PROX1 Inhibits PDGF-B Expression to Prevent Myxomatous Degeneration of Heart Valves

BACKGROUND

Cardiac valve disease is observed in 2.5% of the general population and 10% of the elderly people. Effective pharmacological treatments are currently not available, and patients with severe cardiac valve disease require surgery. PROX1 (prospero-related homeobox transcription factor 1) and FOXC2 (Forkhead box C2 transcription factor) are transcription factors that are required for the development of lymphatic and venous valves. We found that PROX1 and FOXC2 are expressed in a subset of valvular endothelial cells (VECs) that are located on the downstream (fibrosa) side of cardiac valves. Whether PROX1 and FOXC2 regulate cardiac valve development and disease is not known.

METHODS

We used histology, electron microscopy, and echocardiography to investigate the structure and functioning of heart valves from Prox1ΔVEC mice in which Prox1 was conditionally deleted from VECs. Isolated valve endothelial cells and valve interstitial cells were used to identify the molecular mechanisms in vitro, which were tested in vivo by RNAScope, additional mouse models, and pharmacological approaches. The significance of our findings was tested by evaluation of human samples of mitral valve prolapse and aortic valve insufficiency.

RESULTS

Histological analysis revealed that the aortic and mitral valves of Prox1ΔVEC mice become progressively thick and myxomatous. Echocardiography revealed that the aortic valves of Prox1ΔVEC mice are stenotic. FOXC2 was downregulated and PDGF-B (platelet-derived growth factor-B) was upregulated in the VECs of Prox1ΔVEC mice. Conditional knockdown of FOXC2 and conditional overexpression of PDGF-B in VECs recapitulated the phenotype of Prox1ΔVEC mice. PDGF-B was also increased in mice lacking FOXC2 and in human mitral valve prolapse and insufficient aortic valve samples. Pharmacological inhibition of PDGF-B signaling with imatinib partially ameliorated the valve defects of Prox1ΔVEC mice.

CONCLUSIONS

PROX1 antagonizes PDGF-B signaling partially via FOXC2 to maintain the extracellular matrix composition and prevent myxomatous degeneration of cardiac valves.

Echocardiographic findings in acromegaly: prevalence of concentric left ventricular remodeling in a large single-center cohort

PURPOSE

Acromegaly is a rare disease and is associated with increased cardiovascular (CV) morbidity and mortality, especially in patients with uncontrolled disease. We aimed to analyze the prevalence and severity of cardiomyopathy and valvular heart disease in a large cohort of patients with a confirmed acromegaly diagnosis, at baseline and after treatment.

METHODS

We retrospectively reviewed an institutional approved database; 190 patients with confirmed acromegaly and follow-up data available (years 2006-2018). Patients with at least one baseline echocardiogram, were included. Demographic, disease control and echocardiogram variables were collected for analysis.

RESULTS

Of the 190 patients 110 (58%) had a baseline echocardiogram and 43 (39.1%) had at least one follow-up echocardiogram after surgical, medical or multimodal treatment. Baseline left ventricular hypertrophy (LVH) prevalence was 17.8% (64.7% concentric; 35.3% eccentric), diastolic and systolic dysfunction, and overt cardiomyopathy with heart failure were 15.8, 7.9, and 3.0%, respectively. Concentric remodeling of the left ventricle (LV) was noted in 31.4% of patients without LVH. Valve defects were found in 87.3% of patients (14.6% with significant valvular heart disease).

CONCLUSION

Early diagnosis of acromegaly and disease control should be attempted to prevent LVH/LV dysfunction and development of valvular heart disease. Concentric LV remodeling develops prior to obvious LV hypertrophy in almost a third of patients with acromegaly, which is a novel finding. Similar to other epidemiological studies, we found a high prevalence of LVH/LV dysfunction. Although possible, reversal of systolic and diastolic dysfunction is sporadic after treatment of acromegaly.

Ginkgo Biloba Extract EGB761 Alleviates Warfarin-induced Aortic Valve Calcification Through the BMP2/Smad1/5/Runx2 Signaling Pathway

ABSTRACT

Calcific aortic valve disease is a common heart disease that contributes to increased cardiovascular morbidity and mortality. There is a lack of effective pharmaceutical therapy because its mechanisms are not yet fully known. Ginkgo biloba extract (EGB761) is reported to alleviate vascular calcification. However, whether EGB761 protects against aortic valve calcification, a disease whose pathogenesis shares many similarities with vascular calcification, and potential molecular mechanisms remain unknown. In this study, porcine aortic valve interstitial cell (pAVIC) calcification was induced by warfarin with or without the presence of EGB761. Immunostaining was performed to establish and characterize the pAVIC phenotype. Calcium deposition and calcium content were examined by Alizarin Red S staining and an intracellular calcium content assay. Alkaline phosphatase activity was detected by the p-nitrophenyl phosphate method. The expression levels of bone morphogenetic protein-2 (BMP2), Runt-related transcription factor 2 (Runx2), homeobox protein MSX-2, and phosphorylated (p)-Smad1/5 were detected by reverse transcription-quantitative polymerase chain reaction (PCR) and Western blot analysis. Consistent with these in vitro data, we also confirmed the suppression of in vivo calcification by EGB761 in the warfarin-induced C57/Bl6 mice. The results indicated that both pAVICs and aortic valves tissue of mice stimulated with warfarin showed increased calcium deposition and expression of osteogenic markers (alkaline phosphatase, BMP2, homeobox protein MSX-2, and Runx2) and promoted p-Smad1/5 translocation from the cytoplasm to the nucleus. The addition of EGB761 significantly inhibited p-Smad1/5 translocation from the cytoplasm to the nucleus, thus suppressing calcification. In conclusion, EGB761 could ameliorate warfarin-induced aortic valve calcification through the inhibition of the BMP2-medicated Smad1/5/Runx2 signaling pathway.

Cholesterol induced heart valve inflammation and injury: efficacy of cholesterol lowering treatment

BACKGROUND

Heart valves often undergo a degenerative process leading to mechanical dysfunction that requires valve replacement. This process has been compared with atherosclerosis because of shared pathology and risk factors. In this study, we aimed to elucidate the role of inflammation triggered by cholesterol infiltration and cholesterol crystals formation causing mechanical and biochemical injury in heart valves.

METHODS

Human and atherosclerotic rabbit heart valves were evaluated. New Zealand White male rabbits were fed an enriched cholesterol diet alone or with simvastatin and ezetimibe simultaneous or after 6 months of initiating cholesterol diet. Inflammation was measured using C-reactive protein (CRP) and RAM 11 of tissue macrophage content. Cholesterol crystal presence and content in valves was evaluated using scanning electron microscopy.

RESULTS

Cholesterol diet alone induced cholesterol infiltration of valves with associated increased inflammation. Tissue cholesterol, CRP levels and RAM 11 were significantly lower in simvastatin and ezetimibe rabbit groups compared with cholesterol diet alone. However, the treatment was effective only when initiated with a cholesterol diet but not after lipid infiltration in valves. Aortic valve cholesterol content was significantly greater than all other cardiac valves. Extensive amounts of cholesterol crystals were noted in rabbit valves on cholesterol diet and in diseased human valves.

CONCLUSIONS

Prevention of valve infiltration with cholesterol and reduced inflammation by simvastatin and ezetimibe was effective only when given during the initiation of high cholesterol diet but was not effective when given following infiltration of cholesterol into the valve matrix.

Retinoids Repress Human Cardiovascular Cell Calcification With Evidence for Distinct Selective Retinoid Modulator Effects

OBJECTIVE

Retinoic acid (RA) is a ligand for nuclear receptors that modulate gene transcription and cell differentiation. Whether RA controls ectopic calcification in humans is unknown. We tested the hypothesis that RA regulates osteogenic differentiation of human arterial smooth muscle cells and aortic valvular interstitial cells that participate in atherosclerosis and heart valve disease, respectively. Approach and Results: Human cardiovascular tissue contains immunoreactive RAR (RA receptor)-a retinoid-activated nuclear receptor directing multiple transcriptional programs. RA stimulation suppressed primary human cardiovascular cell calcification while treatment with the RAR inhibitor AGN 193109 or RARα siRNA increased calcification. RA attenuated calcification in a coordinated manner, increasing levels of the calcification inhibitor MGP (matrix Gla protein) while decreasing calcification-promoting TNAP (tissue nonspecific alkaline phosphatase) activity. Given that nuclear receptor action varies as a function of distinct ligand structures, we compared calcification responses to cyclic retinoids and the acyclic retinoid peretinoin. Peretinoin suppressed human cardiovascular cell calcification without inducing either secretion of APOC3 (apolipoprotein-CIII), which promotes atherogenesis, or reducing CYP7A1 (cytochrome P450 family 7 subfamily A member 1) expression, which occurred with cyclic retinoids all-trans RA, 9-cis RA, and 13-cis RA. Additionally, peretinoin did not suppress human femur osteoblast mineralization, whereas all-trans RA inhibited osteoblast mineralization.

CONCLUSIONS

These results establish retinoid regulation of human cardiovascular calcification, provide new insight into mechanisms involved in these responses, and suggest selective retinoid modulators, like acyclic retinoids may allow for treating cardiovascular calcification without the adverse effects associated with cyclic retinoids.

Clinical Characteristics, Complications, and Treatment Practices in Patients With RHD: 6-Year Results From HP-RHD Registry

BACKGROUND

Despite the high prevalence of rheumatic heart disease (RHD) in developing countries such as India, data on characteristics, complications, and treatment practices are lacking. The HP-RHD (Himachal Pradesh Rheumatic Heart Disease) registry aimed at reporting these parameters in patients with RHD from a northern state of India.

METHODS

A total of 2,005 consecutive patients of RHD were enrolled over a period of 6 years (2011 to 2016) in the present study. The clinical characteristics, complications, and treatment practices were systematically recorded.

RESULTS

The mean age for patients with RHD was 40.3 ± 14.3 (range 5 to 83 years). RHD predominantly affected females (72.3%) and population from rural background (92%). Multivalvular involvement was frequent (43.2%), mitral valve was the commonest affected valve (83.3%). The majority of the patients had moderate-to-severe valvular dysfunction (69.3%). Mitral and tricuspid valve involvement was more frequent in female subjects compared with more frequent aortic valve involvement in male subjects (p < 0.001). The major adverse cardiovascular events were recorded in 23.4% patients at the time of registry and comprised mainly advanced heart failure (15.6%), peripheral embolism (4.1%), and stroke (3.9%). The independent risk determinants of major adverse cardiovascular events (were advanced age (odds ratio [OR]: 1.01; 95% confidence interval [CI]: 1.00-1.02), severe mitral stenosis (OR: 1.73; 95% CI: 1.34-2.20), severe tricuspid regurgitation (OR: 2.11; 95% CI: 1.48-3.02), presence of pulmonary artery hypertension (OR: 1.33; 95% CI: 1.04-1.69), and atrial fibrillation (OR: 1.64; 95% CI: 1.28-2.11). Evidence-based use of oral anticoagulant therapy was documented in 77.7% of high-risk patients. Only 28.5% of study population was receiving secondary prophylaxis.

CONCLUSIONS

Complications in patients with RHD increase with age and worsening valvular dysfunction. Programs focused on early detection and evidence-based management will assist in improving outcomes.

Subclinical leaflet thrombosis in surgical and transcatheter bioprosthetic aortic valves: an observational study

BACKGROUND

Subclinical leaflet thrombosis of bioprosthetic aortic valves after transcatheter valve replacement (TAVR) and surgical aortic valve replacement (SAVR) has been found with CT imaging. The objective of this study was to report the prevalence of subclinical leaflet thrombosis in surgical and transcatheter aortic valves and the effect of novel oral anticoagulants (NOACs) on the subclinical leaflet thrombosis and subsequent valve haemodynamics and clinical outcomes on the basis of two registries of patients who had CT imaging done after TAVR or SAVR.

METHODS

Patients enrolled between Dec 22, 2014, and Jan 18, 2017, in the RESOLVE registry, and between June 2, 2014, and Sept 28, 2016, in the SAVORY registry, had CT imaging done with a dedicated four-dimensional volume-rendered imaging protocol at varying intervals after TAVR and SAVR. We defined subclinical leaflet thrombosis as the presence of reduced leaflet motion, along with corresponding hypoattenuating lesions shown with CT. We collected data for baseline demographics, antithrombotic therapy, and clinical outcomes. We analysed all CT scans, echocardiograms, and neurological events in a masked fashion.

FINDINGS

Of the 931 patients who had CT imaging done (657 [71%] in the RESOLVE registry and 274 [29%] in the SAVORY registry), 890 [96%] had interpretable CT scans (626 [70%] in the RESOLVE registry and 264 [30%] in the SAVORY registry). 106 (12%) of 890 patients had subclinical leaflet thrombosis, including five (4%) of 138 with thrombosis of surgical valves versus 101 (13%) of 752 with thrombosis of transcatheter valves (p=0·001). The median time from aortic valve replacement to CT for the entire cohort was 83 days (IQR 33-281). Subclinical leaflet thrombosis was less frequent among patients receiving anticoagulants (eight [4%] of 224) than among those receiving dual antiplatelet therapy (31 [15%] of 208; p<0·0001); NOACs were equally as effective as warfarin (three [3%] of 107 vs five [4%] of 117; p=0·72). Subclinical leaflet thrombosis resolved in 36 (100%) of 36 patients (warfarin 24 [67%]; NOACs 12 [33%]) receiving anticoagulants, whereas it persisted in 20 (91%) of 22 patients not receiving anticoagulants (p<0·0001). A greater proportion of patients with subclinical leaflet thrombosis had aortic valve gradients of more than 20 mm Hg and increases in aortic valve gradients of more than 10 mm Hg (12 [14%] of 88) than did those with normal leaflet motion (seven [1%] of 632; p<0·0001). Although stroke rates were not different between those with (4·12 strokes per 100 person-years) or without (1·92 strokes per 100 person-years) reduced leaflet motion (p=0·10), subclinical leaflet thrombosis was associated with increased rates of transient ischaemic attacks (TIAs; 4·18 TIAs per 100 person-years vs 0·60 TIAs per 100 person-years; p=0·0005) and all strokes or TIAs (7·85 vs 2·36 per 100 person-years; p=0·001).

INTERPRETATION

Subclinical leaflet thrombosis occurred frequently in bioprosthetic aortic valves, more commonly in transcatheter than in surgical valves. Anticoagulation (both NOACs and warfarin), but not dual antiplatelet therapy, was effective in prevention or treatment of subclinical leaflet thrombosis. Subclinical leaflet thrombosis was associated with increased rates of TIAs and strokes or TIAs. Despite excellent outcomes after TAVR with the new-generation valves, prevention and treatment of subclinical leaflet thrombosis might offer a potential opportunity for further improvement in valve haemodynamics and clinical outcomes.

FUNDING

RESOLVE (Cedars-Sinai Heart Institute) and SAVORY (Rigshospitalet).

Improved Pig Model to Evaluate Heart Valve Thrombosis

BACKGROUND AND AIM OF STUDY

Although the sheep is the most acceptable animal model for heart valve evaluation, it has severe limitations for detecting heart valve thrombosis during preclinical studies. While the pig offers an alternative model and is better for detecting prosthetic valve thrombogenicity, it is not often used because of inadvertent valve thrombosis or bleeding complications. The study aim was to develop an improved pig model which can be used reliably to evaluate mechanical heart valve thrombogenicity.

METHODS

Mechanical heart valves were implanted in the mitral position of indigenous pigs administered aspirin-clopidogrel, and compared with similar valves implanted in control pigs to which no antiplatelet therapy had been administered. The pigs were observed for six months to study their overall survivability, inadvertent bleeding/valve thrombosis and pannus formation. The efficacy of aspirinclopidogrel on platelet aggregation and blood coagulation was also recorded and compared between test and control animals.

RESULTS

In comparison to controls, pigs receiving anti-platelet therapy showed an overall better survivability, an absence of inadvertent valve thrombosis/ bleeding, and less obstructive pannus formation. Previously unreported inhibitory effects of aspirin-clopidogrel on the intrinsic pathway of blood coagulation were also observed in the pig model. Notably, with aspirin-clopidogrel therapy inadvertent thrombus formation or bleeding can be prevented.

CONCLUSIONS

The newly developed pig model can be successfully used to evaluate heart valve thrombosis following chronic orthotopic valve implantation. The model may also be utilized to evaluate other bloodcontacting implantable devices.

The imbrication technique: an alternative to the sliding leaflet technique

Systolic anterior motion (SAM) represents a common and troublesome complication of mitral valve repair. The prevention of SAM has traditionally been based on the sliding leaflet technique, which involves resection of posterior leaflet tissue. However, this approach has not been universally adopted owing to its technical difficulty and inconsistent efficacy. We present an imbrication technique that avoids additional leaflet resection and achieves a reliable prevention of SAM. The approach has been successfully implemented in the treatment of 124 consecutive patients at high risk for SAM.

Echocardiographic integrated backscatter for assessing reduction of aortic valve calcifications by R-568 in a rat model of chronic kidney disease

Chronic kidney disease (CKD) and secondary hyper-parathyroidism are associated with calcific aortic valve disease (CAVD). Innovative modalities for imaging CAVD are warranted. Our aim was to use echocardiographic calibrated integrated backscatter (cIB) to quantitatively determine the preventive effect of the calcimimetic R-568 on CAVD in a CKD rat model, and to compare the results with those of micro-computed tomography and histology. Thirty-six male Wistar rats were followed for 7 wk. Rats were divided into four groups with respect to treatment: (1) adenine 0.5% to induce CKD + vehicle; (2) adenine + R-568 (30 mg/kg/d); (3) control, normal diet + vehicle; (4) controls, normal diet + R-568. At week 7, cIB values of the aortic valve were significantly lower in R-568-treated group 2 than in vehicle-treated group 1. This was confirmed by the significantly lower calcified volume observed on micro-computed tomography and the calcified area observed on histology. There were no significant differences in fractional area change and aortic valve area between groups. In conclusion, echocardiographic cIB was able to quantitatively assess a reduction in CAVD by R-568 in a rat model of CKD.

Technique to treat extensive abscesses in double valve replacement for prosthetic valve endocarditis

A 52-year-old man, who underwent double valve replacement for native valve infectious endocarditis, developed prosthetic valve endocarditis (PVE) at nine months after the initial operation. Operative findings revealed a wide aortic annular abscess, which extended through the intervalvular fibrous body to the mitral annulus. The infected mitral valve was excised through the atrial septum. After complete debridement of the abscess, a xenopericardial patch was sutured on to the abscessed area in the partially destroyed intervalvular fibrous body. Using this procedure, the affected annuli were reinforced and the abscessed area was isolated from the blood flow, reducing the probability of recurrent endocarditis. For valve implantation, 'anchoring' sutures were threaded externally through the aortic root, taking into consideration the fragility of the reconstructed annulus. The patient recovered with intensive administration of antibiotics and showed no sign of recurrent infection. The reinforcement of the intervalvular fibrous body and the use of 'anchoring' sutures may represent good alternatives for the surgical treatment of PVE.

Icodextrin eliminates phosphate and ameliorates cardiac hypertrophy and valvular calcification in patients with end-stage renal disease and diabetes mellitus undergoing peritoneal dialysis

Among end-stage renal disease (ESRD) patients, cardiovascular disease is a common comorbidity and one of most important factors affecting clinical prognosis. Calcium deposition has been reported to correlate with plasma phosphate. Icodextrin (Ico)-based peritoneal dialysis (PD) has many advantages over glucose (Glu)-based PD. We aimed to identify factors that suppress arteriosclerosis and valvular disease in patients with ESRD and diabetes mellitus (DM) undergoing Ico-based PD. In this retrospective study, we evaluated the effects of Ico-based PD (n = 20) on phosphate elimination and cardiovascular disease progression in patients with ESRD andDM, and we compared the results with those for Glu-based PD (n = 20). Left ventricular mass index (LVMI) and aortic valve calcification (AVC) score were significantly decreased and daily phosphate elimination was significantly increased in the Ico group compared with the Glu group. Furthermore, mean daily phosphate elimination was significantly and negatively correlated with the amelioration in LVMI and AVC score. Our study suggests that, compared with glucose, icodextrin has the ability to eliminate more phosphate from the body, indicating that phosphate elimination might potentially be a means of controlling cardiovascular disease in PD patients with DM.

Statins in non-ischaemic cardiomyopathy: an update on our current clinical and pathophysiological understanding

Statins are a cornerstone in reducing cardiovascular events. Studies show that statins are beneficial even in patients with normal or low cholesterol levels, indicating pleiotropic mechanisms of therapeutic benefit apart from their antihyperlipidemic effect. Non-randomised, observational and retrospective studies suggest that statins are associated with better outcomes in patients with heart failure (HF) of both ischaemic and non-ischaemic aetiologies. While cholesterol reduction and plaque stabilisation likely play a role in reducing cardiovascular events in ischaemic HF patients, the mechanisms underlying the benefit in non-ischaemic HF patients is less clear. This review suggests the pleiotropic effects of statin therapy can beneficially alter the pathophysiological mechanisms underlying the clinical benefit observed in non-ischaemic HF patients.

[Anticoagulant therapy in a pregnant patient with prosthetic mitral valve-emergency for caesarian section and postoperative bleeding]

Pregnant patients with prosthetic valve need anticoagulation therapy during pregnancy to prevent stuck valve. Regarding the thrombosed valve, there is a dilemma between anticoagulation to prevent further thrombus formation and postoperative bleeding after caesarian section until valve replacement surgery. A 35-year-old woman in her 34th weeks of pregnancy with a thrombus on prosthetic mitral valve was scheduled for emergency caesarian section under general anesthesia. Anticoagulation therapy with heparin was started after admission to the intensive care unit targeting the range between 70-100 second of activated partial thromboplastin time to prevent further thrombus formation. Heparin was administered intravenously (25,000 units per day), but APTT was kept over 110 seconds. Abdominal wall hematoma was detected by percutaneous echo next day and surgery for removal of hematoma was performed. Mitral valve replacement surgery was performed on the postoperative third days successfully. Postoperative anticoagulation therapy with heparin should be started carefully in consideration of physiological change of clotting ability after the termination of pregnancy.

An agonist of liver X receptor slows valvular disease in a hypercholesterolemia mouse model

BACKGROUND AND AIM OF THE STUDY

Cholesterol is a known risk factor in aortic stenosis and valve degeneration, and the liver X receptor (LXR) is a regulator of cholesterol and phospholipid metabolism. It was hypothesized that an LXR agonist would reduce calcium and lipid deposition in aortic valves.

METHODS

Apolipoprotein E-/- (ApoE-/-) mice fed a high-fat diet were implanted with glutaraldehyde-fixed porcine valve fragments. The animals were treated with either the LXR agonist T1317 or vehicle for eight weeks.

RESULTS

The LXR agonist reduced lipid deposition in native aortic roots and sinuses about two-fold (p < 0.05), and echocardiography revealed lower transvalvular velocities in vivo (p < 0.05). Similarly, treatment with the LXR agonist significantly reduced the calcium content (by ca. 50%, p < 0.05) and lipid content (by ca. 20%, p < 0.01) of explanted porcine valve tissue. Serum low-density lipoprotein (LDL) and total cholesterol levels were also lower in treated mice (p < 0.01). Serum levels of the inflammatory chemokine platelet factor 4 were reduced by 30% compared to controls. Cultured valvular cells treated with oxidized LDL (ox-LDL) developed greater numbers of calcific nodules. The ox-LDL treatment of valvular endothelial cells increased adhesion to mononuclear cells, while the LXR agonist reversed both the increase in adhesion and vascular cell adhesion protein-1 expression mediated by ox-LDL.

CONCLUSION

The data acquired suggested that calcium and lipid deposition in heart valves can be altered by inhibiting lipid metabolism via LXR, and that the mechanism may involve inflammatory cell signaling. These results indicate that enhancement of cholesterol efflux activity may have the potential to reduce bioprosthetic and native valve degeneration.

[Effect of liangxue shengji recipe on incidence of post-percutaneous coronary intervention restenosis and adverse cardiovascular events]

OBJECTIVE

To observe the intervention effect of Liangxue Shengji Recipe (LSR) on incidence of post-percutaneous coronary intervention (post-PCI) restenosis and adverse cardiovascular events.

METHODS

With a randomized, single-blinded methods adopted, 100 patients with coronary artery disease (CHD) and underwent stent implantation were randomized into two groups, the control group and the treated group, conventional Western treatment was administered to them all, but with LSR to patients in the treated group additionally. They were followed up for at least six months. The incidences of post-PCI restenosis and adverse events, including cardiogenic death, acute myocardial infarction, recurrent angina pectoris, severe heart failure, further intervention and coronary artery bypass grafting, were observed to estimate the effect of LSR.

RESULTS

No statistically significant difference between the two groups was shown in terms of incidences of intra-stent restenosis, recurrent angina pectoris, estimator of restenosis and its cumulative risk, as well as in reducing the incidence of single adverse event, but did show statistically significant difference between groups in reducing the incidence of united cardiovascular event (P=0.032) and its cumulative risk (P=0.036).

CONCLUSION

Administration of LSR in post-PCI stage could significantly reduce the probability and cumulative risk of united cardiovascular events, and the beneficial effect presents at about six months post-PCI.

Exercise training and cardiac rehabilitation in primary and secondary prevention of coronary heart disease

Substantial data have established a sedentary lifestyle as a major modifiable risk factor for coronary heart disease (CHD). Increased levels of physical activity, exercise training, and overall cardiorespiratory fitness have provided protection in the primary and secondary prevention of CHD. This review surveys data from observational studies supporting the benefits of physical activity, exercise training, and overall cardiorespiratory fitness in primary prevention. Clearly, cardiac rehabilitation/secondary prevention (CRSP) programs have been greatly underused by patients with CHD. We review the benefits of CRSP programs on CHD risk factors, psychological factors, and overall CHD morbidity and mortality. These data support the routine referral of patients with CHD to CRSP programs. Patients should be vigorously encouraged to attend these programs.

Epidemiology and prevention of valvular heart diseases and infective endocarditis in Africa

Valvular heart diseases in Africa affect mainly children and young adults and are a result of rheumatic fever. Rheumatic fever is a preventable disease, but in Africa the combination of a lack of resources, lack of infrastructure, political, social and economic instability, poverty, overcrowding, malnutrition and lack of political will contributes to the persistence of a high burden of rheumatic fever, rheumatic valvular heart diseases and infective endocarditis. Combating and eradicating rheumatic fever and rheumatic heart diseases requires economic development and implementation of best practices of primary and secondary prevention measures. The barriers to achieving this goal in Africa are numerous, but not insurmountable.

Beware of prosthetic valve thrombosis despite therapeutic anticoagulation

Patients with mechanical heart valves require anticoagulation within carefully controlled ranges to prevent valve thrombosis, a life-threatening condition. The majority of doctors will be required to manage anticoagulation, often on a temporary basis such as during elective procedures. As long-term anticoagulation management moves away from specialised hospital clinics, there needs to be widespread awareness of the complications of sub-therapeutic international normalised ratios (INRs).

Acquired Heart Disease in Pregnancy

The incidence of rheumatic heart disease in most industrialized countries is decreasing. Those women who have regurgitant lesions will commonly experience an improvement in symptoms, and therapy is required only in the most severe cases. Women with mild to moderate stenotic lesions can usually expect a good outcome to pregnancy, but women with severe stenotic lesions require close monitoring by both their obstetricians and their cardiologists, especially during the third trimester, labour and delivery, and the early postpartum period. This is the third in a series of five articles reviewing in detail the assessment and management of specific cardiac disorders in pregnancy.

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.

Prävalenz und Pathogenese von Aortenklappenkalzifikationen

BACKGROUND

Calcific aortic valve disease is present in more than 25% of patients > 65 years of age and is associated with a 50% increased risk of cardiovascular events. The clinical significance of aortic valve calcification detected incidentally by radiologic examinations, especially on CT scans of the chest, was unknown. Concerning the multifactorial pathogenesis of aortic valve calcification, recent data indicate that, besides other factors, also the regulators of calcification play a key role in the disease process.

PURPOSE

This study aims to give an overview of the prevalence and clinical significance of incidentally detected aortic valve calcifications. Moreover, the role calcification inhibitors in the pathogenesis of aortic valve calcification is discussed.

Degeneration of native and tissue prosthetic valve in aortic position: do statins play an effective role in prevention?

Degenerative aortic valve stenosis is a common disease in western countries. When it becomes severe, it confers significant morbidity and mortality. Aortic stenosis has been recognized as a complex inflammatory and highly regulated process with histological and immunochemical similarities with the process of atherosclerosis. Hypertension, smoking and diabetes mellitus have consistently been linked to the development of aortic stenosis. Endothelial injury or other processes that contribute to coronary disease may play a role in calcific aortic stenosis. Several observational studies suggests that the key factors of aortic stenosis are lipoproteins and that medical therapies with cholesterol lowering drugs may retard its progression. Similarly, it has been suggested that the process of degeneration of the tissue heart valve has been associated with the same risk factors of atherosclerosis and shares many histological and molecular characteristics. Assuming all this concept, and evaluating the results of a retrospective study it has been suggested to use statin also as medical therapy able to prevent tissue valve degeneration. Randomized controlled clinical trials will be needed to demonstrate the role of lipid intervention to prevent the progression of aortic stenosis and the degeneration of tissue heart valves.

[Stentless bioprostheses they are better?]

The history and evolution of the bioprostheses is revised, above all the stentless. According to the international literature these were the first prosthesis that were established to cardiac level with very good results in the haemodynamic aspect, but that to lack an adequate preparation to diminish its antigenicity, to enlarge its resistance and to avoid the deterioration by calcification, less lasting than the mechanics did them. Nevertheless, it given that the real valvular area is much better than in all the other prostheses, their magnificent haemodynamic performance, the not mandatory use of anticoagulants, they do it a good offering for the patients with valvulopathy, above all the aortic. That international experience, now also shows how the use of anticalcification has improved even more the performance of these prostheses, to enlarge considerably its useful time of long-term life, reasons these by that are being utilized in form increasingly more extensive, above all indicating its use in patients more young, which before was almost prohibitive. Finally the initial experience with these bioprotheses in the National Institute of Cardiology of México is mentioned.

Linezolid in prophylaxis against experimental aortic valve endocarditis due to Streptococcus oralis or Enterococcus faecalis

There are no experimental studies regarding the prophylactic efficacy of linezolid against infective endocarditis. Nonbacterial thrombotic endocarditis of the aortic valve was induced in rabbits by the insertion of a polyethylene catheter. Twenty-four hours later, animals were randomly assigned to a control group, and groups receiving either ampicillin (two doses of 40 mg/kg of body weight each, given intravenously, 2 h apart) or linezolid (a single per os dose of 75 mg/kg). The first dose of ampicillin and the single dose of linezolid were administered 0.5 and 1 h, respectively, prior to the intravenous inoculation of approximately 10(7) CFU of Streptococcus oralis or Enterococcus faecalis. Linezolid peak levels in rabbit serum were similar to the peak serum levels in humans following a 600-mg oral dose of linezolid. Linezolid prevented endocarditis in 87% of S. oralis-challenged rabbits (P < 0.001 versus controls; P = 0.026 versus ampicillin). In rabbits challenged with E. faecalis, linezolid prevented endocarditis in 73% (P = 0.003 versus controls; P = 0.049 versus ampicillin). Ampicillin prevented endocarditis due to S. oralis or due to E. faecalis in 47% (P = 0.005 versus controls) and in 30% (P = not significant versus controls) of the challenged animals, respectively. In conclusion, linezolid was effective as prophylaxis against endocarditis caused by a strain of S. oralis and to a lesser degree against that caused by a strain of E. faecalis. Its prophylactic efficacy was superior to that of ampicillin.

Rheumatic and nonrheumatic valvular heart disease: epidemiology, management, and prevention in Africa

BACKGROUND

Unlike the Western world, valvular disease ranks among the major cardiovascular afflictions in Africa. Acute rheumatic fever and chronic rheumatic valvular disease in their most virulent form are still commonly encountered and impose a huge burden on limited healthcare resources.

METHODS AND RESULTS

We performed a systematic review of the literature with PubMed using rheumatic fever, rheumatic heart disease, valvular disease, warfarin anticoagulation, and pregnancy as search items. Literature emanating from Africa was emphasized. Epidemiology, current concepts on pathogenesis, and aspects of the medical and surgical management of this disease as seen from an African perspective are presented. The association of pregnancy with mitral stenosis is common and may be fatal if not managed appropriately. A practical approach to these patients is presented to optimize maternal and fetal outcome. Pregnant patients with mechanical valves require careful attention to ensure maternal survival and prevent fetal warfarin embryopathy. Prolonged subcutaneous heparin and frequent monitoring of the partial thromboplastin time are impractical in this setting, and the merits of different anticoagulation regimens are discussed. Congenital submitral aneurysms are a unique cause of mitral regurgitation, with the vast majority of cases originating from sub-Saharan Africa. Although the precise etiology is as yet unclear, the clinical and echocardiographic features are sufficiently characteristic to allow a preoperative diagnosis to be made. Transesophageal echocardiography allows much better definition of the size and anatomic relationships of the aneurysm. Surgical resection can be difficult but is usually curative. Mitral valve prolapse and endocarditis constitute the remaining frequent causes of valvular disease and are discussed briefly.

CONCLUSIONS

The spectrum and presentation of valvular disease in Africa are uniquely different from elsewhere. Together with socioeconomic issues and the HIV pandemic, this fact makes it imperative that further epidemiological and clinical studies be undertaken and guidelines developed that are appropriate to the practice of medicine on the African continent.

Stuck Bioprosthetic Aortic Valve--A New Entity? A Case Report

We describe herein a case of bioprosthetic valve malfunction, which closely imitates a stuck valve. Although the term "stuck" was used originally for the immovable mechanical valve leaflets, the echocardiographic manifestation of this malfunction is similar to those of a mechanical one. The clinical presentation of the stuck bioprosthesis is, however, far more benign than a stuck mechanical valve. Familiarity with this entity is important.

Successful moxifloxacin prophylaxis against experimental streptococcal aortic valve endocarditis

OBJECTIVES

Studies related to the prophylactic efficacy of fluoroquinolones against infective endocarditis are scarce. The aim of this study was to evaluate the efficacy of moxifloxacin, a quinolone active in vitro against Gram-positive cocci, in preventing streptococcal aortic valve endocarditis.

METHODS

Non-bacterial thrombotic endocarditis of the aortic valve was induced by the insertion of a polyethylene catheter. Twenty-four hours later, rabbits were randomly assigned to a control group, and groups receiving either two doses of ampicillin (40 mg/kg, intravenously), 2 h apart, or a single dose of moxifloxacin (15 mg/kg, intravenously). Ampicillin and moxifloxacin were administered 0.5 and 1 h, respectively, prior to the intravenous inoculation of 10(7) cfu of Streptococcus oralis.

RESULTS

Eighty-nine percent of the control animals developed infected vegetations. In rabbits challenged with this very high inoculum, moxifloxacin and ampicillin prevented endocarditis in 80% (P < 0.001 versus controls) and in 50% (P = 0.022 versus controls) of animals, respectively. The difference between ampicillin and moxifloxacin was not statistically significant (P = 0.128).

CONCLUSIONS

Moxifloxacin was at least as effective as ampicillin in preventing streptococcal endocarditis.

Atorvastatin inhibits calcification and enhances nitric oxide synthase production in the hypercholesterolaemic aortic valve

OBJECTIVE

To study in a rabbit model the expression of endothelial nitric oxide synthase (eNOS) in association with the development of calcification of the aortic valve, and to assess the effects of atorvastatin on eNOS expression, nitrite concentration, and aortic valve calcification.

METHODS

Rabbits (n = 48) were treated for three months: 16, forming a control group, were fed a normal diet; 16 were fed a 0.5% (wt/wt) high cholesterol diet; and 16 were fed a 0.5% (wt/wt) cholesterol diet plus atorvastatin (2.5 mg/kg/day). The aortic valves were examined with eNOS immunostains and western blotting. Cholesterol and high sensitivity C reactive protein (hsCRP) concentrations were determined by standard assays. Serum nitrite concentrations were measured with a nitric oxide analyser. eNOS was localised by electron microscopy and immunogold labelling. Calcification in the aortic valve was evaluated by micro-computed tomography (CT).

RESULTS

Cholesterol, hsCRP, and aortic valve calcification were increased in the cholesterol fed compared with control animals. Atorvastatin inhibited calcification in the aortic valve as assessed by micro-CT. eNOS protein concentrations were unchanged in the control and cholesterol groups but increased in the atorvastatin treated group. Serum nitrite concentrations were decreased in the hypercholesterolaemic animals and increased in the group treated with atorvastatin.

CONCLUSION

These data provide evidence that chronic experimental hypercholesterolaemia produces bone mineralisation in the aortic valve, which is inhibited by atorvastatin.

Prevention of Calcification of Bioprosthetic Heart Valve Cusp and Aortic Wall With Ethanol and Aluminum Chloride

BACKGROUND

Calcification is frequently associated with device failure of bioprostheses fabricated from either glutaraldehyde pretreated porcine aortic valves or bovine pericardium. It was hypothesized that differential pretreatment with ethanol-aluminum chloride will prove safe and efficacious for inhibiting the calcification of both the porcine aortic valve bioprosthetic cusp and the aortic wall.

METHODS

Glutaraldehyde-fixed porcine aortic valves were subjected to differential aluminum chloride (AlCl3) and ethanol pretreatment; aortic wall segments were treated exclusively with AlCl3 (0.1 moles/L) for 45 minutes, 6 hours, or 8 hours (groups 3A, B, and C, respectively), followed by valve cusp incubations in ethanol (80%, pH 7.4). Nontreated control bioprosthetic valves were either stent-mounted porcine aortic valve bioprostheses (Carpentier-Edwards, group 1) (Edwards, Santa Anna, CA) or St. Jude Toronto SPV valves (St. Jude Medical, St. Paul, MN) (group 2). Mitral valve replacements were carried out in juvenile sheep for 150 days.

RESULTS

Calcium in cusps from group 3A was 2.84 +/- 0.62 mg calcium/g tissue versus control, 22.79 +/- 8.46 mg calcium/g tissue, p = 0.04. Valves pretreated with AlCl3 for 45 minutes, 6 hours, and 8 hours had significantly lower levels of calcium in the aortic wall compared to controls (40.38 +/- 5.66, 26.77 +/- 4.02, and 28.94 +/- 8.25 mg calcium/g tissue for groups 3A, 3B, and 3C, respectively, vs 95.47 +/- 17.14 mg calcium/g tissue for group 1, p < 0.001, and 133.42 +/- 3.96 mg calcium/g tissue for group 2, p < 0.001).

CONCLUSIONS

Differentially applied ethanol and aluminum chloride pretreatment significantly inhibited calcification of both the glutaraldehyde-fixed porcine aortic valve bioprosthetic cusp and the aortic wall.

Gene therapy ameliorates cardiovascular disease in dogs with mucopolysaccharidosis VII

BACKGROUND

Mucopolysaccharidosis VII (MPS VII) is a lysosomal storage disease caused by deficient beta-glucuronidase (GUSB) activity resulting in defective catabolism of glycosaminoglycans (GAGs). Cardiac disease is a major cause of death in MPS VII because of accumulation of GAGs in cardiovascular cells. Manifestations include cardiomyopathy, mitral and aortic valve thickening, and aortic root dilation and may cause death in the early months of life or may be compatible with a fairly normal lifespan. We previously reported that neonatal administration of a retroviral vector (RV) resulted in transduction of hepatocytes, which secreted GUSB into the blood and could be taken up by cells throughout the body. The goal of this study was to evaluate the effect on cardiac disease.

METHODS AND RESULTS

Six MPS VII dogs were treated intravenously with an RV-expressing canine GUSB. Echocardiographic parameters, cardiovascular lesions, and biochemical parameters of these dogs were compared with those of normal and untreated MPS VII dogs.

CONCLUSIONS

RV-treated dogs were markedly improved compared with untreated MPS VII dogs. Most RV-treated MPS VII dogs had mild or moderate mitral regurgitation at 4 to 5 months after birth, which improved or disappeared when evaluated at 9 to 11 and at 24 months. Similarly, mitral valve thickening present early in some animals disappeared over time, whereas aortic dilation and aortic valve thickening were absent at all times. Both myocardium and aorta had significant levels of GUSB and reduction in GAGs.

[Actualities regarding the degenerative valvular heart]

The degenerative valvular heart disease became prioritary from the epidemiological point of view by contrast with the rheumatismal one, as a consequence of the increase of the economic standard and of average life expectancy. The calcific aortic stenosis is the most frequently encountered among the valvular heart lesions. Since the history of this disease is not well known, many efforts have been made in order to research all its aspects from the etiology to therapeutical and prophylactic methods.

Inflammatory and immune processes: the neglected villain of bioprosthetic degeneration?

In an attempt to avoid the destructive process of bioprosthetic heart-valve calcification associated with the use of glutaraldehyde, valves are today prepared using low concentrations of the crosslinking reagent. In this review, we summarize our findings and those of others that confirm that the immunogenicity of such tissue is not sufficiently masked and that a defined humoral response is indeed mounted against a repertoire of antigens unrelated to those associated with vascularized and non-cross-linked xenograft organs. We demonstrate the need for increased cross-linking of tissue to satisfactorily mitigate that response; furthermore, we examine the impact of increased cross-link density on the macrophage as antigen presenting cell with respect to its involvement in both tissue erosion and pannus overgrowth. Finally we present evidence for a role of circulating antibodies in bioprosthesis calcification.

Glutaraldehyde fixation revisited

Our ability to stabilize animal heart valves and to manufacture equivalent prostheses using collagenous tissues has proven to be of significant value to large number of patients over the last 30 years. Such tissue-derived bioprostheses are being gradually improved by modifications of design and slight changes in the processing of the tissues from which they originate. Nevertheless their durability does not seem to have significantly improved, and some of their drawbacks, such as their propensity to calcify, have not been eliminated. Because of this children are excluded from receiving such implants. Enhancing such structures using cells from various sources or with the aid of growth factors does not seem likely to succeed because such inert matrices are not compatible with growth and remodeling. On the other hand, stabilizing these structures by means of novel crosslinking approaches, the addition of "plasticizing" molecules, or the addition of covalently bound residues that inhibit the growth of mineral deposits, could prove to be practical ways of improving such devices.

Failure of low molecular-weight heparin in the prevention of prosthetic mitral valve thrombosis during pregnancy: case report and a review of options for anticoagulation

All mechanical heart valves are thrombogenic and may be associated with thromboembolic complications if anticoagulation is inadequate. This risk is increased in pregnancy due to a hypercoagulable state. The ideal anticoagulation regimen in pregnant patients with prosthetic heart valves is uncertain. Oral dicoumarol anticoagulants, subcutaneous low molecular-weight heparin, subcutaneous high-dose heparin and continuous high-dose intravenous heparin each have their own merits and demerits. A case is presented of a pregnant patient who had prosthetic valve thrombosis while receiving low molecular-weight heparin and who required re-do prosthetic mitral valve replacement. An analysis is also included of the options available for anticoagulating this difficult patient group.

Atorvastatin inhibits hypercholesterolemia-induced cellular proliferation and bone matrix production in the rabbit aortic valve

BACKGROUND

Despite the common occurrence of aortic stenosis, the cellular causes of the disorder are unknown, in part because of the absence of experimental models. We hypothesized that atherosclerosis and early bone matrix expression in the aortic valve occurs secondary to experimental hypercholesterolemia and that treatment with atorvastatin modifies this transformation.

METHODS AND RESULTS

To test this hypothesis, we developed an experimental hypercholesterolemic rabbit model. New Zealand White rabbits (n=48) were studied: group 1 (n=16), normal diet; group 2 (n=16), 1% (wt/wt) cholesterol diet; and group 3 (n=16), 1% (wt/wt) cholesterol diet plus atorvastatin (3 mg/kg per day). The aortic valves were examined with hematoxylin and eosin stain, Masson trichrome, macrophage (RAM 11), proliferation cell nuclear antigen (PCNA), and osteopontin immunostains. Cholesterol and highly sensitive C-reactive protein (hsCRP) serum levels were obtained by standard assays. Computerized morphometry and digital image analysis were performed for quantifying PCNA (% area). Electron microscopy and immunogold labeling were performed for osteopontin. Semiquantitative RT-PCR was performed for the osteoblast bone markers [alkaline phosphatase, osteopontin, and osteoblast lineage-specific transcription factor (Cbfa-1)]. There was an increase in cholesterol, hsCRP, PCNA, RAM 11, and osteopontin and osteoblast gene markers (alkaline phosphatase, osteopontin, and Cbfa-1) in the cholesterol-fed rabbits compared with control rabbits. All markers except hsCRP were reduced by atorvastatin.

CONCLUSIONS

These findings of increased macrophages, PCNA levels, and bone matrix proteins in the aortic valve during experimental hypercholesterolemia provide evidence of a proliferative atherosclerosis-like process in the aortic valve associated with the transformation to an osteoblast-like phenotype that is inhibited by atorvastatin.

HMG CoA reductase inhibitor (statin) and aortic valve calcium

There is no known pharmacological therapy for calcific aortic valvular sclerosis or stenosis. Because leaflet calcification occurs in areas of lipoprotein deposition, we hypothesised that 3-hydroxy-3-methylglutaryl-coenzyme A (HMG COA) reductase inhibitors (statins) might slow aortic valve calcium (AVC) accumulation. We retrospectively identified 65 patients who had undergone two electron-beam computed tomography scans at a mean (SD) interval of 2.5 (1.6) years. 28 (43%) patients were receiving statins. Patients who were treated with statins had a 62-63% lower median rate of AVC accumulation (p=0.006) and 44-49% fewer statin patients had definite AVC progression (p=0.043). These findings suggest that statins may decrease AVC accumulation.

The amino bisphosphonate ibandronate prevents vitamin D toxicity and inhibits vitamin D-induced calcification of arteries, cartilage, lungs and kidneys in rats

Experiments were carried out to determine whether the doses of the amino bisphosphonate ibandronate that inhibit bone resorption inhibit soft tissue calcification and death in rats treated with a toxic dose of vitamin D. These studies were prompted by the recent discovery that ibandronate doses that inhibit bone resorption potently inhibit artery calcification induced by treatment with the vitamin K antagonist warfarin. All 16 rats treated with the toxic dose of vitamin D (12.5 mg cholecalciferol x kg(-1)) died by d 6 after the first vitamin D injection (median survival: 4.5 d), whereas the 12 rats treated with vitamin D plus ibandronate (0.25 mg x kg(-1) x d(-1)) were alive and in good health at d 10. Rats treated with vitamin D alone and examined at d 4 had extensive Alizarin red staining for calcification in the aorta, the carotid, hepatic, mesenteric, renal and femoral arteries, kidneys and lungs, whereas rats treated with vitamin D plus ibandronate had no evidence for calcification at any of these tissues when examined at d 7 and 10. Ibandronate treatment also inhibited the dramatic increase in the levels of calcium and phosphate seen in the abdominal aorta, kidneys, lungs and trachea of the vitamin D-treated rats (P < 0.001). Serum calcium levels were, however, not different in rats treated with vitamin D alone (3.4 +/- 0.2 mmol x L(-1)) and in rats treated with vitamin D plus ibandronate (3.5 +/- 0.2 mmol x L(-1)). Treatment with vitamin D alone increased levels of matrix Gla protein, an inhibitor of soft tissue calcification, in the arteries, kidneys, lungs and trachea by 10- to 100-fold, and ibandronate treatment prevented this increase. The importance of these studies in the rat model is that they identify a class of drugs in current clinical use that can be used to treat patients with vitamin D toxicity and that they identify the dose of the drug that is predicted to be effective, namely the dose that inhibits bone resorption. Because there is no other known treatment for vitamin D toxicity, there would seem to be good reason to try bisphosphonates such as ibandronate in future studies aimed at treating patients who have been exposed to toxic levels of vitamin D.

Enoxaparin treatment in women with mechanical heart valves during pregnancy

OBJECTIVE

This prospective audit reports pregnancy outcomes, anticoagulation complications, and anti-Xa levels in women with mechanical heart valves who were treated with therapeutic enoxaparin plus aspirin during pregnancy.

STUDY DESIGN

Between 1997 and 1999, 11 women with mechanical heart valves were treated with enoxaparin, 1 mg/kg twice daily, and aspirin, 100 to 150 mg daily during 14 pregnancies. Predose and 4-hour postdose anti-Xa levels were monitored monthly.

RESULTS

There were 9 live births, 3 miscarriages, and 2 terminations. In 48 months of enoxaparin treatment, one woman who had a documented valve thrombosis when she presented at 8 weeks' gestation also had a valve thrombosis at 20 weeks' gestation. There were no enoxaparin-related hemorrhagic complications. Mean (SD) anti-Xa levels were 0.46 (0.12) U/mL predose and 0.89 (0.22) U/mL 4 hours postdose.

CONCLUSION

Successful pregnancy outcome may be achieved with therapeutic subcutaneous enoxaparin, but its efficacy at preventing valve thrombosis remains uncertain. Further data are required before use of enoxaparin during pregnancy in women with mechanical heart valves can be recommended.