Prosthetic heart valves and pregnancy

Valvular heart disease: focus on women

Calcific aortic stenosis is a disease of the elderly and aortic valve replacement should always be considered for severe symptomatic disease; comorbidities, not age, determine surgical risk. Aortic regurgitation imposes a pressure and volume load on the left ventricle so that close monitoring is needed to identify patients at risk for irreversible left ventricular dysfunction, although symptoms are the most common indication for valve replacement. Early intervention now is recommended for rheumatic mitral stenosis due to the effectiveness of percutaneous balloon valvotomy. Earlier intervention also may be considered in selected patients with mitral regurgitation at experienced centers when valve anatomy is favorable for a successful repair. Semiquantitative descriptors of regurgitation as mild, moderate, or severe are no longer adequate; management of adults with chronic valve disease requires quantitation of both the severity of valve disease and of left ventricular size and systolic function.

Low molecular weight heparin treatment in pregnant women with a mechanical heart valve prosthesis

No definitive recommendation is available concerning optimal antithrombotic therapy in pregnant women with a mechanical heart valve. The purpose of the current study was to evaluate the clinical results of nadroparin treatment with respect to pregnancy outcome and maternal complications. From 1997 to 2005, 31 pregnancies were reviewed in 25 women. Nadroparin (7,500 U, twice daily) was used in 23 pregnancies between 6 and 12 weeks of gestation and close-to-term only, and coumarin derivatives were used with aspirin at other times. Eight pregnant women treated with coumarin derivatives throughout pregnancy were compared to evaluate the safety and efficacy of nadroparin. No maternal death or bleeding complication occurred in either of the two groups, and frequencies of maternal thromboembolism including valve thrombosis (8.7% vs. 12.5%, p>0.05) were similar. However, the frequencies of live born (91.3% vs. 50%, p=0.01) and healthy babies (90.4% vs. 25%, p<0.01) were significantly higher, and the fetal loss rate was significantly lower (8.7% vs. 50%, p=0.01) in the nadroparin-treated group. Regarding the efficacy and safety of antithrombotic treatment in pregnant women with prosthetic heart valves, nadroparin treatment during the first trimester is an acceptable regimen and produces better results than coumarin derivatives.

[Pregnancy and heart disease]

Pregnancy and delivery are associated with substantial physiological changes that require adaptations in the cardiovascular system. These changes, well-tolerated in pregnant women without heart disease, expose woman with cardiovascular disease to serious risk. In fact, heart disease is the most frequent cause of maternal death, after psychiatric disorders, and the number of pregnant women with heart disease is expected to grow in the coming years. Preventing cardiovascular complications should be the main aim of every cardiologist involved in managing pregnant woman with congenital or acquired heart disease. Unfortunately, there is a lack of data which would help in the management of these patients during pregnancy and the clinical practice guidelines are often based on assumptions regarding how a specific substrate is going to respond to the physiological changes occurring due to pregnancy.

Pregnancy in women with valvular heart disease

Patients with valvular disease who desire pregnancy or are already pregnant require specialised care. Ideally, women undergo preconceptual counselling that addresses any procedures needed to decrease the risks of pregnancy, including valve replacement, if the patient has symptoms at baseline. Management during pregnancy includes replacing any contraindicated medications with safer alternatives, optimising loading conditions, careful monitoring and aggressive treatment of any exacerbating factors. Rarely, percutaneous or surgical intervention is required during pregnancy. Labour and delivery often require invasive haemodynamic monitoring and a multi-disciplinary team for optimal maternal and fetal outcomes.

Long-term evaluation of bovine pericardial bioprostheses in young women: influence of pregnancy

OBJECTIVES

To avoid the fetal and maternal risks associated with anticoagulant therapy during pregnancy, the use of bioprostheses has been advocated for young women with cardiac valve disease during the childbearing years. Several reports have suggested the probability of pregnancy-related accelerated structural valve deterioration (SVD). The aim of this study was to assess the effect of pregnancy and delivery on bovine pericardial bioprostheses.

METHODS

Between 1986 and 2004, 13 female patients received 14 bioprostheses. The women were segregated into two groups based on whether pregnancy occurred during follow-up: eight in the Pregnant Group (Group P) (including one case who underwent two operations), and six in the Nonpregnant Group (Group NP).

RESULT

Early mortality was not observed. Late mortality was 12.5% for Group P and 16.7% for Group NP. There were a total of ten valve-related reoperations (seven in Group P and three in Group NP); the major reason was SVD in 64.3% of the cases. Freedom from valve-related reoperation at nine years was 28.6% in Group P and 33.3% in Group NP (p=0.338). Overall time from primary surgery to reoperation was 111 +/- 24.7 months, with no significant difference between the two groups (p=0.615). The Group P of eight patients had 12 pregnancies: ten deliveries and two abortions. There were no maternal or neonatal deaths.

CONCLUSION

Pregnancy did not significantly influence the incidence of SVD and reoperation. The bioprostheses appears to provide female patients with more opportunity for uncomplicated pregnancies, deliveries and normal children than mechanical valves.

Valvular Heart Disease and Pregnancy

A large number of prosthetic heart valves (PHV) are being implanted in patients with both congenital and acquired valvular disease. Many of the recipients of such valves are women of childbearing age who desire to have children. The main issues involved with pregnancy in a patient with PHV include the selection of PHV in women during their childbearing age, risks to both the mother and the fetus associated with pregnancy and the management of the patients with PHV during gestation.

Mitral mechanical replacement in young rheumatic women: Analysis of long-term survival, valve-related complications, and pregnancy outcomes over a 3707-patient-year follow-up

OBJECTIVE

A follow-up study was performed to assess long-term survival, valve-related complications, and pregnancy outcomes in young rheumatic women undergoing isolated mitral mechanical replacement. The influence of prosthetic type on outcomes was also investigated.

METHODS

Between 1975 and 2003, 267 isolated mitral mechanical prostheses were implanted. Follow-up reached 3707.8 patient-years.

RESULTS

Actuarial survival at 1, 5, 10, 15, 20, and 25 years was 97% +/- 0.01%, 90.4% +/- 0.017%, 85.3% +/- 0.023%, 82.3% +/- 0.025%, 71.7% +/- 0.036%, and 70.2% +/- 0.038%, respectively. At multivariate analysis, atrial fibrillation at follow-up was identified as an independent risk factor for late mortality, whereas left ventricular ejection fraction at 12 postoperative months proved to be a protective factor. Freedom from thromboembolism at 1, 5, 10, 15, 20, and 25 years was 98.1% +/- 0.01%, 94.1% +/- 0.015%, 89.1% +/- 0.021%, 85.9% +/- 0.025%, 81.1% +/- 0.031%, and 75.3% +/- 0.063%, respectively. Atrial fibrillation and Carbomedics device were significantly associated with an increase in thromboembolic events. Freedom from reoperation at 1, 5, 10, 15, 20, and 25 years was 99.2% +/- 0.005%, 95% +/- 0.014%, 91.6% +/- 0.018%, 88.6% +/- 0.022%, and 85.7% +/- 0.041%. Type of prosthesis (tilting disc) was identified as a predictor of reoperation. At the end of the study, 208 patients were still alive: 94.7% were in New York Heart Association class I or II. When receiving warfarin therapy, no patient undertaking pregnancy (n = 35) experienced adverse cardiac or valve-related events. Fetal events were significantly less frequent with a daily warfarin dose less than 5 mg.

CONCLUSIONS

Mechanical devices provided excellent performance, safety, and durability. The prognostic role of left ventricular function and atrial fibrillation overwhelmed any differences that might exist between different prosthetic designs. Pregnancies entail virtually no maternal risk and predictable fetal complications.

Complications of prosthetic heart valves

Treatment of native valvular heart disease has resulted in an increasing number of patients with prosthetic valves. Although an improvement over the diseased native valve removed at surgery, prosthetic valves have suboptimal hemodynamics; mechanical valves require anticoagulation and tissue valves wear out over time. Serious complications of prosthetic valves occur at a rate of about 2% to 3% per patient-year. Complications include thromboembolism, prosthesis-patient mismatch, structural valve dysfunction, endocarditis, and hemolysis. Prosthetic valve endocarditis is a lethal disease with mortality rates of 50% to 80% even with appropriate therapy. Echocardiography now provides detailed information on valve function and hemodynamics, allowing early detection of complications. Many of these complications can be prevented by choosing the optimal valve at the time of surgery, rigorous control of anticoagulation and adherence to established anticoagulation guidelines, dental hygiene and endocarditis prophylaxis, and periodic echocardiographic monitoring by a cardiologist.

First-generation agents: aspirin, heparin and coumarins

Aspirin, heparin and the coumarins are the classical anti-thrombotic agents. They represent the platform upon which newer drugs holding the promise of greater efficacy and less toxicity are being developed. Even as such newer drugs arrive into clinical practice, the older agents remain remarkable for their decades-long pre-eminence. All derive from natural sources, and none from a search for therapeutic anti-thrombotic agents; they have saved countless lives but also served as essential probes into basic mechanisms of thrombosis. Testament to their clinical importance is that these agents are the only drugs profiled on a regular basis in special scientific statements by the American Heart Association/American College of Cardiology and by the American College of Chest Physicians. This chapter reviews their biology, uses and limitations.

Periprocedural thromboprophylaxis in patients receiving chronic anticoagulation therapy

Patients receiving chronic anticoagulation therapy pose a clinical challenge when therapy needs to be interrupted for surgical or invasive procedures. Maintaining anticoagulation places them at risk for serious bleeding complications, whereas discontinuing anticoagulation puts them at risk of thromboembolic complications. Most patients can undergo dental procedures, cataract surgery, and diagnostic endoscopy without discontinuing anticoagulation. The main patient groups that may require a periprocedural alternative to oral anticoagulation (periprocedural thromboprophylaxis or bridging) include patients with prosthetic heart valves, atrial fibrillation, and hypercoagulable states and patients with chronic venous thrombosis who are undergoing surgery. Currently, there is little consensus on the appropriate perioperative treatment of patients on long-term warfarin therapy. There are an increasing number of studies that evaluate the benefits of periprocedural bridging with low-molecular-weight heparin (LMWH) in place of unfractionated heparin (UFH). An advantage of LMWH over UFH is that perioperative conversion from warfarin therapy with LMWH can be carried out in the outpatient setting, which is more convenient for patients and is cost effective. As with the use of UFH, there are reports of maternal thromboembolic complications with LMWHs in pregnant women with mechanical heart valves. This review brings together the available data on periprocedural bridging to assess the available options for patients on long-term warfarin therapy who are undergoing surgical procedures. It provides a rationale for using LMWHs while individualizing the risks versus benefits in a given patient population.