Aortic valve prosthesis-patient mismatch and exercise capacity in adult patients with congenital heart disease

In vivo performance of a tri-leaflet mechanical heart valve prosthesis in an ovine model

OBJECTIVES

We present the long-term results of a trileaflet (Triflo) versus bileaflet (On-X) mechanical valve in both aortic and pulmonary positions in a sheep model.

METHODS

The Triflo valve was implanted in 21 female sheep in aortic (n = 8) and pulmonary position (n = 13). The On-X valve was implanted in 7 female sheep in aortic (n = 1) and pulmonary (n = 6) positions. No antithrombotic medication of any kind was given postoperatively. In the aortic group, survival cohorts were 3 and 5 months. In the pulmonary group, survival cohorts were 10 and 20 weeks. Valve performance was assessed using haematology, echocardiography and acoustic measurements combined with post-mortem pathology analysis of the downstream organs.

RESULTS

The mean gradients were lower for the Triflo valve in both pulmonary [4.30 mmHg (3.70-5.73) vs 6.80 mmHg (4.63-7.96), P = 0.012] and aortic [5.1 mmHg (4.2-7.7) vs 10.7 mmHg (8.7-12.9), P = 0.007] positions. Peak gradients were lower for the Triflo valve in both pulmonary [8.05 mmHg (6.75-10.23) vs 13.15 mmHg (9.20-14.76), P = 0.005] and aortic [8.7 mmHg (7.5-12.5) vs 16.5 mmHg (14.2-19.6), P = 0.009] positions. In both positions, leaflets and housing surface were free from any deposits macro- and microscopically and comparable to nonimplanted control valves. Peripheral organs showed no signs of thrombo-embolic damage. Biochemical and haematological were comparable to preoperative. The closing click sound pressure level of the Triflo was significantly lower in both aortic [108.4 sound pressure level (102.0-115.7) vs 111.7 sound pressure level (105.5-117.0), P < 0.001] and pulmonary [103.6 sound pressure level (99.1-108.9) vs 118.5 sound pressure level (116.7-120.2), P < 0.001] position.

CONCLUSIONS

Preliminary in vivo results of the Triflo valve are promising in both aortic and pulmonary positions in an ovine model. Excellent haemodynamics, stable long-term function, low valve noise and no thrombo-embolic events in the absence of antithrombotic medication lay the foundation to a future clinical first-in-man trial.

Patient–Prosthesis Mismatch in Contemporary Small-Size Mechanical Prostheses Does Not Impact Survival at 10 Years

Background: The effect of PPM in mechanical prostheses on long-term survival is not well-established. Methods: Patients who received a 21 mm or smaller aortic valve between 2000 and 2011 were retrospectively analyzed (n = 416). Propensity matching was used in order to account for baseline differences in patient subgroups (PPM vs. no PPM; severe PPM vs. no severe PPM). Results: Five- and ten-year survival was 78 ± 3.52% and 64.51 ± 4.51% in patients with PPM, versus 83.3 ± 3.12% and 69.37 ± 4.36% in patients without (p = 0.28) when analyzed at 10.39 ± 5.25 years after the primary procedure. Independent risk factors for impaired survival, after matching, were age, serum creatinine, and severe pulmonary hypertension. Five- and ten-year survival in patients with severe PPM was 73.34 ± 6.01% and 61.76 ± 8.17%, respectively, versus 74.72 ± 5.68% and 67.50 ± 7.09% in those without (p = 0.49), at 8.82 ± 5.17 years after SAVR. Age was the only independent variable that influenced long-term survival when severe PPM was added to the model. Conclusions: PPM or severe PPM does not impact long-term survival up to 10 years in mechanical valve recipients when matching for preoperative variables.

Aortic valve replacement in sheep with a novel trileaflet mechanical heart valve prosthesis without anticoagulation

Background

Even after decades of intensive research, an ideal heart valve prosthesis remains elusive. Shortcomings of conventional devices include reduced durability of bioprostheses and the thrombogenicity of mechanical substitutes, necessitating anticoagulation and resulting in imperfect hemodynamics. Here we present in vivo results of a novel mechanical heart valve prosthesis aiming for freedom from anticoagulation.

Methods

Four female sheep had their aortic valves replaced using the novel mechanical heart valve (size 21 mm), with no postoperative anticoagulation treatment. This trileaflet heart valve was designed with the pivots in the systolic central flow. Hemodynamics, biochemistry, hematology, and macroscopy and microscopy were studied at 90 days in 2 sheep and at 1 year in the other 2 sheep.

Results

Mean (<6 mm Hg) and peak (<10 mm Hg) aortic transvalvular gradients remained low during the study period. Aortic regurgitation was trivial, and central traces were only rarely observed. The rate of thrombotic events was very low, with none macroscopically and microscopically visible thrombotic material on the device. Biochemistry and hemotology were unchanged without hemolysis. In 3 sheep, the fibrous pannus and mitral leaflet were partially folded over the edge of the annular body. Apart from organic/inorganic deposits on the leaflets after 1 year, the ultrastructurally evaluated leaflets were similar to those of nonimplanted controls.

Conclusions

The preliminary in vivo results of this novel anticoagulation-free aortic mechanical heart valve are promising with excellent hemodynamics and a very low risk of thrombotic events.

Longitudinal Changes in Exercise Capacity in Patients Who Underwent Ross Procedure and Mechanical Aortic Valve Replacement: Does the Type of Surgery Matter?

The surgical options for significant aortic valve disease include either Ross procedure (RP) or aortic valve replacement (AVR). The exercise stress test is routinely performed in these patients to assess the objective functional capacity. This retrospective study was conducted to evaluate the differences and the longitudinal changes of exercise capacity in patients following the RP and AVR for aortic valve disease. This is an IRB approved retrospective study and included patients who had either RP or AVR performed for aortic valve disease and had at least one exercise stress test performed after the surgical procedure. Patients with other congenital heart disease, pacemaker or defibrillators, and those with inadequate data were excluded. Demographic data including age at surgery, type of surgery and type of aortic valve was collected. Data regarding treadmill cardiopulmonary exercise test (CPET) was also collected. A total of 47 patients met inclusion criteria and were equally represented in each group, i.e. RP [n = 23, 73.9% male, age at surgery 11.2 (4.5-15.9) years] vs. AVR [n = 24, 88% mechanical AVR, 60.9% male, age at surgery 15.1 (12.8-19.4) years]. There was a significant decline in predicted oxygen consumption (%VO₂) at time of first post-operative CPET in patients after AVR compared to RP (79 vs. 88%, p = 0.048) over a similar accrued median interval follow-up (4.6 vs. 6.2 years, p = 0.2). The longitudinal follow-up analysis of following AVR (n = 11, 54.5% male, median inter-test duration of 5 years) showed significant decline in peak exercise capacity or VO₂ (34.2 vs. 26.2 vs., p = 0.006). In contrast, after RP (n = 12 patients [58.3% male, median inter-test duration 7.1 of years], exercise capacity and other key parameters remained preserved. In this small sentinel study, we report a better initial exercise capacity among patients after RP compared to AVR over an intermediate follow-up. During longitudinal follow-up in a subset of patients, exercise capacity remained preserved amongst the RP group while it further declined in the AVR group.

Aortic valve repair in adult congenital heart disease

Aortic valve repair in adult congenital heart disease (ACHD) went through a major development during the last two decades to become an increasingly established treatment option in experienced heart valve repair centers. This mini-review addresses valve-sparing treatment strategies in the two most common clinical entities of patients with adult congenital aortic valve disease, namely those presenting with bicuspid (BAV) and unicuspid (UAV) aortic valve disease. Both diseases are integral components of the continuum of congenital aortic valve diseases and represent one of the most common reasons of cardiovascular morbidity in young and otherwise healthy adult patients. The review will highlight the most important advantages of aortic valve sparing procedures as compared to the conventional valve replacement strategy. New treatment aspects will be reviewed including minimally-invasive surgical approaches for aortic valve repair as well as modern protocols of enhanced perioperative recovery which will potentially improve the perioperative recovery and quality of life of the patients undergoing valve-sparing surgical procedures in the future.

Biological versus mechanical heart valve prosthesis during pregnancy in women with congenital heart disease

BACKGROUND

We evaluate pregnancy outcome and anticoagulation regimes in women with mechanical and biological prosthetic heart valves (PHV) for congenital heart disease.

METHODS

Retrospective multicenter cohort studying pregnancy outcomes in an existing cohort of patients with PHV.

RESULTS

52 women had 102 pregnancies of which 78 pregnancies (46 women) ≥20 weeks duration (59 biological, 19 mechanical PHV). Miscarriages (n = 19, ≤20 weeks) occurred more frequently in women using anticoagulation (P < .05). During 42% of pregnancies of women with mechanical PHV a combined low molecular weight heparin (LMWH) vitamin-K-antagonist anticoagulation regime was used (n = 8). Overall, cardiovascular, obstetric and fetal/neonatal complications occurred in 17% (n = 13), 68% (n = 42) and 42% (n = 27) of the pregnancies. Women with mechanical PHV had significantly higher cardiovascular (12% vs 32%, P < .05), obstetric (59% vs 85%, P = .02) and fetal/neonatal (34% vs 61%, P < .05) complication rates than women with biological PHV. This was related to PHV thrombosis (n = 3, P < .02), post-partum hemorrhage (P < .02), cesarean section (P < .02), low birth weight and small for gestational age (both P < .05). PHV thrombosis occurred in 3 pregnancies, including 2/5 pregnancies with pulmonary mechanical PHV. PHV thrombosis was related to necessary cessation of anticoagulation therapy or insufficient monitoring of LMWH. Other cardiovascular complications occurred equally frequent in both groups.

CONCLUSION

Complications occur more often in pregnancies of women with a mechanical PHV than in women with a biological PHV, mainly caused by PHV thrombosis and bleeding complications. Meticulous monitoring of anticoagulation in pregnant women is necessary. Women with a pulmonary mechanical PHV are at high risk of complications.

NT-proBNP and exercise capacity in adult patients with congenital heart disease and a prosthetic valve: a multicentre PROSTAVA study

Objectives

N-terminal B‑type natriuretic peptide (NT-proBNP) is an important biomarker for the detection of heart failure. Adults with congenital heart disease (ACHD) and a prosthetic heart valve are at risk for heart failure. This study aimed to determine the value of NT-proBNP in ACHD patients with a prosthetic valve and investigate its relationship with cardiac function and exercise capacity.

Methods

In this multi-centre cross-sectional observational study, data regarding medical history, echocardiography, exercise testing (VO₂peak) and laboratory blood evaluation (including NT-proBNP) were collected in ACHD patients with a single prosthetic valve (either homografts, heterografts or mechanical valves).

Results

A total of 306 ACHD patients with pulmonary valve replacement (PVR, n = 139), aortic valve replacement (n = 141), mitral valve replacement (n = 21) or tricuspid valve replacement (n = 5) were investigated. The majority of patients (77 %) were in NYHA class I or II. Elevated NT-proBNP levels (cut-off ≥125 pg/ml) were found in 50 % of the patients, with the highest levels in patients with mitral valve replacements. In this study population, NT-proBNP levels were associated with gender (p = 0.029) and VO₂max (p < 0.001). In PVR patients, NT-proBNP levels were associated with lower VO₂peak, also after adjustment for age, gender and age at valve replacement in a multivariate model (p = 0.015).

Conclusions

In patients with ACHD and a prosthetic valve, elevated NT-proBNP levels are frequently observed despite preserved NYHA class. In PVR patients, a higher NT-proBNP level was associated with a lower VO₂peak. These results may be of importance in the ongoing discussion about the timing of valve replacement in patients with CHD.