Ann Thorac Surg 2006;82:858-864
© 2006 The Society of Thoracic Surgeons
Original article: Cardiovascular
How To Deal With Recipients of Valves Prone to Structural Failure in the 2000s: Padua Experience With the TRI Technologies Valve
Gino Gerosa, MDa,*,
Riccardo Carta, MDb,
Massimo Montisci, MDc,
Loira Leoni, MD, PhDb,
Sabino Iliceto, MD, FACCb,
Giulio Rizzoli, MDa,
Francesca di Marco, MDa
a Division of Cardiac Surgery, Department of Cardiac, Thoracic and Vascular Sciences, Padua University Medical School, Padua, Italy
b Division of Cardiology, Department of Cardiac, Thoracic and Vascular Sciences, Padua University Medical School, Padua, Italy
c Department of Environmental Medicine and Public Health, Section of Legal Medicine, Padua University Medical School, Padua, Italy
Accepted for publication April 24, 2006.
* Address correspondence to Dr Gerosa, Division of Cardiac Surgery, Department of Cardiac, Thoracic and Vascular Sciences, Padua University Medical School, Via Giustiniani 2, 35100 Padova, Italy (Email: gino.gerosa{at}unipd.it).
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Abstract
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BACKGROUND: TRI Technologies (TT) valves evidenced a propensity to structural failure, consisting in fracture of the pivoting system, leading to leaflet escape. At our institution, between 2000 and 2002, 36 TT valves were implanted in 34 patients. Here we report the final results of the Tritech survey program.
METHODS: In February 2002, the first valve-related death occurred. After the event, patients were enrolled in the TT valve survey program and strictly followed up. The option of a reintervention was advised to each patient and weighed against the redo operative risk. The prophylactic TT valve replacement program took place in two time frames, dependent on each patient's personal choice: between September 2002 and October 2003 (first phase), and between September 2004 and October 2004 (second phase). Overall, 22 (10 women, 12 men) patients underwent reoperation. Mean time interval between TT valve implantation and replacement was 23 ± 11 months. Patients' mean age was 59 ± 11 years (median age, 64 years).
RESULTS: All recipients adhering to the program successfully underwent reoperation. Operative mortality was 0%.
CONCLUSIONS: We believe that the timing of the second surgery was fundamental for the favorable outcome of each patient and the absence of operative mortality. We are convinced that the tailored programming of the reintervention, together with the strong motivation of each patient, contributed in minimizing the risks related to surgery. The circumscribed cohort of patients involved was compatible with a tailored therapeutic plan. We strongly advise prophylactic reoperation of recipients of TT valves.
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Introduction
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In a recently published editorial, Blackstone, referring to the Bjork-Shiley Convexo-Concave (BSCC) valve story, wondered whether it could happen again [1]. Actually, it did happen again and again, with different models of mechanical prostheses [2–4], one of the latest being represented by mechanical valves produced by TRI Technologies [5, 6].
The TRI Technologies (TT) mechanical valve is a low-profile, bileaflet prosthesis commercialized in the late 1990s by TRI Technologies, Belo Horizonte, Brazil. It is designed for in situ rotation; reduced turbulence and enhanced flow are guaranteed by the curvature of the leaflets. The valve is made of solid pyrolitic carbon, and the housing ring is reinforced by a metal band; the proximal and distal surface of the polyester sewing ring are covered by a small ledge of pyrolitic carbon. As we have previously reported [5], these valves evidenced a propensity to structural failure, owing to possible fractures of the pivoting system with subsequent leaflet escape.
At our institution, between November 2000 and February 2002, 36 TT valves were implanted in 34 patients. At the time of our preliminary report [5], a few patients had already undergone successful reintervention. In this report, we present the final results of the survey program of TT valve recipients.
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Material and Methods
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At our institution, the first TT valve prosthesis was implanted in November 2000. Between November 2000 and February 2002, 36 TT valves were implanted in 34 patients. Hospital mortality was 8.8% (3 patients). Late mortality is shown in Table 1.
As we have already reported [5], in February 2002, the first valve-related death occurred in a 52-year-old male patient, who had received a TT valve in the aortic position 10 days before; the autopsy revealed a leaflet escape as the possible underlying cause of sudden death.
This first catastrophic event led to the immediate withdrawal of TT valve prosthesis from the Italian market and to an accurate evaluation of the patients with this prosthesis. Each recipient patient was thoroughly informed about the risk of a possible structural failure of the TT valve and was enrolled into a strict monitoring program, which was established according to the guidelines dictated by the ISS (Istituto Superiore di Sanità-Superior Institute of Health) of the Italian Ministry of Health [7]. The surveillance program mandated by the Health Ministry consisted of the following:
- Cinefluoroscopic examination of the leaflet movements
- Blood samples for early detection of hemolysis, at repeated intervals
- Echocardiographic evaluation, at repeated intervals
Meanwhile, a second leaflet escape requiring emergent reoperation occurred in 1 patient with a TT valve implanted in the mitral position, 20 months after surgery.
Facing the catastrophic events involving TT valve recipients, the opportunity to prophylactically replace the prostheses was carefully evaluated. According to the ISS guidelines, the option to undergo a prosthesis replacement, weighed against the specific reoperative risk (computed with Euroscore) [8], was proposed to each patient. In the absence of clear prosthesis malfunctioning, the ultimate decision to undergo the reintervention was left to the patients.
Four patients underwent reoperation for TT valve replacement at other institutions. At our institution, between September 2002 and October 2004, all TT valve recipients underwent reintervention. The prophylactic TT valve replacement program took place during two time frames, dependent on the individual decision of each patient: between September 2002 and October 2003 (first phase), and between September 2004 and October 2004 (second phase).
During the first phase, 17 patients underwent reoperation; 6 patients, who refused the operation at that time, were followed up with transthoracic echocardiograms repeated at 4- to 6-month intervals. As dictated by ISS, after each control, the option of a reintervention was advised to the patients, with constant refusal. In August 2004, a third leaflet escape caused the sudden death of one of those patients. As verified at the postmortem examination, the leaflet had embolized in the iliac artery. The echocardiographic evaluation, performed the previous day, did not identify any functional abnormality of the TT prosthesis (Figs 1, 2).
This episode persuaded 5 of the remaining 6 patients to undergo surgery during a second phase (September and October 2004). In December 2004, the last patient who had refused reoperation died. The autopsy revealed that the death was not valve-related.
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Fig 1. Parasternal long-axis showing correct opening of the emidisks (arrows) of an aortic TRI Technologies valve.
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Overall, at our institution, 22 patients (10 women, 12 men) underwent reoperation. Mean time interval between TT implantation and replacement was 23 ± 11 months (median time, 23 months). Patients' mean age was 59 ± 11 years (median age, 64 years). Most of them were in good functional status (91% of patients were in New York Heart Association functional class I and II). One male patient (4.5%) presented with permanent neurologic impairment (hemiplegia secondary to ischemic stroke on the 3rd postoperative day, after a TT mitral–aortic implant). During the time interval between TT implant and explant, he also experienced two episodes of transient cerebral ischemia; his international normalized ratio was found not to be within the target range of 3 to 3.5 at the time of one of the episodes. One female patient who experienced a transient cerebral ischemia during the first postoperative course did not present further neurologic episodes during follow-up time before TT valve replacement.
Demographic data of all the TT valve recipients as well as data regarding the cohort of patients who were reoperated on are reported in Table 1.
Statistical Analysis
Actuarial freedom from TT prosthesis-related adverse events and overall survival were calculated according to Kaplan–Meier methods and expressed as percentage ± standard deviation. Software Statistica 6 (Statsoft Inc, Tulsa, OK) was used for the calculations.
Leaflet Escape
Actuarial freedom from leaflet escape was 74% ± 17% at 45 months. The actuarial curve for freedom from leaflet escape is shown in Figure 3.
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Fig 3. Actuarial freedom from leaflet escape curve, showing percent event-free survival for patients at risk at time 0 (n = 34), 5 (n = 30), 10 (n = 28), 15 (n = 23), 20 (n = 19), 25 (n = 16), 30 (n = 10), 35 (n = 5), 40 (n = 4), and 45 (n = 2) months.
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Major Thromboembolic Events
Actuarial freedom from major thromboembolic events in TT valve recipients was 89% ± 5% at 45 months. The actuarial curve for freedom from thromboembolism is shown in Figure 4.
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Fig 4. Actuarial freedom from major thromboembolism curve, showing percent event-free survival for patients at risk at time 0 (n = 34), 5 (n = 30), 10 (n = 28), 15 (n = 23), 20 (n = 19), 25 (n = 16), 30 (n = 10), 35 (n = 5), 40 (n = 4), and 45 (n = 2) months.
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Actuarial Survival
Actuarial survival was 62% ± 15% at 45 months. The actuarial survival curve is shown in Figure 5.
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Fig 5. Actuarial survival curve, showing percent event-free survival for patients at risk at time 0 (n = 34), 5 (n = 30), 10 (n = 28), 15 (n = 23), 20 (n = 19), 25 (n = 16), 30 (n = 10), 35 (n = 5), 40 (n = 4), and 45 (n = 2) months.
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Preoperative Evaluation
At transthoracic echocardiography, mean ejection fraction was 0.57 ± 0.1. In 3 (14%) patients, left ventricular function was severely impaired (ejection fraction < 0.40). Mean left ventricular end-diastolic volume was 78 ± 24 mL/m2. The preoperative prostheses function was extensively evaluated: leaflets' movements were investigated, and peak gradient, mean gradient, and effective orifice area (by Bernoulli equation) were calculated (Table 2); possible regurgitation was quantified. There were no evident malfunctions. Nevertheless, in 3 patients an unusual finding was reported: a mild delay in the closure of the posterior leaflet and a diastolic fluttering of both leaflets were observed in two mitral valves, and a stiff excursion of the anterior leaflet, which appeared thickened and hyperechogenous, was observed in an aortic valve. Mild regurgitation was present in eight aortic and four mitral prostheses.
Reoperative Risk
Reoperative risk was calculated for each patient according to Euroscore grading: in 16 of 22 patients (72%) Euroscore was below 10, with a mean mortality risk of 7% ± 3% (median risk, 6%; range, 4% to 13%); in the remaining 6 (28%) patients, Euroscore was higher than 10, with a mean operative risk of 33% ± 9% (median risk, 36%; range, 19% to 43%).
Surgical Technique
All patients underwent reoperation through a median resternotomy, with cardiopulmonary bypass, moderate hypothermia, and aortic cross-clamping. As a precaution, femoral vessels were surgically isolated, but femoral cannulation was not necessary in any patient. Antegrade and retrograde cold blood cardioplegia was administered and repeated at 20-minute intervals. Aortic prostheses were replaced through a transaortic approach. A paraseptal incision of the left atrium was performed to replace mitral protheses.
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Results
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Operative Results
The prostheses were carefully examined before proceeding with the explant. At visual inspection, they all appeared to be well-functioning, with normal opening and closure of the leaflets. In 1 patient, a small thrombus was present on the atrial side of the mitral cuff. A modest endothelial pannus was observed on one aortic prosthesis. No equivalent abnormality of the doubtful abovementioned preoperative echocardiographic findings could be traced.
Sixteen St. Jude's mechanical valves were implanted in the aortic position and 8 St. Jude's medical valves were implanted in the mitral position, by means of multiple 2-0 Ticron (Tyco HealthCare ECE) interrupted sutures, reinforced by polytetrafluoroethylene (Teflon) pladgets. In 2 patients, a double mitral and aortic prosthesis replacement was performed. Three patients (14%) required an additional procedure (tricuspid valve repair, ascending aorta reconstruction, pulmonary veins opening plasty).
Mean cardiopulmonary bypass time was 140 ± 53 minutes. Mean aortic cross-clamp time was 98 ± 35 minutes.
Hospital Mortality
In the total series, operative mortality was 0% (95% confidence limits, 0% to 15.4%; 70% confidence limits, 0% to 8.3%).
Postoperative Morbidity
A transient low output syndrome requiring intraaortic balloon pump and inotropic infusion occurred in 2 (9%) patients. Surgical revision for bleeding was performed in 3 patients (14%). Supraventricular tachyarrhythmias occurred in 4 (18%) patients (3 atrial flutter, 1 atrial fibrillation). Antiarrhythmic therapy was effective in restoring sinus rhythm in 3 patients. In 1 patient atrial flutter was converted into atrial fibrillation. Postoperative data are reported in Table 3.
Postoperative Stay
Mean intubation time was 12 ± 8 hours (median time, 8 hours). Mean intensive care unit stay was 3 ± 2 days (median length, 2 days).
Postoperative echocardiographic evaluation was performed in all patients. All the prostheses implanted presented with normal function (gradients and area are reported in Table 4). Mean ejection fraction was 0.58 ± 0.1. Mean left ventricular end-diastolic volume was 69 ± 21.6 mL/m2.
Patients were discharged to home after a floor stay of 9 ± 3 days (median, 9 days).
Follow-up
Mean follow-up time was 30 ± 9 months (median time, 36 months): there were no deaths and no valve-related complications.
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Comment
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Catastrophic complications after heart valve replacement with mechanical prostheses, caused by acute structural failure, have already been described. More than 600 cases of outlet strut fracture of the BSCC valves have been reported; leaflet escape or fracture has been recorded also in other models of valve prostheses [2–4, 9, 10]. Structural failure led to market withdrawal of the BSCC, Omnicarbon monoleaflet, Edwards Duromedics, and Tekna valve prosthesis models.
The TT valves, belonging to the latest generation of bileaflet prostheses, were launched on the market in the late 1990s. The valve, which was CE (Conformitè Europèenne) marketed since 1998, was presented as a low-profile bileaflet valve, composed of solid pyrolitic carbon, with an in situ rotation mechanism; the curvature of the leaflets guaranteed improved blood flow with reduced turbulence.
At our institution, between November 2000 and February 2002, 36 TT valves were implanted in 34 patients. The first TT valve–related death occurred in February 2002: a 52-year-old male patient, who had received a TT valve in the aortic position, died suddenly on the 10th postoperative day. The postmortem examination showed the occurrence of migration of an escaped leaflet into the thoracic aorta, and the leaflet escape was recognized as the possible underlying cause of sudden death. As we have previously reported [5], the valve was extensively examined: a fracture of the pivot system was observed. An asymmetry of the heights of the tabs was hypothesized to be responsible for the fracture, with subsequent leaflet escape. Similar events were also reported by others [6]. Unfortunately, the other explanted valves could not be examined because they were confiscated by the legal authorities.
The catastrophic episode recalls the BSCC story, but something has changed in the current era, as testified by the fact that the first TT valve–related lethal event led to the immediate withdrawal of the TT valves from the market [5], whereas—as mentioned by Blackstone in his recent editorial—86,000 BSCC valves were implanted worldwide before their market removal [1]. Nevertheless, as in previous similar situations, the event opened the prickly question of the proper management of the recipients [11–14]. Unlike the past experience, though, the timeliness of the information's spreading to the international scientific community and the prompt marketing withdrawal of the valves led to a circumscribed number of recipients. The limited patient cohort to handle allowed a strict monitoring, as well as the chance to plan a tailored therapeutic strategy, with evident advantages in terms of patients' psychological and clinical backing.
After the first valve-related death, each patient and his or her relatives were informed of the event. According to the guidelines dictated by ISS, the patients were made aware of the possibility of a structural failure of the prostheses, and an extensive follow-up program was proposed. The complete availability of the institution in terms of medical assistance and the chance of a reoperation were repeatedly offered. One patient refused to adhere to the program. Four patients were successfully reoperated on at other institutions (one of them necessitated an emergent procedure because of a leaflet escape). The remaining patients underwent the planned examinations and kept constantly in touch with our institution. No TT valve malfunction was evidenced during the entire follow-up period, either at transthoracic echocardiography or at cinefluoroscopy. All patients were in good functional status. In the entire series, leaflet escape occurred in 3 patients; 2 of them were fatal, and the third required an emergent replacement procedure.
Specific reoperative risk was calculated according to Euroscore grading and presented to each patient and his or her family: in 6 (29%) patients, the predicted mortality risk was rather high. The decision to undergo a prophylactic replacement of the prosthesis was autonomous for all the recipient patients. Except for the patient who refused to take part to the program, all the remaining patients decided to undergo reintervention.
The decision to reoperate on a recipient of a TT valve prosthesis with a propensity for acute lethal disruption is obviously extremely challenging. Ideally, a reintervention is advisable whenever the risk of valve failure is superior to the operative risk. Therefore, risk rupture assessment is essential to define the need of prophylactic replacement.
The clinical experience with BSCC valves, which number around 85,000 implants worldwide, has taught the scientific community that it is possible to draw guidelines, thanks to follow-up results, to support the decision-making process [15, 16]. In 1992, the Dutch BSCC Follow-Up Study recognized valve-opening angle, valve size, mitral position, and young age as risk factors of outlet strut fracture. The results of the study were exploited to sketch a decision model, which was periodically updated [17]. Guidelines are crucial to identify patients at risk and spare unnecessary procedures as well as surgery in patients with expected low postoperative life expectancy [18].
In our experience, the comparatively very low number of TT implants, together with the sudden cascade of legal events and media hammering that followed the first leaflet escape episode, made it impossible to identify any risk factor for valve failure (valve-related or patient-related). In fact, only the first ruptured prosthesis could be examined as the subsequent explanted valves have been confiscated by the magistracy authorities. As we previously reported, an asymmetric distance between the tabs and the leaflet base was detected in the inspected valve, but no consideration could be made on the other explanted valves. A supposed responsibility of the asymmetry of the height of the tab was formulated [5]. Nevertheless, it was not possible to confirm the presence of the anomaly in the remaining explanted valves at our institution. We did not find any element predictive of valve malfunctioning at the preoperative examinations: three preoperative doubtful findings at transthoracic and transesophageal echocardiography did not have a correspondence with the in vivo inspection observed intraoperatively. Above all, the second patient who died suddenly because of leaflet fracture had undergone a transthoracic echocardiogram 24 hours before, which demonstrated a normally functioning prosthesis.
Once each patient was informed about his or her specific operative risk, as dictated by ISS, we submitted to the patients' own decision. All patients (except 1) decided to undergo reoperation. We hypothesize that the media's reporting of the tragic happenings played a relevant role in the psychological distress caused to the patients. On the contrary, no difference in psychological distress was observed between BSCC recipients and patients who received a normally functioning valve [19].
All patients were reoperated on successfully, and there were no operative deaths. At a mean follow-up of 30 ± 9 months, neither deaths nor valve-related complications occurred. Mortality at repeated valve surgery is reported to be higher compared with first operation [20]. Jones and colleagues [21] reviewed their experience with repeated heart valve operations, reporting an overall 8.6% operative mortality, which was comparable to other reports [22, 23]. Among patients undergoing redo for prosthetic valve replacement, mortality was as high as 26% for replacement with mechanical prostheses. In particular, reoperation because of mechanical valve thrombosis requiring urgent surgery was associated with higher early mortality compared with prosthetic replacement for chronic periprosthetic leak. Similarly, advanced functional class [24] and emergent procedure [25] were significantly associated with higher early mortality in previous reports. In our study, reoperation was carried out before development of signs of cardiovascular decompensation or clinical debilitation.
We believe that timing of the second surgery was fundamental for the favorable outcome of the patients and the absence of operative mortality. Furthermore, compared with previous reports, reoperation intent was purely prophylaptic, as no signs of prosthesis malfunctioning could be identified. Subsequently, no advantage in terms of cardiac improvement was expected; instead, potential detrimental effects of extracorporeal circulation and myocardial ischemia were feared.
All patients were strictly followed up, both clinically and instrumentally. Follow-up evaluations did not show any sign of prosthesis malfunctioning but gave precious information about patients' clinical and hemodynamic status, enabling all reoperations to be performed before development of signs of cardiovascular decompensation or clinical debilitation.
We are convinced that careful planning of reintervention (allowed by the strict monitoring) together with the strong motivation of patients contributed to minimize the risks related to surgery. The circumscribed cohort of patients involved was compatible with a tailored therapeutic plan. In light of the incidence of leaflet escape episodes reported for TT valves compared with the favorable surgical outcome we experienced, we strongly advise the prophylactic reoperation of recipients.
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Acknowledgments
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We thank Mr Nicola Paccagnella for preparing the pictures.
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References
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Abstract
Introduction
