When patients who underwent FCI (44%) were compared to controls who did not (33%) in terms of survival to neonatal hospital discharge, there was a non-significant difference. The lack of survival benefit raises the question of the best technique and timing for Fetal Cardiac Intervention (FCI) on the atrial septum, despite the improved late gestation haemo dynamics supporting the idea that FCI can alter the abnormal physiology in this disease. As of now FCI on the atrial septum is commonly performed at 24-30 weeks’ incubation. By this gestational age, significant lung disease, including nutmeg lung, has already developed in the majority of fetuses, as demonstrated by fetal ultrasound and magnetic resonance imaging. Therefore, in order for FCI to improve postnatal outcomes in this high-risk cohort, new methods for creating a durable atrial communication and/or earlier FCI timing should be the focus of future research.

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