circulation system 陳建榮
TRANSCRIPT
Circulation system
陳建榮
http://web.nchu.edu.tw/pweb/users/chenjr/
Normal development of Heart-Early Events
-Migration of cardiogenic mesenchyme -Differentiation of mesenchyme -Chamber formation -Folding of the heart tube
-Critical Changes -Vascular Changes
Migration of cardiogenic mesenchyme
血管母細胞索
The early heart is a simple tube which commences beating during the third week (Day 21-22). Cardiogenic mesenchyme differentiates into three distinct cell populations:-Endocardium 心內膜-Myocardium 心肌-Epicardium 心外膜
Differentiation of mesenchyme
Cell Population Functions and Fates
Endocardium Endothelial lining Connective tissue precursor (Valves and fibrous skeleton)
MyocardiumMyocytes Conduction system (Purkinje fibres) Myoendocrine cells (Atrial Natriuretic Factor production)
Epicardium Coronary vessel precursors Visceral pericardial lining
Early heart chambers
Sinus venosus (SV) 靜脈竇
This is the collecting compartment of the heart. Oxygenated blood from the placenta and deoxygenated blood from embryonic tissues are mixed in the sinus.
Primitive atrium (PA) 心房原基
This is the compartment destined for further partition to the definitive atria.
Primitive ventricle (PV) 心室原基
This is the compartment destined for further partition to the definitive ventricles.
Bulbus cordis (BC) 心球
This will contribute to the pulmonary trunk and aorta, along with the truncus arteriosus.
Truncus arteriosus (TA) 動脈幹
This will contribute to the aortic arches.
Fibrous skeleton (FS) 纖維骨架
This is the area of connective tissue proliferation, site of future valves.
Folding of the heart tube
Apoptosis in the dorsal mesocardium will allow movement of the early heart tube within the pericardial cavity
The folding of the heart tube brings the inflow and outflow trunks in an adjacent position at the superior aspect of the developing heart.
The dorsal fold forms the two pericardial sinuses and places the fibrous skeleton in a single plane
Inflow and outflow trunks are positioned posteriorly as a result of the dorsal fold
Normal development of Heart-Early Events -Critical Changes
-Endocardial cushion (心內墊) growth and fusion -Bulboventricular looping -Interatrial septum (心房間隔) formation -Interventricular septum (心室間隔) formation -Aortico-pulmonary septum (主肺動脈隔) formation
-Vascular Changes
Endocardial cushion fusion
Endocardial cushions are areas of the fibrous skeleton forming between the atrium and ventricle. Endocardial cushions serve two important functions:
-form a partition in the heart tube between the atrium (PA) and ventricle (PV) (tricuspid and bicuspid valves)-provide a "scaffold" of the interatrial septae and the interventricular septum
Defects in endocardial cushion fusion are associated with trisomies 18 and 21 (Down's syndrome).
Valvular atresia
Valvular atresias arise from the uneven partition of the AV canal. Depending on the size and position of the narrowed channel, a tricuspid atresia or a biscuspid atresia results. Atresias arising from anomalous partition of the canal are referred to as congenital atresias
Bulboventricular looping
BV looping is a consequence of several changes:- Dorsal folding The first dorsal fold forms an expanded primitive ventricle, referred to as the bulboventricular loop. - Ventricular growth Differential growth of the proximal ventricular tissue causes a counter-clockwise rotation of the folded heart tube. The site of ventricular growth marks the future left ventricle. Abnormal growth of the distal primitive ventricle causes clockwise rotation, an anomaly known as dextrocardia 心偏右 .- AV canal 房室管 partitioning The Atrio-Ventricular (AV) canal between the primitive atrium and ventricle has now been partitioned by the fusing endocardial cushions. - Shunting of venous return The development of the venous system causes an increase in right-sided venous return to the primitive atrium. Combined with the partitioning of the AV canal, the change in blood flow volume and directions assists in the outgrowth of the left ventricle.
Looping anomalies(dextrocardia)
Interatrial septum formation
Blue arrows - direction of growth; Red arrow - direction of blood flow;ECC - endocardial cushion; RA - right atrium; LA - left atrium.
原隔
原孔
次孔
次隔
Fossa ovalis 卵圓窩
Atrial septal defects 心房間隔缺損 (ASD)
Atrial septal defects (ASD) are fairly common, present in 10-15% of patients with congenital cardiac anomalies. It is more commonly observed in females than males (2-3:1).
Formation of left atrium
IVS Part Origin
muscular ventricular wall
membranous fused bulbar ridges 球狀脊fused endocardial cushions
AP - aorticopulmonary; ECC - endocardial cushion;Blue arrow - direction of bulbar ridge growth; Red arrow - direction of ventricular growth
Interventricular septum formation
球狀脊
室間孔
Ventricular septal defects 心室間隔缺損 (VSD)
Atrioventricular septum defect 房室瓣缺損
Aortico-pulmonary septum formation
The aortico-pulmonary (AP) septum arises within the truncus arteriosus. The septum results from the downwards growth and fusion of bulbar ridges, induced by invasion of neural crest cells. The AP septum serves to divide the ventricular outflow between the pulmonary artery and the ascending aorta
Tetralogy of Fallot The tetralogy of Fallot results from the asymmetric division of the AP septum. The result is a stenosed pulmonary artery and a VSD.
Tetralogy of fallot:-Pulmonary valve stenosis-Ventricular septal defect-Overriding aorta-Hypertrophy of right ventricle
Eisenmenger's syndrome
Characteristics of Eisenmenger's syndrome:-persistent truncus arteriosus -ventricular septal defect -left-right ventricular shunt -right ventricle hypertrophy
Normal development of Heart-Early Events -Critical Changes -Vascular Changes
-Overview of embryonic circulatory system -Venous development -Arterial development -Anatomical correlations
Overview of embryonic circulatory system
Venous system development
Arterial system development
Aortic arch derivatives
動脈導管動脈韌帶
Recurrent laryngeal n. and 6th aortic arch
Coarctation of aorta主動脈弓緊縮
Right arch of aorta
Anomalies of right subclavian artery
Anatomical correlations
Ductus arteriosus
Patent ductus arteriosus
Blue-pulmonary trunk; Red-aorta and tributaries; Green-patent ductus arteriosus
Embryologic Structure Adult Equivalent
Left anterior cardinal vein
disappears proximally distal portion contributes to Left superior intercostal vein anastomoses with Right anterior cardinal vein distally to form Left brachiocephalic vein
Left common cardinal vein oblique vein of left atrium
Left posterior cardinal vein disappears
Left horn of sinus venosus coronary sinus
Right anterior cardinal vein superior vena cava
Right common cardinal vein superior vena cava
Right posterior cardinal vein azygous vein
Primitive atrium right auricle
Foramen ovale fossa ovalis and limbus
First aortic archmaxillary artery contribution to external carotid artery
Second aortic arch persists dorsally as stapedial artery
Third aortic archproximal portions form common carotid artery distal portions form internal carotid artery
Fourth aortic archleft arch (with aortic sac) forms ascending aorta and arch right arch contributes to right subclavian artery
Fifth aortic arch does not persist
Sixth aortic arch
proximal left arch - left pulmonary artery distal left arch - ligamentum arteriosum proximal right arch - right pulmonary artery distal right arch - does not persist
Ductus venosus ligamentum venosum
Left umbilical vein
ligamentum teres distally degenerates proximally portion within septum transversum contributes to hepatic portal system
Right umbilical veindegenerates proximally and distally portion within septum transversum contributes to hepatic portal system
Left vitelline vein fuses with right vitelline vein to form portal vein
Right vitelline vein fuses with left vitelline vein to form portal vein
Development of lymphatic system