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.
Some Recent Findings
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Heart Abnormalities
Ventricular Septal Defect
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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.
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Atrial Septal Defects
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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.
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.
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Patent Ductus Arteriosus
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Patent ductus arteriosus (PDA), or Patent arterial duct (PAD), occurs commonly in preterm infants, and at approximately 1 in 2000 full term infants and more common in females (to male ratio is 2:1). Can also be associated with specific genetic defects, trisomy 21 and trisomy 18, and the Rubinstein-Taybi and CHARGE syndromes. The opening is asymptomatic when the duct is small and can close spontaneously (by day three in 60% of normal term neonates), the remainder are ligated simply and with little risk, with transcatheter closure of the duct generally indicated in older children. The operation is always recommended even in the absence of cardiac failure and can often be deferred until early childhood.
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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.
- Links: Gene expression in cardiac tissues from infants with idiopathic conotruncal defects | Search PubMed
Hypoplastic Left Heart
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Characterized by hypoplasia (underdevelopment or absence) of the left ventricle obstructive valvular and vascular lesion of the left side of the heart.
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Double Outlet Right Ventricle
De-oxygenated blood enters the aorta from the right ventricle and is returned to the body.
- Links: Search PubMed
Tricuspid Atresia
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Blood is shunted through an atrial septal defect to the left atrium and through the ventricular septal defect to the pulmonary artery. The shaded arrows indicate mixing of the blood.
Fontan Procedure: a surgical procedure developed by Fontan and Baudet (1971) to restore a circulation in patients with tricuspid atresia.
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Dextrocardia
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| Dextrocardia anatomical heart position[4] | Dextrocardia (postnatal 1 year old)[4] |
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.
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)
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
- Links: Search PubMed
Heart Vessel Abnormalities
Transposition of the Great Vessels
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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).
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.
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Coarctation of the Aorta
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Prevalence ranges from 5% to 8% of all congenital heart defects.
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Interrupted Aortic Arch
- LInks: Search PubMed
Pulmonary Atresia
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Abnormal blood flow (as indicated by the shaded blue arrow) is from the right atrium and right ventricle through an atrial septal defect to the left side of the heart. Blood can reach the pulmonary arteries only through a patent ductus arteriosus.
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Total Anomalous Pulmonary Venous Connection
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Total Anomalous Pulmonary Venous Connection (TAPVC) or Total Anomalous Pulmonary Venous Return (TAPVR) occurs when pulmonary veins connect to the right atrium (RA) and not the left atrium (LA). This abnormal connection returns oxygenated pulmonary blood from the lungs back to the right atrium or a vein flowing into the right atrium.
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Complete atrioventricular canal
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Partial Anomalous Pulmonary Venous Drainage
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Aortic Stenosis
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Pulmonary Stenosis
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References
Articles
<pubmed>17967198</pubmed>
Search Pubmed
Search Pubmed: Cardiovascular System Abnormalities
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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
