Cardiac diseases in pregnancy
Dr. Batool A. Hashim
Physiological effects of pregnancy on the cardiovascular system
Peripheral vasodilatation leads to fall in systemic vascular resistance.
Increased cardiac output s(CO), mainly due to increased in stroke volume and to lesser
extent due to increase in heart rate.
Cardiac output increases to about a maximum of 40% above non pregnant values by 24-28
wks.(patients with obstructive heart lesions such as aortic and mitral stenosis and
coarctation, will be less able to compensate for this extra work load and are , therefore, at
particular risk of heart failure in pregnancy)
In labour, sympathetic response to pain and uterine contractions produce a further increase
in cardiac output, blood pressure and circulating volume (500ml of blood return back to the
circulation with each contraction).
Postpartum, immediate relief of inferior vena caval compression, uterine contractions and
retraction redistributes blood into the systemic circulation, fluid is transferred from
extravascular spaces (edema) back to intravascular compartment.
CO returns to normal 2 wk after delivery.
Normal changes in heart sound during pregnancy:
Loud S1
Wide splitting of mitral and tricuspid components of 2nd heart sound
Physiological 3rd heart sound by 20 wk of gestation
>95% develop systolic murmur at left sterna angle
10% develop continuous murmur due to increased mammary blood flow.
There is may be bounding pulses. and ectopic beats are very frequent in pregnancy.
Risks to the mother:
1-Risk of pregnancy associated death increase with presence of 1) cyanosis
2) pulmonary hypertension 3 ) left outflow obstructive lesions 4)previous peripartum
cardiomyopathy5)impaired myocardial function6)poor functional class. Termination of
pregnancy should be discussed in women with
Pulmonary hypertension (primary or Eisenmenger syndrome)
Dilated cardiomypathy
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Marfan's syndrome (with dilated aortic root)
Severe obstructive lesion
2-increased morbidity including (endocarditis, arrhythmias, embolic events, heart failure,
and pulmonary hypertension).
Risks to the fetus:
1-Incidence of structural cardiac defects is 0.8% increased to 3-50% in babies of women with
cardiac disease.(screening for Down syndrome-2% association with major cardiac defectsFetal echocardiography at 14-16wk and 80% of major lesions will be detected at around 20
wk anomaly scan.
2-there is risk of IUGR
3-Iatrogenic and spontaneous preterm delivery with associated increased neonatal
morbidity
4- fetal abnormalities with medication e.g. warfarin, ACEinhibitors, amiodarone.
Antenatal management:
A joint clinic with a multidisciplinary team consisting of an obstetrician, cardiologist,
anesthetist and specialist midwives is essential
Detailed plan for antenatal and intrapartum care is discussed and documented.
Low risk cases are managed at local hospital and primary care team( after proper risk
assessment at specialist clinic)
Women with moderate-severe lesions should be cared for in a tertiary unit with a
multidisciplinary team available 24hr.
Proper history taking:
Age at diagnosis, previous surgery, results of previous investigations, previous cardiac
events, medications, exercise tolerance, symptoms-palpitations, chest pain, syncope,
oedema-, previous pregnancy and obstetric outcome, medication,
Examination:
PR, BP, heart sounds, murmurs, auscultation of lung bases.
Investigations:echocardiography, ECG,CXR-with abdominal shielding, MRI are safe in
pregnancy.
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Subsequent visit:
Direct questioning about symptoms, examination,PR,BP,heart sounds, and chest exam,signs
of PE, pregnancy induced hypertension, look for anemia, infection(UTI), if preterm labour
occurred, B2-agonists are contraindicated because of side effects of tachycardia,
palpitation,and hypotension, atosiban can be used with appropriate monitoring,
Steroid administration for fetal lung maturation can also be used as a single dose.
Anticoagulant is indicated
In patients with congenital heart disease who have pulmonary hypertension
Artificial valve replacement
Those with atrial fibrillation
Intrapartum management:
Spontaneous labour is safer and is to be awaited, providing the best possible analgesia using
regional block, avoiding maternal bearing down by performing instrumental delivery,
caeserian section is associated with a higher risk of hemorrhage, infection and DVT,
however, emergency CS poses higher risk than elective CS and they should be avoided either
by performing an elective section when vaginal birth is contraindicated or early intervention
when progress of labour is slow or there is fetal compromise.
Intrapartum maternal monitoring with ECG, o2 saturation, BP , in more severe cases, central
venous pressure monitoring is recommended.assessment of fetal condition by continous
electronic fetal monitoring ,regional block using a slow incremental, low dose epidural block.
Induction of labour is considered for obstetric indication, with doubled syntocinon
concentration, to reduce volume of fluid given, close eye on partogram and signs of
obstructed labour is diagnosed earlier .
Prophylactic antibiotic for endocarditis is indicated in artificial heart valves, previous history
of endocarditis, all women with structural defects requiring an instrumental or operative
delivery, 3rd and 4th degree perineal tear, and for manual removal of placenta . 1 gm
amoxicillin and 120 mg gentamicin IV, followed by 5 days course of oral ampicillin.
Ergometrine for management of 3rd stage is associated with intense vasoconstriction,
hypertension, and heart failure and is contraindicated in heart disease.
Postpartum monitoring in high dependency unit, strict input/output chart , return to
postnatal ward is delayed48-72 hr.
Thrumboprophylaxis with LMWH is recommended until the patient is fully mobilized
Most cardiac medication are safe with lactation except for some B blocker which can cause
neonatal bradycardia.
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Contraception
Barrier method of contraception are safe but unreliable
COCP is contraindicated where thrumbosis is a risk
Progesterone-only contraception have better side effect profile and long acting slow release
preparation such as implanon and mirena have improved efficacy compared to oral
preparation. Mirena insertion should be done in the hospital as the response to cervical
dilatation is unpredicted, screen for genitourinary infection with endocarditis prophylaxis is
recommended prior to insertion, sterilization for patients who complete their families,
laporoscopic procedures carry higher risk compared to vasectomy.
Specific heart condition occurring during pregnancy:
Mitral stenosis:
It is the commonest acquired cardiac lesion, accounting for 90%of rheumatic valvular
problem. The stenosis produce left atrial obstruction with consequent elevated left atrial
and pulmonary wedge pressures. Eventually, pulmonary oedema and atrial fibrillation may
occur. There is a fixed cardiac output, with limited ability to adapt to the increased demands
placed on the heart during pregnancy by raised intravascular volume and heart rate.
Significant problems may be anticipated if the valvular area falls below 2 cm^2. The woman
is at particular risk as the cardiacOP increases in early pregnancy and at immediately after
delivery as the 3rd stage leads to autotransfusion of blood from the uterus to the venous
circulation.
Surgical valvotomy in suitable cases can be performed before pregnancy, as well can be
performed safely in pregnancy.
Eisenmenger's syndrome
Condition associated with 50% maternal mortality, develop when the initial left-right shunt
reverses and cyanosis occurs. major risk in pregnancy is during labour and delivery when
there may be sudden changes in systemic vascular resistance leading to increase right- left
shunting and desaturation, the option of termination the pregnancy should be discussed due
to high maternal mortality, when pregnancy is continued , miscarriageand fetal growth
restriction are common because of relative hypoxia and cyanosis.
Coaractation of the aorta and Marfan's syndrome
Coaractation may be detected in childhood and is therefore is usually repaired when
encountered in pregnancy, in less severe cases it may not present until the 2nd and 3rd
decades when hypertension develops.The principle risk is of dissection of the aorta
associated with increased COof pregnancy and a possible increase in medial vessel
degeneration, in addition, endocarditis, intracranial hemorrhage and death have been
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reported.there is 2% for the fetus to develop aortic coaractation. The risk of maternal death
from uncorrected coaractation is 15%, the option of TOP should be discussed.
Antenatally any hypertension should be aggressively treated.
Marfan's syndrome is AD connective tissue abnormality that may lead to mitral valve
prolapsed and aortic regurgitation, aortic root dilatation and aortic rupture or dissection.
Pregnancy increases the risk of aortic rupture or dissection and has been associated with
maternal mortality of up to50% with very marked aortic root dilatation.
Echocardiography is able to determine the size of the aortic root, and should be performed
serially throughout pregnancy.
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