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Complete summary with diagramatic presentations of defects of the Heart
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CONGENTALHEART
DISEASE
By Dickens ATURWANAHO &ORIBA DAN LANGOYA
MAKchs, MBchB
Introduction
CHDs are abnormalities ofthe heart or great vesselsthat are present at birth.
Common type of heartdisease among children.
Pathogenesis The cause is unknown in
almost 90% of cases. Environmental factors,
such as congenital rubellainfection
Genetic factors Mutations of the TBX5
transcription factor causethe atrial and ventricularseptal defects seen in Holt-Oram syndrome.
Mutations in thetranscription factorNKX2.5-atrial septaldefects (ASDs).
Pathogenesis
Genes located onchromosome 22 have amajor role in forming theconotruncus, thebranchial arches, and thehuman face.
Deletions ofchromosome 22q11.2underlie 15% to 50% ofoutflow tractabnormalities
CHD can besubdivided into 3major groups:
1) Malformations causinga left-to-right shunt
2) Malformations causinga right-to-left shunt(cyanotic congenitalheart diseases)
3) Malformations causingobstruction
Left-to-Right Shunts
Left-to-right shunts: mostcommon type of congenitalcardiac malformation.
They include atrial andventricular septal defects,and patent ductusarteriosus.
Atrial septal defects:increased pulmonary bloodvol, while ventricular septaldefects and patent ductusarteriosus: increasedpulmonary blood flow andpressure
Can be asymptomatic orcan cause fulminant CHFat birth.
Dev’t of Atrial Septum & Defects
AS begins as an ingrowth ofthe septum primum
Minor degree of patencypersists in about 25% of thegeneral population.
1) The most common (90%) isthe ostium secundum ASD.
2) Ostium primum ASDs areless common (5% of cases).
3) The sinus venosus ASDs (5%of cases) associated withframeshift mutations in theNKX2.5 transcription factor.
Morphology
Ostium secundum ASDsa) smooth-walled defects near
the foramen ovale.
b) Hemodynamic lesions areaccompanied by RA &ventricular dilation.
c) RV hypertrophy, anddilation of the pulmonaryartery.
d) This reflect the effects of achronically increasedvolume load on the rightside of the heart.
Ostium primum ASDs
occur at the lowest part of theatrial septum and can extendto the mitral and tricuspidvalves
Abnormalities of the AVvalves are usually present
VSD and severe mitral andtricuspid valve deformities,with a resultant common AVcanal.
Clinical Features
ASDs initially cause left-to-right shunts, as aresult of the lowerpressures in thepulmonary circulationand right side of theheart.
Pulmonary vascularresistance can increase,resulting in pulmonaryhypertension
Ostium primum defectsare more likely to beassociated with evidenceof CHF, in part becauseof the high frequency ofassociated mitralinsufficiency
In general these defectsare well tolerated
Symptoms
• Generally asymptomatic
• Pulmonary plethoric: frequent chest infections
• Systemic Circulation Insufficiency:Failure to thrive、poor weight gain、feeding difficulty 、fatigue、shortness of breathe、sweating
• Cyanosis:Severe cyanosis in large lesions,softer heartmurmur and accentuated P2.
Clinical findings of ASD
X-ray findings
Plethoric Lung fields
RA and RVenlargement
Prominent PA segment
Normal or small aorticshadow
USG findingsRA , RV enlargement
RV overloaded
Parallel shunt between atria inDoppler
Complication of ASD
1. Bronchopneumonia
2. Congestive heart failure
3. Infective endocarditis
Ventricular Septal Defects
Incomplete closure of theVS allows L-to-R shunting,the most commoncongenital cardiac anomalyat birth.
VS is formed by fusion ofan intraventricularmuscular ridge that growsupward from the apex ofthe heart with a thinnermembranous partition thatgrows downward from theendocardial cushion.
The basal (membranous)region is the last part of theseptum to develop and isthe site of approximately90% of VSDs.
30% of VSDs occur inisolation; more commonly,they are associated withother cardiacmalformations.
Morphology
1. The size and location ofVSDs are variable.
2. Range from minutedefects to large defectsinvolving virtually theentire septum
3. RV is hypertrophied andoften dilated.
4. Increased diameter of thepulmonary artery.
5. Pulmonary hypertension
L→R Shunts – General Points
PDA & VSD Presents in infancy w/
heart failure, murmur,and poor growth
Left heart enlargement(LHE)
Transmits flow andpressure
ASD Presents in childhood w/
murmur or exerciseintolerance (AVSD or 1o
ASD presents earlier) Right heart enlargement
(RHE) Transmits flow only
AVSD can present as either depending on size of ASD & VSD component
Clinical Features
a) Small VSDs may be asymptomatic.
b) Larger defects, however, cause a severe left-to-rightshunt.
c) Pulmonary hypertension and CHF.
d) Reversal of the shunt and cyanosis.
e) Small- or medium-sized defects that produce jet lesionsin the right ventricle are also prone to superimposedinfective endocarditis.
Feature of the shuntsLeft to right shunts Right to left shuntsGenerally no cyanosis Cyanosis appears early
Increased pulmonarycirculation
Pulmonary circulationincrease or decrease
Decreased systemiccirculation
Deoxygenated bloodmix with oxygenatedblood in systemiccirculation
Pulmonary arterialhypertention(hyperkinetic、obstructive)
Persistent cyanosis in late stage(Eissenmager’s syndrome)
Patent Ductus Arteriosus
During intrauterine life, theductus arteriosus permitsblood flow from thepulmonary artery to the aorta,thereby bypassing theunoxygenated lungs.
Shortly after birth, the ductusconstricts; this occurs inresponse to increased arterialoxygenation, decreasedpulmonary vascularresistance, and declining locallevels of prostaglandin E2.
Complete, structuralobliteration occurs within thefirst few months ofextrauterine life to form theligamentum arteriosum.
PDAs account for about 7% ofcases of congenital heartlesions.
Morphology
The ductus arteriosus arises from the left pulmonary artery and joinsthe aorta just distal to the origin of the left subclavian artery.
In PDAs some of the oxygenated blood flowing out from the leftventricle is shunted back to the lungs.
Because of the resultant volume overload, the proximal pulmonaryarteries, left atrium, and ventricle can become dilated.
Dev’t of pulmonary hypertension, atherosclerosis of the mainpulmonary arteries and proliferative changes in more distal pulmonaryvessels are seen, followed by right heart hypertrophy and dilation.
PDA: Clinical Signs
Murmur Hyperactive precordium Bounding peripheral pulses Increase in pulse pressure Hypotension Respiratory deterioration
Clinical Features
PDAs are high-pressureleft-to-right shunts.
Audible as harsh"machinery-like"murmurs.
Eisenmenger syndromewith cyanosis and CHF
Infective endocarditisdue to high pressure
Eisenmenger’s Syndrome
A long standing L→R shunt will eventually causeirreversible pulmonary vascular disease
This occurs sooner in unrepaired VSDs and PDAs (vsan ASD) because of the high pressure
Once the PVR gets very high the shunt reverses (ie-now R→L) and the patient becomes cyanotic
If the ductus arteriosus remains open afterbirth and fails to close it is referred to as apatent ductus arteriosus. The term “patent”means open. Complications associated withpatent ductus arteriosus are poor growth andeating, easy tiring, and a rapid heart rate. Itis also common to notice that the infant is bluein color, especially while feeding, due to alack of oxygen.
Patent Ductus Arteriosus
PDA: Factors that increaseincidence
RDS
Correlated with severity of RDS. After surfactant treatment increased risk of clinically symptomatic
PDAo Prematurity:
1. Inversely related to gestational age
2. Found in approx. 45% of infants <1750gm80% of infants <1000gm
Right-to-Left Shunts
Cardiac malformationsassociated with right-to-left shunts aredistinguished bycyanosis at or near thetime of birth
Important right-to-left shunts(cyanotic congenital heart disease). A,Tetralogy of Fallot. B, Transposition ofthe great vessels with and withoutVSD. (Ao, aorta; LA, left atrium; LV,left ventricle; PT, pulmonary trunk;RA, right atrium; RV, right ventricle.)
Right-to-Left Shunts
Two important conditionsassociated with cyanoticcongenital heart diseaseare tetralogy of Fallotand transposition ofthe great vessels
Clinical findings Cyanosis Clubbing of the fingertips
(hypertrophicosteoarthropathy)
Polycythemia
R→L Shunts
Reduced PBF Presents more often with
cyanosis See oligemic lung fields Closure of PDA may
worsen cyanosis
Dynamic subvalvularobstruction here
causes “Tet spells”
Why arepressures
equal?
Tetralogy of Fallot
Most common cause ofcyanotic congenital heartdisease. (CCHD)
Accounts for about 5% ofall congenital cardiacmalformations.
4 features of thetetralogy
1) VSD2) Obstruction to the right
ventricular outflowtract (subpulmonicstenosis)
3) An aorta that overridesthe VSD
4) Right ventricularhypertrophy
Morphology
The heart is large and"boot shaped" as a resultof RV hypertrophy
Proximal aorta is largerthan normal, with adiminished pulmonarytrunk.
Right ventricular wall ismarkedly thickened.
PDA or ASD; are actuallybeneficial because theypermit PBF
The pulmonary outflowtract is narrowed
Clinical Features
Predominantmanifestation of TGA isearly cyanosis.
Infusions ofprostaglandin E2 can beused to maintain patencyof the ductus arteriosus
Maneuvers such as atrialseptostomy areperformed to createASDs that enhancearterial oxygensaturation. Even withstable shunting
Obstructive Lesions
Congenital obstruction toblood flow can occur atthe level of the heartvalves or within a greatvessel.
Common examples ofcongenital obstruction
1. Pulmonic valvestenosis,
2. Aortic valve stenosis oratresia.
3. Coarctation of theaorta.
Coarctation of the Aorta
Coarctation- is narrowing of the aorta at varying pointsanywhere from the transverse arch to the iliac bifurcation.
98% of coarctations are juxtaductal
Male: Female ratio 3:1.
Accounts for 7 % of all CHD.
It is accompanied by a bicuspid aortic valve. Congenitalaortic stenosis, ASD, VSD, or mitral regurgitation may alsooccur. In some cases berry aneurysms in the circle of Williscoexist.
Coarctation of the Aorta
Hemodynamics Obstruction of left ventricular outflow pressure
hypertrophy of the LV.
Coarctation of the Aorta
Clinical Signs & Symptoms Classic signs of coarctation are diminution or
absence of femoral pulses.
Higher BP in the upper extremities as comparedto the lower extremities.
90% have systolic hypertension of the upperextremities.
Pulse discrepancy between rt & lt arms.
Coarctation of the Aorta
Clinical Signs & Symptoms With severe coarc. LE hypoperfusion, acidosis, HF
and shock.
Differential cyanosis if ductus is still open
II/VI systolic ejection murmur.
Cardiomegaly, rib notching on X-ray.
Coarctation of the Aorta
Treatment With severe Coarctation maintaining the ductus
with prostaglandin E is essential.
Surgical intervention, to prevent LV dysfunction.
Angioplasty is used by some centers.
Re-coarctation can occur, balloon angioplasty isthe procedure of choice.
Transposition of the Great Arteries
The predominantmanifestation of TGA isearly cyanosis
Tissue hypoxia Right ventricular
hypertrophy
Left ventricle becomesatrophic
TGA is a discordantconnection of theventricles to theirvascular outflow.
Embryologic defect inabnormal formation ofthe truncal andaortopulmonary septa.
THE END
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