CONGENITAL HEART DISEASE

                        

CONGENITAL HEART DISEASE

Etiology

            Environmental

            genetic

            multifactorial causes

Chromosomal abnormalities

trisomy 21, 13 or 18.

40% of those with Down syndrome can have a cardiac defect, with atrioventricular septal defect and ventricular septal defect accounting for approximately 80% of lesions.

Cardiac defects are common in trisomy 18 (Edwards’ syndrome) and 13 (Patau’s syndrome).

Turner’s syndrome, 45XO, left heart lesions with Coarctation of the aorta in 10% of cases.

autosomal abnormalities = low birthweight, mental retardation, small stature and

Single gene defects

Pompe’s disease = causes cardiomyopathy,

Marfan’s syndrome = aorta root dilation

Noonan’s syndrome, = pulmonary valve or artery stenosis,

CATCH 22 syndrome: cardiac defects, abnormal facies, thymic aplasia, cleft palate, hypocalcemia.

DiGeorge syndrome

Teratogens

maternal infection

illness

ingestion of certain drugs

congenital rubella syndrome = peripheral pulmonary stenosis or an arterial duct.

offspring of diabetic mothers,

uncontrolled maternal phenylketonuria

Maternal ingestion of therapeutic drugs

lithium =Ebstein’s anomaly

phenytoin =semilunar valve stenosis, coarctation, arterial duct

isotretinoin

fetal alcohol syndrome

Syndromes

de Lange= VSD

Williams = supravalvar aortic stenosis,

Friedreich’s ataxia =hypertrophic cardiomyopathy

Jervell and Lange-Nielsen =prolonged QT

Holt–Oram = atrial septal defect,

VATERL=VSD

Recurrence Risk

risk for another pregnancy rises to about 2% if one previous child is affected

If two previous children are affected the risk rises to 6–8%

if the mother is affected there is an even higher risk (5–15%)

Fetal echocardiography provides an accurate means of diagnosing fetal cardiac abnormalities from about 18 weeks’ gestation

Nomenclature Of Congenital Heart Disease

heart has three parts –

            Atrial chambers

            Ventricular chambers

            Arterial trunks

Connections and relationships of these can be determined

Determine of how each of the three basic components or segments of the heart are connected.

Determine the arrangement and connections of the atrial chambers

Then to analyze the atrioventricular and ventriculoarterial junction.

Then position of the heart.

Atrial arrangement

atrial arrangement or situs has first to be determined.

This does not always follow the situs of the abdominal viscera

but usually that of the thoracic viscera and

thus the bronchial morphology.

analyse of the bronchial anatomy on X-ray, - with a penetrated film.

The right main bronchus is more vertical and shorter than the left,

branching above the lower lobe pulmonary artery while the left branches below it.

The right atrium lies on the same side as the right bronchus.

The usual atrial arrangement is described as solitus

its mirror image as inversus.

When the atrial situs is uncertain it is frequently called ambiguous

Careful analysis may show bilateral manifestations of right or left atrial morphology, which can then be described as right or left atrial isomerism.

            In the former, (right atrial isomerism) asplenia is the usual association

            in the latter, polysplenia.

Atrial arrangement or situs is summarized as follows:

            solitus: right atrium on right, left atrium on left

            inversus: left atrium on right, right atrium on left

            isomerism – right: bilateral right atria

            isomerism – left: bilateral left atria

            ambiguous: used if arrangement cannot be identified.

Atrioventricular connection

            The atrioventricular connection then describes the way the atria communicate with the ventricles at the atrio-ventricular junction.

            If the connections follow the normal pattern they are said to be concordant, e.g. right atrium to right ventricle and left atrium to left ventricle,

            Discordant atria connect with the contra-lateral ventricle.

            When both atrio-ventricular valves enter one ventricular chamber, the connection is described as double inlet

            if one or other atria is not directly connected to a ventricle, then that atrio-ventricular connection is said to be absent.

            it may not be possible to state exactly the atrio-ventricular connection which is then described as ambiguous.

These are summarized as follows:

            concordant: right atrium to right ventricle, left atrium to left ventricle

            discordant: right atrium to left ventricle, left atrium to right ventricle

            ambiguous: with atrial isomerism and one atrium entering each ventricle

            double inlet: both atria connect to the same ventricle

            absent right or left: no true or potential connection from the right or left atrium to a ventricle.

Ventriculoarterial connection

            This describes the means by which the great arteries take origin from the ventricular chambers.

            If an artery overrides the septum, and thus arises from both ventricles, it is assigned to that from which more than half takes origin.

Connections can thus be:

            concordant: pulmonary trunk from right ventricle, aorta from left

            discordant: aorta from right ventricle, pulmonary trunk from left

            double outlet: both great arteries from one ventricle

            single outlet: single great artery.

Three further steps

            are then necessary to complete the analysis: a statement of the relationship of structures; tabulation of associated lesions; and description of the cardiac position within the chest.

Relationships

These are described in simple terms,

            such as right/left,

            anterior/posterior,

            superior/inferior,

            side by side.

These relationships neither imply nor give any information on morphology or connections.

Additional abnormalities

These will include factors such as

            venous drainage,

            Septal defects,

            Stenosis or atresia of valves, and great artery anomalies such as coarctation.

Cardiac position

            When the heart is on the left side this is not usually stated if there is situs solitus,

            should be described as levocardia where there is an abnormal situs.

            Dextrocardia describes the situation in which more than half of the cardiac shadow on X-ray is in the right side of the chest

            it makes no assumptions as to the atrial situs or intracardiac anatomy.

            Mesocardia is used when the heart appears to be in the center of the thorax.

Comment

nomenclature may seem complicated

not required in the majority of patients who have normal chamber connections,   morphology and relations.

it simplifies assessment and description of complex defects

prevents any ambiguity in communication between different cardiologists and surgeons.

use the terms which have been in use for some time

Thus atrial situs solitus, atrioventricular concordance and ventriculoarterial discordance is simply to say  transposition of the great arteries.

Medical Care Of Congenital Heart Disease

cardiologist use interventional catheterization techniques to undertake corrective procedures for some less complex lesions

role of the physician is to provide general medical care

use the appropriate investigations to make an accurate diagnosis

refer the patient to the surgeon at the appropriate time.

The Newborn Infant With Congenital Heart Disease

The patient with congenital heart disease who survives beyond infancy has a good outlook,

Nowadays surgery generally carry a low risk.

With modern surgery, up to 15–20% of live-born children in whom a defect is recognized in infancy can die in the first year of life,

Infant with congenital heart disease may show rapid progression to severe cardiac failure or cyanosis with hypoxia and acidosis

Heart disease in the newborn is usually recognized by the presence of cyanosis or heart failure.

Early detection of cyanotic heart disease is difficult

hyperoxic test is useful where there is uncertainty

in response to hyperoxia (80–100% oxygen)  -  a _PO₂ of over 150 mmHg (21 kPa) from the upper body excludes a major right to left shunt and a failure to rise suggests a cardiac defect.

important early signs of heart failure are

            tachycardia       >160/min

            tachypnea         >50/min

            hepatomegaly

Palpation of the pulses

compare not only the right arm and the leg pulse but also the pulses in both arms.

With coarctation of the aorta or hypoplastic left heart syndrome the femoral pulses may feel normal initially when the ductus is open.

Low volume pulses occur with obstruction to left ventricular output such as hypoplastic left heart syndrome or severe aortic stenosis.

A parasternal or subxiphoid heave may indicate the presence of a significant defect in a patient where there is no abnormality on auscultation.

A single second heart sound should be considered abnormal after the first day of life.

Gallop rhythm indicates cardiac failure.

Many infants with significant heart disease have no murmur

When a murmur is heard it is not diagnostic but suggests the presence of an underlying defect.

ECG

Difficult to interpret in the first few days of life

            an infant with severe congenital heart disease can have a normal ECG.

chest X-ray is useful.

            contour of the heart and the great arteries and the effect of the anatomical abnormality on the pulmonary vascularity

            typical appearances are not always found.

            A large thymus may cause difficulty in interpretation of the cardiac silhouette

            increased pulmonary blood flow is not always reflected in the X-ray appearances.

Echocardiography may be more accurate

Catheterization is usually only required for interventional procedures such as atrial septostomy.

This is easily performed through the umbilical vein within the first 2 days of life.

Transfer to the cardiac centers should be as rapid as possible in a suitable transport incubator.

General care of temperature, acidosis and electrolyte imbalance is essential.

Prostaglandin therapy

The use of E-type prostaglandins to dilate the ductus arteriosus is an essential part in the management of the newborn infant with a ductus dependent circulation. T

his occurs either when there is

            marked obstruction to pulmonary blood flow (such as pulmonary atresia)

            in aortic arch abnormality (such as critical aortic stenosis or coarctation).

Prostaglandin E2, which is readily available in most obstetric hospitals, is cheaper than prostaglandin E1, and equally effective

Prostaglandins should be administered as a peripheral venous infusion

a suitable initial rate being 0.02 mg/kg/min

the dose being increased up to 0.05–0.10 mg/kg/min

depending on the clinical response.

serious complication of prostaglandin therapy is respiratory depression,

normal respiration rapidly returns when the infusion is stopped.

It should then be restarted at a reduced dosage.

Other side-effects include fever, tachycardia and jitteriness.