Development and teratology of cardiovascular systems 27.2.2023 Anna Mac Gillavry Danylevska Formation of primary heart field • WHEN? - middle of the 3rd week (day 16) • WHAT? - progenitor heart cells • WHERE? - from epiblast through the primitive streak to the visceral layer of lateral plate mesoderm • DO WHAT? - form PHF T.W. Sadler, Langman´s medical embryology, 14th edition Formation of the heart tube • WHEN? - day 22-28 • WHAT? – cells of the PHF • DO WHAT? – form cardiac myoblasts and the blood islands ---> the horseshoeshaped endothelial-lined tube surrounded by myoblast (=cardiogenic region/field), further the caudal portion fuse except for the caudalmost part The heart tube lengthening •WHEN? - day 22-28 •WHAT? – SHF in splanchnic mesoderm ventrally to the posterior pharynx •WHERE? - thoracic region •DO WHAT? – provides cells to lenghten both poles of the heart tube: atria and sinus venosus, right ventricle, conus cordis and truncus arteriosus T.W. Sadler, Langman´s medical embryology, 14th edition https://radiologykey.com/embryology/ Looping of the heart • WHEN? - day 23-28 • WHAT? - the primitive heart tube • DO WHAT? - cephalic portion bends ventrally, caudally and to the right; caudal portion bends dorsally, cranially and to the left https://teachmeanatomy.info/the-basics/embryology/cardiovascular-system/ https://youtu.be/a0qyagIgBPw Formation of the cardiac septa • WHEN? - day 27-37 (size of the embryo 5-16 mm!) • WHAT? – septum in the common atrium – septum in the atrioventricular canal – septum in the truncus arteriosus and conus cordis – septum in ventricles Formation of the cardiac septa T.W. Sadler, Langman´s medical embryology, 14th edition Septum in the common atrium K. Moor, Before we are born Septum in the atrioventricular canal T.W. Sadler, Langman´s medical embryology, 12th edition End of the 4th till end of the 5th week Septum in the truncus arteriosus and conus cordis K. Moor, Before we are born 5th week – truncus swellings: right superior –grows distally to the left left inferior – grows distally to the right conus swellings – grow towards each other and distally to fuse with the truncus swellings NEURAL CREST CELLS Congenital heart defects (CHDs) in 1% of live born infants; Rubella, thalidomide, RA, alcohol, maternal insulin-dependent diabetes Laterality – during the gastrulation, signaling cascade includes serotonin, thus the SSRI class antidepressants are linked to the increase in heart defects: - dextrocardia (situs inversus, heterotaxy) - ventricular septal defects (VSDs) - atrial septal defects (ASDs) - double outlet right ventricle (DORV) - transposition of the great vessels - pulmonary stenosis - atrial/ventricular isomerism - inversions http://radiologycases.my/2020/08/08/isolated-dextrocardia/https://en.wikipedia.org/wiki/Chest_radiograph Atrial septal defects (ASDs) 6,4/10 000; 2:1 prevalence in F to M; acyanotic Patent foramen ovale in 10-20% of population 4 clinically significant ASD: - ostium sekundum ASDs (90% cases; 10-15% of all CHDs) - endocardial cushion defects with a foramen primum (in 25% of patients with Down syndrome) - sinus venosus ASDs - common atrium (cor triloculare biventriculare) - combination of the above extra blood volume goes to the right side of the heart (delay in the pulmonary valve closure – splitting of the S2 sound), paradoxical embolism Ventricular septal defects (VSDs) most common CHDs 12/10 000; acyanotic; 80% in the muscular region and resolve during the childhood membranous part defects are more severe and associated with other abnormalities the blood volume carried by pulmonary artery increases (can be 1,2-1,7 times more than aorta) leading to the pulmonary hypertension and can cause Eisenmenger syndrome https://youtu.be/e7ObXrdtXek Tetralogy of Fallot (TOF) results from anterior displacement of conotruncal septum 9,6/10000; 10% of all CHDs; cyanotic leading to 4 abnormalities: 1. Pulmonary infundibular stenosis 2. VSD 3. overriding aorta 4. hypertrophy of the right ventricle https://youtu.be/JKpVlPFGjaQhttps://link.springer.com/article/10.1186/s12872-018-0996-9 Congenital heart defects (CHDs) Ectopia cordis – ventral body wall defect Persistent truncus arteriosus – (0,8/10 000) – always present with VSD Transposition of great arteries (4,8/10 000) Aortic stenosis and aotric atresia Pulmonary stenosis and pulmonary atresia Unequal division of TA Foetal blood circulation