congenital heart disease (chd)

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