Off-pump transapical balloon-expandable aortic valve endoprosthesis implantation

Abstracts

OBJETIVO: A troca valvar aórtica é procedimento rotineiro, envolve substituição da valva nativa/prótese. Na maioria destes pacientes o risco é aceitável, porém, em alguns casos, o risco predito pode justificar contra-indicação. O implante de valva aórtica minimamente invasivo transcateter e sem circulação extracorpórea (CEC) tem se mostrado viável, com menor morbi-mortalidade. O objetivo deste trabalho foi desenvolver bioprótese aórtica, montada em cateter, para implante sem CEC. MÉTODOS: Após desenvolvimento em animais, três pacientes com EuroSCORE elevado foram submetidos ao implante. Caso 1: portador de bioprótese com disfunção; Caso 2: estenose aórtica grave; Caso 3: disfunção de bioprótese aórtica. Após minitoracotomia e sob controle ecocardiográfico e fluoroscópico, cateter-balão foi posicionado sobre posição aórtica e insuflado. Após, segundo cateter-balão, com endoprótese valvada, foi posicionado e liberado sob alta frequência ventricular. Controles angiográficos e ecocardiográficos foram realizados e pacientes encaminhados para UTI. RESULTADOS: No primeiro caso foi possível implante sem CEC com resultados adequados. Evoluiu com melhora da função ventricular. Cursou com broncopneumonia, fístula traqueo-esofágica e óbito por mediastinite. Necropsia confirmou bom posicionamento valvar e preservação dos folhetos. O segundo caso apresentou migração do dispositivo após insuflação do balão, necessidade de esternotomia mediana de urgência, CEC e troca valvar convencional. O paciente evoluiu bem, recebendo alta da UTI 14 dias após procedimento e sem complicações. Cursou com infecção respiratória, choque séptico e óbito no 60º pós-operatório. O terceiro caso foi submetido a implante com sucesso. CONCLUSÃO: O implante de bioprótese transapical montada em cateter sem CEC mostrou ser procedimento factível. Detalhes técnicos e a curva de aprendizado demandam discussão.

Valva aórtica; Ponte cardiopulmonar; Cateterismo cardíaco

BRIEF COMMUNICATION

Off-pump transapical balloon-expandable aortic valve endoprosthesis implantation

Diego Felipe Gaia^I; José Honório Palma^II; José Augusto Marcondes de Souza^III; José Cícero Stocco Guilhen^IV; Andre Telis^V; Claudio Henrique Fischer^VI; Carolina Baeta Neves Duarte Ferreira^VII; Enio Buffolo^VIII

^IMaster's Degree (Physician of the Cardiovascular Discipline)

^IIFull Professor (Head of the Cardiovascular Surgery Discipline at UNIFESP)

^IIIPhD in Medicine (Hemodynamicist of UNIFESP)

^IVCardiovascular Surgeon (Resident Physician at UNIFESP)

^VCardiovascular Surgeon (Resident Physician at UNIFESP)

^VIPhD in Medicine (Echocardiographer at UNIFESP)

^VIIMaster's Degree. Anesthesiologist. Anesthesia, Pain and Intensive Therapy Discipline - UNIFESP)

^VIIITitular Professor of Cardiovascular Surgeon (UNIFESP)

Correspondence address

ABSTRACT

OBJECTIVE: The aortic valve replacement is a routine procedure, and involves replacement of the native valve/ prosthesis. In most of the patients who undergo such procedure the risk is acceptable, but in some cases, such risk can justify contraindication. The minimally invasive transcatheter aortic valve implantation without cardiopulmonary bypass (CPB) has been shown to be viable, with lower morbidity and mortality. The aim of this study was to develop a catheter-mounted aortic bioprosthesis for implantation without CPB.

METHODS: After developing in animals, three patients with high EuroSCORE underwent implantation. Case 1: patients with bioprosthesis dysfunction; Case 2: severe aortic stenosis; Case 3: dysfunction of aortic bioprosthesis. After minithoracotomy and under echocardiographic and fluoroscopic control, a balloon catheter was placed on aortic position and inflated. After, a second balloon with valved endoprosthesis was positioned and released under high ventricular rate. Echocardiographic and angiographic controls were performed and the patients were referred to ICU.

RESULTS: In the first case, implantation without CPB was possible with appropriate results. The patient evolved with improvement of ventricular function. After, this patient developed bronchopneumonia, tracheoesophageal fistula and died due to mediastinitis. Autopsy confirmed proper valve positioning and leaflets preservation. The second case showed the device migration after inflation of the balloon, with the need for urgent median sternotomy, CPB and conventional valve replacement. This patient evolved well and was discharged from the ICU on the 14^th postoperative day without complications. This patient developed respiratory infection, septic shock and died on the 60^th postoperative day. The patient from the third case underwent successful implantation.

CONCLUSION: The off-pump transapical implantation of catheter-mounted bioprosthesis was shown to be a feasible procedure. Technical details and learning curve require further discussion.

Descriptors: Aortic valve. Cardiopulmonary bypass. Heart catheterization.

INTRODUCTION

The aortic valve replacement in elderly patients is a routine procedure that usually involves replacement of the damaged native valve or replacement of its prosthetic impaired substitute by a bioprosthesis of different performances and models. In most of these patients, the surgical risk associated with the procedure is acceptable and appropriate long-term outcome is well established [1].

The expected result can still be quite acceptable even in octogenarians [2]. However, in some cases and especially in reoperations, the risk predicted by various scores can reach levels that justify the contraindication of the procedure, up to 6% -15% [3].

In search of alternatives for this group of high-risk patients, the minimally invasive transcatheter implantation and without use of cardiopulmonary bypass has been shown to be, in experimental and clinical series, a viable alternative with lower morbidity and mortality for patients with high surgical risk with the possibility of performing such procedure even in reoperations [4].

Some devices such as CoreValve (CoreValve, Paris, France) and Edwards Sapiens (Edwards Lifescience Inc, Irvine, CA, USA) are under study, but no of them are widely available in our country in addition to the high cost of using.

Thus, it became necessary to develop national technology in this field in order to facilitate the production and use of this new knowledge. After the experimental phase of development and training in experimental animals, it was possible to obtain a safe device, easy to implant and with performance similar to that found in porcine bioprostheses currently available in our market (Figure 1).

Based on these results, it was possible to perform the transapical implantation of a catheter-mounted balloon-expandable bioprosthesis without cardiopulmonary bypass in three high surgical risk patients.

CASE REPORTS

Case 1

64-year male patient, hypertensive and carrier of biological prosthesis in aortic position (second prosthesis: the first 30 years and the second 20 years ago, without outpatient follow-up) was admitted to our emergency service with atrial flutter with high ventricular response. After control and reversal of arrhythmia, the patient remained under observation at the Chest Pain Unit. After a few hours he presented cardiogenic shock, evolving to functional class IV (New York Heart Association) and propaedeutic compatible with severe aortic insufficiency.

The transesophageal echocardiogram showed severe aortic insufficiency by rupture of the bioprosthesis leaflet, moderate pulmonary hypertension, mild-to-moderate mitral regurgitation and moderate left ventricular dysfunction and severe right ventricle dysfunction.

In a few hours, the patient evolved with presentation refractory to vasoactive drugs, lung congestion, oliguria, worsening of renal function and need for invasive mechanical ventilation. The operative risk estimated by the logistic EuroSCORE was of 54%.

It was decided to perform the valve-in-valve transcateter transapical implant without cardiopulmonary bypass, based on experience acquired in centers that already used to perform the procedure, and experimental development of a satisfactory national device tested in experimental animals. Furthermore, meeting of consensus among the specialties involved has occurred, informed consent from those responsible for the patient and approval by the Research Ethics Committee were obtained .

The implant was performed in high technology hybrid operating room, with the presence of various devices (hemodynamics, echocardiography, cardiopulmonary bypass support in addition to materials and surgical equipments and usual anesthetics).

After anesthetic induction, a small antero-lateral thoracotomy in the fifth left intercostal space was performed to expose the left ventricular apex. Then a double purse-string suture supported in a Teflon felts was performed. A 6F vascular introducer was positioned with the aid of a guidewire by puncturing in the center of the suture under echocardiographic and fluoroscopic vision.

With the aid of a hydrophilic guidewire and a pigtail catheter was possible to get through the aortic valve into the descending thoracic aorta.

The initial aortography confirmed the aortic insufficiency and favored the identification of the prosthetic aortic valve ring and the position of the coronary ostia.

The aortic valve annulus was measured by transesophageal echocardiography, with an internal diameter of 19 mm. A balloon-expandable stainless steel catheter-mounted bioprosthesis with "oversize" of 20% was selected and placed on the ring of the impaired bioprosthesis through a 24F introducer (Figure 2).

Cardiac output was reduced with the aid of temporary epimyocardial pacemaker, and then the balloon was inflated with maximum pressure of 5 atmospheres (atm) and the prosthesis was released (Figure 3).

After the recovery of heart rate and blood pressure, echocardiography confirmed the absence of significant aortic insufficiency and the control aortography showed good prosthetics apposition and free coronary ostia (Figure 3).

The patient improved his ventricular function and the possibility of mechanical ventilation disconnection on the 2nd postoperative day. On the 30^th postoperative day, presented with bronchopneumonia, need for tracheostomy, tracheo-esophageal fistula and died due to mediastinitis. Necroscopic finding confirmed good positioning and maintenance of valve leaflets (Figure 4).

Echocardiogram performed at the 30^th postoperative day showed no dysfunction or leak, with a maximum aortic gradient of 39 mmHg.

Case 2

81-year-old female patient, carrier of severe aortic stenosis with aortic maximum gradient of 72 mmHg and an ejection fraction of 42% was admitted in the emergency service with decompensated heart failure and need for use of vasoactive drugs.

The patient remained in heart failure with severe pulmonary congestion and the need for non-invasive mechanical ventilation despite optimized medical therapy.

The logistic EuroSCORE was 60%. After obtaining the written informed consent, the patient underwent transapical implantation of a balloon-expandable aortic valve.

Using the same technique described in case 1, a catheter-balloon was inflated up to its maximum pressure (5 atm) in order to relieve the aortic stenosis. A stent with 22 mm in diameter was expanded to its limit on the native ring under reduction of the cardiac output by using a pacemaker.

After expansion, it could be noted by fluoroscopic view the migration of the device into the aortic arch. Following, it has been chosen by median sternotomy and conversion to conventional procedure with cardiopulmonary bypass for salvage of the prosthesis and aortic valve replacement.

The patient evolved satisfactorily and was discharged from the intensive care unit on the 14th postoperative day. However, on the 20^th postoperative day, presented with respiratory infection, renal failure, septic shock and death on the 60^th postoperative day.

Case 3

84-year-old male patient, with aortic bioprosthesis for 16 years, hypertensive and with nondialytic chronic renal failure, admitted in the emergency service with congestive heart failure in functional class IV (New York Heart Association). Transthoracic echocardiogram showed rupture of the bioprosthesis leaflets with aortic insufficiency and severe left ventricular dysfunction (ejection fraction of 42%).

The cineangiocoronariography showed no coronary lesions and aortography confirmed the aortic insufficiency.

The logistic EuroSCORE was 64%. After obtaining the written informed consent, transapical intervention was indicated.

Using the technique described in case 1, under echocardiographic, transesophageal and fluoroscopic control, a catheter-mounted balloon bioprosthesis was positioned on the impaired bioprosthesis and, during reduction of cardiac output, the bioprosthesis was expanded by balloon on the impaired bioprosthesis.

After recovering of cardiac output, echocardiography showed the correct apposition of the prosthesis without significant systolic gradient (25 mmHg) or central or perivalvular aortic insufficiency. The aortography confirmed such findings and the absence of interference with the coronary ostia.

The patient was disconnected from mechanical ventilation in the operating room and referred to intensive care unit. In the immediate postoperative period, the renal failure has become more acute, with need for temporary dialytic therapy.

The patient is currently stable in ward. Control echocardiogram without dysfunction, left ventricular ejection fraction of 57%, pulmonary artery pressure of 40 mmHg, aortic transvalvular gradient of 16 mmHg and without central or periprosthetic leak. Hospital discharge was scheduled on the 10^th postoperative day.

DISCUSSION

The transcateter aortic valve implantation is a new technique and under study in various centers around the world [4-6]. The main objective of the procedure is to provide a satisfactory technical quality with lower morbidity and mortality when compared to the conventional approach, especially by avoiding the use of cardiopulmonary bypass, median sternotomy and aortic clamping.

Preliminary results have been encouraging, with mortality at 30 days around 8% [4]. In addition to implants on native valves, implants on impaired bioprostheses are also reported [7].

Various prosthetic devices have been tested in different centers, but the greater world experience focuses on the Edwards Lifesciences prosthesis, which is under investigation in a multicenter study (Partner trial- Placement of AoRTic traNscathetER valve).

This study may demonstrate the development of a prosthetic device of national technology, as well as other previous national experiences, such as cardiopulmonary bypass circuits, biological valve prostheses and aortic stents, an outcome of the interaction between industry and academia.

The local development of these technologies makes possible the disclosure of high technology procedures on our country, also allowing its access by the Unified Health System

The three cases reported herein highlight important points related to the procedure: its applicability and possibility of accomplishment, with immediate success in valve-on-valve implant and failure in implant on native prosthesis.

Failure on implantat on native prosthesis possibly occurred due to a learning curve in the expansion of the balloon, which was partially within the introducer, thus ejecting the prosthesis into the ascending aorta.

The experience proves to be essential the interaction between different specialties, demanding cardiovascular surgeon, hemodynamicist, echocardiographer and anesthesiologist specially trained and involved in the procedure. It is also necessary a hybrid surgical environment capable of integrating surgical and endovascular technologies with the presence of device for fluoroscopic images acquisition (with capacity of real-time reproduction of images) and transesophageal echocardiogram, in addition to surgical material adapted for radioscopic use [8] .

The transapical route was selected instead of the transfemoral due to reports of increased mortality at 30 days and increased occurrence of stroke by this approach [9].

There were no vascular complications related to the access - a concern in the handling of the ventricular apex in the elderly patients - stroke or atrioventricular block, a complication reported specially with the self-expandable devices [10].

This little initial experiment does not allow us to suggest so reliable results of survival or complications because it deals with an initial procedure and also considering the learning curve of the procedure.

The evaluation of each of the devices, including the reported herein, is imperative in order to determine the correct profile of patients candidates to the procedure. Analysis of maintenance of results, often considered suboptimal, especially when compared to conventional valve replacement is also essential.

Another point of discussion are the criteria used to define the severity of the selected patient, as the EuroSCORE and the STS score. Some authors have reported rates below the predicted rate in respect to the complication and mortality in aortic valve replacement in high-risk patients [2].

CONCLUSION

Minimally invasive transapical implant of catheter-mounted balloon-expandable aortic bioprosthesis is a viable technique. There is significant learning curve and need for a team from multiple specialties in order to favor the procedure. The long-term result, and the correct selection of patients remain unresolved.

REFERENCES

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• 2. Grossi EA, Schwartz CF, Yu PJ, Jorde UP, Crooke GA, Grau JB, et al. High-risk aortic valve replacement: are the outcomes as bad as predicted? Ann Thorac Surg. 2008;85(1):102-6.
• 3. Iung B, Baron G, Butchart EG, Delahaye F, Gohlke-Bärwolf C, Levang OW, et al. A prospective survey of patients with valvular heart disease in Europe: the Euro Heart Survey on Valvular Heart Disease. Eur Heart J. 2003;24(13):1231-43.
• 4. Walther T, Falk V, Kempfert J, Borger MA, Fassl J, Chu MW, et al. Transapical minimally invasive aortic valve implantation: the initial 50 patients. Eur J Cardiothorac Surg. 2008;33(6):983-8.
• 5. Walther T, Simon P, Dewey T, Wimmer-Greinecker G, Falk V, Kasimir MT, et al. Transapical minimally invasive aortic valve implantation: multicenter experience. Circulation. 2007;116(11 Suppl):I240-5.
• 6. Svensson LG, Dewey T, Kapadia S, Roselli EE, Stewart A, Williams M, et al. United States feasibility study of transcatheter insertion of a stented aortic valve by the left ventricular apex. Ann Thorac Surg. 2008;86(1):46-54.
• 7. Walther T, Kempfert J, Borger MA, Fassl J, Falk V, Blumenstein J, et al. Human minimally invasive off-pump valve-in-a-valve implantation. Ann Thorac Surg. 2008;85(3):1072-3.
• 8. Walther T, Dewey T, Borger MA, Kempfert J, Linke A, Becht R, et al. Transapical aortic valve implantation: step by step. Ann Thorac Surg. 2009;87(1):276-83.
• 9. Webb JG, Pasupati S, Humphries K, Thompson C, Altwegg L, Moss R, et al. Percutaneous transarterial aortic valve replacement in selected high-risk patients with aortic stenosis. Circulation. 2007;116(7):755-63.
• 10. Piazza N, Grube E, Gerckens U, den Heijer P, Linke A, Luha O, et al. Procedural and 30-day outcomes following transcatheter aortic valve implantation using the third generation (18 Fr) corevalve revalving system: results from the multicentre, expanded evaluation registry 1-year following CE mark approval. EuroIntervention. 2008;4(2):242-9.

Publication Dates

• Publication in this collection
  14 Sept 2009
• Date of issue
  June 2009

History

• Accepted
  11 May 2009
• Received
  20 Jan 2009