Upload
chin-chan
View
221
Download
0
Embed Size (px)
Citation preview
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 1/15
PATHOPHYSIOLOGY OF CONGENITAL HEART DISEASE
OBJECTIVES:
•
At the end of the lecture students will be able to• understand and describe the Pathophysiology of:
• Congenital heart defects
• Acyanotic heart diseases
• Cyanotic heart diseases
• Left to right shunts
• Right to left shunts
CONGENITAL HEART
DEFECTS
• Faulty embryogenesis (week 3-8)þ
• Usually MONO-morphic (i.e., SINGLE lesion) (ASD, VSD, hypo-
RV, hypo-LV)
• May not be evident until adult life (Coarctation, ASD)
• Overall incidence 1% of USA births
• INCREASED simple early detection via non invasive methods,
e.g., US, MRI, CT, etc.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 2/15
Tricuspid atresia
1120Total anomalous pulmonary venous connection
1136Truncus arteriosus
4388Transposition of great arteries
4388Aortic stenosis
4396Atrioventricular septaldefect
5492Coarctation of aorta
5577Tetralogy of Fallot
7781Patentductus arteriosus
8836Pulmonary stenosis
101043Atrial septaldefect
424482Ventricular septaldefect
%Incidence per Million Live
BirthsMALFORMATION
GENETICS
• Gene abnormalities in only 10% of CHD
• Trisomies 21, 13, 15, 18, XO
• Mutations of genes which encode for transcription
factorsTBX5ASD,VSD
NKX2.5ASD
• Region of chromosome 22 important in heart development,22q11.2 deletionconotruncus, branchial arch, face
ENVIRONMENT
• RUBELLA
• TERATOGENS
CONGENITAL HEART DISEASE
• Congenital heart disease is often divided
• into two types:
• Cyanotic (blue discoloration caused by a relative lack of oxygen)
• non-cyanotic
• LR SHUNTS: all “D’s” in their names
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 3/15
• NO cyanosis
• Pulmonary hypertension
• SIGNIFICANT pulmonary hypertension is IRREVERSIBLE
• RL SHUNTS: all “T’s” in their names
• CYANOSIS (i,.e., “blue” babies)• VENOUS EMBOLI become SYSTEMIC
• OBSTRUCTIONS
LR
• ASD
• VSD
• ASVD
• PDA
CONGENITAL HEART DISEASE
• Non-cyanotic: (left to right shunt)
• Ventricular septal defect (VSD)
• Atrial septal defect (ASD)
• Patent ductus arteriosus (PDA)
• Aortic stenosis
•Pulmonic stenosis
• Coarctation of aorta
• Atrioventricular canal (endocardial cushion defect)
ASD
• NOT patent foramen ovale
• Usually asymptomatic until adulthood
• SECUNDUM (90%): Defective fossa ovalis
• PRIMUM (5%): Next to AV valves, mitral cleft• SINUS VENOSUS (5%): Next to SVC with anomalous pulmonary
veins draining to SVC or RA
• Sinus venosus defect: high in the septum.
• Ostium secundum defect: midseptum.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 4/15
• Ostium primum defect: low in the septum.
• Pathophysiology: L-R shunt-increased flow across Rt heart-RV
& PA enlargement.
• Clinical features: asymptomatic, slow wt gain,
• Diagnosis: Rt ventricular heave, systolic murmur, fixed widesplit S2.
ATRIAL SEPTAL DEFECT
ATRIAL SEPTAL DEFECT
VSD
• By far, most common CHD defect
• Only 30% are isolated
• Often with TETRALOGY of FALLOT
• 90% involve the membranous septum
• If muscular septum is involved, likely to have multiple holes• SMALL ones often close spontaneously
• LARGE ones progress to pulmonary hypertension.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 5/15
• VENTRICULAR SEPTAL DEFECT
• Most common CHD (26%),may be single or
• multiple
• Pathophysiology: Lt-Rt shunt as long as pulmonary vascular
resistance is lower than systemic resistance, if reverse shuntreverses
• Large defects lead to pul. hypertension-Eissenmenger
syndrome.
• Clinical features: depend on size, asymptomatic, growth failure,
recurrent LRTI, congestive heart failure,
• Diagnosis: pansystolic murmur,
• Asymptomatic if defect is small.
• Heart failure with dyspnea, frequent respiratory infections, and
poor growth if defect is large.
• Pansystolic murmur maximal at the left sternal border.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 6/15
PDA
• 90% isolated
• HARSH, machinery-like murmur
• LR, possibly RL as pulmonary hypertension approaches
systemic pressure• Closing the defect may be life saving
• Keeping it open may be life saving (Prostaglandin E1). Why?
Ans: TGA, TA, TAPVC
• Connection between PA & descending aorta
• 10% of CHD
• Pathophysiology: Lt-Rt shunt, reverses if pulmonary resistance
increases-RV enlargement. If PDA is large Eissenmenger syndrome can develop
• Clinical features: depend on size & direction of flow, slowgrowth
• Diagnosis: bounding pulse, continous murmur, loud S2
• Murmur usually systolic, sometimes continuous, “machinery”
• Poor feeding, respiratory distress, and frequent respiratory
infections in infants with heart failure
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 7/15
• Physical exam and echocardiography
AVSD
•
Associated with defective, inadequate AV valves• Can be partial, or COMPLETE (ALL 4 CHAMBERS FREELY
COMMUNICATE)þ
• COMPLETE ATRIOVENTRICULAR CANAL
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 8/15
RL
• Tetralogy of Fallot
• Transposition of great arteries
• Truncus arteriosus
• Total anomalous pulmonary venous connection
• Tricuspid atresia
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 9/15
CONGENITAL HEART DISEASE
• Cyanotic: (right to left shunt)
• Tetralogy of Fallot
•Transposition of the great vessels
• Tricuspid atresia
• Total anomolous pulmonary venous return
• Truncus arteriosus
• Hypoplastic left heart
• Pulmonary atresia
• Some forms of total anomalous pulmonary venous return
• Ebstein’s anomaly
RL SHUNTS
• TETRALOGY of FALLOT most COMMON
• 1) VSD, large
• 2) OBSTRUCTION to RV flow
• 3) Aorta OVERRIDES the VSD
• 4) RVH
• SURVIVAL DEPENDS on SEVERITY of SUBPULMONIC
STENOSIS• Can be a “PINK” tetrology if pulmonic obstruction is small, but
the greater the obstruction, the greater is the RL shunt
TETRALOGY OF FALLOT
• Pulmonary stenosis
• VSD of the membranous portion
• Overriding aorta
• Right ventricular hypertrophy due to shunting of blood• Addition of an atrial septal defect falls in the category of
Pentalogy of Fallot.
• Hypoxic spells and squatting.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 10/15
• Cyanosis and clubbing.
• Addition of an atrial septal defect falls in the category of
Pentalogy of Fallot.
• Hypoxic spells and squatting.
• Cyanosis and clubbing.
TGA (TRANSPOSITIONof GREAT ARTERIES)
• NEEDS a SHUNT for survival, obviously
• PDA or PFO (65%), “unstable” shunt
• VSD (35%), “stable” shunt
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 11/15
• RV>LV in thickness
• Fatal in first few months
• Surgical “switching”
• Aorta from right ventricle, pulmonary artery from left ventricle
• Cyanosis from birth, hypoxic spells sometimes present• Heart failure often present
• Cardiac enlargement and diminished pulmonary artery segment
on x-ray
• Anatomic communication must exist between pulmonary and
systemic circulation, VSD, ASD, or PDA.
• TRUNCUS ARTERIOSUS
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 12/15
• Single large vessel overrides the ventricular septum and
distributes all the blood ejected from the heart.
• Large VSD is present.
TRICUSPID ATRESIA
• Tricuspid valve is completely absent in about 2% of newborns
with congenital heart disease.
• Blood flows from right atrium to left atrium through foramen
ovale.
• Early cyanosis.
• Hypoplastic RV
• Needs a shunt,
• ASD, VSD, or PDA
• High mortality.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 13/15
• Total Anomalous Pulmonary Venous Connection (TAPVC)
• PULMONARY VEINS do NOT go into LA, but into L. innominate
v. or coronary sinus
• Needs a PFO or a VSD
• HYPOPLASTIC LA
• Pulmonary veins do not make a direct connection with the left
atrium.
• Blood reaches the left atrium only through an atrial septal defect
or patent foramen ovale.
• Pulmonary congestion, tachypnea, cardiac failure, and variable
cyanosis.
OBSTRUCTIVE CHD
• COARCTATION of aorta
• Pulmonary stenosis/atresia
• Aortic stenosis/atresia
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 14/15
PULMONARY STENOSIS
• No symptoms in mild or moderately severe lesions.
• Cyanosis and right-sided heart failure in patients with severe
lesions.
• High pitched systolic ejection murmur maximal in second left
interspace.• Ejection click often present.
7/27/2019 lec4-sem5-CVSwk3-year3-20120505 (3)
http://slidepdf.com/reader/full/lec4-sem5-cvswk3-year3-20120505-3 15/15
COARCTATION OF AORTA
• M>F
• But XO’s frequently have it• INFANTILE FORM (proximal to PDA) (SERIOUS)
• ADULT FORM (CLOSED DUCTUS, i.e., NO PDA)
• Bicuspid aortic valve 50% of the time
AORTIC STENOSIS/ATRESIA
• VALVULAR
• If severe, hypoplastic LVfatal
• SUB-valvular (subaortic)þ
•
Aortic wall THICK BELOW cusps• SUPRA-valvular
• Aortic wall THICK ABOVE cusps in
ascending aorta
• Asymmetric Septal Hypertrophy
(Idiopathic
Hypertrophic Subaortic Stenosis)