Anesthesia and Analgesia in the Pregnant Cardiac Patient

Katherine W. Arendt

Key Points

•The majority of maternal deaths from cardiovascular disease are from acquired heart disease

•The pregnancy heart team is a multidisciplinary team consisting of obstetrician, maternal-fetal medicine, anesthesiologist, and cardiologist working together to optimize outcome of pregnant cardiac patient

•Women with high-risk maternal cardiovascular disease should deliver at a Level 4 Regional Perinatal Health Center

•Neuraxial labor analgesia is an important component of labor management in patients with moderate to severe cardiovascular disease

•In certain circumstances general anesthesia is a safer option than a neuraxial technique for surgical anesthesia

Introduction

Over the past 20 years, cardiovascular disease has gradually become the leading cause of maternal mortality in the United States [1]. Increased survival of congenital heart disease (CHD) patients has resulted in more women reaching childbearing age and presenting to labor and delivery units [2–4]. Factors such as increased maternal age and increased incidence of obesity, chronic hypertension, and diabetes has likely led to expansion of acquired heart disease seen among the childbearing population. Currently, acquired heart disease comprises the majority of maternal cardiac deaths [5,6].

Both the European Society of Cardiology and the American College of Obstetricians and Gynecologists (ACOG) guidelines for pregnancy and heart disease recommend that a pregnancy heart team care for pregnant patients with complex cardiovascular disease [7,8]. Such a team involves cardiologists, obstetricians, perinatologists, and anesthesiologists working together to achieve the best outcome for the pregnant patient with complex heart disease. The focus of this chapter is on the role of the anesthesiologist as a member of the pregnancy heart team. Specifically, this chapter will focus on anesthetic risk stratification, the physiologic changes of pregnancy, labor and delivery, hemodynamic goals for patients as they present for delivery, and appropriate anesthetic techniques to achieve those goals.

Anesthetic Risk Stratification

Stratification of the overall risk of pregnancy for women with cardiac disease is discussed elsewhere in this text (see Chapter 4). Tables 8.1 through 8.3 review tools used for risk-stratifying women with cardiac disease who are pregnant [9–11].

Table 8.1 CARPREG II Risk Score
Risk Factors	Points
Prior cardiac event or arrhythmia	3
NYHA class >II or cyanosis	3
Mechanical valve	3
Ventricular dysfunction	2
High-risk left-sided valve disease/LVOT obstruction	2
Pulmonary hypertension	2
Coronary artery disease	2
High-risk aortopathy	2
No prior cardiac intervention	1
Late pregnancy assessment	1
Total Score	Risk of Cardiac Complications
0–1 points	5%
2 points	10%
3 points	15%
4 points	22%
>4 points	41%
Source: Adapted from Silversides CK et al. J Am Coll Cardiol. 2018;71(21):2419–30. Abbreviations: NYHA, New York Heart Association; LVOT, left ventricular outflow tract.

Table 8.2 ZAHARA Risk Score
Risk Factors		Points
Mechanical valve prosthesis		4.25
Left heart obstruction		2.5
History of arrhythmia		1.5
Cardiac medication prior to pregnancy		1.5
Cyanotic heart disease (corrected or uncorrected)		1.0
NYHA class ≥II		0.75
Systemic atrioventricular valve regurgitation > Mild		0.75
Pulmonic atrioventricular valve regurgitation > Mild		0.75
Total Score	Risk of Cardiac Complications
0–0.5 points	2.90%
0.51–1.5 points	7.50%
1.51–2.5 points	17.50%
2.51–3.5 points	43.10%
>3.51 points	70%
Source: Adapted from Drenthen W et al. Eur Heart J. 2010;31(17):2124–32. Abbreviation: NYHA, New York Heart Association.

Table 8.3

WHO Classification for Pregnancy

Risk Classification

Cardiac Lesions

Class I

No detectable increased risk of maternal mortality and no or minimal increase in maternal morbidity

•Uncomplicated mild pulmonary stenosis

•Ventricular septal defect

•Patent ductus arteriosus

•Mitral valve prolapse with no more than trivial mitral regurgitation

•Successfully repaired simple lesions (atrial or ventricular septal defect, patent ductus arteriosus, anomalous pulmonary venous drainage)

•Isolated ventricular extrasystoles and atrial ectopic beats

Class II

Small increased risk of maternal mortality or moderate increase in morbidity

•Unoperated atrial or ventricular septal defect

•Repaired tetralogy of Fallot

•Most arrhythmias

Class II–III

Depends on patient

•Hypertrophic cardiomyopathy

•Native or tissue valvular heart disease not considered WHO I or IV

•Repaired coarctation

•Marfan syndrome without aortic dilatation

•Bicuspid valve with aorta <45 mm

•Mild ventricular impairment

•Heart transplantation

Class III

Significantly increased risk of maternal mortality or severe morbidity, and expert cardiac and obstetric pre-pregnancy, antenatal, and postnatal care are required

•Mechanical valve

•Systemic RV

•Fontan circulation

•Unrepaired cyanotic heart disease

•Other complex congenital heart disease

•Marfan syndrome with aorta 40–45 mm

•Bicuspid aortic valve with aorta 45–50 mm

Class IV

Pregnancy is contraindicated

•Pulmonary hypertension

•Eisenmenger syndrome

•Systemic ventricular EF <30%

•Systemic ventricular dysfunction with NYHA class III–IV

•Severe mitral stenosis

•Severe symptomatic aortic stenosis

•Marfan syndrome with aorta >45 mm

•Bicuspid aortic valve with aorta >50 mm

•Native severe coarctation

•Prior peripartum cardiomyopathy with any residual impairment of ventricular function

Risk stratification is important to the anesthesiologist because anesthesiologists are an integral part of the multidisciplinary team who help identify pregnancies at high risk for maternal harm during childbirth and triage these women to deliver at appropriate hospitals. To do this, anesthesia teams should have the ability to see high-risk pregnant patients in advance of delivery in a clinical setting to obtain an anesthetic, obstetric, and cardiac history; perform a physical exam; and review cardiac testing. The most important aspects of this consultation are reviewed in Box 8.1.

Box 8.1 Elements of the Pre-Delivery Anesthesiology Consultation

History

•Anesthetic history

•Obstetric history

•Cardiac history with special attention to:

•All prior cardiac testing including surgeries, echocardiograms, ECGs, Holter monitors, etc.

•Prior or current episodes of heart failure

•Intracardiac shunting and cyanosis

•Prior arrhythmias

•Left heart obstructive lesions

•Left and right heart function

•Pacemaker or defibrillator management

•Anticoagulation therapy

Physical Exam

•Airway

•Cardiac exam

•Pulmonary exam

•Exam of the back to assess for ease of neuraxial techniques

Discuss

•Potential hemodynamic monitoring plans for labor or cesarean delivery

•Potential risks, benefits, and alternatives of neuraxial techniques

•Potential need to manage anticoagulation around the time of delivery to facilitate neuraxial techniques

•Potential post-delivery plans for monitoring

Table 8.4 Normal Cardiovascular Changes during Pregnancy
Variable	Direction of Change	Average Change
Blood volume	↑	+35%
Plasma volume	↑	+45%
Red blood cell volume	↑	+20%
Cardiac output	↑	+40%
Stroke volume	↑	+30%
Heart rate	↑	+15%
Femoral venous pressure	↑	+15 mmHg
Total peripheral resistance	↓	−15%
Mean arterial blood pressure	↓	−15 mmHg
Systolic blood pressure	↓	−0 to 15 mmHg
Diastolic blood pressure	↓	−10 to 20 mmHg
Central venous pressure	↔	No change
Source: Modified from Bucklin BA, Fuller AJ. Physiologic changes of pregnancy. In: Suresh MS et al (eds). Shnider and Levinson’s Anesthesia for Obstetrics, 5th ed. Wolters Kluwer Health, Inc. 2013. Chapter 1, pp. 2.

Anesthesiologists often prefer to think in physiologic systems when risk-stratifying patients for surgery or delivery. Understanding the hemodynamic changes of pregnancy and combining these changes with the physiologic vulnerabilities of various cardiac lesions allows the anesthesiologist to understand which lesions will perform poorly during pregnancy, under anesthesia, or under the physiologic stressors of labor, emergency surgery, or obstetric hemorrhage. The physiologic changes of pregnancy are reviewed in Table 8.4. How these changes affect the hemodynamics of a woman with specific cardiac lesions are reviewed in Table 8.5.

Table 8.5 The Hemodynamic Effects of Pregnancy in Specific Cardiovascular Diseases
Lesion	Hemodynamic Effects of Pregnancy and Delivery
Coronary artery disease	(−) The decreased SVR of pregnancy can result in lesser coronary perfusion to the myocardium (−) The increase in HR during pregnancy can result in decreased coronary filling time (−) Cardiac work can increase significantly during labor, especially painful labor
Severe LV dysfunction (e.g., dilated or peripartum cardiomyopathy)	(−) The increase in cardiac output and blood volume during pregnancy can result in heart failure/pulmonary edema (−) The decrease in oncotic pressure during pregnancy can result in greater risk for pulmonary edema (−) Angiotensive converting enzyme inhibitors must be stopped during pregnancy secondary to teratogenicity (−) Patients with a prior episode of peripartum cardiomyopathy are at risk for further deterioration in LV function with subsequent pregnancies
Pulmonary hypertension	(−) The increased cardiac output of pregnancy may not be accommodated by the fixed pulmonary vasculature resulting in right heart failure and death (−) The decreased SVR of pregnancy can decrease coronary filling to a dilating and failing right ventricle (−) The hypercoagulable state of pregnancy can result in pulmonary emboli which are especially lethal in patients with pulmonary hypertension
Unstable arrhythmia history	(−) Pregnancy, labor, and delivery can trigger tachyarrhythmias
Aortopathy (e.g., Marfan syndrome)	(−) Pregnancy, labor, and delivery may increase dilation of aortic root (−) Pregnancy, labor, and delivery increase the risk of aortic rupture in women with Marfan syndrome
Valvular lesions
Mechanical prosthetic valve	(−) Hypercoagulable state of pregnancy increases risk of valve thrombosis (−) Vitamin K antagonists (most effective way to prevent valvular clot formation) are teratogenic; often suboptimal anticoagulation regimens are used during pregnancy
Mitral stenosis	(−) Because of relatively fixed preload to the LV, the heart may not be able to generate increased cardiac output and pulmonary edema will develop (−) Decreased oncotic pressure further increases risk of pulmonary edema (−) The increase in blood volume and heart rate in pregnancy increases left atrial pressure and may lead to atrial fibrillation and pulmonary edema
Aortic stenosis	(−) The decreased SVR of pregnancy can result in lesser coronary perfusion pressure to the thickened LV myocardium (−) Because of LV diastolic dysfunction, excess volume can lead to pulmonary edema
Mitral/aortic insufficiency	(+) The decreased SVR results in a lesser regurgitant volume (−) Pregnancy can worsen ventricular dilation
Shunt lesions
R-to-L shunt (e.g., TOF, Eisenmenger’s)	(−) The decrease in SVR increases right-to-left shunting and possible cyanosis (+) In unrepaired TOF and normal RV function, the increase in blood volume is beneficial because adequate RV preload is necessary to eject blood past the outflow obstruction and increase pulmonary blood flowa
L-to-R shunt (e.g., VSD or ASD)	(+) The decrease in SVR decreases the left-to-right shunting (−) The increase in blood volume can precipitate failure because the patient is in a state of compensatory hypervolemia
Source: Modified from Arendt KW, Lindley KJ. Int J Obstet Anesth. 2019;37:73–85. Abbreviations: SVR, systemic vascular resistance; HR, heart rate; CD, cesarean delivery; LV, left ventricle; RV, right ventricle; PEEP, positive end expiratory pressure; AICD, automatic implantable cardioverter defibrillator; CCHD, cyanotic congenital heart disease; TOF, tetralogy of Fallot; ASD, atrial septal defect; VSD, ventricular septal defect. a CCHD, Eisenmenger’s, and all pulmonary vascular hypertensive diseases carry a high mortality rate in pregnancy, labor, delivery, and the postpartum period; full pregnancy implications and anesthetic management are beyond the scope of this table