Cardiovascular System - Abnormalities
Introduction
Heart defects and preterm birth are the most common causes of neonatal and infant death. The long-term development of the heart combined with extensive remodelling and post-natal changes in circulation lead to an abundance of abnormalities associated with this system.
A UK study literature showed that preterm infants have more than twice as many cardiovascular malformations (5.1 / 1000 term infants and 12.5 / 1000 preterm infants) as do infants born at term and that 16% of all infants with cardiovascular malformations are preterm. (0.4% of live births occur at greater than 28 weeks of gestation, 0.9% at 28 to 31 weeks, and 6% at 32 to 36 weeks. Overall, 7.3% of live-born infants are preterm) [1]
"Baltimore-Washington Infant Study data on live-born cases and controls (1981-1989) was reanalyzed for potential environmental and genetic risk-factor associations in complete atrioventricular septal defects AVSD (n = 213), with separate comparisons to the atrial (n = 75) and the ventricular (n = 32) forms of partial AVSD. ...Maternal diabetes constituted a potentially preventable risk factor for the most severe, complete form of AVSD." [2].
In addition, there are in several congenital abnormalities that exist in adults (bicuspid aortic valve, mitral valve prolapse, and partial anomalous pulmonary venous connection) which may not be clinically recognized.
Australian Statistics (1981-1992) | USA Statistics (1997-2003) | Aortic Stenosis | Atrial Septal Defects | Coarctation of Aorta | Dextrocardia | Hypoplastic Left Heart | Long QT Syndrome | Patent Ductus Arteriosus | Pulmonary Atresia | Pulmonary Stenosis | Tetralogy of Fallot | Transposition of Great Vessels | Tricuspid Atresia | Total Anomalous Pulmonary Venous Connection | Ventricular Septal Defect | Abnormalities of Conducting System | Prenatal Diagnosis | Surgery for Congenital Heart Disease
Some Recent Findings
Heart Abnormalities
Ventricular Septal Defect
The Ventricular Septal Defect (VSD) usually occurs in the membranous (perimembranous) rather than muscular interventricular septum, and is more frequent in males that females.
Perimembranous defects are located close to the aortic and tricuspid valves and adjacent to atrioventricular conduction bundle.
Atrial Septal Defects
Atrial Septal Defects (ASD) are a group of common (1% of cardiac) congenital anomolies defects occuring in a number of different forms and more often in females.
- patent foramen ovale- allows a continuation of the atrial shunting of blood, in 25% of people a probe patent foramen ovale (allowing a probe to bepassed from one atria to the other) exists.
- ostium secundum defect
- endocardial cushion defect involving ostium primum
- sinus venosus defect - contributes about 10% of all ASDs and occurs mainly in a common and less common form. Common ("usual type") - in upper atrial septum which is contiguous with the superior vena cava. Less common - at junction of the right atrium and inferior vena cava. (More? eMedicine - Atrial Septal Defect, Sinus Venosus | Medline Plus - ASD Repair Video)
- common atrium
Treatment: The surgical repair requires a cardiopulmonary bypass and is recommended in most cases of ostium secundum ASD, even though there is a significant risk involved. Ostium primum defects tend to present earlier and are often associated with endocardial cushion defects and defective mitral or tricuspid valves. In such cases, valve replacement may be necessary and the extended operation has a considerable chance of mortality.
Increasingly closure by a transcatheter device closure has been applied. (More? Medline Plus - ASD Repair Video)
Patent Ductus Arteriosus
Patent Ductus Arteriosus (P.D.A.) occurs commonly in preterm infants, can close spontaneously (by day three in 60% of normal term neonates) the remainder are ligated simply and with little risk. The operation is always recommended even in the absence of cardiac failure and can often be deferred until early childhood.
Tetralogy of Fallot
Named after Etienne-Louis Arthur Fallot (1888) who described it as "la maladie blue" and is a common developmental cardiac defect. The syndrome consists of a number of a number of cardiac defects possibly stemming from abnormal neural crest migration.
Hypoplastic Left Heart
Characterized by hypoplasia (underdevelopment or absence) of the left ventricle obstructive valvular and vascular lesion of the left side of the heart.
Double Outlet Right Ventricle
De-oxygenated blood enters the aorta from the right ventricle and is returned to the body.
Dextrocardia
Initial malrotation of the heart tube bending left instead of right. Results in heart and greater vessels reversed. Can also occur with situs invertus, where viscera are transposed LR.
Anatomical left-right normal asymmetry is called situs solitus. The alternative heterotaxy can be either randomization (situs ambiguus) or a complete reversal (situs inversus) of normal organ position.
Search NCBI Bookshelf: Dextrocardia
Search PubMed: Search term = Dextrocardia (Jun06 1,857 Articles and 95 Reviews)
Links: Early Embryonic Chick Heart Movie |
Abnormalities of Conducting System
Also variously called the cardiac conduction system (CCS), cardiac pacemaking and conduction system (CPCS), or atrioventricular conduction system (AVCS). Recently animal models (CCS-lacZ transgenic mouse) have helped identify key processes in the development of this specialized conduction system.
"Known arrhythmogenic areas including Bachmann's bundle, the pulmonary veins, and sinus venosus derived internodal structures, demonstrate lacZ expression." (Jongbloed et al, 2004)
Search NCBI Bookshelf: heart+conduction+developmental+abnormalities
Long QT Syndrome
Congenital long QT syndrome (LQTS) is a group of rare genetic disorders with prolonged ventricular repolarization and a risk of ventricular tachyarrhythmias. Cause is mutations in genes encoding either cardiac ion channels or channel interacting proteins.
Search NCBI Bookshelf: Congenital long-QT syndrome
Search PubMed: Search term = Congenital long-QT syndrome (Jun06 702 Articles and 204 Reviews)
Heart Vessel Abnormalities
Transposition of Great Vessels
Characterized by aorta arising from right ventricle and pulmonary artery from the left ventricle and often associated with other cardiac abnormalities (e.g. ventricular septal defect).
(Image: Government of Manitoba - Report 2001)
International Classification of Diseases code 745.1
Australian national rate (1982-1992) 3.6/10,000 births.
Of 988 infants 4.1% were stillborn and 23.2% liveborn died during neonatal period. slightly more common in twin births than singleton. Congenital Malformations Australia 1981-1992 P. Lancaster and E. Pedisich ISSN 1321-8352 Neonates with transposed great arteries die without an arterial switch operation, first carried out in 1975. Murphy DJ Jr. Transposition of the great arteries: long-term outcome and current management. Curr Cardiol Rep. 2005 Jul;7(4):299-304.
Search NCBI Bookshelf: Transposition of Great Vessels
Search PubMed: Search term = Transposition of Great Vessels (Jun06 5,386 Articles and 293
Coarctation of Aorta
Prevalence ranges from 5% to 8% of all congenital heart defects.
References
- ↑ Tanner K, Sabrine N, Wren C. Cardiovascular malformations among preterm infants. Pediatrics. 2005 Dec;116(6):e833-8. PMID: 16322141
- ↑ Loffredo CA, Hirata J, Wilson PD, Ferencz C, Lurie IW. Atrioventricular septal defects: possible etiologic differences between complete and partial defects. Teratology. 2001 Feb;63(2):87-93 PMID: 11241431
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Cite this page: Hill, M.A. (2024, April 30) Embryology Cardiovascular System - Abnormalities. Retrieved from https://embryology.med.unsw.edu.au/embryology/index.php/Cardiovascular_System_-_Abnormalities
- © Dr Mark Hill 2024, UNSW Embryology ISBN: 978 0 7334 2609 4 - UNSW CRICOS Provider Code No. 00098G
