Prenatal diagnosis and management of congenital complete heart block

Abstract

Congenital complete heart block (CCHB) is a life‐threatening medical condition in the unborn fetus with insufficiently validated prenatal interventions. Maternal administration of medications aimed at decreasing the immune response in the fetus and beta‐agonists intended to increase fetal cardiac output have shown only marginal benefits. Anti‐inflammatory therapies cannot reverse CCHB, but may decrease myocarditis and improve heart function. Advances in prenatal diagnosis and use of strict surveillance protocols for delivery timing have demonstrated small improvements in morbidity and mortality. Ambulatory surveillance programs and wearable fetal heart rate monitors may afford early identification of evolving fetal heart block allowing for emergent treatment. There is also preliminary data suggesting a roll for prevention of CCHB with hydroxychloroquine, but the efficacy and safety is still being studied. To date, intrauterine fetal pacing has not been successful due to the high‐risk invasive placement techniques and potential problems with lead dislodgement. The development of a fully implantable micropacemaker via a minimally invasive approach has the potential to pace fetal patients with CCHB and thus delay delivery and allow fetal hydrops to resolve. The challenge remains to establish accepted prenatal interventions capable of successfully managing CCHB in utero until postnatal pacemaker placement is successfully achieved.

A Broader Perspective on Anti-Ro Antibodies and Their Fetal Consequences—A Case Report and Literature Review

“…The two-dimensional ultrasound can be used in diagnosing specific arrhythmias, in evaluating cardiac anatomy and function, as well as in searching for signs of hydrops fetalis. Arrhythmias can be further characterized by using the M-mode ultrasonography , which detects atrial and ventricular wall motion and the relative timing of cardiac events (see clinical case [ 80 ]. Fetal bradycardia, the result of both second- and third- heart block, can be easily detected by routine fetal auscultation.…”

“…The weekly pulsed-Doppler fetal echocardiography is the preferred method of in utero surveillance for heart block. However, if not available, there is an alternative that consists of home monitoring for fetal bradycardia, twice per day, with a handheld Doppler system [ 80 ]. The postnatal testing is recommended for mothers of neonates with heart block in the absence of causal structural abnormalities, as most cases of congenital heart blocks appear as a result of the presence of anti-Ro/SSA and/or anti-La/SSB antibodies.…”

Prenatal Management Strategy for Immune-Associated Congenital Heart Block in Fetuses

“…M-mode echocardiography can simultaneously measure atrial motion (a wave) and ventricular motion (v wave) through the sampling line to determine the time sequence of atrial and ventricular motion, and atrioventricular conduction can then be inferred. Due to the limitations of atrioventricular contraction, peak value, and the variable position of the fetus during pregnancy however, it is still difficult to accurately measure the sampling line perpendicular to the atrioventricular node ( 30 ). Pulsed wave Doppler echocardiography (PD) can measure simultaneous flow across the mitral and aortic valve, and in cases of complete CHB it can demonstrate dissociation of atrial inflow and ventricular outflow ( 30 ).…”

“…Due to the limitations of atrioventricular contraction, peak value, and the variable position of the fetus during pregnancy however, it is still difficult to accurately measure the sampling line perpendicular to the atrioventricular node ( 30 ). Pulsed wave Doppler echocardiography (PD) can measure simultaneous flow across the mitral and aortic valve, and in cases of complete CHB it can demonstrate dissociation of atrial inflow and ventricular outflow ( 30 ). This can also be evaluated with simultaneous Doppler flows in the superior vena cava and aorta, as well as in the pulmonary vein and pulmonary artery ( 31 ).…”

“…The above-described fetal echocardiography techniques are sufficient for distinguishing and interpreting certain types of fetal CHB, particularly second-degree and third-degree AVB. in terms of the diagnosis of fetal first-degree AVB however, differences between PD and TDI need to be further balanced because the different methods to determine fetal atrioventricular intervals and the reference data of atrioventricular intervals vary significantly between the two approaches ( 30 ). The measurement of atrioventricular intervals using PD can be performed in two ways; from the mitral valve to the aorta (MV-Ao), and from the beginning of the retrograde venous a wave in the superior vena cava to the beginning of the aortic ejection wave (SVC-Ao) ( 31 ), which is influenced by fetal position and orientation.…”