Hemodinamic Cvs During Pregnancy

7/23/2019 Hemodinamic Cvs During Pregnancy

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Approximately 2% of pregnancies involve maternal cardiovascular disease, and as such, this poses an

increased risk to both mother and fetus. Most women with cardiovascular disease can have a

pregnancy with proper care, but a careful pre-pregnancy evaluation is mandatory. ardiac disease may

sometimes be manifested for the first time in pregnancy because the hemodynamic changes may

compromise a limited cardiac reserve.

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onversely, the symptoms and signs of a normal pregnancymay mimic the presence of cardiac disease. $ightheadedness, diiness, shortness of breath,

peripheral edema, and even syncope often occur in the course of a normal pregnancy, and for the

unwary physician, cardiac disease may be suspected. An understanding of the normal cardiac

examination of a pregnant patient is therefore important. &or those physicians counseling patients

with cardiac disease about the potential risks of a pregnancy, a comprehensive knowledge of the

underlying defect as well as of the hemodynamic changes that pregnancy will impose is imperative.

'ith the declining incidence of rheumatic heart disease in 'estern countries, most maternal cardiac

disease is now congenital in origin. (ther cardiovascular problems seen include cardiomyopathies,

both dilated and hypertrophic, and valvular disease, such as bicuspid aortic valve and mitral valve

prolapse. $ess common problems include pulmonary hypertension and, rarely, coronary artery

disease. )re-pregnancy counseling is important to give prospective mothers appropriate informationabout the advisability of pregnancy and to discuss the risks to her and the fetus. *uch patients should

be seen in a high-risk pregnancy unit and have a clinical examination, electrocardiogram, and chest

radiograph. An echocardiogram facilitates a detailed evaluation of myocardial function, valvular

disease, and pulmonary pressures. &or patients with congenital heart disease, their perception of

normal activity may be skewed, and an exercise test is helpful in delineating their true functional

aerobic capacity. +n general, patients who cannot achieve more than % of their predicted functional

aerobic capacity are unlikely to tolerate a pregnancy safely. uring this visit, it is important to take a

careful family history to assess whether there is any congenital heart disease in the family. /enetic

counseling may also be considered, if necessary. A careful discussion of the maternal and fetal risks

should be made at the time of pre-pregnancy counseling, and if the mother is going to pursue a

pregnancy, a strategy should be outlined regarding the fre0uency of follow-up by the cardiologist, and

a plan should be put in place for labor and delivery.!2#

A multicenter anadian study has suggested that maternal cardiac risk may be predicted by the use of

a risk index.!1# &our predictors of maternal cardiac events are as follows 3"4 prior cardiac event 3e.g.,

heart failure, transient ischemic attack, or stroke before pregnancy4 or arrhythmia5 324 baseline 6ew

7ork 8eart Association 3678A4 class higher than lass ++ or cyanosis5 314 left-sided heart obstruction

3mitral valve area smaller than 2 cm2, aortic valve area less than ".9 cm2, or peak left ventricular

outflow tract gradient more than 1 mm 8g by echocardiography45 and 3:4 reduced systemic

ventricular systolic function 3e;ection fraction less than :%4. <ach of 9== pregnancies was assigned

" point when each predictor was present. 6o pregnancy received more than 1 points. >he estimated

risk of a cardiac event in pregnancies with , ", and more than " point was 9%, 2%, and 9%,

respectively. +t was concluded that those with a low cardiac risk of could safely be delivered in acommunity hospital, but those at intermediate or high cardiac risk 3risk score of " or more4 should be

delivered at a regional center.

uring pregnancy, a multidisciplinary team approach is recommended, with close collaboration with

the obstetrician so that the mode, timing, and location of delivery can be planned. !:# >he management

should be tailored to the specific needs of the patient. uring pregnancy, fetal growth is monitored by

the obstetric team, and for the woman with congenital heart disease, a fetal cardiac echocardiogram is

offered at about 22 to 2? weeks of pregnancy to determine whether the baby has a congenital cardiac

anomaly.



Hemodynamic Changes

During Pregnancy

The hemodynamic changes are profound and begin early in the first trimester. The plasma volume begins to increase in the sixth week of pregnancy and by the second

trimester approaches 50% above baseline (Fig. !"#$. The plasma volume then tends to

plateau until delivery. This increased plasma volume is followed by a slightly lesser rise

in red cell mass which results in the relative anemia of pregnancy. The heart rate begins

to increase to about !0% above baseline to facilitate the increase in cardiac output (Fig.

!"!$. &terine blood flow increases with placental growth and there is a fall in

peripheral resistance. This decreased peripheral resistance may result in a slight fall in

blood pressure which also begins in the first trimester. The venous pressure in the lower

extremities rises which is why approximately 0% of healthy pregnant women develop

pedal edema. The adaptive changes of a normal pregnancy result in an increase in

cardiac output which also begins in the first trimester and by the end of the second

trimester approaches '0% to 50% above baseline.

FIGURE 82-1 )lasma volume and red blood cell 3@4 increase during the trimesters of

pregnancy. >he plasma volume increases to approximately 9% above baseline by the second

trimester and then virtually plateaus until delivery.

FIGURE 82-2 8emodynamic changes during pregnancy relate to increased cardiac output and a

fall in peripheral resistance. lood pressure in most patients remains the same or falls slightly.

Benous pressure in the legs increases, causing pedal edema in many patients.



>hese hemodynamic changes may cause problems for the mother with cardiac disease. >he added

volume load may obviously compromise a patient who has impaired ventricular function and limited

cardiac reserve. *tenotic valvular lesions 3e.g., aortic stenosis4 are less well tolerated than regurgitant

lesions because the decrease in peripheral resistance exaggerates the gradient across the aortic valve.

*imilarly, the tachycardia of pregnancy reduces the time for diastolic filling in a patient with mitral

stenosis, with resultant increase in left atrial pressure. +n contrast, with a lesion such as mitralregurgitation, the afterload reduction helps offset the volume load on the left ventricle that gestation

imposes.

During Labor and Dei!ery

The hemodynamic changes during labor and delivery are abrupt. ith each uterine

contraction up to 500 m) of blood is released into the circulation prompting a rapid

increase in cardiac output and blood pressure. The cardiac output is often 50% above

baseline during the second stage of labor and may be even higher at the time of delivery.

*uring a normal vaginal delivery approximately +00 m) of blood is lost. ,n contrast

with a cesarean section about 00 m) of blood is often lost and may pose a more

significant hemodynamic burden to the parturient. -fter delivery of the baby there is anabrupt increase in venous return in part because of autotransfusion from the uterus but

also because the baby no longer compresses the inferior vena cava. ,n addition there

continues to be autotransfusion of blood in the !+ to ! hours after delivery and this is

when pulmonary edema may occur.

-ll these abrupt changes mandate that for the high"risk patient with cardiac disease a

multidisciplinary approach during labor and delivery is essential. The cardiologist and

obstetrician should work with the anesthesiologist to determine the safest mode of delivery.

&or most patients with cardiac disease, a vaginal delivery is feasible and preferable5 a cesarean section

is indicated only for obstetric reasons. <xceptions to this include the patient who is anticoagulated

with warfarin because the baby is also anticoagulated, and vaginal delivery carries an increased risk to

the fetus of intracranial hemorrhage. esarean section may also be considered in patients who have a

dilated unstable aorta 3e.g., Marfan syndrome4, severe pulmonary hypertension, or a severe

obstructive lesion such as aortic stenosis. 8igh-risk patients should be delivered in a center where

expertise is available to monitor the hemodynamic changes of labor and delivery and to intervene

when necessary. +f vaginal delivery is elected, fetal and maternal electrocardiographic monitoringshould be performed. elivery can be accomplished with the mother in the left lateral position so that

the fetus does not compress the inferior vena cava, thereby maintaining venous return. >he second



stage should be assisted, if necessary 3e.g., forceps or vacuum extraction4, to avoid a long labor. lood

and volume loss should be replaced promptly. &or those patients with tenuous hemodynamics, *wan-

/an catheteriation before active labor facilitates optimiation of the hemodynamics and should be

continued for at least 2: hours after delivery, when pulmonary edema commonly occurs.

Although there is no consensus regarding the administration of antibiotic prophylaxis at the time of delivery for patients with lesions vulnerable to infective endocarditis, many institutions routinely give

antibiotics because of the documented bacteremia. >his can occur even during an uncomplicated

delivery.!9# )atients who are most vulnerable to the deleterious effects of endocarditis are those with

cyanotic heart disease and prosthetic valves.!?#

hest @adiography

A chest radiograph is not obtained routinely in any pregnant patient because of concern about

radiation to the fetus, but it should be considered in any patient when there are concerns about her

cardiac status and new onset of dyspnea or failure. >he chest radiograph in a normal healthy patient

may show slight prominence of the pulmonary artery, and as pregnancy advances, elevation of the

diaphragm may suggest an increase in the cardiothoracic ratio.

>ransthoracic <chocardiography

>his is the cornerstone of cardiac evaluation in pregnancy and facilitates differentiation of the features

of cardiac disease from those of a normal pregnancy. +t is used most fre0uently to determine the

ventricular function, to assess the status of native and prosthetic valve disease, and, by use of the

tricuspid regurgitant velocity, to assess pulmonary artery pressure. &or those patients with congenital

heart disease, a detailed assessment of any shunt and complex anatomy may be made.

uring pregnancy, because of the increased cardiac output, the velocities across the left and right

ventricular outflow tracts increase, which may mimic an increase in outflow tract gradient. areful

examination of the two-dimensional anatomic appearances will help differentiate this from a true

valvular abnormality, and calculation of valve area will be helpful. *imilarly, because of the increased

stroke volume, any valvular regurgitation will appear to be accentuated. *erial echocardiograms may

be particularly useful in a patient with a mechanical valve prosthesis who is vulnerable to thrombosis

during pregnancy. >he valve area calculation, in addition to pressure half-time determination, may be

more helpful than a simple measurement of valve gradient5 this may appear to be increased as pregnancy advances because the circulation becomes more hyperkinetic and cardiac output increases.

+n patients with impaired ventricular function, particularly those with cardiomyopathy,

echocardiography plays the most important role in assessing left ventricular function. +n a normal

pregnancy, the left ventricular end-diastolic measurement is increased, and there may be similar

increases in right ventricular sie as well as in the volumes of both atria. Measurement of e;ection

fraction is determined by changes in preload and afterload, and in the supine position, preload may be

reduced because the fetus may compress the inferior vena cava.

>ransesophageal <chocardiography

>ransesophageal echocardiography is seldom performed during pregnancy but may be necessary to

provide more detailed imaging of valvular disease, the presence or absence of a shunt, or intracardiac



thrombus. +n addition, it may be useful to determine the presence or absence of endocarditis to

facilitate the detection of a valvular vegetation or perivalvular abscess. >ransesophageal

echocardiography can be performed safely, although careful monitoring of maternal oxygen saturation

is necessary if midaolam is used for sedation. Antibiotic prophylaxis is unnecessary.

&etal <chocardiography

<xcellent imaging of the fetal heart can usually be obtained by 2 weeksC gestation. >he four-chamber

view may be obtained in most pregnancies and should demonstrate two atrioventricular valves, the

crux of the heart, and whether two ventricles of e0ual sie are present. >he patent foramen ovale

should also be demonstrated. >ypically, the heart should be smaller than one third of the sie of the

fetal thorax.

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Hemodinamic Cvs During Pregnancy