Background—The goal of this statement is to review available literature and to put forth a scientific statement on the current practice of fetal cardiac medicine, including the diagnosis and manage...

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Diagnosis and Treatment of Fetal Cardiac Disease A Scientific Statement From the American Heart Association

Prenatal alleviation of severe fetal aortic valve obstructions by percutaneous ultrasound-guided balloon valvuloplasty has been performed to improve the fate of affected fetuses. The purpose of this study was to analyze the current world experience of these procedures in human fetuses. Data from 12 human fetuses were available for analysis. The mean gestational age at intervention was 29.2 weeks (range 27 to 33). The mean time period between initial presentation and intervention was 3.3 weeks (range 3 days to 9 weeks). Technically successful balloon valvuloplasties were achieved in 7 fetuses, none of whom had an atretic valve. Only 1 of these fetuses remains alive today. Of the 5 remaining technical failures, 1 patient with severe aortic stenosis underwent successful postnatal intervention and remains alive. Six patients who survived prenatal intervention died from cardiac dysfunction or at surgery in the first days or weeks after delivery. Four fetuses died early within 24 hours after the procedure, 1 from a bleeding complication, 2 from persistent bradycardias, and 1 at valvotomy after emergency delivery. Thus, the early clinical experience of percutaneous ultrasound-guided fetal balloon valvuloplasty in human fetuses with severe aortic valve obstruction has been poor due to selection of severe cases, technical problems during the procedure, and high postnatal operative mortality in fetuses who survived gestation. Improved patient selection and technical modifications in interventional methods may hold promise to improve outcome in future cases.

World experience of percutaneous ultrasound-guided balloon valvuloplasty in human fetuses with severe aortic valve obstruction.

OBJECTIVE: To document the growth of the left heart structures and outcome of fetuses with aortic stenosis. DESIGN: Retrospective echocardiographic and clinical study. SETTING: Tertiary centre for fetal cardiology. PATIENTS: 27 consecutive fetuses with aortic stenosis. MAIN OUTCOME MEASURES: Survival of affected fetuses. Measurement of left ventricular end diastolic volume (LVEDV), aortic root diameter, and ejection fraction. RESULTS: Before 25 weeks' gestation, the LVEDV was normal or increased in all cases. In six of eight fetuses studied sequentially, the LVEDV fell across normal centiles. Initial ejection fraction was reduced in 23 fetuses (88%). Before 28 weeks' gestation, the aortic root was normal in all but one case, but after 29 weeks, 11 of 13 fetuses had values below the 50th centile. In two fetuses prenatal aortic valvoplasty was attempted, 10 babies had postnatal interventions, and there were six survivors. Biventricular repair was attempted in eight cases, of whom five survived. A first stage Norwood operation was performed in three babies, of whom one survived. The four fetuses with the highest aortic root z scores had successful biventricular repair. The two fetuses with initially normal ejection fractions survived. Successful biventricular repair was achieved even where the LVEDV was below the 5th centile. CONCLUSIONS: In aortic stenosis diagnosed prenatally, failure of growth of the left ventricle and aortic root often occurs. The outcome of affected fetuses is better than previously reported. Prenatal echocardiography may assist selection of suitable candidates for biventricular versus Norwood repair.

https://heart.bmj.com/content/heartjnl/77/3/205.full.pdf

Natural history and outcome of aortic stenosis diagnosed prenatally.

The human fetal heart develops arrhythmias and conduction disturbances in response to ischemia, inflammation, electrolyte disturbances, altered load states, structural defects, inherited genetic conditions, and many other causes. Yet sinus rhythm is present without altered rate or rhythm in some of the most serious electrophysiological diseases, which makes detection of diseases of the fetal conduction system challenging in the absence of magnetocardiographic or electrocardiographic recording techniques. Life-threatening changes in QRS or QT intervals can be completely unrecognized if heart rate is the only feature to be altered. For many fetal arrhythmias, echocardiography alone can assess important clinical parameters for diagnosis. Appropriate treatment of the fetus requires awareness of arrhythmia characteristics, mechanisms, and potential associations. Criteria to define fetal bradycardia specific to gestational age are now available and may allow detection of ion channelopathies, which are associated with fetal and neonatal bradycardia. Ectopic beats, once thought to be entirely benign, are now recognized to have important pathologic associations. Fetal tachyarrhythmias can now be defined precisely for mechanism-specific therapy and for subsequent monitoring of response. This article reviews the current and future diagnostic techniques and pharmacologic treatments for fetal arrhythmia.

Fetal cardiac arrhythmia detection and in utero therapy

Congenital heart defects (CHDs) have a multifactorial etiology and therefore their prenatal detection cannot be achieved solely by concentrating on the high-risk population defined by parental medical history. Screening ultrasound is usually performed in the second trimester and is still the best means of detecting cardiac defects. Signs of cardiac disease are often subtle, necessitating careful targeted examination. In the 1980s, the fourchamber view was proposed as the most important plane for screening, allowing a greater detection rate for anomalies. Recently, however, incorporation of views of the great vessels has been recommended as part of the routine screening examination. Many studies in the last 10 years have emphasized the importance of cardiac screening, but they have achieved widely divergent results, with reported detection rates varying from 5% to 92% (Table 1). However, it should be noted that these studies employed different approaches, which are summarized in Table 2, and are therefore not directly comparable. The anticipated potential in the 1980s of the fourchamber view to detect ‘most’ or at least the severe cardiac anomalies was fulfilled in very few areas and centers, and widespread improvements in detection rates were not achieved. In my opinion, there are four possible reasons why the four-chamber view appears to fail. This editorial analyses these four reasons and attempts to suggest solutions to increase detection rates.

https://obgyn.onlinelibrary.wiley.com/doi/epdf/10.1002/uog.187

The four‐chamber view: four reasons why it seems to fail in screening for cardiac abnormalities and suggestions to improve detection rate

The pre- and postnatal course of a child surviving after successful intrauterine balloon aortic valvoplasty for critical aortic stenosis is described. She is now well at 4 years of age. A clearer understanding of the hemodynamics in such cases and improved catheter technology are necessary before this is advocated as a generally applicable technique. However, the outcome in this case is promising for the future of fetal interventional procedures.

https://obgyn.onlinelibrary.wiley.com/doi/pdf/10.1046/j.1469-0705.1995.05020090.x

Survival after fetal aortic balloon valvoplasty

Ventricular tachycardia is a very rare fetal arrhythmia accounting for fewer than 2% of fetal tachycardias. We describe a fetus presenting at 30 weeks' gestation with ventricular tachycardia at a rate of 220 beats per min and fetal hydrops. The tachycardia was unresponsive to flecainide but was controlled within 12 h by an intravenous infusion of magnesium to the mother. Despite rapid control of the arrhythmia the fetus developed severe periventricular leukomalacia before birth for which a poor neurological prognosis was given. The baby was delivered preterm at 32 weeks' gestation and died on the sixth day after birth. Long QT syndrome was identified postnatally on the electrocardiogram, and was confirmed by genetic testing which showed a mutation in the KCNH2 gene (p.T613M).

D J Maxwell

Papers

Survival after fetal aortic balloon valvoplasty

Fetal ventricular tachycardia secondary to long QT syndrome treated with maternal intravenous magnesium: case report and review of the literature.