|
( HLHS , see figure 3 ), which often
results in the parents seeking a termination .
Most anomalies , including minor lesions , are generally not detected until the later scan . Even then , the findings depend on the skill of the operator and the nature of the abnormality . Screening services now reach a positive diagnosis of CHD of almost 50 % compared with 95 % at specialised centres . 4 , 5 Despite this , significant abnormalities may be missed , depending on the nature of the anomaly , the habitus of the patient , previous abdominal scarring and the position of the fetus . Complex lesions — such as aortic arch anomalies , anomalous pulmonary venous drainage and , occasionally , transposition of the great vessels — may still be missed , where there is no intracardiac malformation , such as a small ventricular septal defect ( VSD , see figure 1 ) and / or pulmonary stenosis , as occurs in 70 % of cases . 14-17 A so-called four-chamber view that is routinely performed is
|
Figure 1 . Ventricular septal defect . |
Centers for Disease Control and Prevention , National Center on Birth Defects and Developmental Disabilities |
Box 1 . Features that should prompt referral in a newborn
• Tachypnoea , especially after the first 24-48 hours when most of the respiratory causes have settled .
• If the pulses are uniformly poor or unequal with , for example , weaker femoral and / or brachial pulses .
• Cyanosis . Source : Menahem S et al 2016 25
especially in the premature infant , may result in a soft systolic murmur at the lower left sternal edge or the base of the heart , respectively .
Box 1 lists the features that should prompt referral to clarify the diagnosis and to allow for timely intervention even if an earlier fetal scan was reported as normal . Retrieval may be in order if it is not possible to carry out and interpret an echocardiogram onsite .
|
|||||
normal in such cases , with the need to |
A neonate may , rarely , present in |
|||||||
review the cardiac connections on the |
cardiac failure on day one , with full |
|||||||
three-vessel view , which is technically |
pulses , tachypnoea and an enlarged |
|||||||
more difficult . 18 |
liver from an extracardiac cause of aor- |
|||||||
A fetal scan will fail to determine |
tic run-off — for example , from a cer- |
|||||||
whether an atrial septal defect ( ASD ) or a small patent ductus arteriosus ( PDA , see figure 2 ) will close follow- |
ebral vein of Galen fistula or a large hepatic haemangioma . 3 In the former , a continuous murmur may be heard |
|||||||
ing the birth of the infant , although most do . 5 It is also difficult to diagnose minor stenosis of the pulmonary or |
with the bell over the eye socket or over the temporal region . The early onset of cardiac failure relates to the shunt |
|||||||
aortic valves because the imaging is |
being outside the pulmonary circu- |
|||||||
often normal and Doppler interroga- |
lation where the initial high pulmo- |
|||||||
tion is unhelpful as both circulations |
nary vascular resistance will limit the |
|||||||
are at systemic pressures . Small VSDs , |
shunt even from large communications |
|||||||
especially in the perimembranous |
between the two circulations . |
|||||||
areas , may be missed or overdiag- |
Neonatal myocarditis may present |
|||||||
nosed . It is also difficult to image mild |
as a shocked baby with poor pulses , |
|||||||
|
narrowing of the pulmonary arteries or the aorta . 5 The fine details of complex abnormalities are best left to the cardiology and radiology experts .
A prenatal diagnosis of a serious
|
tachypnoea and an enlarged liver ( best determined by percussion to assess the liver span ); this is often misdiagnosed as being due to sepsis . 11 A chest X-ray will show an enlarged heart with pul- |
|||||||
cardiac abnormality , while influenc- |
monary congestion . An ECG may show |
|||||||
ing both the timing and mode of deliv- |
low-voltage complexes and widespread |
|||||||
ery with the aim of delivery as close to |
ST- / T-wave changes . An echocardio- |
|||||||
term as possible , will especially dictate |
gram will confirm a poorly contracting |
|||||||
the site of delivery — whether at a cen- |
LV and , at times , also the right ventri- |
|||||||
tre of the mother ’ s choosing or at a tertiary centre . 19 The latter is essential if the fetus is diagnosed with a duct-de- |
cle ( RV ). These infants require early referral and occasionally intensive care , including extracorporeal membrane |
|||||||
pendent pulmonary or systemic cir- |
oxygenation for survival . |
|||||||
culation — for example , pulmonary atresia or an interrupted aortic arch , respectively . |
Hyperoxaemic test
Occasionally , it is uncertain whether
|
|||||||
Maintaining duct patency by an |
the newborn ’ s tachypnoea and cyano- |
|||||||
infusion of prostaglandin E1 will contribute to a stable haemodynamic state before early surgical and / or catheter intervention . 20 Any delay in arriving at a diagnosis and instituting appropriate management may result in a baby with a pulmonary dependent-duct cir- |
will influence the timing of delivery if the affected fetus does not respond |
which is further compounded by the nature of the cardiac anomaly . It |
Figure 2 . Patent ductus arteriosus
( PDA ).
left-to-right shunt will only develop following a drop in the pulmonary vas-
|
sis are related to cyanotic CHD or to a respiratory problem that may be managed at the birth centre . Transferring such an infant to a tertiary centre is a major undertaking . A hyperoxaemic test may be helpful . 3 , 26 Blood gases are performed on the infant initially in air |
||||
culation becoming increasingly cyanosed , hypoxic and acidotic , or with a systemic dependent-duct circulation |
to maternally administered medication . 5 , 22 In addition , ventricular function may also deteriorate as a result of |
remains essential for those attending newborns to call upon their clinical skills to ensure that the baby does not |
cular resistance ( PVR ). The drop in PVR occurs because the alveoli in the lung expand and rid themselves of amni- |
and then in 100 % oxygen — for example , while in a head box . Table 1 outlines the changes in pO2 in respiratory |
||||
developing cardiogenic shock if there |
profound anaemia in Rh-immunised |
have a significant cardiac abnormality |
otic fluid . In addition , new lung tissue |
and cardiac conditions . |
||||
is rapid closure of the duct , often misdiagnosed as sepsis . 3 In infants where the diagnosis is made after delivery , starting a prostaglandin infusion is required before transfer to a tertiary centre . |
pregnancies or in twin-to-twin transfusion ( see figure 4 ). Here , the obstetrician is guided by serial fetal scans aided by other parameters .
In summary , while fetal echocardiography has significantly altered
|
despite a normal fetal scan .
DIAGNOSIS OF HEART DISEASE IN THE NEWBORN
A FETAL diagnosis prewarns the clini-
|
is laid down , which contributes to a greater lung vascular bed and a drop in PVR . This results in an increasing leftto-right shunt , which if substantial , as in a large VSD or PDA , may lead to cardiac failure . |
Neonatal pulse oximetry screening
Despite the signs noted earlier , the
baby may appear well even though there may be a significant underly-
|
||||
The fetal scan will also be helpful in |
the natural history of heart disease |
cian of an underlying cardiac abnor- |
A specialist referral may be required |
ing cardiac abnormality . This is espe- |
||||
visualising poor ventricular function |
in newborns , occasionally , serious |
mality . Hopefully , only those infants |
if a murmur of moderate ( 2-3 / 6 ) or loud |
cially so if it is a duct-dependent |
||||
as may occur with a familial cardio- |
abnormalities may still be missed , |
who do not have a duct-dependent cir- |
( 4 / 6 ) intensity is heard in the new- |
systemic circulation and the ductus |
||||
myopathy or an intrapartum myocarditis . 21 Review of ventricular function is also essential if there are recurrent |
with one or more scans designated as normal . The findings will be influenced by the skill of the operator ; |
culation will be delivered away from tertiary centres .
It is reasonable to discharge a baby
|
born , and the diagnosis is uncertain . These murmurs suggest an underlying cardiac abnormality . However , many |
arteriosus remains patent . For example , in a tight coarctation of the aorta ( see figure 5 ), the RV will aid descend- |
||||
episodes of sustained supraventricu- |
the habitus of the mother , especially |
who is well and who has any commu- |
babies develop soft ‘ flow ’ murmurs |
ing aorta perfusion through the pat- |
||||
lar tachycardia ( SVT ) or a profound |
if obese ; the presence of abdominal |
nication between the systemic and |
( 1-2 / 6 ), with no other cardiovascular |
ent ductus . The femoral pulse volume |
||||
bradycardia from a congenital heart block . A failing left ventricle ( LV ) with developing signs of a hydropic fetus |
scarring or excess fluid ; and especially the position of the fetus . These may all result in suboptimal imaging , |
pulmonary circulations with plans for review over the next few weeks . 19 For example , with a large VSD , a significant |
signs , and require only ongoing observation . 24 Occasionally , a small muscular VSD or mild pulmonary artery stenosis , |
may be equal and , at times , greater than the brachial pulse . A murmur that may be heard between PAGE 24 |