Development of the Development of the VeinsVeins

Dr. Zeenat ZaidiDr. Zeenat Zaidi

The veins develop from the three major venous circuits, The veins develop from the three major venous circuits, vitellinevitelline, , umbilicalumbilical and and cardinal cardinal   

Like the arteries they develop in a Like the arteries they develop in a cephalocaudal direction cephalocaudal direction

The precursors to the veins are The precursors to the veins are never all present at the never all present at the same time. same time. 

In addition, In addition, as new structures develop the course of veins as new structures develop the course of veins changeschanges

The formation of the liver and the mesonephric kidney has The formation of the liver and the mesonephric kidney has profound affects in redirecting blood flowprofound affects in redirecting blood flow

Most of the venous blood is channeled from the Most of the venous blood is channeled from the left side left side to the right side of the body to the right side of the body through the through the anastomosing anastomosing vesselsvessels

Development of the VeinsDevelopment of the VeinsIn a In a 4 weeks4 weeks embryo, three embryo, three paired veins open into the paired veins open into the tubular heart:tubular heart: Vitelline veinsVitelline veins, returning , returning

deoxygenated blood deoxygenated blood from from the the yolk sacyolk sac

Umbilical veinsUmbilical veins, bringing , bringing oxygenated blood oxygenated blood from the from the placentaplacenta. .

Common cardinal veinsCommon cardinal veins, , returning returning deoxygenated deoxygenated blood blood from the from the body of the body of the embryoembryo

Vitelline VeinsVitelline VeinsPass through the Pass through the septum transversumseptum transversum and drain into the and drain into the sinus sinus venosusvenosusIn relation to the liver In relation to the liver developing within the developing within the septum transversum, septum transversum, the vitelline veins are the vitelline veins are divided into:divided into: Pre-hapatic part: Pre-hapatic part:

forms anastomosis forms anastomosis around the duodenum around the duodenum which later on gives which later on gives rise to the rise to the portal veinportal vein

Hepatic part: Hepatic part: interrupted interrupted by the liver cords, forms by the liver cords, forms an extensive vascular an extensive vascular network called the network called the hepatic sinusoideshepatic sinusoides

Post-hepatic part:Post-hepatic part: Left vein disappearsLeft vein disappears Right veinRight vein forms the: forms the:

Hepatic veins Hepatic veins && Hepatic Hepatic segment of segment of

inferior vena cavainferior vena cava

Umbilical VeinsUmbilical VeinsBring oxygenated blood Bring oxygenated blood from the placentafrom the placentaInitially run on each side Initially run on each side of the developing liver of the developing liver and drain into the and drain into the sinus sinus venosusvenosusAs the liver grows, the As the liver grows, the umbilical veins loose umbilical veins loose their connection with their connection with heart and open into the heart and open into the liverliverThe The right vein right vein disappearsdisappears by the end by the end of the embryonic period. of the embryonic period. The The left vein persistsleft vein persists

A wide channel, the A wide channel, the ductus venosusductus venosus, , appears through the appears through the substance of liver to substance of liver to connect the connect the left left umbilical vein with the umbilical vein with the inferior vena cavainferior vena cava

After birth: The left umbilical vein obliterate to form

the ligamentum teres of the liver The ductus venosus obliterate to form the

ligamentum venosum

Cardinal VeinsCardinal VeinsAre responsible to drain the Are responsible to drain the body of the embryobody of the embryo The cranial part of the embryo The cranial part of the embryo

is drained by paired is drained by paired anterioranterior cardinalcardinal veins veins

The caudal part of the embryo The caudal part of the embryo is drained by paired is drained by paired posteriorposterior cardinalcardinal veins veins

The anterior & posterior The anterior & posterior cardinal veins join to form cardinal veins join to form common cardinal veinscommon cardinal veins, which , which drain into the drain into the sinus venosus sinus venosus

Anterior Cardinal VeinsAnterior Cardinal Veins

Become connected by an Become connected by an oblique anastomosisoblique anastomosis which which shunts blood from left to shunts blood from left to rightrightThis anastomosing channel This anastomosing channel becomes the becomes the left left brachiocephalic veinbrachiocephalic veinLeft anterior cardinal veinLeft anterior cardinal vein Cranial part: Cranial part: becomes becomes

the the left internal jugular left internal jugular veinvein

Caudal part: Caudal part: degeneratesdegenerates

Right anterior cardinal veinRight anterior cardinal vein Cranial part: Cranial part: (cranial to (cranial to

the 7the 7thth intersegmental intersegmental vein) becomes the vein) becomes the right right internal jugular veininternal jugular vein

Middle part: Middle part: gives rise to gives rise to the the right right brachiocephalic veinbrachiocephalic vein

Caudal part of rightCaudal part of right anterior cardinal vein anterior cardinal vein and the and the right common right common cardinal veincardinal vein form the form the superior vena cava superior vena cava

Posterior Cardinal VeinsPosterior Cardinal VeinsDrain the Drain the caudal part caudal part of the of the body of embryo including body of embryo including the developing the developing mesonephroimesonephroi and largely and largely disappear with this disappear with this transitory kidneys.transitory kidneys.Caudally the two veins get Caudally the two veins get connected by an connected by an anastomosing channel anastomosing channel that that directs the blood from the directs the blood from the left to the right left to the right veinvein

Gradually the Gradually the posterior posterior cardinal veins cardinal veins are replaced are replaced by two new by two new veins: veins: subcardinalsubcardinal & & supracardinalsupracardinal

The adult The adult derivatives of derivatives of the the posterior posterior cardinal veins cardinal veins are the:are the: Root of the Root of the

azygosazygos veinvein &&

Common Common iliac veinsiliac veins

Subcardinal VeinsSubcardinal VeinsAppear before the Appear before the supracardinal veinssupracardinal veinsBecome connected:Become connected: To To each other each other by the by the

subcardinal subcardinal anastomosisanastomosis

With the With the posterior posterior cardinal veins cardinal veins through the through the mesonephrosmesonephros

With With supracarinal supracarinal veinsveins through through subsupracardinal subsupracardinal anastomosisanastomosis

The adult derivatives of The adult derivatives of the subcardinal veins are the subcardinal veins are the:the: Stem of the left renal Stem of the left renal

veinvein Suprarenal veinsSuprarenal veins Gonadal veinsGonadal veins PrerenalPrerenal segment of segment of

IVC IVC

Supracardinal VeinsSupracardinal VeinsLast pair of veins to Last pair of veins to developdevelop

Appear lateral to the Appear lateral to the subcardinal veinssubcardinal veins

Become connected Become connected at both ends, to the at both ends, to the posterior cardinal posterior cardinal veinsveins

Get disrupted in the Get disrupted in the region of the kidneyregion of the kidney

Cranial to the kidney:Cranial to the kidney: An anastomosis develops An anastomosis develops

between the two veins between the two veins shunting blood from the left to shunting blood from the left to the right veinthe right vein

Anterior connection of the left Anterior connection of the left vein with the posterior vein with the posterior cardinal vein disappearscardinal vein disappears

Gives rise to Gives rise to azygosazygos and and hemiazygoshemiazygos veins veins

Caudal to the kidney:Caudal to the kidney: LeftLeft veinvein degenerates degenerates RightRight veinvein forms forms postrenalpostrenal

segmentsegment of IVCof IVC

Development of Superior Vena Development of Superior Vena CavaCava

SVCSVC is derived from is derived from the:the: Caudal part of the Caudal part of the

right anterior right anterior cardinal veincardinal vein

& & Right common Right common

cardinalcardinal veinvein

Development of Azygos VeinsDevelopment of Azygos VeinsAzygos veinAzygos vein is derived is derived from the:from the: Cranial part of the right Cranial part of the right

supracardinal vein supracardinal vein & & Terminal part of the Terminal part of the

right posterior cardinalright posterior cardinal veinvein

Hemiazygos veinHemiazygos vein is is derived from thederived from the cranial cranial part of the left supra-part of the left supra-cardinal veincardinal vein

Development of Inferior Vena Development of Inferior Vena CavaCava

The The IVCIVC develops during a develops during a series of changes in the series of changes in the primordial veinsprimordial veinsComposed of:Composed of:Hepatic segmentHepatic segment derived derived

from the from the right vitelline right vitelline veinveinPrerenal segmentPrerenal segment derived derived

from the from the right subcardinal right subcardinal veinvein

Renal segmentRenal segment derived derived from the from the subcardinal-subcardinal-supracardinal anastomosissupracardinal anastomosis

Postrenal segmentPostrenal segment derived derived from the from the right supr-right supr-acardinal acardinal veinvein

Anomalies of the Venous SystemAnomalies of the Venous System

Persistent left SVC (double SVC): is the Persistent left SVC (double SVC): is the most common defectmost common defect

Left SVCLeft SVC

Absence of IVCAbsence of IVC

Double IVCDouble IVC

Double Arch of Aorta With Double Superior Vena Cava

Fetal CirculationFetal CirculationThe main features of the The main features of the

fetal circulation are:fetal circulation are:

Nonfunctioning lungsNonfunctioning lungs

Course of the Course of the blood from blood from the placenta to the heartthe placenta to the heart

Three shunts permitting permitting the blood to bypass the the blood to bypass the liver and lungs:liver and lungs: Foramen ovaleForamen ovale Ductus venosusDuctus venosus Ductus arteriosusDuctus arteriosus

The oxygenated blood The oxygenated blood from the placenta reaches from the placenta reaches the fetus by the fetus by umbilical veinumbilical veinMost of the blood Most of the blood bypasses the bypasses the liverliver through the through the ductus ductus venosusvenosus, although little , although little blood enters the liverblood enters the liverIn the In the inferior vena cavainferior vena cava, , the oxygenated blood the oxygenated blood mixes with the mixes with the deoxygenated blood deoxygenated blood arriving from the fetusarriving from the fetus

IVC opens into the right IVC opens into the right atrium. In the atrium. In the right atriumright atrium, , the caval blood is guided the caval blood is guided into the left atrium through into the left atrium through the the foramen ovaleforamen ovale..However, little blood However, little blood remains in the remains in the right atriumright atrium, , which mixes with the blood which mixes with the blood arriving through the arriving through the superior vena cava.superior vena cava.In the In the left atrium left atrium also, the also, the oxygenated blood mixes oxygenated blood mixes with deoxygenated blood with deoxygenated blood arriving from the lungs.arriving from the lungs.

Blood enters the Blood enters the left ventricle left ventricle and then into the and then into the ascending ascending aorta. aorta. Thus the Thus the heart and the heart and the brain receive better oxygenated brain receive better oxygenated blood.blood.The blood from the right atrium The blood from the right atrium enters into the right ventricle, enters into the right ventricle, and from there into the and from there into the pulmonary arterypulmonary artery..Most of the blood from the Most of the blood from the pulmonary artery enters into the pulmonary artery enters into the aorta through the aorta through the ductus ductus arteriosus.arteriosus.From the From the aortaaorta, the blood is , the blood is distributed to body tissues distributed to body tissues and and flows flows through the umbilical through the umbilical arteries into the placenta.arteries into the placenta.

The blood circulating in The blood circulating in the fetal arterial system the fetal arterial system is is not fully oxygenatednot fully oxygenated

There is There is mixing mixing of of oxygenated and oxygenated and deoxygenated blood in deoxygenated blood in the: the:

I.I. Liver sinusoidsLiver sinusoids

II.II. Inferior vena cavaInferior vena cava

III.III.Right atriumRight atrium

IV.IV.Left atriumLeft atrium

V.V. Descending aorta.Descending aorta.

I

II

V

IV

III

What happens at birth?What happens at birth?

Oh… let me take a deep breath… and then everything will be OK

At birth, At birth, dramatic changes occur in the dramatic changes occur in the circulatory pattern.circulatory pattern.

The changes are The changes are initiated by baby’s initiated by baby’s first first breath.breath. Fetal lungs begin to functionFetal lungs begin to function Placental circulation ceasesPlacental circulation ceases The The three shunts three shunts that short-circuited the that short-circuited the

blood during the fetal life blood during the fetal life ceasecease to to functionfunction

1. The infant’s lungs begin to function: The lungs inflate, which tends to draw blood from the

right ventricle. Oxygenated blood from the lungs passes through

pulmonary veins to left atrium. The increased pressure in the left atrium results in closure of the foramen ovale. effectively separating the two atria.

This also increases blood flow to the lungs as blood entering the right atrium can no longer bypass the right ventricle, which pumps it into the pulmonary artery and on to the lungs.

Neonatal CirculationNeonatal Circulation

2. The placental circulation ceases.2. The placental circulation ceases. Umbilical vessels Umbilical vessels are no longer needed. They are no longer needed. They

become become obliteratedobliterated Occlusion of the placental circulation causes Occlusion of the placental circulation causes fall of fall of

blood pressure in the inferior vena cava and right blood pressure in the inferior vena cava and right atriumatrium

3. The shunts stop to function:3. The shunts stop to function: Within a day or two of birth, the Within a day or two of birth, the ductus arteriosus ductus arteriosus

closes offcloses off, preventing blood from the aorta from , preventing blood from the aorta from entering the pulmonary arteryentering the pulmonary artery

The The ductus venosus closes off ductus venosus closes off so that all blood so that all blood entering the liver passes through the hepatic entering the liver passes through the hepatic sinusoids.sinusoids.

Adult Derivatives of Fetal Vascular Adult Derivatives of Fetal Vascular StructuresStructures

Ductus venosus Ductus venosus becomes the becomes the ligamentum venosumligamentum venosum, , attached toattached to the inferior vena cava. the inferior vena cava.

Ductus arteriousus Ductus arteriousus becomes becomes ligamentum arteriousumligamentum arteriousum

Foramen ovale Foramen ovale closes shortly after birth, fuses closes shortly after birth, fuses completely in first yearcompletely in first year and becomes and becomes fossa ovalisfossa ovalis

The intra-abdominal portions of the The intra-abdominal portions of the umbilical arteries umbilical arteries become become the the medial umbilical ligamentsmedial umbilical ligaments

The intra-abdominal portion of the The intra-abdominal portion of the umbilical vein umbilical vein becomes becomes the the ligamentum teresligamentum teres. . (the umbilical vein remains(the umbilical vein remains patent for a long patent for a long time and may be used for time and may be used for exchange transfusions exchange transfusions during early infancy. during early infancy. The lumen of the umbilical vein usually does not disappear completely; The lumen of the umbilical vein usually does not disappear completely; hence, the ligamentum teres can be hence, the ligamentum teres can be cannulated cannulated in adults for the injection in adults for the injection of contrast medium or chemotherapeutic drugs).of contrast medium or chemotherapeutic drugs).

Persistence of Fetal CirculationPersistence of Fetal CirculationPatent ductus arteriosus Patent ductus arteriosus and and patent foramen ovale patent foramen ovale each characterize about 8% each characterize about 8% of congenital heart defects. of congenital heart defects. Both cause a Both cause a mixing of mixing of oxygen-rich and oxygen-oxygen-rich and oxygen-poor bloodpoor bloodBlood reaching tissues is Blood reaching tissues is not fully oxygenated and not fully oxygenated and can cause can cause cyanosiscyanosis..Many of these defects go Many of these defects go undetected until child is at undetected until child is at least school age.least school age.