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Congenital Heart Block

Congenital Atrioventricular Block

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.


Presentation

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 [1]. 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) [1] [2]. Bradycardia, however, is also documented and carries the poorest prognosis [3]. CHB may also lead to myocardial fibrosis and myocarditis, which often presents as cardiomyopathy, pericarditis or pericardial effusion, both prenatally and postnatally [1] [2]. In fact, dilated cardiomyopathy is the most important complication in the first year of life, as mortality rates reaching up to 40% [4]. Although only 1-2% of fetuses are born to mothers carrying anti–SSA/Ro-SSB/La antibodies [5], they encompass between 60-90% of all cases reported in the literature [1] [2] [5]. 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 [1]. The term neonatal lupus is used to describe CHB when it appears along with these findings

Heart Disease
  • No reports of congenital heart disease among the children of mothers with connective tissue disease fit this description.[ncbi.nlm.nih.gov]
  • Congenital heart block is frequently associated with underlying structural congenital heart disease ( 40%).[pedecho.org]
Skipped Beats
  • 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]
Slow Pulse
  • 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]
Cutaneous Manifestation
  • 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
Sudden Hearing Loss
  • We have previously reported the presence of antibodies directed against inner ear antigens in patients with Cogan syndrome, a disease characterized by sudden hearing loss and interstitial keratitis.[ncbi.nlm.nih.gov]
Myelopathy
  • This may predispose the infant to transient hydrocephalus, seizures, or vascular myelopathy. The infant's posture and muscle tone, primitive reflexes, and Babinski reflex should be assessed.[nursingcenter.com]

Workup

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 [3]. 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 [1]. Decreased contractility is one of the main findings pointing myocarditis [3]. Moreover, tricuspid regurgitation, ventricular inversion, and other structural heart anomalies are seen in some cases [3]. 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 [3] [4] [5]. The wider the PR interval, the more severe the block.

Liver Enzymes Abnormal
  • The liver enzyme abnormalities and blood count irregularities are usually self-limited and require no specific treatment.[ncbi.nlm.nih.gov]
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]
Atrioventricular Dissociation
  • Fetal echocardiography revealed atrioventricular dissociation, with an atrial rate of 170 bpm and a ventricular rate of 54 bpm.[ncbi.nlm.nih.gov]
Cannon A-Waves
  • Signs include those of AV dissociation, such as cannon a waves, BP fluctuations, and changes in loudness of the 1st heart sound (S 1 ). Risk of asystole-related syncope and sudden death is greater if low escape rhythms are present.[msdmanuals.com]

Treatment

  • Intrauterine steroid treatment in the presence of fetal hydrops and congenital heart block is discussed.[ncbi.nlm.nih.gov]

Prognosis

  • In a case of fetal heart block, maternal administration of ritodrine may be a therapeutic intervention to improve the fetal and neonatal prognosis.[ncbi.nlm.nih.gov]

Etiology

  • We discuss the 2 major etiologies of congenital heart block and the implications in subsequent pregnancies.[ncbi.nlm.nih.gov]
  • Interestingly, two cases of fetal congenital heart block occurred in women without known risk factors (eg, positive anti-Ro/SSA antibody, previous pregnancy with congenital heart block). [9] Many times, no clear etiology is determined for isolated CAVB[emedicine.medscape.com]
  • Etiology: 1. Autoimmune antibodies. 2. Structural heart abnormalities due to congenital heart disease (eg-L-TGA, Endocardial cushion defects , syndromic ASD) 3. Idiopathic familial congenital CHB 21.[slideshare.net]
  • (First-degree heart block) Introduction Clinical definition an impairment of the electrical transmission from the atria to the ventricles Etiology idiopathic (most common) e.g., fibrosis and sclerosis of the conduction system ischemic heart disease (2nd[step2.medbullets.com]

Epidemiology

  • In this Review, we discuss the epidemiology, classification and management of women whose pregnancies are affected by autoimmune CHB, with a particular focus on the autoantibodies associated with autoimmune CHB and how we should test for these antibodies[ncbi.nlm.nih.gov]
  • , pathophysiology, classification & diagnosis of bradyarrhythmias suitabe for permanent cardiac pacing therapy Persitent bradycardia Intermittent (documented) bradycardia Suspected (undocumented) bradycardia Indications for cardiac resynchronization Epidemiology[escardio.org]
  • Neonatal lupus: Epidemiology, pathogenesis, clinical manifestations, and diagnosis [visitado 2017 Nov 21]. Disponible en: . Saxena A, Izmirly PM, Mendez B, Buyon JP, Friedman DM.[revista.fecolsog.org]
  • References 1 Epidemiology, etiology, detection, and treatment of autoantibody-associated congenital heart block in neonatal lupus , Curr Rheumatol Rep , 2007 , vol. 9 (pg. 101 - 8 ) 2 Congenital heart block risk to newborns of mothers with anti-Ro/SSA[academic.oup.com]
  • Epidemiologic studies suggest that a genetic or environmental cause for CHD is identifiable in approximately 20%–30% of cases, with 3%–5% of CHD due to a detectable single-gene disorder.[invitae.com]
Sex distribution
Age distribution

Pathophysiology

  • The possible pathophysiological mechanisms underlying CHB associated with 1 degrees SS are discussed.[ncbi.nlm.nih.gov]
  • Presentation Published in 2013 Reference CP Published in 2013 Reference Addenda -Eur Heart J - doi:10.1093/eurheartj/eht180 Table of contents: Full Text (ESC Clinical Practice Guidelines) Preamble Indications for pacing Epidemiology, natural histroy, pathophysiology[escardio.org]
  • Congenital and childhood atrioventricular blocks: pathophysiology and contemporary management. Eur J Pediatr 2016; 175:1235. • Epstein AE, Dimarco JP, Ellenbogen KA, et al.[slideshare.net]
  • Grasp the full scope of the pathophysiology of CHD with well-organized, expert guidance. Quickly search the contents online, download images in JPG or PPT format, and view 70 echocardiogram videos at expertconsult.com.[books.google.ro]

Prevention

  • Preventive treatment during pregnancy, however, before the critical period of cardiac development, can prevent the development of CHB.[ncbi.nlm.nih.gov]

References

Article

  1. 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.
  2. Brucato A. Prevention of congenital heart block in children of SSA-positive mothers. Rheumatology (Oxford). 2008;47(3):iii35-37.
  3. Friedman D, Duncanson L, Glickstein J, Buyon J. A review of congenital heart block. Images Paediatr Cardiol. 2003;5(3):36-48.
  4. Gordon PA. Congenital heart block: clinical features and therapeutic approaches. Lupus. 2007;16(8):642-646.
  5. 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.

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Last updated: 2019-07-11 20:54