St. Jude medical valve in pulmonary position: anticoagulation and thrombosis

Long-Term Outcome Following Pulmonary Valve Replacement in Repaired Tetralogy of Fallot

BACKGROUND

Late pulmonary valve replacement following repair of tetralogy of Fallot may become necessary in patients with chronic pulmonary insufficiency. There is limited information on the long-term outcome of these prostheses, which is the focus of this study.

METHODS

We conducted a retrospective study of patients with repaired tetralogy of Fallot who underwent pulmonary valve replacement from 1990 to 2015 in our institution. We investigated imaging and clinical parameters including mortality and late adverse events (reintervention [surgical or transcatheter]), infective endocarditis, or arrhythmias requiring device implantation or ablation.

RESULTS

There were 69 patients divided into 3 groups: Carpentier-Edwards (n = 14), Contegra (n = 40), and pulmonary homograft (n = 15). The mean age at the time of pulmonary valve replacement was 21 ± 12 years. The mean follow-up was 8.5 ± 4.7 years. The mean preoperative and postoperative right ventricular end-diastolic volume index was 210 ± 42 and 120 ± 24 mL/m², respectively. There were no mortalities. Late adverse events were observed in 23 (33%) patients: 15 (22%) reintervention (surgical or transcatheter), 11 (16%) endocarditis, and 11 (16%) arrhythmias. Overall, 1-, 5-, and 10-year freedom from surgical reintervention was 98.5%, 93.6%, and 79.3%, respectively. The Contegra group had significantly higher pulmonary valve gradients, a higher risk of developing late adverse events compared to Carpentier-Edwards (P = .046) and pulmonary homograft (P = .055) in multivariate analysis and increased risk for reintervention in the univariate analysis (hazard ratio: 3.4; 95% CI: 0.92-13; P value.066).

CONCLUSION

Pulmonary valve replacement in patients with repaired tetralogy of Fallot has acceptable short- and intermediate-term outcomes. Contegra prosthesis had a higher risk of late adverse events with higher pulmonary valve gradients.

Mechanical Pulmonary Valve Replacement

Although most valve operations performed annually address lesions of the aortic or mitral valves, the frequency of pulmonary valve replacement (PVR) is increasing because most patients with congenital heart disease are surviving into the adult years. The vast majority of patients, especially children that require PVR, obtain a tissue valve because of the relative good durability and the lack of a need for anticoagulation. Because the need for repeat operation is inevitable for most patients, and the population of adults with congenital heart disease continues to grow, there are increasing situations in which a mechanical pulmonary prosthesis may be appropriate. Most patients being considered for mechanical PVR have a congenital diagnosis and require multi-valve procedures, and quality of life and need for repeat operation(s) are major issues. Mechanical valves are durable but require anticoagulation, which carries its own inherent set of risks. There are conflicting reports regarding the late outcome of mechanical PVR. There are few reports that indicate that, in the pulmonary position, bileaflet valves are at higher risk for complications compared with monodisc valves; however, the majority of these patients were not anticoagulated with warfarin, but simply maintained on aspirin. There is a growing body of literature documenting low rates of thrombosis or pulmonary prosthesis dysfunction when proper anticoagulation and monitoring are applied.

Visualization of thrombosis on a prosthetic pulmonary valve using electrocardiogram-gated multidetector computed tomography

We report a case of prosthetic valve thrombosis in an 18-year-old man. Total surgical repair of tetralogy of Fallot was performed at 3 years of age. At the age of 18, he underwent pulmonary valve replacement because of exacerbating pulmonary trunk obstruction. After surgery, valve malfunction was suspected. We attempted to employ electrocardiogram (ECG)-gated multidetector computed tomography (MDCT). The stuck valve was clearly visualized together with a thrombus within. Thrombolytic therapy was undertaken on these findings. ECG-gated MDCT allowed us to make a definitive diagnosis of valve thrombosis as the cause of valve malfunction, which led us to avoid surgical reintervention.

Early detection of mechanical valve dysfunction using a new home monitoring device

BACKGROUND

After heart valve replacement, patients are at risk of complications that are linked to irregular oral anticoagulation therapy. Depending on the type and position of the valve, the complication rate is 3% to 6% per patient-year. This study presents clinical results of a device enabling early detection of prosthetic dysfunction by frequency measurements.

METHODS

Between November 2003 and March 2006, ThromboCheck devices were handed out to 483 patients after mechanical heart valve replacement from six heart centers. In each case, the devices were calibrated for individual patients early postoperatively. Taking control measurements, the device calculated deviations from calibrated frequency and amplitude ranges using a fast Fourier transform and sent a warning message to the display if any relevant changes occurred. This message was taken as cause to determine morphologic correlations of the disturbance using imaging techniques, for example, echocardiography or fluoroscopy (observation period, 550.7 patient-years; median application period, 15.1 months).

RESULTS

Twenty-five true positive, 1 false positive, and no false negative measurements occurred. Eleven patients (44%) received thrombolytic therapy with streptokinase or recombinant tissue-type plasminogen activator, resulting in normalization of the digital frequency analysis. In 4 patients (16%), international normalized ratio levels were adjusted under temporary heparinization therapy. Normalization of the valve sounds were achieved within 3 to 7 days. Seven patients (28%) required reoperation despite lysis therapy. Sensitivity was 100% during the observation period; specificity was 99.8%.

CONCLUSIONS

Digital frequency analysis represents a reasonable addition to the monitoring of patients after artificial heart valve replacement to detect prosthesis-related complications early on.

Is There a Role for Mechanical Valved Conduits in the Pulmonary Position?

BACKGROUND

The use of allografts or xenografts is the treatment of choice for pulmonary valve replacement. However, the limited durability is responsible for multiple reoperations associated with increased morbidity. In search of a definitive solution, the implantation of a mechanical valved conduit might be an option in highly selected patients. This study evaluated short-term results after pulmonary valve replacement with a mechanical valved conduit.

METHODS

Fourteen patients underwent pulmonary valve replacement with a mechanical valved conduit. All patients had a mean of 3.0 +/- 1.2 previous operations. Seven patients were previously operated on for tetralogy of Fallot, 3 patients for pulmonary atresia, 3 patients for common arterial trunk, and 1 patient for subaortic stenosis.

RESULTS

All patients survived the operation and are currently well. At follow-up (11 to 63 months), all but 2 patients showed normal right ventricular function, with a mean gradient of 14 +/- 9 mm Hg (range, 4 to 30 mm Hg) across the pulmonary valve. At follow-up, there was no evidence of valve failure or tissue growth within the valve annulus. All patients are receiving anticoagulants to maintain an international normalized ratio of 3.0 to 4.5.

CONCLUSIONS

In highly selected patients, the use of a mechanical valved conduit in the pulmonary position leads to satisfactory results. To avoid a predictable reoperation after multiple right ventricular outflow tract reconstruction, and therefore reoperation-related morbidity, the implantation of a mechanical prosthesis as a lifelong solution requires consideration. Selection criteria for this permanent solution should include older age, multiple previous operations, and patient compliance with anticoagulant therapy.

Results with the freestyle porcine aortic root for right ventricular outflow tract reconstruction in children

BACKGROUND

The ideal choice for valved reconstruction of the right ventricular outflow tract (RVOT) in children is undetermined. This study explores the Freestyle porcine aortic root for these patients.

METHODS

From January 1998 to December 2002, 56 patients ages 1.6 to 29.9 years old (mean 11.8 years old) underwent RVOT reconstruction using a Freestyle porcine aortic root. The patients averaged 1.9 prior operations (range 0 to 5) for tetralogy of Fallot +/- pulmonary atresia (28 patients), critical pulmonary stenosis (10 patients), Ross procedure (5 patients), pulmonary atresia/intact ventricular septum (4 patients), complete atrioventricular septal defect +/- tetralogy of Fallot (4 patients), and others (5 patients). At time of RVOT reconstruction, 42 patients (75%) had additional procedures including the following: tricuspid or mitral repair (24 patients), pulmonary arterioplasty +/- Glenn (12 patients), ventricular septal defect closure (5 patients), aortic valve replacement (3 patients), placement of a cardioverter/defibrillator or pacemaker (3 patients), and others (8 patients).

RESULTS

One patient developed mediastinitis; another was treated for Candida endocarditis (his excised homograft unexpectedly grew Candida). All patients are well on follow-up from 2 to 60 months (mean 30 +/- 20 months) with no deaths. The patient with endocarditis underwent conduit replacement for recurrent pulmonary stenosis 3.5 years postoperatively. Echocardiography revealed mild or no pulmonary insufficiency in 93%. The calculated mean peak systolic RVOT gradient by echocardiography was 19.7 +/- 15.4 mm Hg.

CONCLUSIONS

These data demonstrate excellent results with the Freestyle bioprosthesis for RVOT reconstruction in children. This valve may serve as a readily available alternative to homograft valves in RVOT reconstruction, particularly since early insufficiency seems to be less problematic. Questions of long-term durability and significance of echocardiographic stenosis remain unanswered.