Congenital heart block is defined as the presence of atrioventricular block and heart damage between 16-24 weeks of gestation. Structural cardiac abnormalities and maternal autoimmune disorders are the key events in pathogenesis. The diagnosis can be made perinatally or postnatally. Treatment often mandates pacemaker implantation, but mortality rates may be very high in severe forms of the condition.
The clinical presentation of a complete heart block (CHB) may significantly vary, depending on the severity of the block (first degree, second degree, or complete heart block) and presence of additional structural heart disorders, such as congenital - corrected transposition of the great arteries and heterotaxia have been associated with this condition . CHB develops between 16-24 weeks of gestation, and symptoms may start during fetal life. Numerous cardiac rhythm abnormalities are described, including atrial flutter, the presence of both atrial and ventricular ectopic beats, sinus node dysfunction, and ectopic tachycardia (both ventricular and junctional)  . Bradycardia, however, is also documented and carries the poorest prognosis . CHB may also lead to myocardial fibrosis and myocarditis, which often presents as cardiomyopathy, pericarditis or pericardial effusion, both prenatally and postnatally  . In fact, dilated cardiomyopathy is the most important complication in the first year of life, as mortality rates reaching up to 40% . Although only 1-2% of fetuses are born to mothers carrying anti–SSA/Ro-SSB/La antibodies , they encompass between 60-90% of all cases reported in the literature   . For this reason, CHB is often accompanied by various non-cardiac symptoms - liver failure, transient thrombocytopenia, neutropenia, neonatal hyperbilirubinemia, and cholestasis, as well as annular erythematous plaques on the skin . The term neonatal lupus is used to describe CHB when it appears along with these findings
Second degree heart block or AV block, is characterized by dropped or skipped beats because some signals from the atria do not reach the ventricles. This form of the disorder may be separated into two subgroups: Wenckebach (Mobitz I) and Mobitz II. [rarediseases.org]
Atrioventricular block For 1st-degree block, conduction is slowed without skipped beats. All normal P waves are followed by QRS complexes, but the PR interval is longer than normal ( 0.2 sec). [msdmanuals.com]
This condition, however, must be seriously considered in a child with a slow pulse rate when a history of acquired disease, such as diphtheria, rheumatic fever, syphilis or severe pyogenic infection is not obtained. [jamanetwork.com]
Izmirly PM1 and Tonello et al recently reported cutaneous manifestations of neonatal lupus and risk of subsequent CHB. The most serious complication of NLE is complete atrioventricular (AV) block. [ncbi.nlm.nih.gov]
Photosensitive Skin Rash
skin rashes, nephritis, and glandular and extraglandular symptoms. [nursingcenter.com]
Auscultation of the heart during prenatal or postnatal assessment is the key step in the detection of cardiac abnormalities and may provide sufficient clinical suspicion for a more detailed evaluation. Obstetrical ultrasonography, maternal-fetal monitoring, or fetal echocardiogram with Doppler techniques are useful during the perinatal period, while standard echocardiography is the mainstay of diagnosis in neonates and infants . Patent ductus arteriosus (PDA), atrial septal defects (ASDs), ventricular septal defects (VSDs), as well as dysplasia, stenosis or regurgitation of either atrioventricular and/or semilunar valves may be identified . Decreased contractility is one of the main findings pointing myocarditis . Moreover, tricuspid regurgitation, ventricular inversion, and other structural heart anomalies are seen in some cases . The detection of heart blocks, however, is the most important finding that can lead to the diagnosis of CHB, which is detected by observing the length of the PR interval, but QT prolongation is also noted   . The wider the PR interval, the more severe the block.
Wide QRS Complex
Combining several CCHB studies, 6–9 risk factors for CHF, Stokes Adams attacks or sudden death include: low newborn ventricular rate ( 9 low foetal atrial rate ( 9 wide QRS complex on electrocardiogram (EKG); 10 corrected QT interval prolongation 460ms [ecrjournal.com]
On the other hand, if 2:1 AV block is seen with a wide QRS complex, infranodal block is the most likely diagnosis. [thecardiologyadvisor.com]
Provided that the pre-paced rhythm is not complete heart block with a wide QRS complex, the 12-lead ECG should give the diagnosis before the patient enters the pacing theatre! If not, fluoroscopy will suggest the abnormality ( figure 1 ). [bjcardio.co.uk]
Jugular Venous Pressure
- Capone C, Buyon JP, Friedman DM, Frishman WH. Cardiac Manifestations of Neonatal Lupus: A Review of Autoantibody Associated Congenital Heart Block and its Impact in an Adult Population. Cardiol Rev. 2012;20(2):72-76.
- Brucato A. Prevention of congenital heart block in children of SSA-positive mothers. Rheumatology (Oxford). 2008;47(3):iii35-37.
- Friedman D, Duncanson L, Glickstein J, Buyon J. A review of congenital heart block. Images Paediatr Cardiol. 2003;5(3):36-48.
- Gordon PA. Congenital heart block: clinical features and therapeutic approaches. Lupus. 2007;16(8):642-646.
- Friedman DM, Kim MY, Copel JA, et al. Utility of cardiac monitoring in fetuses at risk for congenital heart block: the PR Interval and Dexamethasone Evaluation (PRIDE) prospective study. Circulation. 2008; 117:485-93.