Formation of heart tube?
mesodermal cells make Endocardial cushions which fuse ventrally to make one heart tube. The heart tube will eventually become the endocardium. splanchnic mesoderm will become the myocardium
What will the endocardial cushions eventually become (specific structures:)
membranous intraventricular septum -- Atrioventricular canal = tricuspid and mitral orfices
What cells make up the aorticopulmonary septum? What is the function of the aorticopulmonary septum?
5th week of gestation, neural crest derived mesenchymal cells proliferate. - 180 degree spiral - Divide truncus arterioles into Atrial cannals: pulmonic artery and aorta
Fetal blood circulation:
Umbilical cord Ductus venosus: bypass liver circulation IVC Goes into RA and two paths can be taken: 1. Foramen ovale to LV LV --> ascending aorta: coronary arteries, upper body and brain; descending aorta 2. Mix with blood from superior vena cava --> RV --> Pulmonary Artery --> Ductus Arteriosus ---> descending aorta From descending aorta Umbilical vein back to Placenta
What happens after birth in infant circulation?
- Lungs expand and 1. decrease pulmonary resistance via dilation of wall and therefore vessels 2. Vascular resistance in vessels of lungs dilate in response to rich O2 blood supply = Decreases RVP and increases LAP. LAP > RAP and foramen ovale is shut Ductus Arteriosus starts closing due to decrease in prostaglandin and increase O2 saturation
blue-purple coloration of the skin and mucous membranes caused by an elevated blood concentration of deoxygenated Hb. Due to Right --> left shunting in congenital heart defects * bypassing lungs
Atrial Septal Defects anatomical cause:
Acyanotic: L--> R shunt Persistent opening in the intratrial septum after birth Direct communication between L. and R. A. Common site: ostium secundum
Physiology of Atrial Septal Defects
Oxygenated blood from LA →RA Volume overload of RA and RV. Eisenmenger syndrome may occur with increase RV compliance – if developed closure is contraindicated
Clinical presentations of Atrial Septal Defects
Most are asymptomatic (infant) If symptoms occur: dyspnea on exertion, fatigue, recurrent lower respiratory tract infections Adults: decreased stamina, palpitations (atrial tachy due to RA enlargement)
Physical findings on exam for Atrial Septal Defects (ASD)
Murmur in childhood/ adolescents (upper left systolic)
* murmur not common because pressure gradients are the same.
Systolic impulse along lower-left sternal border (RV heave)
S2 = widened, fixed pattern
Catherization: RA O2 saturation >> SVC (usually they are the same)
Treatment for ASD?
Closure in early infancy
Anatomy and physiology of a Patent Foramen Ovale (PFO) What is it usually associated with?
not a true ASD = persistant opening of foramen ovale (persistence of fetal anatomy) Usually silent because it remains closed due to LAP> RAP HOWEVER it can become significant if RAP>LAP – ex. pulmonary hypertension Paradoxical emoblism: thrombus in systemic vein breaks loos : RA -> LA --> systemic arterial circulation
Ventricular Septum defect ( Anatomy)
Abnormal opening in the inter-ventricular septum Membranous *
L→R shut - large shunt: volume overload in RV (not frequently), pulmonary circulation, LA, and LV = chamber dilation—systolic dysfunction can lead to pulm. Vascular disease as early as 2 yrs old. -pulm vas resistance = Eisenmenger syndrome
VSD clinical findings (symptoms)
Usually asymptomatic if small. Symptoms of heart failure Infants: tachypnea, poor feeding, failure to thrive, frequent lower respiratory tract infections Cyanosis/hypoxia and dyspnea (Eisenmenger syndrome) endocarditus
Physical findings on exam on VSD:
AND TREATMENT of VSD
Harsh holosystolic murmur best heard at left sternal border
*smaller = louder
CXR/ECG = Left sided enlargement
-R. enlargement when eisenmenger develops
-cyanosis and loud P2 closure (due to increase in Pul. vascular pressure)
Tx. Surgical or percutaneous closure
Anatomy of Patent Ductus Arteriosus (PDA)?
Physiology-- including 3 major causes?
Vessel that connects the left pulmonary artery to the decending aorta in fetal anatomy remains open.
Composed of smooth muscle (which usually reacts to O2 levels)
L --> R shunt that causes volume overload in pulmonary system, LA, LV and aorta
LV – dilate
* Left side of heart dilates
Desaturated blood to go to lower extremities.
-Rubella (1st trimester)
-born@ high altitued
Clinical findings on someone with PDA?
Early congestive heart failure, tachycardia, poor feeding, slow growth, recurrent lower respiratory
Moderate size lesion= fatigue, dyspnea, palpitations
Adult: Atrial fibrillation due to LA dilation
Turbulent flow = endocarditis (aka Endoarteritis)
Anatomy of Congenital Aortic Stenosis
BICUSPID AORTIC VALVE
Valvular orifice is significantly narrowed
-eccentric stenotic opening
= increase LV P= LVH due to PRESSURE LOAD
(dilation of aorta)
-bicuspid valve becomes progressively fibrosed and calcified (stenosis)
Clinical symptoms of congenital aortic stenosis?
Severe –infants: tachycardia, tachypnea, failure to thrive, poor feeding
Older children/adult – asymptomatic
- But when severe = fatigue, exertion dyspnea, angina pectoris, and syncope
Clinical findings for chronic aortic stenosis?
Harsh crescendo-decrescendo systolic murmur best heard at base of <3 with radiation to the neck
Bicuspid = murmur is preceded by an ejection click.
Severe disease = paradoxical splitting of S2
CXR/ECG: enlarged heart with dilated aorta; LVH
Treatment for Congenital Aortic stenosis?
Balloon valvuloplasty in infancy * immediately! but only in severe AS
SURGERY may be needed later.
Anatomy and physiology
Congenital fusion of the pulmonic valve commissures
Impairment of RV outflow = increase in RV pressure
Clinical symptoms of pulmonic stenosis?
mild vs. severe:
Mild/moderate = asymptomatic
Severe = dyspnea, exercise intolerance, decompensation, symptoms of right heart failure
Physical findings of pulmonic Stenosis?
- CXR/ ECG findings?
Palpable liver/ abdominal fullness
RV heave over sternum
Loud late-peaking crescendo-decrescendo systolic ejection murmur heard at upper-left sternal border—associated with a palpable thrill
Widening of S2
Pulmonic valve click decreases with inspiration (push cusps into pulm. Artery= muffle sound
CXR/ECG = RVH ; echocardiogram = increased gradient across Pulm. Valve, elevated Rt. Side pressures, RVH
Tx: balloon valvuloplasty
Coartation of Aorta: anatomy and physiology?
Preductal or postductal discrete narrowing of aortic lumen.
Usually associated with bicuspid valve
decrease anterograde flow = Increase afterload = increase LVP
Dilation of intercostal artiers that bypass site of coarctation
= costal notching
Clinical symptoms in people with coartation of aorta:
-infant and severe
-prognosis in asymtomatic patients?
Infants: Severe coartation= differential cyanosis (LE are cyanotic)
Less severe: mild weakness or pain in the LE following exercise (claudication) and detected later in childhood due to HTN.
Asymptomatic = UE hypertension later in life
Physical findings from examination of coartation of aorta:
-CXR and echo findings?
Femoral pulses are weak/ delayed
Differential BP if UE are still getting enough blood (coartaction is in descending aorta)
CXR—notching on inferior surface of posterior ribs; if severe may see actually constriction of aorta
Definitive diagnosis: CT, Doppler Echocardiography, MRI= imaging of aorta
Treatment of coarctation of aorta
- if less severe
neonates: prostaglandin infusion to maintain patency
Less severe = elective repair via surgery or percutaneous balloon dilatation
Tetralogy of Fallot
Abnormal anterior and cephalad displacement of infundibular portion of intraventricular septum
2. subvalvular Pulmonic stenosis
3. overriding aorta
4. RVH (due to pulmonic stenosis)