tutorial (a child with heart murmur 1) (1)

8/11/2019 Tutorial (a Child With Heart Murmur 1) (1)

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Child with Heart Murmur 1


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Fetal Circulation


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Fetal Circulation

Right and left ventricles exist in parallel circuit.

Placentaprovides for gas and metabolite exchange.

The lungs do not provide gas exchange.

Vessels in the pulmonary circulation are vasoconstricted.


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Cardiovascular structures for mantainingparallel circulation in fetus

1) Ductus venosus

2) Foramen ovale

3) Ductus arteriosus


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Oxygenated blood fromplacenta flows to the fetus

through umbilical vein

PO2=33-35mmHg

50%of the oxygenatedblood enters hepatic

circulation

The rest bypasses theliver and joins the inferior

vena cava via ductusvenosus

Mixed up with poorlyoxygenated inferior vena

cava

PO2=26-28mmHg

Mixed blood enters rightatrium and flows across the

foramen ovale to the leftatrium

The blood flows into the leftventricle and ejected into the

ascending aorta

The less oxygenated blood fromsuperior vena cava enters theright atrium and transversetricuspid valve to the right

ventricle

The blood is ejected to thepulmonary artey

10% of right ventricular outflowenters the lungs as the

pulmonary arterial circulationis vasoconstricted

Major portion of the bloodbypasses the lungs and flowsthrough ductus arteriosus into

the descending aorta

Then the bloodreturns to the

placenta via twoumbilical arteries.


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Fetal Cardiac Output

The total fetal cardiac output = the combined outputof both the left and right ventricles

450 mL/kg/min

65% of descending aortic blood flow returns to the

placenta

35% perfuses fetal organs and tissues

Fetal cardiac output depends on the heart rate, if the

heart rate drops, as in fetal distress, cardiac output willbe falls.

Fetal heart is unable to increase stroke volume whenthe heart rate falls because it has low compliance.


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Dimensions of cardiac chamber

Major blood vessels are reflected in the relative dimensions of the bigproportions of chambers and vessels.

The branches of pulmonary arteries are small as the lungs receiveonly 15% of combined ventricular output.

The pressure in the Right ventricular is identical to that in the Leftventricle.


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Physiological changes of CVS at birth


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Primary change in circulation after birth is a shift of blood flow forgases exchange from placenta to the lungs.

Placental circulation dissapearspulmonary circulation established.

The removal of the placenta results in:

- Increase in systemic vascular resistance (because placenta had lowestvascular resistance in the fetus)

- Cessation of blood flow in the umbilical vein results in closure of theductus venosus.


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Lung expansion results in:

- Reduction of the pulmonary vascular resistance, increase inpulmonary blood flow and a fall in pulmonary artery pressure.

- Functional closure of foramen ovale as a result increase pressure inthe left atrium in excess of the pressure in the right atrium.

- Left atrium pressure increase as a result of the increased pulmonaryblood flow and increased pulmonary venous return to Left atrium.

- Closure of patent ductus arteriosus as a result of increased arterialoxygen saturation.


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Closure of the ductus arteriosus

Occurs within 10-15 hours after birth by constriction of the medialsmooth muscle in the ductus.

Anatomic closure is completed by 2-3 weeks of age by permanentchanges in the endothelium and subintimal layers of the ductus.


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Factors involve in the closure of the ductus:

- Oxygen level

- Prostaglandin E2 (PGE2) levels

- Maturity of the newborn+ Acetylcholine

+ Bradykinin


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Oxygen and the ductus

- Postnatal increase in oxygen saturation of the systemic circulation(strong stimulus for constriction of the ductal smooth muscle whichlead to the closure of the ductus)

- Decreased responsiveness of the immature ductus to oxygen is due to

decreased in sensitivity to oxygen-induced contraction.


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Coarctation of the aortaConstrictions of the aorta

May occur at any point from the transverse arch to the iliac bifurcation


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Clinical features

Recognized after infancy

Some children complain of weakness or pain in the legs afterexercise

Classic sign :

- Disparity in pulsation and blood pressure in the arms and legs

- The femoral, popliteal, posterior tibial, and dorsalis pedis pulses areweak / absent in 40% of patients

- Bounding pulses on the arms and carotid vessels- The radial and femoral pulses should always be palpatedsimultaneously for the presence of radial-femoral delay.

- Blood pressure in the legs is lower than in the arms.


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Clinical features continued

The precordial impulse and heart sounds are normal

A short systolic murmur is often heard along the left sternal border at the 3rdand 4thintercostal spaces.

The murmur is well transmitted to the left infrascapular area and occasionally to theneck.

Typical murmur of mild aortic stenosis can be heard in the 3rdright intercostal space.

The presence of a low-pitch mid-diastolic murmur at the apex suggests mitral valvestenosis

Neonates or infants with more severe coarctation with some degree of transverse archhypoplasia, initially have signs of lower body hypoperfusion, acidosis and severe heartfailure.

If detected before ductal closure, patients may exhibit differential cyanosis.

On physical examination, the heart is large, and a systolic murmur is heard along the leftsternal border with a loud 2ndheart sound.


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Haemodynamics CoA may be initiated by the presence of a cardiac abnormality that results in

decreased blood flow anterograte through the aortic valve.

In discrete juxtaductal CoA, ascending aortic blood flows through thenarrowed segment to reach the descending aorta, although left ventricularhypertension and hypertrophy result.

With more severe juxtaductal CoA, right ventricular blood is ejected throughthe ductus to supply the descending aorta.

Perfusion of the lower part of the body dependent on right ventricularoutput.

The ductal right to left shunting is shown as differential cyanosis with upperextremities (pink) and lower extremities(blue)

Blood pressure is elevated in the vessels that arise proximal to the coarctation(blood pressure as well as pulse pressure is lower below the constrictions.


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Differential diagnosis

Aortic stenosis

Cardiomyopathy

Congenital Adrenal Hyperplasia

Hypertension Myocarditis


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Management

Neonatal severe CoA:

-frequently associated with large malaligned VSD, intractable heart failure

-sick infants require temporary stabilization:

Mechanical ventilation

Correction of metabolic acidosis, hypoglycemia, electrolyte disorders

IV prostaglandin E infusion

-early surgical repair (single-stage CoA repair + VSD closure / 2 stage CoA repairfollowed by VSD closure at later date)


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Management

Asymptomatic / older children with discrete CoA:

-Presents with incidental hypertension / heart murmur.

-Choice of treatment (primary transcatheter balloon angioplasty, stentimplantation / surgical repair) depends on morphology of CoA and

age of presentation.


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Complications

High blood pressure

Stroke

Rupture of the aorta

Premature coronary artery disease Weakend or bulging artery in the brain


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Prognosis

Long-term prognosis following coarctation repair is excellent,although recurrence of coarctation at the area of repair is possible,even years following treatment.


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Acyanotic congenital disease includes left-to-right shunts resulting inan increase in pulmonary blood flow usually seen in

patent ductus arteriosus (PDA)

ventricular septal defect (VSD)

atrial septal defect (ASD) Obstructive lesions (such as aortic stenosis, pulmonary stenosis,

coarctation of the aorta) which usually have normal pulmonaryblood flow


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Cyanotic congenital heart disease occurs when some of the systemicvenous return crosses from the right side of the heart to the left andreturns to the body without going through the lungs (right-to-leftshunt).

Cyanosis,the visible sign of this shunt, occurs when approximately 5g/100 mL of reduced haemoglobin is present in systemic blood.


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Acyanotic

i. Ventricular Septal Defectii. Atrial Ventricular Defect

iii. Patent Ductus Arteriosus

iv. Endocardial Cushion Defect

v. Pulmonary Stenosis

vi. Aortic Stenosis

vii. Coarctation of the Aorta

Cyanotic (Most common cyanotic congenital hearts defects arethe five Ts)

i. Tetralogy of Fallot

ii. Transportation of the Great Arteries

iii. Tricuspid Atresia

iv. Truncus Arterious

v. Total Anomalous Pulmonary Venous Return

vi. Hypoplastic Left Heart Syndrome


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Classification ofCongenital Heart

Disease


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Clinical Manifestationsof Infant and Childrenwith Congenital Heart

Disease.


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Introduction

Congenital heart disease (CHD) emcompasses a spectrum ofstructural abnormalities of the heart or intrathoracic vessels.

Commonly presents in the newborn with;

i. central cyanosis

ii. Heart failureiii. Sudden collapse

iv. Heart murmur


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Cardiovascular Response In Congenital Heart Defects

PatientsPatients with minor CHD (e.g., small left-to-right shunt lesions or mild obstructivelesions) experience little or no effect on exercise capacity.

Large left-to-right shunt lesions decrease exercise capacity because a ventricle that has amuch increased stroke volume at rest has a limited ability to increase the stroke volumefurther.

In patients with severe obstructive lesions, the ventricle may not be able to maintain anadequate cardiac output, so that with exercise thesystemic BP may not increaseappropriately and decreased blood flow to the exercising muscles may lead to prematurefatigue.

In cyanotic lesions, the arterial hypoxemia tends to increase cardiac output and decreasemixed venous oxygen saturation, thereby limiting the usual increment in stroke volumeand oxygen extraction that occurs with exercise. Furthermore, these patients have anincreased minute ventilation at rest and with exercise. In this way, ventilatory as well ascardiac mechanisms may limit exercise capacity.


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Cyanotic Congenital Heart

Disease


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Occur when some of the systemic venous

return crosses from the right side to the left

side of the heart without going through the

lungs

Also known as right to left shunt


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Cyanotic Congenital heart defects


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Transposition of the great arteries - group

of congenital heart defects involving an

abnormal spatial arrangement of any ofthe great vessels: superior or inferior vena

cava, pulmonary artery, pulmonary veins,

and aorta.


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Truncus arteriosus- the embryological structure known as

the truncus arteriosus fails to properly divide into

the pulmonary trunk and aorta. This results in one arterial

trunk arising from the heart and providing mixed blood to

the coronary arteries, pulmonary arteries, and systemic

circulation.


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Total anomalous pulmonary venous return - all

four pulmonary veins are malpositioned and

make anomalous connections to the systemicvenous circulation.


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Tricuspid atresia - is a form of congenital heartdisease whereby there is a complete absence

of the tricuspid valve. Therefore, there is anabsence of right atrioventricular connection.This leads to absent of right ventricle. Thisdefect is contracted during prenatal

development, when the heart does not finishdeveloping. It causes the heart to be unable toproperly oxygenate the rest of the blood in thebody


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Eisenmenger's syndrome - is defined as the

process in which a left to right shunt caused by

a congenital heart defect in the fetal heart

causes increased flow through the pulmonaryvasculature, causing pulmonary

hypertension,which in turn causes increased

pressures in the right side of the heart andreversal of the shunt into a right-to-left shunt.


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Tetralogy of Fallot

Anatomically there are four features

-Ventricular septal defect

-pulmonary stenosis

-Overriding aorta

-right ventricular hypertrophy


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Clinical feature

Cyanosis which depends on the amount of

pulmonary stenosis.

Heart failure is not a usual feature in patients

with tetralogy of Fallot, with the exception of

some young infants with pink or acyanotic

tetralogy of Fallot.

Initially it can be acyanotic

Pulmonary stenosis murmur


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If the pulmonary become more severe the

right to left shunt at VSD increase and the

patient become more cyanotic

Hypoxic spellchild become restless and

agitated and may cry inconsolably


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Hyperpnea occur gradually with cyanosis

In severe spells, prolonged unconsciousness

and convulsions, hemiparesis, or death may

occur


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Two-dimensional echocardiography is the definitivenoninvasive test to determine the presence ofcongenital heart disease.

Cardiac catheterization is less often used for diagnostic

purposes, and is usually performed to examinestructures that are sometime less well visualized byechocardiography, such as distal branch pulmonaryarteries or aortopulmonary collateral arteries inpatients with tetralogy of Fallot with pulmonary

atresia, coronary arteries and right ventricularsinusoids in patients with pulmonary atresia and intactventricular septum


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Treatment

For hypoxic spells consist of oxygen

administration and place the child in the knee

chest position to increase venous return.

IV line and administration of phenylephrine,

morphine sulphate and propanolol.

Complete surgical repair with VSD closure and

removal or patching of the pulmonary stenosiscan be performed in infancy


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Occasionally palliative shunt surgery between

the subclavian artery and pulmonary artery

are performed for complex form of tetralogy of

Fallot


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Prognosis

Untreated, the combination of right to left

shunt, chronic cyanosis and polycythaemia

predispose to :

Cerebral thrombosis and ischaemia

Brain abscess

Bacterial endocarditis

Congestive cardiac failure


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ACYNOTIC HEART

DISEASE


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1) ATRIAL SEPTAL

DEFECT

Failure of septal growth or excessive reabsorption oftissue.


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Three types of ASDs exist

secundum defect,

primum defect

sinus venosus defect.

Another rare form of defect is coronary sinus ASD.


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Ostium secundumdefect is the most common typeof ASD, accounting for 50% to 70% of all ASDs. Thisdefectis present at the site of fossa ovalis

Ostium primumaffecting the endocardial cushiontissue that gives rise to the mitral and tricuspid valve.

It is located in the lower atrial septum . Often seen inDown syndrome.

Sinus venosusdefect is most commonly located atthe entry of the superior vena cavaand rarely at

the entry of the inferior vena cava (IVC) . May beassociated with anomalous pulmonary venousreturn


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In acyanotic patients with atrial septal defect(ASD), the direction of the shunt is from left to

right

The magnitude of the left-to-right shunt isdetermined by the size of the defect and the

relative compliance of the right ventricle (RV)

and left ventricle (LV)

The magnitude of the shunt is reflected in the

degree of cardiac enlargement


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HAEMODYNAMICS

cause enlargement of RA , RV and PA

CLINICAL


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CLINICAL

MANIFESTATION Even with large large ASD and significant shunts, infants and

children are rarely symptomatic.

A widely split of S2 often audible due to delayed closure

of pulmonary valve

A prominent right ventricular impulse at the left lower sternalborder often can be palpated.

A soft (grade I or II ) systolic ejection murmur at the pulmonary

valve area ( upper left sternal border). (The heart murmur in ASDis not caused by the shunt at the atrial level but it is originates fromthe pulmonary valve because of the increased blood flow passingthrough this normal-sized valve, producing a relative stenosis ofthe pulmonary valve)


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A large shunt may result in a mid diastolic

murmur at the tricuspid area (left lower sternalborder) as a result of the increased volume

passing across the triscupid valve.

DIFFERENTIAL


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DIFFERENTIAL

DIAGNOSIS

Atrioventricular Septal Defect, Partial and

Intermediate

Partial Anomalous Pulmonary Venous

Connection

Pulmonary Stenosis, Infundibular

Pulmonary Stenosis, Valvar


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PRINCIPAL

MANAGEMENT

If a significant shunt is still present at around 3

years age, closure is usually recommended.

Many secundum ASDs can be closed with an

ASD closure device in the catheterisation

laboratory


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PROGNOSIS

Ostium secundum defect are well tolerated and

symptoms and complication only present in 3rd

decade or later

Ostium primum defect depend on the degree of

left to right shunt, pulmonary hypertension and

severity of mitral regurgitation. Without surgicalrepair congestive cardiac failure will develop in

infancy/ early childhood.


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COMPLICATION

Heart failure

infective endocarditis


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VENTRICULAR SEPTAL

DEFECT


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Ventricular septum is a complex structure that

can be divided into four component.

Muscular septum, endocardial cushion tissue,supracristal septum and membranous septum.

VSD occur when any of these component fails to

develop normally


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SUBTYPE of VSD

Large/ Small VSD

Perimembranous

Muscular

Multiple / Small defect ( Maladie de Roger)

Perimembranous VSDs are the most common of

all VSDs


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Large VSDs are not symptomatic at birthbecause the pulmonary vascular resistance is

normally elevated at this time.

As the pulmonary vascular resistancedecreases over the first 6 to 8 weeks of life, the

amount of shunt increases and symptoms may

develop.


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HAEMODYNAMICS

PA ,LA and LV will be enlarged

CLINICAL


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CLINICAL

MANIFESTATION

Size of the VSD affects the clinical

presentation.

Small VSDs with little shunts are oftenasymptomatic but have a loud murmur.

Moderate to large VSD result in pulmonary

over circulation and heart failure, presenting asfatigue , diaphoresis (profuse sweating) with

feeding and poor growth.


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DIFFERENTIAL


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DIFFERENTIAL

DIAGNOSIS

Aortic Stenosis, Subaortic

Double Outlet Right Ventricle, NormallyRelated Great Arteries

Double-Chambered Right Ventricle

Pulmonary Stenosis, Infundibular

PRINCIPAL


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PRINCIPAL

MANAGEMENT 1/3 of all VSD close spontaneously.

Small VSD usually close spontaneously and, if they do

not close, surgical closure may not be required.

Initial treatment for moderate to large VSDs include

diuretics, digoxin and after load reduction.

Continued poor growth or pulmonary hypertension require

closure of the defect

Some VSDs especially muscular defect can be closed

with devices placed at cardiac catherization.


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PROGNOSIS

The majority defect will close spontaneously


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PATENT DUCTUSARTERIOSUS

(PDA)


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Functional closure of the ductus arteriosus occurs within 10 to 15hours after birth by constriction of the medial smooth muscle in theductus.

Anatomic closure is completed by 2 to 3 weeks of age by permanent

changes in the endothelium and subintimal layers of the ductus. Oxygen, prostaglandin E2(PGE2) levels, and maturity of the newborn

are important factors in closure of the ductus.

Acetylcholine and bradykinin also constrict the ductus.


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Etiology and Epidemiology

The ductus arteriosus allows blood to flowfrom the pulmonary artery to the aortaduring fetal life. Failure of the normal

closure f this vessel result in a PDA With a falling pulmonary vascular resistance

after birth, left to right shunting of bloodand increased pulmonary blood flow occur.

Excluding premature infants, PDAs represent

approximately 5% to 10% of congenitalheart disease.


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The physical examination findings depend on the size of the shunt.

A widened pulse pressure is often present as a result of the runoff ofblood into the pulmonary circulation during diastole.

A continuous, machine-like murmur can be heard at the left

infraclavicular area. Larger shunts with increased flow across the mitral valve may result in

a mid-diastolic murmur at the apex and a hyperdynamic precordium.

Splitting of S2and intensity of P2depend on the pulmonary arterypressure. A thrill may be palpable.


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Management

Small PDA:

i. No treatment is required if there is no murmur

ii. If murmur present: Elective closure as risk of endarteritis (inflammation ofthe inner lining of an artery).

Moderate to large PDA:

i. Anti-failure therapy if there is heart failure // initial management is withdiuretics, but eventually require closure.

ii. Timing, method of closure (surgical vs. transcatheter) depends onsymptoms severity, size of PDA and body weight // catheterizationlaboratory by either coil embolization or a PDA closure device.


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Complications

Poor growth

Heart failure

Pulmonary haemorrhage

Bacterial endocarditis


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Prognosis

Generally good once PDA closed. PDA is much less likely to closewhen present in well term infants (It would be problematic is stillpatent at 2 weeks since spontaneous closure is very rare then).

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