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Pulmonary valve implantation using self-expanding tissue valve without cardiopulmonary bypass reduces operation time and blood product use

Open ArchivePublished:June 19, 2012DOI:https://doi.org/10.1016/j.jtcvs.2012.05.036

      Objective

      The study objective was to review our initial experience with newly developed off-pump pulmonary valve implantation techniques and compare outcomes with the conventional approach.

      Methods

      Thirteen symptomatic patients with severe pulmonary regurgitation underwent pulmonary valve implantation, 6 without cardiopulmonary bypass (group 1: age, 28 ± 21 years; range, 12-62; body surface area range, 1.38-2.39 m2) and 7 with cardiopulmonary bypass (group 2: age, 23 ± 13 years; range, 10-46; body surface area range, 1.31-1.89 m2). Ten patients had previous repair of tetralogy of Fallot, and 3 patients had pulmonary valvotomy/valvuloplasty.

      Results

      Mean operation times were 166 minutes (range, 110-240) in group 1 and 299 minutes (range, 221-375) in group 2 (P < .001). Hemoglobin level after chest closure was 13.4 and 9.8 g/dL in groups 1 and 2, respectively (P < .001). Postoperative chest drainage (median) was 78 and 300 mL in groups 1 and 2, respectively (P = .003). Blood product requirement was zero and 3 units (median) in groups 1 and 2, respectively (P < .014). There was no significant difference in postoperative ventilation time or lengths of intensive care unit and hospital stays between the 2 groups. Mean follow-up was 15 months; all patients are in New York Heart Association I/II. Echocardiography showed that peak velocity across the pulmonary valve was 2.2 and 2.0 in groups 1 and 2, respectively (P = .46). No patient had a paravalvular leak or more than mild pulmonary regurgitation.

      Conclusions

      Off-pump pulmonary valve implantation is a good alternative for pulmonary valve replacement. The procedure reduces operating time, blood loss, and blood product requirement.

      CTSNet classification

      Abbreviations and Acronyms:

      CPB (cardiopulmonary bypass), ICU (intensive care unit), MRI (magnetic resonance imaging), OPPI (off-pump pulmonary valve implantation), PA (pulmonary artery), PR (pulmonary regurgitation), RV (right ventricular), RVOT (right ventricular outlet tract)
      One of the most common late complications after repair of congenital heart defects, such as tetralogy of Fallot, is pulmonary regurgitation (PR). Significant PR results in progressive dilatation and dysfunction of the right ventricle, decrease in exercise tolerance, arrhythmias, heart failure, and increased risk of sudden death. The conventional approach of dealing with this problem is to perform pulmonary valve replacement using cardiopulmonary bypass (CPB). However, this approach is associated not only with long operative time but also side effects related to the use of CPB. Furthermore, because of the natural history of prosthetic valve failure, patients often require multiple repeat open operations for valve replacement over their lifetime, the reoperation becoming increasingly complex on each occasion.
      Minimally invasive pulmonary valve implantation is therefore warranted. In recent years, percutaneous pulmonary valve implantation has been developed. However, with the percutaneous technique, a limited size of prosthesis can be inserted, currently up to 26 mm diameter with the Sapien transcatheter heart valve (Edwards Lifesciences LLC, Irvine, Calif) and up to 22 mm with the Melody valve (Medtronic Inc, Minneapolis, Minn).
      • Coats L.
      • Khambadkone S.
      • Derrick G.
      • Sridharan S.
      • Schievano S.
      • Mist B.
      • et al.
      Physiological and clinical consequences of relief of right ventricular outflow tract obstruction late after repair of congenital heart defects.
      • Garay F.
      • Webb J.
      • Hijazi Z.M.
      Percutaneous replacement of pulmonary valve using the Edwards-Cribier percutaneous heart valve: first report in a human patient.
      Moreover, the technique does not offer the opportunity of treating additional defects that are frequently associated with severe PR, such as pulmonary artery (PA) dilatation, and it cannot be used in a native right ventricular outlet tract (RVOT) because it requires a conduit for adequate fixation.
      A newly developed tissue valve mounted on a self-expanding stent, the No-React Injectable BioPulmonic (BioIntegral Surgical Inc, Toronto, Canada) (Figure 1), allows the pulmonary valve to be implanted without using CPB, thereby avoiding its adverse side effects.
      • Berdat P.A.
      • Carrel T.
      Off-pump pulmonary valve replacement with the new Shelhigh Injectable Stented Pulmonic Valve.
      • Schreiber C.
      • Hörer J.
      • Vogt M.
      • Fratz S.
      • Kunze M.
      • Galm C.
      • et al.
      A new treatment option for pulmonary valvar insufficiency: first experiences with implantation of a self-expanding stented valve without use of cardiopulmonary bypass.
      • Marianeschi S.M.
      • Santoro F.
      • Ribera E.
      • Catena E.
      • Vignati G.
      • Ghiselli S.
      • et al.
      Pulmonary valve implantation with the new Shelhigh Injectable Stented Pulmonic Valve.
      This off-pump pulmonary valve implantation (OPPI) technique requires only minimal mobilization of the heart and great vessels and thus reduces both the operative time and the risks associated with extensive dissection, such as bleeding and injury to the heart, great vessels, and adjacent structures (eg, phrenic nerves). The Injectable BioPulmonic prosthesis currently is available in sizes up to a diameter of 31 mm. The valve was evolved from a previous Shelhigh injectable pulmonic valve (Shelhigh Inc, Union, NJ) and is now CE marked under the management of BioIntegral Surgical Inc.
      Figure thumbnail gr1
      Figure 1The No-React Injectable BioPulmonic (BioIntegral Surgical Inc, Toronto, Canada) self-expanding tissue valve.
      We reviewed our initial experience with this valve and compared outcomes with the conventional surgical approach to test the hypothesis that because of its reduced invasiveness, implantation of the No-React Injectable valve is associated with shorter operating time, reduced blood product use, shorter intubation times, and decreased intensive care unit (ICU) and hospital stays.

      Patients and Methods

      This study was approved by the local ethics committee for a new interventional procedure introduced to the Trust. All patients gave their informed consent. This is a retrospective, descriptive study of our initial experience.
      Between May 2010 and January 2011, all patients requiring pulmonary valve replacement for significant PR who had a native RV outflow tract (ie, had not undergone previous RV-PA conduit placement) and did not have significant RVOT stenosis were considered for the injectable pulmonary valve. Other anatomic factors did not influence the inclusion of patients into either group. Indications for surgery were an aggregate assessment of multiple factors: clinical symptoms (particularly exercise limitation assessed by formal exercise testing), occurrence of arrhythmias, indexed right ventricular (RV) end-diastolic and end-systolic volumes, RV ejection fraction, and pulmonary regurgitation pressure half-time.
      Six patients underwent pulmonary valve implantation without CPB (group 1: age, 28 ± 21 years; range, 12-62, body surface area range, 1.38-2.39 m2), and 7 patients underwent pulmonary valve implantation with CPB (group 2: age, 24 ± 14 years; range, 12-46; body surface area range, 1.31-1.89 m2). Ten patients had previously undergone repair of tetralogy of Fallot, and 3 patients had previously undergone pulmonary valvotomy. Preoperative patient characteristics are listed in Table 1. Because of the theoretic benefits of avoiding CPB in high-risk cases (particularly patients with significant comorbidities), more of these patients were included in group 1.
      Table 1Patient characteristics
      ParametersGroup 1 (n = 6)Group 2 (n = 7)P value
      Age (y)28.2 ± 21 (12-62)23.4 ± 13 (10-46).63
      Body surface area (m2)1.86 ± 0.37 (1.38-2.39)1.02 ± 0.22 (1.31-1.89).16
      Diagnosis at initial operation
       Tetralogy of Fallot46
       Isolated PS11
       PA/IVS10
      Data presented as number or mean ± standard deviation (range). PS, Pulmonary stenosis; PA, pulmonary atresia; IVS, intact ventricular septum.
      In group 1, the self-expanding pulmonary valve was implanted using a transventricular approach via full sternotomy and the valve was fixed with external sutures. In group 2, stented bioprostheses (n = 5) or homografts (n = 2) were implanted using CPB.
      The No-React Injectable BioPulmonic valve consists of a porcine pulmonic valve mounted inside a self-expanding Nitinol stent covered by No-React–treated porcine pericardium (NR No-React, BioIntegral Surgical Inc). No-React is a proprietary process for detoxification of glutaraldehyde-treated tissue.

      Surgical Procedure

      Under general anesthesia, the patient underwent a full median sternotomy. Dissection of adhesions was carried out to expose the anterior surface of the right ventricle and right atrium, main PA and its bifurcation, ascending aorta, and superior and inferior venae cavae. A cell-saver was used routinely in patients undergoing a redo procedure.
      In group 1, if the main PA was more than 29 mm in diameter, it was plicated with pledgeted sutures. The PA was then carefully sized using transesophageal and epicardial echocardiography or, if plication had not been necessary, a detailed preoperative magnetic resonance imaging (MRI) scan. A valve 2 mm in diameter larger than the maximum size measured was selected. The selected valve was gently compressed into the introducer, which is similar to a giant syringe, and slid into the provided trocar. Double pledgeted purse-strings were then placed on the anterior surface of the proximal RVOT just proximal to the infundibulum/infundibular patch, avoiding calcified tissue. The location is chosen to lie immediately in line with the PA and far enough away from the annulus of the valve to permit comfortable angulation of the trocar up to the PA.
      After heparinization (100 IU per kg of body weight to achieve an active clotting time of 200-300 seconds), a stab incision was made at the site of purse-string sutures. The injector was then slid into the RVOT and advanced to the main PA. With the tip of the injector stabilized and the operator’s fingers holding the PA below its bifurcation, the valve was deployed in the main PA immediately distal to the native annulus. The trocar delivery system was then withdrawn and the purse-string sutures controlled. Transesophageal and epicardial echocardiogram was used to assess the valve position throughout the process of deployment. At this stage, manipulation of the valve is still possible by the operator placing his/her finger through the stab incision and passing it through the center of the valve. By catching the distal end of the stent, the valve can be eased more proximally, or if necessary more distally by pressing on the proximal edge of the stent. Care must be taken not to tear the vessel because the stent has small hooks at its proximal and distal margins to aid anchoring. The valve was then secured with external Prolene sutures placed in the proximal and distal rim of the valve.
      In group 2, the homograft or xenograft was implanted using CPB with standard aortic and bicaval cannulation and mild hypothermia (35°C). Similar postoperative care was provided to the 2 groups in a routine fashion, and patients were prescribed warfarin or aspirin for 3 months.
      The operative time (skin to skin), perioperative blood loss, blood products use (defined as any blood component, eg, packed red cells, platelets, and fresh-frozen plasma), hemoglobin levels, chest drainage, mechanical ventilation time, and ICU and hospital stays were recorded. Follow-up was by clinical assessment and echocardiography in the outpatient clinic.

      Statistics

      Two-sample Student t tests were used to compare the means of the 2 groups. Where variables were not normally distributed, groups were compared using the Mann–Whitney U test and medians (ranges) were used for data summary. The Fisher exact test was used to compare proportions. All tests were 2-tailed, and a 5% level of significance was used throughout.

      Results

      There were no operative deaths. During the period of OPPI valve deployment, there was significant reduction in cardiac output, which was always self-limiting after introducer removal. All patients were hemodynamically stable during the postoperative period. In particular, we have experienced no episodes of coronary artery compromise during or after deployment of the valve.
      In group 1, the pulmonary valve sizes implanted were 25 mm in 3 patients, 27 mm in 1 patient, and 29 mm in 2 patients. In group 2, the pulmonary valve sizes were 21 mm in 1 patient, 23 mm in 3 patients, 24 mm in 1 patient, and 25 mm in 2 patients (P = .005). The mean operation time was significantly shorter in group 1 than in group 2 (Table 2). Hemoglobin level after chest closure was significantly lower in group 2 than in group 1. Patients in group 1 had less postoperative chest drainage, and none of them required blood product transfusion.
      Table 2Intraoperative and postoperative data
      ParametersGroup 1 (n = 6)Group 2 (n = 7)P value
      Size of valve (mm)27 ± 2 (25-29)23 ± 1 (21-25).005
      OT (skin to skin, min)166 ± 43 (110-240)299 ± 57 (221-375)<.001
      CPB time (min)---109 ± 48
      Valve deployment time (min)14 ± 3 (11-20)---
      Preoperative hemoglobin (g/dL)14.6 ± 0.8 (13.9-15.7)13.5 ± 2.0 (10.2-15.5).25
      Postoperative hemoglobin (g/dL)13.4 ± 1.7 (11.4-15.6)9.8 ± 1.7 (6.7-11.7)<.001
      Chest drainage (mL)78 (50-120)300 (210-1150).003
      Blood products (units)0 (0-0)3 (2-11).014
      Intubation time (h)4.8 (1.5-16)11 (5-79).10
      ICU stay (d)1.5 (1-4)2 (1-4).45
      Hospital stay (d)6 (3-11)7 (5-9).42
      Values are presented as mean ± standard deviation (range) or median (range). Data expressed as mean ± standard deviation (range). OT, Operative time; CPB, cardiopulmonary bypass; ICU, intensive care unit.
      In group 1, a pericardial effusion developed in 1 patient 11 days after surgery, which required surgical drainage. In group 2, 1 patient required surgical exploration for bleeding on the day of operation.
      There was no significant difference in postoperative ventilation time or length of ICU and hospital stays between the 2 groups, although there was a trend toward these being shorter in group 1. However, it should be noted that more patients with increased body mass index and significant comorbidities were specifically selected for treatment using the injectable valve.
      Mean follow-up was 15 months; all patients are in New York Heart Association I/II. Echocardiography showed that peak velocity across the pulmonary valve was insignificant in both groups (Table 3), and no patient had a paravalvular leak. No patient in group 1 had any PR, but in group 2, 1 patient had mild regurgitation and 1 patient had mild to moderate regurgitation. Valve function of the new prosthesis was excellent (Figure 2) with no regurgitation or gradient. Follow-up MRI of the first patient at 1 year showed marked reduction in RV end-diastolic and end-systolic volume indexes and increased RV stroke volume (134 vs 76 mL/m2, 54 vs 29 mL/m2, and 158 vs 99 mL, respectively).
      Table 3Follow-up echocardiogram data
      ParametersGroup 1 (n = 6)Group 2 (n = 7)P value
      PR.46
       None65
       Mild01
       Mild to moderate01
       Moderate or severe00
      Valve velocity (m/s)2.2 (2-2.4)2.0 (1-3).46
      Data presented as number or median (range). PR, Pulmonary regurgitation.
      Figure thumbnail gr2
      Figure 2Pre- and postoperative echocardiograms demonstrate the correct positioning of the injectable valve. Valve function is excellent with no regurgitation or gradient (A and C, preoperatively; B and D, postoperatively).

      Discussion

      OPPI has been reported in both animal and clinical settings, mainly in European countries.
      • Berdat P.A.
      • Carrel T.
      Off-pump pulmonary valve replacement with the new Shelhigh Injectable Stented Pulmonic Valve.
      • Schreiber C.
      • Hörer J.
      • Vogt M.
      • Fratz S.
      • Kunze M.
      • Galm C.
      • et al.
      A new treatment option for pulmonary valvar insufficiency: first experiences with implantation of a self-expanding stented valve without use of cardiopulmonary bypass.
      • Marianeschi S.M.
      • Santoro F.
      • Ribera E.
      • Catena E.
      • Vignati G.
      • Ghiselli S.
      • et al.
      Pulmonary valve implantation with the new Shelhigh Injectable Stented Pulmonic Valve.
      • Amin Z.
      Available transcatheter pulmonary valves: perventricular technique with the Shelhigh valve.
      • Schreiber C.
      • Bauernschmitt R.
      • Augustin N.
      • Libera P.
      • Busley R.
      • Eicken A.
      • et al.
      Implantation of a prosthesis mounted inside a self-expandable stent in the pulmonary valvar area without use of cardiopulmonary bypass.
      • Dittrich S.
      • Gloeckler M.
      • Arnold R.
      • Sarai K.
      • Siepe M.
      • Beyersdorf F.
      • et al.
      Hybrid pulmonary valve implantation: injection of a self-expanding tissue valve through the main pulmonary artery.
      • Ustunsoy H.
      • Celkan M.A.
      • Burma O.
      • Kazaz H.
      • Baspinar O.
      Off-pump pulmonary valve implantation.
      After training in both wet laboratory and animal models, we have performed the first series of clinical OPPI in the United Kingdom. The current study is the first to compare this new technology with conventional techniques. Previous publications using the Shelhigh injectable pulmonic valve were limited to case reports and small case series with relatively short-term follow-up period. So far, no long-term follow-up data are available to confirm the durability of the new No-React Injectable BioPulmonic valve. However, a recent publication reported excellent long-term results for the No-React BioConduit (BioIntegral Surgical, Inc) used in the aortic root position.
      • Galiñanes M.
      • Meduoye A.
      • Ferreira I.
      • Sosnowski A.
      Totally biological composite aortic stentless valved conduit for aortic root replacement:10-year experience.
      Ten-year follow-up demonstrated no evidence of stenosis, dilatation, or calcification of the implanted valve. The No-React process is used in all BioIntegral Surgical, Inc, products. It is therefore anticipated that the durability and biocompatibility of the porcine tissue used in the Injectable BioPulmonic valve would be similar to those of the BioConduit.
      We have found the procedure to be reproducible, and none of our patients required conversion to CPB for a conventional procedure. There was a significant reduction in operating time in the OPPI group; the average valve deployment time (from insertion of valve to external fixation of valve) was 14 minutes. Further, because CPB is not required, the extent of dissection of the heart and great vessels is significantly reduced in the OPPI group. This greatly reduces the risk of injury to the heart, great vessels, and adjacent structures. Although we have not experienced any issues, proximity to the coronary arteries is always a concern. If compression is suspected, some repositioning of the valve within the PA is possible by the operator placing his/her index finger via the ventriculotomy into the valve (as described above), although the valve cannot be completely removed from the PA without the use of CPB.
      Patients with chronic PR typically have an enlarged main PA trunk. Furthermore, the RVOT is often dilated, and this is a known source of ventricular arrhythmia and dysfunction.
      • Gatzoulis M.
      • Till J.
      • Somerville J.
      • Redington A.
      Mechanoelectrical interaction in tetralogy of Fallot: QRS prolongation relates to right ventricular size and predicts malignant ventricular arrhythmias and sudden death.
      OPPI allows reduction in the RVOT without using CPB, a significant advantage over percutaneous transcatheter valve implantation. In our OPPI group, 50% of patients underwent plication of the main PA trunk. We found that plication of the main PA could be easily and safely performed on the beating heart and that it reshapes what is often a conical PA trunk to a tubular form, which allows more secure seating of the injectable valve. Secure placement of the valve within the RVOT using sutures is a major advance with this technology. Percutaneous valve deployment techniques currently require the presence of a rigid tube into which the valve can be placed, and stability is maintained by the force between the new valve and the old rigid tube. Because of this, a distensible native outflow tract is a contraindication to the use of non-CPB valve replacement techniques. By using the reported approach, any size and distensibility of outflow tract can safely be managed by plicating the RVOT and fixing the valve with sutures. However, the authors prefer not to use this approach when important narrowing of the RVOT is present.
      Another potential benefit of this approach is that the valve can be placed in the native, distensible PA, allowing a larger prosthesis to be placed than can be achieved using percutaneous techniques. The average size implanted in the OPPI group was 4 mm larger than the conventional group. This might be due to the necessary “oversizing” of the valve for patients undergoing OPPI. Schreiber and colleagues
      • Schreiber C.
      • Hörer J.
      • Vogt M.
      • Fratz S.
      • Kunze M.
      • Galm C.
      • et al.
      A new treatment option for pulmonary valvar insufficiency: first experiences with implantation of a self-expanding stented valve without use of cardiopulmonary bypass.
      recommend oversizing the implanted valve by at least 2 mm to achieve secure seating of the valve within the PA to avoid a paraprosthetic leak. In our OPPI group, all valves implanted were oversized by at least 2 mm above the anatomic measurement made using MRI or intraoperative echocardiogram, and none of our patients had a postoperative paraprosthetic leak. The biggest size of the injectable valve currently available is 31 mm; therefore, we recommend PA reduction/plication in patients with a PA trunk larger than 29 mm. It is encouraging that none of our patients who received an injectable valve had even mild PR at follow-up and that the median maximum velocity across the valve was only 2.2 m/s.
      The reason that the measured size of the injectable valves used is greater than that for the sutured valves is multifactorial. (1) The injectable valve sits in the PA, and the sutured valve lies within the pulmonary annulus. (2) The injectable valve benefits from having a smaller supporting structure. (3). The injectable valve is deliberately oversized to ensure adequate pressure on the adjacent vessel wall. The practice of oversizing conventionally implanted valves recently has been called into question. Intuitively it would be expected that implanting a larger valve would be beneficial. However, a recent study has suggested that oversizing pulmonary homograft conduits in children does not significantly decrease the incidence of allograft failure,
      • Karamlou T.
      • Ungerleider R.M.
      • Alsoufi B.
      • Burch G.
      • Silberbach M.
      • Reller M.
      • et al.
      Oversizing pulmonary homograft conduits does not significantly decrease allograft failure in children.
      whereas another study has suggested that it is actually detrimental.
      • Chen P.C.
      • Sager M.S.
      • Zurakowski D.
      • Pigula F.A.
      • Baird C.W.
      • Mayer Jr., J.E.
      • et al.
      Younger age and valve oversizing are predictors of structural valve deterioration after pulmonary valve replacement in patients with tetralogy of Fallot.
      Whether this is true for all valve types is uncertain, but these data emphasize the importance of rigorous follow-up to ascertain the performance characteristics of all implants.
      We routinely use a cell-saver intraperatively for redo cardiac procedures to limit the need for allogeneic blood transfusion. Despite this, group 2 patients required an average of 3 units of blood products during their hospital stay with a significantly greater amount of blood loss from the chest drain compared with those who underwent OPPI. OPPI therefore offers a potential benefits of reducing blood product transfusion–related complications.
      There was a trend toward reduced ventilation time and length of ICU and hospital stays in our series for the injectable valve group, although the differences are not statistically significant. Most of these patients were extubated soon after the operation and fit to be discharged on the fourth operative day. The fact that the reported mean hospital stay for this group was longer than this is a reflection of the fact that a number of patients who underwent injectable valve implantation were specifically chosen for this approach because of significant comorbidities. Consequently, arranging adequate out-of-hospital support for these highly dependent patients on occasion delayed discharge. We initially chose high-risk patients (eg, very obese and wheelchair-bound patients) because we considered that CPB posed a particularly high risk to them. However, it should be noted that these results for the OPPI group are skewed because of higher-risk patients undergoing this procedure. Table 1 shows that more obese patients underwent OPPI. In both groups, more obese patients had longer hospital stays. Yet, despite this, the ventilation time and ICU and hospital stays trended to be lower in the OPPI group. Further, because of our patient selection, for some patients in the OPPI group who had significant comorbidities, discharge was delayed for social reasons, such as home care requirement.

      Study Limitations

      The study sample size is small with a relatively short follow-up period and is not prospectively randomized. A large-scale, multicenter, prospective, randomized trial is therefore planned to confirm the initial findings and ascertain the durability of the injectable valve.
      Once the safety and durability of the injectable valve are established, the timing and indication for pulmonary valve implantation could be refined. If risks associated with OPPI are confirmed to be small, earlier intervention for PR may be warranted to prevent ventricular dilation/dysfunction and sudden lethal arrhythmias.

      Conclusions

      OPPI provides a good alternative for pulmonary valve replacement for PR after previous cardiac surgery. OPPI reduces operating time, blood loss, and blood products requirement. Further follow-up is necessary to assess its long-term performance.

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