British Heart Journal, 1978, 40, 934-937

Near fatal puerperal thrombosis on Bjork-Shileymitral valve prosthesisANDREW A. McLEOD, KEVIN P. JENNINGS, ANDEDWARD R. TOWNSEND

From the Departments of Cardiology and Cardiothoracic Surgery, King's College Hospital, London

SUMMARY A 22-year-old woman required emergency mitral valve replacement three weeks post partumbecause of thrombotic obstruction of her prosthetic mitral valve. Low dose subcutaneous heparin wasadministered from the 17th week of pregnancy. Though there was a successful fetal outcome, heparindid not prevent thrombosis on the prosthesis and its continuation into the puerperium proved nearlyfatal.

There is as yet no established policy for anticoagu-lant therapy in pregnant patients with prostheticheart valves. The most favourable outcome forfetus and mother is associated with biologicalvalves which do not require lifelong anticoagulation(Oakley and Doherty, 1976). Coumarin anticoagu-lants in pregnant patients with non-biologicalvalves may result in fetal malformation and hae-morrhagic complications (Pettifor and Benson,1975). We describe a case of a healthy 22-year-oldparous woman with a Bjork-Shiley mitral valveprosthesis. She had a large valve, a normal sizedleft atrium, and remained in sinus rhythm. Sub-cutaneous low dose heparin during pregnancy didnot prevent almost complete occlusion of her pros-thesis by thrombus which appeared to increasegradually throughout the pregnancy, and necessi-tated emergency replacement of her prosthesis inthe puerperium.

Case report

The patient is a 22-year-old woman. A cardiacmurmur was first heard at the age of 11 years and at16 years cardiac catheterisation disclosed mild mitralregurgitation. Pregnancy at 18 was uneventfulapart from induction of labour at 39 weeks for pro-teinuria and falling urinary oestriol levels. Eighteenmonths later she noticed that she tired easily, andby 1975 she was dyspnoeic on minimal exercise andunable to perform housework. Repeat catheterisa-tion revealed severe mitral regurgitation and atoperation in June 1975 a 'floppy' mitral valve wasexcised and a No. 29 Bjork-Shiley valve inserted.She was subsequently placed on warfarin. Her life

was dramatically improved and she became preg-nant later the same year but miscarried at 12 weeks.At routine examination in March 1976, shortly

before she became pregnant for a third time, asystolic murmur was noted. This was interpreted asa paravalvar leak. There were no symptoms, and anechocardiogram (Fig. 1) showed a normal sizedleft atrium and a normally functioning prosthesis.She had a threatened abortion and was admitted tohospital at about 10 weeks' gestation. At the 17thweek of pregnancy, warfarin was discontinued andsubcutaneous heparin, 5000 units b.d., was startedand continued throughout pregnancy and into thepuerperium.

She was admitted for rest at 27 weeks for dys-pnoea and remained in hospital until the birth of herbaby. Labour was uneventful and a healthy boy wasdelivered. She began breast feeding, and was dis-charged after 8 days feeling well. Subcutaneousheparin therapy was continued.

She was readmitted as an emergency 3 weeksafter delivery with a one-day history of malaise,weakness, dyspnoea, and dizziness on mild exercise.On examination she was unwell, pale, and peri-

pherally cyanosed, temperature 37 5°C. She was insinus rhythm, rate 120/min, blood pressure 100/70mmHg. There was no peripheral oedema but herjugular venous pressure was raised at 8 cm. She wastachypnoeic and there were widespread inspiratorycrepitations at both lung bases. The cardiac apexwas forceful but not displaced. There was a soft,long, ejection-type systolic murmur, maximal at theapex. No closing click was audible from the pros-thetic valve. Her congestive cardiac failure wastreated with intravenous frusemide, and blood

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Puerperal thrombosis on Bjdrk-Shiley valve 935

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Fig. 1 Echocardiogram of&~~~~ t44%~~~~~~~~~BjJrk-Shiley mitral valveN . ~~~~~~~~~~~~~~prosthesis(my) showing sharp

AZ, opening and closure pattern and~~~~~~.u~~ ~ ~ ~ ~~~. ~~~~ ~good excursion. Depth marks as

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mm Fig. 2 Ecliocardiogramn showingvalvcedpxrxmostei (my),Simiredce vlexurosionsofEjmk-Sile** 4 4 ~~~~~~~~~~~withreduce-d opening and closure'~~~/4 *~~~ rates. The left atrium is greatly

'9,* -. ~~~enlarged. LA, left atrium;I'K ~~~~~~Ao.,aortic root; depth marks at1 cmn intervals.

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A. A. McLeod, K. P. Jrennings, and E. R. Townsend

cultures were taken to exclude itcarditis.

After improving at first, she deteri(over the ensuing few hours. Her blocto 80/30 mmHg, and the heart rate ro!

min. In addition to the earlier cardpronounced parasternal heave was fecardiogram showed sinus tachycardia± 1200, and widespread ST segment (

T wave inversion. The chest x-ra5severe pulmonary oedema. Clinicallon the prosthesis was diagnosed. Agram showed a very large left atriumreduced prosthetic excursion, withand closure rates.Emergency operation was under

Angus Macarthur through a rightusing cardiopulmonary bypass. Thprosthesis was found to be complete]thrombus apart from a small slit-likemajor orifice (Fig. 3). The prosthesand replaced with a 31 Hancock porvalve. After operation she was venhours as the pulmonary oedema was sThereafter she made an uneventfulwas started on short-term warfarin

Discussion

Although the number of young

0 cm I

Fig. 3 Excised prostheis showing virtuallencapsulation by thrombus; scales in cm.

ifective endo- rheumatic heart disease has declined, patients withvalve replacements can perhaps justifiably expect to

orated severely live a normal life, including successful pregnancy,4d pressure fell with the aid of effective drug therapy and con-se to 160 beats/ tinuing technological improvement in valve pros-iac findings, a theses. The case reported here illustrates a younglt. An electro- woman with good myocardial function whose, a QRS axis of desire to obtain a healthy infant at term, and also todepression and allow breast feeding, almost caused her death.y film showed Oakley and Doherty (1976) have reviewed ex-ly, thrombosis perience of pregnancies in patients with valve pros-in echocardio- theses in the United Kingdom, and biological valves(Fig. 2), and a are clearly preferable. In addition, aortic valve pros-slow opening theses appear to be safer than mitral as regards the

likelihood of thromboembolism.taken by Mr A murmur was noticed in our patient shortlyt thoracotomy before she became pregnant, but this was inter-e Bjork-Shiley preted as a paravalvar leak. The possibility ofly occluded by thrombotic malfunction was considered but theaperture in the echocardiogram (Fig. 1) showed apparently satis-iis was excised factory function. Echocardiography of the Bjork-rcine xenograft Shiley prosthesis is very dependent on transducerLtilated for 48 position and angulation (Douglas and Williams,slow to resolve. 1974), but the initial tracings obtained here showedrecovery, and sharp opening and closure, with good excursion, andtherapy. a normal left atrial size. It seems likely that throm-

bosis on the prosthesis increased thereafter and washastened by the introduction of low-dose heparintherapy. The echocardiogram taken during the

women with emergency showed limited excursion of the disc,with reduced opening and closing velocities. Theappearance however was not as gross as that des-cribed by Bourdillon and Sharratt (1976).

Failure to restart warfarin after delivery was un-wise in this patient. The warfarin secreted inbreast milk can be allowed for by giving prophy-lactic vitamin K to the neonate. Retrospectively, herchangeover to heparin therapy, though probably thecorrect management (Hirsh et al., 1970; BritishMedical Journal, 1977) led to inadequate dosagebeing given. The case reported by Bennett andOakley (1968), with a Hanumersmith-Alvarez valve,led to a fatal outcome, despite therapeutic levels ofheparin being maintained throughout pregnancy. Inthe latter instance, however, thrombotic occlusionhad probably also started before the transfer toheparin therapy, as evidenced by embolic episodes.The Bjork-Shiley valve prosthesis provides

excellent haemodynamic function with a lowpressure gradient (Bjork and Olin, 1970; Bjork,1975), but requires adequate anticoagulation. There

3 , have been recent doubts about its suitability as a- tricuspid valve prosthesis (Bourdillon and Sharratt,

1976), but the majority ofthe problems encountered'Iy complete in our patient stemmed from inadequate anticoagu-

lation.

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Puerperal thrombosis on Bjork-Shiley valve

This case illustrates the value of echocardio-graphy in emergency assessment of prosthetic valvetunction, but it is important to note that there mayhave been significant dysfunction at the timethat the echocardiogram appeared normal. Ourpatient received low doses of heparin and this un-doubtedly predisposed to prosthetic valve mal-function, but thrombus formation had probablybegun even while adequate levels of warfarin werebeing maintained. This reinforces the impressiongained from the review of Oakley and Doherty(1976) that biological valves are the prostheses ofchoice for women who wish to become pregnant,and that, in any other situation, meticulous controlof anticoagulation is required.

We thank Dr S. Oram and Mr A. M. Macarthurfor permission to publish this case report. We aregrateful to Dr D. E. Jewitt and Dr P. J. Richardsonfor help with various aspects of this patient's routineand emergency care.

References

Benneit, G. G.. and Oakley, C. M. (1968). Pregnancy in a

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patient with a mitral valve prosthesis. Lancet, 1, 616-619.Bjork, V. 0. (1975). Four and one half years experience with

the aortic and mitral Bjork-Shiley tilting disc valve.Journal of Cardiovascular Surgery, Suppl., p. 347.

Bjork, V. O., and Olin, C. (1970). A hydrodynamic evaluationof the new tilting disc valve (Bjork-Shiley) for mitral valvereplacement. Scandinavian Journal of Thoracic and Cardio-vascular Surgery, 4, 37-43.

Bourdillon, P. D. V., and Sharratt, G. P. (1976). Malfunctionof Bjork-Shiley valve prosthesis in tricuspid position.British Heart Journal, 38, 1149-1153.

British MedicalJournal (1977). Anticoagulants and heart valvereplacement in pregnancy. Leading article. 1, 1047-1048.

Douglas, J. E., and Williams, G. D. (1974). Echocardiographicevaluation of the Bjork-Shiley prosthetic valve. Circulation,50, 52-57.

Hirsh, J., Cade, J. F., and O'Sullivan, E. F. (1970). Clinicalexperience with anticoagulant therapy during pregnancyBritish Medical Journal, 1, 270-273.

Oakley, C., and Doherty, P. (1976). Pregnancy in patientsafter valve replacement. British Heart Journal, 38, 1140-1148.

Pettifor, J. M., and Benson, R. (1975). Congenital malforma-tions associated with the administration of oral anticoagu-lants during pregnancy. Journal of Pediatrics, 86, 459-462.

Requests for reprints to Dr. A. A. McLeod,Cardiac Department, King's College Hospital,Denmark Hill, London SE5 9RS.

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