Percutaneous Valve Procedures: An Update

Clinical outcomes after TAVR with heparin or bivalirudin as periprocedural anticoagulation in patients with and without peripheral arterial disease: Results from the BRAVO-3 randomized trial

OBJECTIVES

This study sought to investigate the clinical outcomes of patients with and without peripheral artery disease (PAD) in the BRAVO-3 trial with respect to the effect of bivalirudin versus unfractionated heparin (UFH).

BACKGROUND

PAD is found frequently in patients undergoing transcatheter aortic valve replacement (TAVR) and is reported to confer an increased risk of adverse events. It is unknown whether patients with and without PAD may demonstrate a differential response to bivalirudin versus UFH.

METHODS

BRAVO-3 was a randomized multicenter trial comparing transfemoral TAVR with bivalirudin versus UFH (31 centers, n = 802). Major adverse cardiovascular events (MACE) were a composite of 30-day death, myocardial infarction, or cerebrovascular accidents (CVA). Net adverse cardiovascular events (NACE) were a composite of major bleeding or MACE.

RESULTS

The total cohort included 119 patients with PAD. Vascular complications occurred significantly more frequently in patients with PAD both in-hospital (25.2 vs. 16.7%; OR 1.68) and at 30 days (29.4 vs. 17.3%; OR 1.99). No significant differences were observed regarding mortality, NACE, MACE, major bleeding or CVA with bivalirudin versus UFH among patients with or without PAD. In patients with PAD, bivalirudin was associated with an increased risk of minor vascular complications at 30 days.

CONCLUSIONS

Patients with PAD undergoing transfemoral TAVR did not exhibit an increased risk of any major adverse events, according to the procedural anticoagulant randomization. However, patients treated with Bivalirudin had significantly higher rates of minor vascular complications.

Fatigue exhaustion of the mitral valve tissue

Sudden failure and rupture of the tissue is a rare but serious short-term complication after the mitral valve surgical repair. Excessive cyclic loading on the suture line of the repair can progressively damage the surrounding tissue and finally cause tissue rupture. Moreover, mechanical over-tension, which occurs in a diseased mitral valve, gradually leads to tissue floppiness, mitral annular dilation, and leaflet rupture. In this work, the rupture mechanics of mitral valve is studied by characterizing the fracture toughness exhaustion of healthy tissue. Results of this study show that fracture toughness of the posterior mitral valve is lower than its anterior counterpart, indicating that posterior tissue is more prone to failure. Moreover, the decrease in fracture toughness by increasing the number of fatigue cycles shows that excessive mechanical loading leads to progressive failure and rupture of mitral valve tissue within a damage accumulative process.

Balloon expandable sheath for transfemoral aortic valve implantation: a viable option for patients with challenging access

BACKGROUND AND OBJECTIVES

Transcatheter aortic valve replacement (TAVR) via femoral access is a new option for patients with severe aortic valve stenosis considered to be at high risk for conventional open-heart surgery. This procedure requires peripheral arteries that are able to accommodate the large sheaths required for valve delivery. We present a series of patients with suboptimal vascular conditions, who received a self-expandable vascular sheath.

METHODS AND RESULTS

From January 2009 to September 2011, a total of 96 patients (43% male) were treated with the 18F Medtronic CoreValve (Medtronic, Minneapolis, MN, USA). The patients' average age was 82.5 ± 4.6 years, and the mean EuroSCORE was 29%. In eight cases, vascular conditions were inadequate either due to advanced atherosclerotic disease (n = 5, 62.5%), or an arterial diameter ≤7 mm (n = 3, 37.5%). Instead of the standard 18F sheath, a balloon-expandable transfemoral introducer (SoloPath Introducer, Onset Medical Corporation, Irvine, CA, USA) was delivered and removed without complications in all but one (87.5%) patient. In the last case, rupture of the right femoral artery occurred after removal of the sheath with the need of vascular surgery.

CONCLUSION

The SoloPath sheath is a feasible alternative to conventional sheaths for transfemoral TAVR patients with difficult femoral vascular access.

Short-term Changes in Aortic Regurgitation after Percutaneous Mitral Valvuloplasty

OBJECTIVES

The aim of this study was to evaluate the short- term effects of percutaneous mitral valvuloplasty (PMV) on coexisting AR.

METHODS

Clinical, echocardiographic and catheterization data from hospital records of a total of 327 patients with rheumatic mitral stenosis who underwent PMV at a tertiary centre were retrospectively reviewed and aortic regurgitation changes 48 hours post PMV was recorded.

RESULTS

The study population consisted of 282 females and 45 males. Mean age at the time of intervention was 47.13±11 years. Before PMV, 142 (43.3%) patients had no AR, 124 (37.9%) had mild AR and 61 (18.7%) had moderate AR. There was no change in AR severity in post- PMV follow-up. AR progression after PMV and during the follow-up was not significant and there was no increase in the need for aortic valve replacement (AVR) procedures.

CONCLUSIONS

Our findings indicated that a considerable number of patients with rheumatic mitral stenosis had concurrent AR. At the time of PMV concomitant AR does affect procedural success and is not associated with inferior outcomes. Patients with moderate degrees of AR remain good candidates for PMV.

Natural History of Aortic Regurgitation following Percutaneous Mitral Valvuloplasty

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Transcatheter valve implantation: damage to the human aorta after valved stent delivery system exposure--an in vitro study

Transcatheter heart valve implantation can be performed transapically and transfemorally. The transfemoral way to the aortic valve is significantly longer than the transapical one. The aim of this study was to analyse the intima of 15 human aortas after the deployment of different conventional valved stent delivery systems. Fifteen human aortas have been analysed (77 ± 8.4 years). These aortas were preserved with formalin and explanted from the common iliac arteries to the ascending aorta. After protocolling all relevant vascular parameters, the deployment force of different conventional valved stent delivery systems was analysed. After that, the intima was closely investigated by endoscopy. The deployment force of the old catheter was not different from the actual system. The endoscopic investigation revealed significant intimal damages in all parts of the aorta after deployment of the delivery system. This study demonstrated that the passage to the aortic valve can result in significant intimal damage regardless of the used deployment catheter. Efforts are necessary to lower the profile of the deployment devices to increase their flexibility. The intima of the aorta and possible damage have to get back into the physicians' focus to avoid possible late aortic complications.

Functional and structural effects of percutaneous edge-to-edge double-orifice repair under cardiac cycle in comparison with suture repair

Percutaneous procedures for double-orifice mitral valve repair using the MitraClip® device (clip) have been recently introduced as new treatment options as alternatives to medical management and open-heart surgery, especially for patients with high estimated operative risk. Similarly to the open-heart surgical technique, where suturing is used, the clip creates a double-orifice configuration that not only improves the closing function of the valve, but also significantly modifies its behaviour, particularly in the diastolic phase. While several clinical trials have been conducted, and are ongoing, in order to assess the safety and effectiveness of this technique, a deeper knowledge of the structural and functional effects on the valve, and of the cyclic loads transmitted to the clip itself, would allow a comparison with other repair techniques, and could serve as a foundation for possible further optimization of the clip design. The effects of the MitraClip® device developed by Evalve Inc. were studied by means of a finite element model of the mitral valve, specifically developed to study the structural effects of the original, suture-based, edge-to-edge technique. A second model was developed in order to simulate the effects of a suture with similar extension from the leaflet edge in a direction to the annulus, in order to compare the two repair techniques. The mitral valve area and transvalvular pressure gradient predicted by the models for the clip and the suture are quite similar. Similar leaflet cyclic stresses, both in value and in location, were noted for the two mechanisms of linking the leaflets, while minor differences were found in the load transmitted to the suture and the clip, with slightly higher values for the clip. The model satisfactorily allowed functional parameters (valve area and transvalvular pressure gradient) and structural parameters (load, leaflet stress) to be determined. Overall, the structural effects of the clip and the suture are quite similar under the cyclic loading conditions imposed by the cardiac cycle.

Emerging approaches of transcatheter valve repair/insertion

Aortic stenosis (AS) and mitral regurgitation (MR) account for the majority of valvular diseases and their prevalence is increasing according to increased life expectancy. Surgical treatment is the gold standard, although operative risk may be high in some patients due to comorbidities and age. A large part of the patients at high surgical risk who could beneficiate of treatment are not referred to surgery. Therefore, there is a need of alternative and less invasive procedures.

Clinical profile, treatment assignment and clinical outcome of patients with severe aortic stenosis not eligible to participate in a clinical trial of percutaneous aortic valve replacement

Patients with severe aortic stenosis and considered at high surgical risk or inoperable, and not eligible for a randomized clinical trial evaluating percutaneous aortic valve replacement (PAVR), were studied. Many of the patients referred to the study did not meet the inclusion criteria and/or had conditions listed in the exclusion criteria. These patients were then deferred to other treatment modalities. The study cohort consisted of 285 patients with severe aortic stenosis referred to participate in a clinical trial of PAVR. Patients were screened for eligibility on the basis of the protocol inclusion and exclusion criteria and deferred to other treatment modalities if they did not meet the enrollment criteria. Those patients were followed clinically by telephone contact or office visits. Of the 285 patients referred for PAVR, 216 (75.8%) were not included. The leading reasons for lack of eligibility were significant peripheral vascular disease in 50 (23.1%), Society of Thoracic Surgeons score <10% in 48 (22.9%), aortic valve area >0.8 cm(2) in 30 (13.9%), significant coronary artery disease in 25 (11.6%), and renal failure in 22 (10.2%). Sixty-nine of these patients (31.9%) were treated medically, 102 (47.2%) with balloon aortic valvuloplasty, and 45 (20.9%) with surgical aortic valve replacement. Major baseline characteristics were similar. Society of Thoracic Surgeons scores were lower in the surgical group compared with the medical and balloon aortic valvuloplasty groups (10.2 +/- 2.5 vs 12.8 +/- 3.3 vs 13.7 +/- 3.3, respectively, p <0.001). During a median follow-up period of 175.5 days (range 55.7 to 344.75), the mortality rate was higher in the balloon aortic valvuloplasty group compared with the medical and surgical aortic valve replacement groups (46 [45.1%] vs 22 [31.9%] vs 10 [22.2%], respectively, p = 0.01). In conclusion, high-risk patients with severe aortic stenosis who are deferred from PAVR often do poorly and incur high mortality rates, especially when treated with balloon valvuloplasty or medical therapy, while a loss of quality of life is apparent in those treated surgically.

Mitral valve surgery in advanced heart failure

The appropriateness and timing of mitral valve surgery in patients with advanced heart failure and severe mitral regurgitation remains controversial. Recent surgical results provide evidence for beneficial effects on left ventricular remodeling and functional capacity. Given the absence of randomized trials comparing the outcomes of mitral valve surgery to medical therapy, however, clinical decision making regarding surgery for these fragile patients poses a dilemma to thoughtful clinicians. This paper reviews the pathophysiology of mitral regurgitation in heart failure and proposes an integrated approach to management.