Cardiovascular Journal of Africa: Vol 29 No 6 (November/December 2018)

CARDIOVASCULAR JOURNAL OF AFRICA • Volume 29, No 6, November/December 2018

AFRICA

397

published on the subject, it is well known that valve dysfunction,

especially stenotic lesions, results in significant physiological

effects during pregnancy, increasing maternal mortality rate and

foetal loss.

This is mainly due to the increase in cardiac output

associated with advance in gestational stage, which increases the

transvalvular gradient.

In addition, the fall in peripheral vascular resistance will

provoke fluid retention and volume expansion, which may be

more marked in women with a stenotic lesion because they are

less able to increase cardiac output in response to pressure drop.

Furthermore, the increased heart rate may be poorly tolerated,

as left ventricular filling depends on an adequate diastolic filling

time. Women may therefore complain of shortness of breath,

heart failure and arrhythmia. Left-sided regurgitant valve lesions

are better tolerated in pregnancy because of the reduction in

the regurgitant volume caused by a fall in systemic vascular

resistance, except if the regurgitation is acute and or occurs in

the context of poor ventricular function.

Imaging diagnosis

Cardiovascular imaging may be required in pregnant women with

known or suspected RHD. The diagnostic imaging modalities

that may be used in pregnancy include chest radiography,

fluoroscopy, echocardiography, invasive angiography,

cardiovascular computed tomography, computed tomographic

pulmonary angiography, cardiovascular magnetic resonance

(CMR) imaging and nuclear techniques. Echocardiography and

CMR appear to be safe in pregnancy and are not associated with

any adverse foetal effects. Despite concerns related to imaging

modalities that involve ionising radiation, namely teratogenesis,

mutagenesis and childhood malignancy, evidence shows that

no single imaging study approaches the cautionary dose of

5 rad (50 mSv or 50 mGy).

Currently, it seems that a single

cardiovascular radiological study during pregnancy is safe and

should be undertaken when clinically justified.

Echocardiography is mandatory for the diagnosis of rheumatic

heart valve disease, but in pregnancy transmitral and transaortic

gradients need to be evaluated with caution. They tend to be

over-estimated due to the physiologically increased heart rate,

but may be underestimated in the presence of impaired systolic

function.

25,28

Furthermore, the increased heart rate

per se

affects

the peak and mean systolic gradients, as calculated from the

Bernoulli transformation; the calculation of the valve orifice

using the continuity equation should also be used.

Management

Healthcare systems and the socio-economic conditions of most

families in Africa do not allow easy provision of the level of

care required by RHD patients to prevent complications, and

therefore many patients reach hospitals with established heart

failure, atrial fibrillation and pulmonary hypertension.

When

managing women of childbearing age, key issues related to

medical and surgical management must be taken into account,

including the desire for a future pregnancy, the need for

intervention prior to pregnancy, and the type of valve surgery,

if this procedure is needed. Discussion on contraceptive options,

risks of pregnancy, as well as maternal and foetal risks related to

pregnancy and delivery, are also mandatory.

Medical therapy

Due to limited access to interventional cardiology and

cardiothoracic surgery in Africa,

the majority of RHD patients

are managed medically. Medical therapy is indicated for all

symptomatic patients and is used as a bridge to surgery or

interventional catheterisation, as well as for those with contra-

indications to surgery.

Diuretics are used in most symptomatic patients to treat

congestive heart failure. Diuretics are usually combined with

ACE inhibitors where there is valve regurgitation and with beta-

blockers in patients with mitral stenosis. Despite the indication

for using corticosteroids for the treatment of episodes of active

carditis, in some instances, aspirin at high doses is preferred

due to fear of reactivation of tuberculosis during pregnancy.

Patients may need anticoagulants for the prevention of valve

thrombosis and/or thrombo-embolism in severe mitral stenosis

or atrial fibrillation. Finally, medicines may also be needed for

the prevention or treatment of infective endocarditis.

Drugs are an important component of a patient’s management

after surgery or balloon valvotomy. An important aspect of medical

management of RHD is secondary prophylaxis

for the prevention

of new attacks of acute rheumatic fever and progression of valve

lesions. Benzathine penicillin G has been the gold standard for

secondary prophylaxis, including for pregnant women.

29,30

Percutaneous mitral dilatation (PMD)

Since its introduction in the early 1980s, PMD has had a

significant impact on the treatment of mitral stenosis.

Randomised trials have demonstrated successful results obtained

with this technique, and explain why it has largely replaced

surgical commissurotomy.

32-34

PMD is particularly important

in the management of women with RHD in Africa, where

haemodynamically severe mitral stenosis presents earlier in life,

and young patients have thickened valve leaflets presenting with

or without concurrent regurgitation.

35,36

When planning for PMD measurement for valve area,

this should be done using planimetry with two-dimensional

echocardiography. Only if planimetry is not feasible should the

Doppler pressure half-time method be used. Continuous-wave

Doppler must be used to assess the mean mitral gradient, and the

structural abnormalities should be described using the Wilkins

score.

Presence (and quantification) of mitral and/or aortic

regurgitation should be assessed, and pulmonary artery pressure

measured in all cases.

Only experienced operators should perform PMD, using the

Inoue or a double-balloon technique. The procedure is stopped

when there is complete opening of at least one commissure, with

a valve area

≥

1.5 cm

(

≥

1.0 cm

of BSA). The appearance

of regurgitation or its increase by more than one-quarter also

determines the end of the procedure.

Marijon and colleagues have shown that despite candidates

for PMD from non-Western countries being younger, with

more severe valve stenosis and pulmonary hypertension, this

procedure was an effective treatment for mitral stenosis in

these populations.

In this study of 350 patients (mean age: 41

years, 81% women) with mitral valve area of less than 1.5 cm

the results of PMD were similar in patients from non-Western

and Western countries; 6% of women submitted to PMD in

non-Western countries were pregnant, compared to only 2% in

developed countries.