Pregnancy in cardiac disease : clinical , obstetric and anaesthetic concerns

In the past patients with cardiac disease were advised against pregnancy. With improved cardiac care and better obstetric as well as anaesthetic facilities, pregnant cardiac patients are on rise. Their management involves joint efforts of cardiologist, obstetrician and anaesthetist. Instead of a specific technique, what underlies a successful anaesthesia in cardiac patients is maintenance of haemodynamic stability and avoiding adverse physiological effects of parturition on maternal pathophysiology. Both regional as well as general anaesthesia provide successful outcomes. Vaginal delivery is preferred over caesarean section.


Introduction
Cardiac disease is the third most common cause of maternal death 1 .Though in early 1900s maternal mortality was high in cardiac disease, now it ranges from 0.5% to 2.7%.0.2% to 4% of pregnant patients have a cardiac disease.20% of such cases have severe cardiac complications [2][3][4][5] .Most of the patients having New York Heart Association (NYHA) class I or II status before pregnancy, accomplish pregnancy safely.Exceptions include patients with fixed left-sided obstruction (mitral or aortic stenosis), those with pulmonary vascular disease or aortic valve disease.Patients with NYHA class III or IV are at a higher risk.Assessment of the ability of the abnormal heart to make the necessary adaptations to the major physiological cardiovascular changes occurring during pregnancy, labour and delivery is necessary.One should be able to predict potential trouble in advance both for the mother and the baby, and reduce likely adverse effects (environmental and genetic) on the foetus 1 .
Physiological changes in the cardiovascular system in pregnancy include a 50% increase in blood volume, 40% increase in cardiac output and a 25% increase in heart rate by the end of second trimester.There is a fall in systemic vascular resistance (SVR) and pulmonary vascular resistance (PVR).There occurs an increase in myocardial oxygen demand by approximately 50% during labour 1,2,6,7 .
Vaginal delivery is preferred over caesarean section (CS) 5,7 .The advantages include reduced blood loss and fluid shifts, reduced metabolic demands and stress response and lower incidence postoperative infections and pulmonary complications.Indications for CS include: severe aortic stenosis, aortic dissection, recent myocardial infarction, Marfan syndrome with aortic root involvement and severe heart failure during delivery (The principle is to avoid haemodynamic stress of labour) 5 .

General considerations
Four main predictors of cardiac events are prior cardiac event (e.g.heart failure, ischemia, dysarrythmia, stroke), baseline NYHA functional class >II or presence of cyanosis, left heart obstruction (mitral valve area <2 cm 2, aortic valve area <1.5 cm 2 , left ventricular outflow tract gradient > 30 mm Hg by echocardiography) and reduced left ventricular function (ejection fraction <40%).For risk estimation each predictor is assigned one point each.The estimated risks for cardiac event with 0,1 and >1 points are 5%, 27% and 75% respectively 4 .

Predelivery
The main aims: antepartum stabilisation of the mother's condition (e.g.use of b-blockers, thromboprophylaxis, or pulmonary arterial vasodilators as required), monitoring any for deterioration; and minimizing stress on the cardiovascular system during delivery and the post-partum period.Diuretics, digoxin, and hydralazine, nitrates, or both as vasodilators to offload the left ventricle may be used for heart failure.Assessment for any foetal problems due to various drugs is required 6 .

Intrapartum
Regional analgesia during labour helps reduce increase in cardiac output and myocardial oxygen Vol.33, No. 4, 2011   Pregnancy in cardiac disease: clinical, obstetric and anaesthetic concerns demand due to pain and anxiety and facilitate instrumental delivery 8 .General and regional anaesthesia (spinal, epidural, or combined spinal-epidural) can all be used for Caesarean section 9 .Cardiovascular stability is the goal 7 .Oxytocin, if required, postdelivery, is given only by infusion 10 .Bolus administration should be avoided.Ergometrine in severe cardiac disease leads to vasoconstriction and hypertension, and increases the risk of myocardial infarction and pulmonary oedema.Therefore, it should be avoided.Carboprost can lead to or exacerbate pulmonary oedema 7 .

Postpartum
In the post-partum period, high-level maternal surveillance is required till the main haemodynamic changes resolve.The patient is monitored in a high dependency unit (HDU)/ intensive care unit (ICU) with haemodynamic and fluid therapy monitoring.Congestive cardiac failure may occur in first 24-72 hours 11 .For unstable cardiac conditions, surveillance may be required in hospital for up to 2 weeks 7 .Chest infection or peripartum cardiomyopathy (which may occur anytime from 1 month predelivery up to 5 months post-delivery) may compromise postpartum period 9 .Adequate posto-perative analgesia should be provided.Due to risk of deep vein thrombosis and subsequent embolisation, early ambulation is advised 12 .

Cyanotic CHD
These include tetralogy of fallot, tricuspid atresia, Eisenmemger syndrome and transposition of great vessels 25 .
Cyanotic lesions have a right to left shunt.Conditions leading to increase in pulmonary vascular resistance (PVR) or a fall in systemic vascular resistance (SVR) should be avoided (Table 1).Uptake of inhalational anaesthetic is reduced leading to prolongation of induction.Onset of intravenous anaesthetic is fast.Nitrous oxide causes rise in PVR and should be used with caution.Air embolism can have disastrous consequences and has to be meticulously avoided.Epidural catheter placement should be done using saline instead of air.Fall in PVR is beneficial.Hence, increasing FiO 2 and respiratory rate helps decrease the shunt fraction [15][16][17][18][19][20][21][22][23][24][25] .

Hyperthermia
Arterial line may be needed.Central venous pressure (CVP) monitoring is reserved for symptomatic patients while pulmonary artery catheter (PAC) placement is anatomically difficult.Transoesophageal echocardiography (TEE) is a useful real time monitor of cardiovascular status, especially under GA 26 .

Tetrallogy of fallot
It constitutes 15% of all congenital cardiac diseases 11 .It comprises ventricular septal defect, pulmonary stenosis/ right ventricular outflow tract obstruction (RVOTO), overriding aorta and RV hypertrophy 11,19,25 .Most pregnant women will have had corrective surgery (closure of the VSD and widening of the pulmonary tract) 27 .Such patients tolerate pregnancy well and are managed like normal obstetric patient alongwith antibiotic prophylaxis and caution for air embolism 11,26 .

Anaesthetic management
Labour: Epidural analgesia or combined spinal epidural (CSE) technique in first stage using intrathecal opiods followed by titrated dilute bupivacaine solutions prevent rapid SVR changes.Hypotension is treated with phenylepherine (though it causes elevation of PVR) 17,28 .CS: Both regional and general anaesthesia can be used 11 .Single shot spinal should be avoided.Epidural anaesthesia with slow titration of local anaesthetic is used 29 .If general anaesthesia (GA) is used, induction with narcotic and etomidate is preferable to avoid haemodynamic changes 11,26 .
Goals: maintain preload (avoid aortocaval compression) and sinus rhythm, avoid increase in PVR and myocardial depressants, maintain spontaneous respiration 24 .

Eisenmenger syndrome
It is defined as PVR>800 dyne per cm 2 along with right to left or bidirectional shunt.Symptoms include fatigue, dyspnoea, cyanosis, oedema and polycythemia 2,25 .These patients are prone to thromboembolism 2 .

Anaesthetic management
Labour: Intrathecal opioids in first stage.Anticoagulation can be a concern.Intravenous patient controlled analgesia is an option.Avoid methergine.Oxytocin and prostaglandins should be used with caution 2 .
Caesarean Section: Subarachnoid block is contraindicated 25,26 .Epidural anaesthesia with slow titrated dose of local anaesthetic can be used 2,29 .However avoid fall in SVR.If GA is used, ketamine and etomidate are preferred.Positive pressure ventilation, however causes increase in PVR 2,25,29 .Goals: maintain preload, SVR and sinus rhythm.Avoid increase in PVR and myocardial depressants 2,19,30 .

Acyanotic CHD
These include atrial septal defect (ASD), ventricular septal defect (VSD), or patent ductus arteriosus (PDA).Shunt is left to right.Patients with small or repaired defects tolerate pregnancy well 1 .
Balance between SVR and PVR determines the shunt fraction.Hence acute changes should be avoided.Avoid air embolism.CVP monitoring is considered in patients with symptomatic heart failure.Arterial catheter may be required in severe cases 2,15,19,31 .

VSD
90% VSDs close spontaneously by 10 years of age.Symptomatic patients have to undergo surgical closure 19,31 .
There is left ventricular overload and dialatation in VSD and PDA 19 .

Anaesthetic management
Epidural anaesthesia is the preferred technique as it reduces SVR to decrease the shunt flow.GA can be used but one should avoid changes in SVR and PVR 11,25,26 .

Valvular heart disease
These comprise 15% of cases with cardiac disease in pregnancy.Rheumatic heart disease (RHD) is the commonest cause.Regurgitant leisions are generally well tolerated in pregnancy.However, stenotic leisions decompensate more commonly 2,11,29 .

Aortic Stenosis (AS)
RHD is the most common acquired cause while bicuspid aortic valve is the commonest congenital cause.Symptoms include fatigue, syncope, dyspnoea and angina pectoris 11,26 .
Vol. 33 In the peripartum period patients with severe AS, due to inability to accommodate increased blood volume and tachycardia, experience worsening of symptoms 2,34 .

Anaesthetic management
1. Labour: Vaginal delivery is preferred in mild to moderate AS.Epidural analgesia with slow titration of opioid and local anaesthetic may be used.However, fall in SVR has to be avoided.In case of hypotension, epinephrine should be avoided as it causes tachycardia.Early analgesia helps avoid stress induced effects 26 .
2. CS: CS is preferred in severe AS 26 .Single shot spinal is contraindicated in severe AS 35 .Titrated epidural anaesthesia may be used.For GA, etomidate along with opioids is preferred.Avoid glycopyrrolate, atropine, ketamine 11,26,33 .
Goals: maintain normal sinus rhythm and haemodynamics, avoid bradycardia, tachycardia, fall in SVR and myocardial depression 2,33 .

Mitral Stenosis (MS)
MS occurs mostly due to RHD.It is one of the most common valvular lesion in pregnancy especially in the developing countries 14 .Signs and symptoms include dyspnoea, palpitations, pulmonary oedema, chest pain, haemoptysis and thromboembolism 26 . 33

Anaesthetic management
1. Labour: avoid tachycardia due to stress.Thus, labour analgesia is important 35,37,38 .CSE with intrathecal opioids in the first stage followed by titrated local anaesthetic in second stage is beneficial.Fall in SVR is managed with phenylepherine.Avoid ephedrine unless there is relative bradycardia (Heart Rate<70) 26 .
2. CS: Spinal anaesthesia should be avoided in moderate to severe cases due to acute changes in SVR 26 .Epidural anaesthesia with titrated doses of local anaesthetic is the preferred technique.Drug of choice for hypotension is low dose phenylepherine (50 to 100 μg) 2,39 .For GA avoid tachycardia inducing drugs (glycolyrrolate, atropine, ketamine, meperidine, pancuronium).Etomidate is a preferred agent (0.2 to 0.3 mg/KG.β-Blocker (Esmolol 30 to 50 μg/Kg) and moderate dose opioid (Remifentanil 0.5 to 1 μg/Kg) should be used.

Mitral regurgitation (MR)
Common causes include trauma, bacterial endocarditis, papillary muscle rupture, prosthetic valve dysfunction (acute MR), RHD or myxomatous degeneration 26,33 .Acute MR leads to left atrial volume load, increase in pulmonary pressures as well as pulmonary oedema.Chronic MR causes dialatation of left atrium predisposing the patient to AF 2,35 .Risk of thromboembolism is increased 2 .Moderate tachycardia, as seen in pregnancy, limits the time for regurgitation 26 .Goals: Avoid bradycardia, myocardial depression and increase in SVR, slight tachycardia is preferred 2,33 .

Mitral valve prolapse (MVP)
Incidence is 10% to 17% of all pregnancies and is usually tolerated well 40 .Anaesthetic management is to decrease cardiac output and left ventricular end diastolic pressure (LVEDP) 11 .Perioperative events causing enhanced left ventricular emptying and reducing the size of left ventricle (increased sympathetic activity, decreased SVR, upright posture, hypovolemia) are avoided as they increase the MVP.Goals of management are similar to MR 33 .

Severe Moderate Mild
Regurgitant jet >60 25-59 4-24 area as percentage of LVOT area LVOT left ventricular outflow tract Anaesthetic management and goals are similar to that of MR 26 .

Prosthetic valves
Risk of foetal complications (foetal haemorrhage due to maternal anticoagulation and teratogenicity) and maternal complications (thrombo-embolic phenomena, valve failure and bacterial endocarditis) is high in a pregnant patient with a prosthetic valve.Porcine heterografts are preferred for women of child bearing age.Both regional and general anaesthesia can be given safely.Regional anaesthesia is preferred.However, chronic use of heparin may result in thrombocytopenia.Also, continuous anticoagulant therapy is a contraindication for regional analgesia.If GA is required, residual valvular or myocardial dysfunction will influence the choice of anaesthetic drugs.Use of additional monitoring i.e.CVP, PA catheter and A-line is recommended 11 .

Endocarditis prophylaxis in cases with cardiac disease
There is no consensus regarding endocarditis prophylaxis for obstetric patients with cardiac disease undergoing delivery (vaginal/caesarean).Antibiotics should be considered for those at highest risk of an adverse outcome and, when appropriate, given as the membranes rupture.Intravenous amoxicillin and gentamicin should be considered for women with high-risk anatomy or previous history of endocarditis 41 .
Those at highest risk include 41 1. Prosthetic cardiac valve or prosthetic material used for cardiac valve repair.
2. CHD if a) unrepaired cyanotic disease (including palliative shunts) b) completely repaired CHD with prosthesis during first 6 months post procedure c) repaired CHD with residual defect.

Ischemic heart disease in pregnancy
Acute myocardial infarction(AMI) occurs in 1 out 0f 35,700 deliveries with a mortality of 7% 42 .Mortality within 2 weeks of AMI is 50% 5 .Hence, a period of 2 weeks should, preferably be provided before delivery 42 .Most of the cases are due to coronary artery spasm 5 .Use of prostaglandins or methergine is associated with coronary atery spasm.Thus, these should be avoided in patients at risk of AMI.Nitrates help avoid AMI due to coronary artery spasm 35 .During the peripartum period coronary artery stenting or thrombolytic therapy may be given if the patient is not about to deliver vaginally or by CS, or is immediately postpartum.Aspirin, β-blockers and nitrates are used for management of AMI during pregnancy 5,26,35,43 .Percutaneous coronary intervention remains the first choice for treatment 8 .

Anaesthetic management
Stress on the heart increases manifold during labour and delivery.Epidural labour analgesia helps reduce heart rate (HR) and haemodynamic stress.β blockade provides a slower HR.Technique of anaesthesia is not important as long as the haemodynamic stability is maintained 26 .

Cardiomyopathy
Cardiomyopathy during pregnancy can be peripartum, hypertrophic obstructive or idiopathic dialated cardiomyopathy.

Peripartum cardiomyopathy (PPCM)
National Heart, Lung, and Blood Institute Working Group (NHLBI) in 1997 defined PPCM as the onset of heart failure within last month of pregnancy or upto first 5 months postpartum in absence of identifiable cause 7,44 .Echocardiographic criteria include ejection fraction <45%, fractional shortening <30%, and/ or diastolic left ventricular dimension greater than 2.72cm/m 2 .Incidence is 1:3000 to 1:4000 live births with a mortality of 18%-50% 11,26 .
Signs and symptoms include fatigue, dyspnoea, peripheral oedema, palpitations and pulmonary oedema.Etiology is unknown.It is associated with advanced maternal age, preeclampasia, multigravida, obesity and coronary artery disease 35 .
Peripartum management: immediate delivery, if near term 35 .Management of heart failure includes salt and water restriction, diuretics (frusimide), ionotropic support, afterload reduction.Angiotensin converting enzyme inhibitors are withheld till delivery 44 .Approximately 50% women recover postpartum.Prognosis depends upon left ventricular function at 6-12 months postpartum 44 .There is high risk of heart failure in subsequent pregnancy 45 .
However, coagulation studies should be done as patient may be on anticoagulant therapy. .
Goals-avoid myocardial depressants and fluid overload.

Hypertrophic obstructive cardiomyopathy
This is a genetic disorder with varying degree of left ventricular outflow tract obstruction (LVOTO) 26,47 .
The patients usually tolerate physiological changes of pregnancy.Tachycardia exacerbates LVOTO due to increased contractility and reduction in LV preload and afterload.Therefore, patient is usually on β blockers 48 .
2. CS: Both regional anaesthesia and GA may be used.However, single shot spinal should be avoided.Hypotension should be treated with phenyepherine 48 .
Goals: avoid tachycardia, fall in SVR, decreased preload, maintain normal to slightly reduced contractility and normal to elevated SVR 26 .

Primary pulmonary hypertension (PPH)
PPH is defined as elevated PA pressures (mean pulmonary artery pressure (PAP)>25 mm Hg at rest) Sri Lanka Journal of Obstetrics and Gynaecology Ravi Jindal, Sukhwinder Kaur Bajwa, Sukhminder Jit Singh Bajwa, Ratika Jindal in absence of primary cardiac disease 2,35 .In the peripartum period right ventricular failure can occur.Thromboembolism is also common during this period 35 .

Anaesthetic management
1. Labour: Epidural analgesia is preferred 26 .Oxytocin should be used with caution to avoid fall in SVR and increase in PVR.Avoid carboprost and methergine 2,35 .
2. CS: CS may be required in cases with severe disease with RV failure 50 .Both epidural anaesthesia and GA may be used.However, a slow induction epidural anaesthesia is advised.Vasopressors increase pulmonary artery pressure and should be used with caution 49 .Invasive monitoring includes arterial catheters, CVP/PAC and TEE 2,35 .

Obstetric care post cardiac transplant
Increasing evidence shows that pregnancy is well tolerated by cardiac transplant patient, provided cardiovascular and renal functions are preserved prior to pregnancy 2,34,51,52 .The transplanted heart is devoid of any nerve supply and relies on intrinsic adrenergic receptors.Hence, baseline tachycardia (HR approximately 100/min) is present.Heart is unresponsive to vagolytics 51,53 .There is accelerated coronary artery disease, impaired cardiac function and immunosuppression 2,34 .There is increased risk of graft rejection, preterm delivery, hypertension, preeclampsia, fetal growth retardation and dysarrythmia in the peripartum period 51 .Dosage of immunosuppressants may need to be altered due to changes in blood volume 26 .Assessment of cardiac function and graft rejection has to be done by recent echocardiography, cardiac catheterisation and myocardial biopsy 2 .The cardiac transplanted patients tolerate vaginal delivery well.CS should be done only for obstetric reasons 54 .However, the cesarean section rate in transplanted women is high 55 .

Anaesthetic management
Spinal, epidural and general anaesthesia have all been successfully used for postcardiac transplant patient.Epidural anaesthesia with slow titration to avoid fall in SVR is the preferred approach.Avoid epinepherine in epidural injections to prevent tachycardia.Bradycardia is treated with direct acting sympathomimetics (isoproternol, epinepherine).Hypotension is managed with phenylepherine.Invasive monitoring is avoided due to high risk of infection in immunosuppressed patients.Stress dose steroids have to be given.GA, if required, has to be tailored to maintain haemodynamic status 26 .Goals: strict asepsis, avoid myocardial depressants, avoid tachycardia, hypertension and aortocaval compression, maintain normal filling pressures 26 .

Conclusion
Every female, including those with cardiac disease, has a right to enjoy motherhood.Given the complexities of cardiac disease, a pregnant cardiac patient has to be managed by coordinated efforts of the obstetrician, cardiologist and the anaesthetist.We need a good antenatal, intranatal and postnatal care to help such patients complete the peripartal period safely.We also need to strengthen our peripheral health infrastructure to cater to the unique requirements of these patients.Proper orientation of the obstetrician and the anaesthetist to the pathophysiological changes of cardiac disease is absolutely necessary.