Percutaneous stent-mounted valve for treatment of aortic or pulmonary valve disease

How Transcatheter Aortic Valve Implantation (TAVI) Was Born: The Struggle for a New Invention

This story is about the invention of transcatheter aortic valve implantation (TAVI), and the people who transformed it from a concept and primitive device to a breakthrough lifesaving treatment for hundreds of thousands of patients with aortic valve stenosis. It is an inspirational example of a new disruptive technology that began with an idea most dismissed. The story describes the ups and downs from idea, design, construction, animal testing, proof-of-concept, scientific publication hurdles, a patent, license agreement, cooperation with several companies, fighting in patent courts in Europe and USA and finally how multinational companies financially bypassed the inventor. It is also a story about the struggles and battles the inventor experienced when injected into a world of lawyers and patent fights. I hope my personal story and journey can provide an inspiration and word of caution for new inventors.

Investigating the Suitability of Carbon Nanotube Reinforced Polymer in Transcatheter Valve Applications

The current delivery size of transcatheter aortic valves, limited by the thickness of their pericardial leaflets, correlates with a high prevalence of major vascular complications. Polyurethane valves can be developed to a fraction of the thickness of pericardial valves through the addition of carbon nanotubes to reinforce their leaflets. This study investigates the suitability of a novel carbon nanotube reinforced leaflet to reduce the delivery profile of transcatheter aortic valves. Carbon nanotube polyurethane composites were developed with thicknesses of 50 μm and their mechanical properties were determined in relation to various environmental effects. The composites demonstrated improvements to the material stiffness, particularly at increasing strain rates compared to the neat polymer. However, increasing nanotube concentrations significantly decreased the fatigue life of the composites. Key findings highlighted a potential for carbon nanotube reinforcement in valve replacement which experience very high strain rates during the cardiac cycle. Further testing is needed to achieve a strong nanotube-matrix interface which will prolong the cyclic fatigue life and further strengthen tensile properties. Testing on the durability and haemocompatibility of these composite heart valves are ongoing.

Perceval Sutureless Valve - are Sutureless Valves Here?

With the advent of transcatheter aortic valve implantation (TAVI) techniques, a renewed interest has developed in sutureless aortic valve concepts in the last decade. The main feature of sutureless aortic valve implantation is the speed of insertion, thus making implantation easier for the surgeon. As a result, cross clamp times and myocardial ischemia may be reduced. The combined procedures (CABG with AVR in particular) can be done with a short cross clamp time. Perceval valve also provides an increased effective orifice area as compared with a stented bioprosthesis. Sutureless implantation of the Perceval valve is not only associated with shorter cross-clamp and cardiopulmonary bypass times but improved clinical outcomes too. This review covers the sutureless aortic valves and their evolution, with elaborate details on Perceval S valve in particular (which is the most widely used sutureless valve around the globe).

Transcatheter aortic valve replacement using the Edwards SAPIEN transcatheter heart valves

Transcatheter aortic valve replacement has a place in the therapy for valvular aortic stenosis in a selected population of patients with increased risk for standard aortic valve replacement. The SAPIEN family of balloon-expandable transcatheter heart valves is the prototype that initiated this therapy and has undergone rapid development and evolution. The SAPIEN system has taught cardiologists and cardiac surgeons much about the nature of aortic stenosis and the potential for less invasive therapy. This article will review the SAPIEN transcatheter heart valves and the clinical experience.

Transcatheter aortic valve implantation in surgically repaired double outlet right ventricle

A 52-year-old male patient, with a medical history of surgically repaired double outlet right ventricle presented with severe aortic stenosis (AS) and hepatitis C with cirrhosis, presented with New York Heart Association Class IV heart failure. During evaluation for a liver transplant, he was deemed a poor surgical candidate due to his aortic valve disease and cirrhosis with model for end-stage liver disease score of 14. Transthoracic echocardiogram showed severe AS with a mean gradient of 62 mm Hg and calculated aortic valve area of 0.74 cm(2) with a normal ejection fraction of 65%. The patient underwent transfemoral implantation of a 23-mm Edwards Sapien commercial heart valve with significant mean gradient reduction across the aortic valve from 62 to 13 mm Hg. The patient was observed in the coronary care unit and discharged home 2 days postprocedure with his clinical symptoms greatly improved.

Transcatheter aortic valve implantation: the evolution of prostheses, delivery systems and approaches

It is two decades since the first report of transcatheter implantation of a stented aortic valve in an animal. The first implantation of a transcatheter aortic valve in a human was accomplished just one decade ago dramatically demonstrating the promise and feasibility of this new therapy. Over the past 10 years, there have been rapid developments in valves, delivery systems and technical approaches. Today, transcatheter valve implantation is a technical possibility for the great majority of patients with aortic stenosis. The next 10 years may well see this become the dominant therapy for aortic stenosis.

Transcatheter valve-in-valve implantation for failing bioprosthetic valves

Transcatheter valve implantation is becoming an alternative to conventional surgical valve replacement in patients at high surgical risk. While experience and acceptance with transcatheter techniques increased rapidly, transcatheter valve implantation within failing bioprostheses has emerged as a new concept (valve-in-valve implantation). Currently, the majority of prostheses implanted in patients are bioprosthetic valves that are expected to degenerate over time. Valve-in-valve implantation provides great utility in high-operative-risk patients since the mortality risk for reoperation can be significantly higher than for first-time isolated valve replacement. Although two current devices are CE Mark approved in Europe for implantation within native valves, off-label clinical implementation of valve-in-valve have been described in numerous case reports. In this article, we provide an overview of transcatheter valve implantation in failing bioprostheses with an emphasis on the aortic position.

Transapical transcatheter aortic valve implantation: follow-up to 3 years

BACKGROUND

We performed the first human case of successful transapical transcatheter aortic valve implantation on a beating heart in October 2005, and therefore we have the longest follow-up on transapical aortic valve implantation in humans. We now report clinical and echocardiographic outcomes of transapical aortic valve implantation in 71 patients.

METHODS

Between October 2005 and February 2009, 71 patients (44 female) underwent transcatheter transapical aortic valve implantation with either 23- or 26-mm Edwards Lifesciences transcatheter bioprostheses. All patients with symptomatic aortic stenosis were declined for conventional aortic valve replacement owing to unacceptable operative risks and were not candidates for transfemoral aortic valve implantation because of poor arterial access. Clinical and echocardiographic follow-ups were performed before discharge, at 1 and 6 months, and then yearly. The mean follow-up was 12.9 +/- 11.5 months with a total of 917.3 months of follow-up.

RESULTS

Mean age was 80.0 +/- 8.1 years and predicted operative mortality was 34.5% +/- 20.4% by logistic EuroSCORE and 12.1% +/- 7.7% by The Society of Thoracic Surgeons Risk Calculator. Valves were successfully implanted in all patients. Twelve patients died within 30 days (30-day mortality: 16.9% in all patients, 33% in the first 15 patients, and 12.5% in the remainder), and 10 patients died subsequently. Overall survival at 24 and 36 months was 66.3% +/- 6.4% and 58.0% +/- 9.5%, respectively. Among 59 patients who survived at least 30 days, 24- and 36-month survivals were 79.8% +/- 6.4% and 69.8% +/- 10.9%, respectively. Late valve-related complications were rare. New York Heart Association functional class improved significantly from preoperative 3.3 +/- 0.8 to 1.8 +/- 0.8 at 24 months. The aortic valve area and mean gradient remained stable at 24 months (1.6 +/- 0.3 cm(2) and 10.3 +/- 5.9 mm Hg, respectively).

CONCLUSION

Our outcome suggests that transapical transcatheter aortic valve implantation provides sustained clinical and hemodynamic benefits for up to 36 months in selected high-risk patients with symptomatic severe aortic stenosis.

Transcatheter pulmonary valve implantation using the Edwards SAPIEN transcatheter heart valve

BACKGROUND

Conduits placed in the right ventricular outflow tract (RVOT) have limited longevity which often requires increasingly complex reoperations. Transcatheter pulmonary valve implantation improves conduit hemodynamics through a minimally invasive approach. We present data for 7 patients treated with the Edwards SAPIEN transcatheter heart valve (THV).

PATIENTS

Patients' ranged in age from 16 to 52 years, one was female, and all had NYHA class II-III symptoms. Patients had pulmonary homografts that had been placed 2-25 years earlier during the Ross procedure (n = 4), repaired double outlet right ventricle with situs inversus (n = 1), or Rastelli repair for D-TGA, pulmonary atresia, and ventricular septal defect (n = 2). Patients had either severe pulmonary stenosis and/or moderate to severe pulmonary regurgitation.

RESULTS

All patients had successful percutaneous implantation of the 23 mm SAPIEN THV under general anesthesia. Fluoroscopy times ranged from 16 to 49 mins and procedure times ranged from 110 to 237 mins. The RV:systemic pressure ratio decreased from 78 +/- 18 to 39 +/- 8%, the RVOT gradient improved from 60.7 +/- 24.3 to 14.9 +/- 6.9 mm Hg, no patients had pulmonary insufficiency, and all patients had symptom improvement. At a maximum follow-up of 3.5 years (median 22.5 months), Doppler peak gradients ranged from 7-36 mm Hg, and there is no evidence of late stent fracture or structural valve failure.

CONCLUSION

The SAPIEN THV can be used successfully in the treatment of patients with right ventricle to pulmonary artery homograft failure. The valve is durable to at least 3.5 years without stent fracture or regurgitation. Clinical trials are underway to assess the long-term safety and efficacy of this valve.

Progress and current status of percutaneous aortic valve replacement: results of three device generations of the CoreValve Revalving system

BACKGROUND

Percutaneous aortic valve replacement is a new emerging technology for interventional treatment of severe aortic valve stenosis in surgical high-risk patients. This study was intended to provide a summary of the development and current safety and efficacy status of the self-expanding CoreValve Revalving prosthesis.

METHOD AND RESULTS

Between 2005 and 2008, we have enrolled 136 consecutive patients with percutaneous aortic valve replacement using the CoreValve prosthesis. In this prospective nonrandomized, single-center trial, we analyzed procedural outcome, complications and clinical status up to 1 year. First, second, and third generation of the CoreValve prosthesis were implanted in 10, 24, and 102 consecutive high-risk patients (logistic EuroScore: 23.1+/-15.0%) with severe symptomatic aortic valve stenosis. Mean transvalvular pressure gradient was 41.5+/-16.7 mm Hg. The procedural success rate increased from generation 1/2 to 3 from 70.0%/70.8% to 91.2% (P=0.003). The 30-day combined rate of death/stroke/myocardial infarction was 40.0%/20.8%/14.7% (P=0.11) for generation 1, 2, and 3, with no procedural death in generation 3. Pressure gradients improved significantly with a final mean gradient of 8.1+/-3.8 mm Hg. Overall functional status assessed by New York Heart Association class improved from 3.3+/-0.5 (pre) to 1.7+/-0.7 (post) (P<0.001) and remained stable in the follow-up.

CONCLUSIONS

In experienced hands, percutaneous aortic valve replacement with the CoreValve system for selected patients with severe aortic valve stenosis has a high acute success rate associated with a low periprocedural mortality/stroke rate as well as remarkable clinical and hemodynamic improvements, which persist over time. Additional studies are now required to confirm these findings, particularly head-to-head comparisons with surgical valve replacement in different risk populations.

Transcatheter aortic valve implantation: predictors of procedural success--the Siegburg-Bern experience

AIMS

The purpose of the present analysis was to identify predictors of procedural success of percutaneous transcatheter aortic valve implantation (TAVI).

METHODS AND RESULTS

We prospectively assessed in-hospital outcome of patients undergoing TAVI at two institutions. We analysed clinical, morphological, and procedural parameters using univariate and multivariate regression models. Between 2005 and 2008, a total of 168 consecutive patients with symptomatic aortic valve stenosis underwent TAVI using the self-expanding CoreValve Revalving prosthesis. Patients (93%) were highly symptomatic with a New York Heart Association grade III/IV and a mean aortic valve area of 0.66 +/- 0.21 cm(2). Acute and in-hospital procedural success rates were 90.5 and 83.9%, respectively, with an in-hospital mortality, myocardial infarction, and stroke rate of 11.9, 1.8, and 3.6%, respectively. Predictors of in-hospital procedural success were type of access (OR 0.33, 95% CI 0.13-0.82, P = 0.017), prior coronary intervention (OR 5.3, 95% CI 1.20-23.41, P = 0.028) and pre-procedural Karnofsky index using univariate regression. Pre-procedural Karnofsky index emerged as the only independent predictor (OR 1.04, 95% CI 1.00-1.08, P = 0.032) in the multivariate analysis.

CONCLUSION

Pre-procedural functional performance status predicts the in-hospital outcome after TAVI. Patients with a good functional status are likely to benefit more from TAVI than previously reported high-risk patients.

History of percutaneous aortic valve prosthesis

This review describes the development of percutaneous transluminal catheter-mounted heart valves for permanent implantation. The time period from the first surgically implanted valve in 1952, through catheter- mounted valves inserted for temporal relief, until the conception of the percutaneous transcatheter heart valve for permanent implantation is summarized. The process involved in the construction of the new valve is detailed in Figure 1, and the future of this new treatment modality is discussed.

Transcatheter Aortic Valve Implantation

There has been significant improvement in device designs, operative techniques, and early clinical outcomes in <5 years. Presently, there are two catheter-based bioprostheses (balloon expandable or self-expandable), which have been widely used in humans and are undergoing clinical investigations. Three approaches, including transvenous, transarterial, and transapical have been used for delivery of the catheter-based bioprostheses, and transarterial and transapical approaches have been adopted by cardiologists and cardiac surgeons worldwide. The most recent clinical results have been very encouraging and promising. With experience, 30-day operative mortality with either balloon-expandable or self-expandable bioprosthesis was reduced significantly to approximately 10% in high-risk patients. In vivo long-term durability of catheter-based bioprostheses remains unknown, and presently transcatheter procedure is limited to the cohort of high-risk patients. Expanding this new technology to low-risk patients should be done with extreme caution because conventional aortic valve replacement still provides the best long-term outcome with minimal operative mortality and morbidity in low-risk patients. Ongoing clinical trials will address many unanswered questions, such as patient selection, long-term in vivo durability, preoperative assessment, and the role of the procedures in management of valvular diseases.

Percutaneous aortic valve replacement

Aortic valve replacement can produce dramatic benefit in the setting of aortic stenosis. The potential for morbidity and mortality associated with thoracotomy, cardiopulmonary bypass, and aortotomy has fostered a search for alternatives. Early experience with transcatheter endovascular aortic valve implantation demonstrated feasibility and durability, but the procedure was difficult to reproduce. However, equipment, techniques, and experience have evolved rapidly. Balloon-expandable and self-expanding prostheses and percutaneous femoral artery and open left ventricular apical access have found favor, each with potential advantages and disadvantages. Procedural success rates and clinical outcomes continue to improve. Current studies suggest that morbidity and mortality are competitive in comparison to conventional surgery in selected high-risk patients.

Percutaneous transarterial aortic valve replacement in selected high-risk patients with aortic stenosis

BACKGROUND

Percutaneous aortic valve replacement represents an endovascular alternative to conventional open heart surgery without the need for sternotomy, aortotomy, or cardiopulmonary bypass.

METHODS AND RESULTS

Transcatheter implantation of a balloon-expandable stent valve using a femoral arterial approach was attempted in 50 symptomatic patients with severe aortic stenosis in whom there was a consensus that the risks of conventional open heart surgery were very high. Valve implantation was successful in 86% of patients. Intraprocedural mortality was 2%. Discharge home occurred at a median of 5 days (interquartile range, 4 to 13). Mortality at 30 days was 12% in patients in whom the logistic European System for Cardiac Operative Risk Evaluation risk score was 28%. With experience, procedural success increased from 76% in the first 25 patients to 96% in the second 25 (P=0.10), and 30-day mortality fell from 16% to 8% (P=0.67). Successful valve replacement was associated with an increase in echocardiographic valve area from 0.6+/-0.2 to 1.7+/-0.4 cm2. Mild paravalvular regurgitation was common but was well tolerated. After valve insertion, there was a significant improvement in left ventricular ejection fraction (P<0.0001), mitral regurgitation (P=0.01), and functional class (P<0.0001). Improvement was maintained at 1 year. Structural valve deterioration was not observed with a median follow-up of 359 days.

CONCLUSIONS

Percutaneous valve replacement may be an alternative to conventional open heart surgery in selected high-risk patients with severe symptomatic aortic stenosis.

Percutaneous heart valve replacement: histology and calcification characteristics of biological valved stents in juvenile sheep

INTRODUCTION

Percutaneous techniques to replace the pulmonary valve are emerging as an alternative to congenital cardiac surgical procedures. Promising experimental and early clinical results have been reported so far, focusing on technical feasibility and valved stent function. The present study aimed to describe the micropathology after experimental percutaneous valve replacement.

METHODS

Self-expanding nitinol stents carrying a valved bovine jugular vein were transfemorally implanted into the pulmonary position of nine sheep. After 3 months of survival, macro- and micropathological examinations were carried out using standard staining techniques and immunohistochemistry. Additionally, calcification characteristics were determined by X-ray examinations and von Kossa stainings.

RESULTS

Six of nine animals survived the 3-month study time with good angiographic and echocardiographic function. All valves were grossly functional at the time of explantation. Slight fibrous overgrowth was seen at the inflow portions of two valved stents. No cuspal perforations or intracuspal hematomas were observed. Light microscopy proved the absence of cellular inflammatory infiltrates in any tissue samples. The myocardium directly proximal to the stent appeared structurally normal without calcification. The overall structure of the native pulmonary artery was well preserved with few mineral deposits spread diffusely throughout the wall distal to the stent. Massive calcification appeared in the bovine jugular-vein wall together with increased numbers of T lymphocytes. Neither calcific deposits in the cusps nor extrinsic mineralization was noted.

CONCLUSION

For the first time, micropathologic evaluation of percutaneously implanted heart valves is described. The results demonstrate that calcification of valved stents occurs in the wall portions without affecting the cusps. The cardiac structures in the vicinity had normal histology without inflammation.

Six-month outcome of transapical transcatheter aortic valve implantation in the initial seven patients

BACKGROUND

The current treatment of choice for symptomatic aortic stenosis is aortic valve replacement (AVR) with cardiopulmonary bypass (CPB), but AVR is associated with significant operative morbidity and mortality in elderly patients with multiple co-morbid conditions. We recently reported the first successful aortic valve implantation procedure (AVI) via a mini-thoracotomy and left ventricular apical puncture without cardiopulmonary bypass. We now report 6-month follow-up in our initial seven patients.

METHODS

Seven patients (77+/-10 years old) with symptomatic aortic stenosis were deemed to be non-surgical candidates for AVR and not suitable for a transfemoral percutaneous heart valve implantation due to aorto-iliac disease. The predicted 30-day operative mortality was 31+/-23% according to logistic Euroscore. Patients underwent minimally invasive transapical AVI. With the guidance of fluoroscopy and transesophageal echocardiography, balloon predilation was followed by deployment of a 26mm Cribier-Edwardstrade mark valve (Edwards Lifesciences Inc., Irvine, CA) during rapid ventricular pacing to reduce forward flow and cardiac motion.

RESULTS

Valve implantation was successful in all seven patients. There were no intra-procedural mortalities or complications. Thirty-day operative mortality was 14%. One patient died at day 12 due to pneumonia. Two patients died from non-cardiac diseases at day 51 and 85. The remaining four patients completed 6-month follow-up. The aortic valve area increased from 0.7+/-0.3 to 1.8+/-0.7 and 1.5+/-0.5cm(2) at 1 and 6 months, respectively. The mean transaortic gradient was reduced from 32+/-8 to 10+/-5 and 11+/-8mmHg at 1 and 6 months, respectively. Following AVI, none or trivial, mild, and moderate aortic regurgitation was observed in 4, 2, and 1 patients, respectively. There were no valve-related complications during the follow-up.

CONCLUSION

Aortic valve implantation can successfully be performed via a minimally invasive apical approach without the need for cardiopulmonary bypass. The early results in this initial series are encouraging. This initial experience suggests that the minimally invasive transapical approach is a viable alternative for patients in whom open-heart surgery is not feasible or poses unacceptable risks.

Feasibility of transcatheter intervention for severe aortic stenosis in patients ≥90 years of age: Aortic valvuloplasty revisited

OBJECTIVES

The goals of this study were to determine the feasibility, safety, and early outcomes of balloon aortic valvuloplasty (BAV) for severe aortic stenosis in a nonagenarian population.

BACKGROUND

This very elderly population is expanding rapidly, has a high incidence of aortic stenosis, and uncommonly undergoes surgical aortic valve replacement. These patients may best be treated with a transcatheter approach due to comorbidities, surgical risk, and personal preference.

METHODS

We reviewed 31 consecutive patients >or=90 years of age who underwent BAV at our institution from July 2003 to August 2006 for data pertinent to patient characteristics, procedural techniques, and 30-day outcomes.

RESULTS

Our patients had a mean age of 93 +/- 3.0 years (90-101). The society of thoracic surgery risk score was 18.5 (+/-10.2) and logistic Euroscore was 35.8 (+/-19.3). Twenty-five patients (81%) underwent retrograde BAV and 6 (19%) antegrade BAV. Five patients (16%) underwent combined BAV and coronary stenting. Overall mean aortic valve area increased from 0.52 cm2 (+/-0.17) to 0.92 cm2 (+/-0.22) and mean New York Heart Association (NYHA) functional class improved from 3.4 to 1.8. Intraprocedural mortality occurred in one patient (3.2%) and 30-day mortality in three patients (9.7%).

CONCLUSIONS

BAV can be carried out in high risk nonagenarian patients with an acceptable complication rate, low perioperative mortality, and early improvement in NYHA functional class.

Sutureless Stented Aortic Valve Implantation Under Direct Vision: Lessons From a Negative Experience in Sheep

BACKGROUND AND AIM OF THE STUDY

Percutaneous aortic valve replacement has been proposed as a valid alternative to surgery in selected cases; however, it still has many problems. As a less radical preliminary step, we implanted a balloon-expandable stented aortic valve under direct vision in sheep.

METHODS

Under cardiopulmonary bypass (CPB) and through a transverse aortotomy, an aortic valve mounted in a long tubular balloon-expandable stent was implanted in six acute sheep. The leaflets were not excised and no anchoring sutures were used between stent and native annulus. Epicardial, two-dimensional color Doppler echocardiography was used to assess the function of the stented valve followed by macroscopic inspection at necropsy.

RESULTS

Direct visualization of the entire annulus when the collapsed, valved stent was placed within the aortic root was difficult in all animals. Valve deployment took less than 1 minute. The surgical procedure resulted in major complications in all cases. Migration (3/6), paravalvular leak (2/6), mitral conflicts resulting in mitral regurgitation (1/6), and coronary ostia obstruction (2/6) were the major events at the origin of the failure. Only three animals could be weaned from CPB but did not recover enough to survive the procedure.

CONCLUSIONS

Sutureless implantation of a stented aortic valve through standard CPB and aortotomy is far more complex than expected. Changes in stent design and surgical approach are indicated.

Percutaneous aortic valve implantation: a case report

The present case demonstrates the percutaneous implantation of a bioprosthetic valve in a patient with severe aortic stenosis. An 85-year-old man with significant comorbidities was determined to be at unacceptable risk with traditional surgical valve replacement. Percutaneous aortic valve implantation was performed, was successful and uncomplicated, with significant clinical and hemodynamic improvement. Currently, this procedure is an option only for symptomatic patients who are not appropriate candidates for surgical valve replacement.

Transapical transcatheter aortic valve implantation in humans: initial clinical experience

BACKGROUND

Aortic valve replacement with cardiopulmonary bypass is currently the treatment of choice for symptomatic aortic stenosis but carries a significant risk of morbidity and mortality, particularly in patients with comorbidities. Recently, percutaneous transfemoral aortic valve implantation has been proposed as a viable alternative in selected patients. We describe our experience with a new, minimally invasive, catheter-based approach to aortic valve implantation via left ventricular apical puncture without cardiopulmonary bypass or sternotomy.

METHODS AND RESULTS

A left anterolateral intercostal incision is used to expose the left ventricular apex. Direct needle puncture of the apex allows introduction of a hemostatic sheath into the left ventricle. The valve prosthesis, constructed from a stainless steel stent with an attached trileaflet equine pericardial valve, is crimped onto a valvuloplasty balloon. The prosthetic valve and balloon catheter are passed over a wire into the left ventricle. Positioning within the aortic annulus is confirmed by fluoroscopy, aortography, and echocardiography. Rapid ventricular pacing is used to reduce cardiac output while the balloon is inflated, deploying the prosthesis within the annulus. Transapical aortic valve implantation was successfully performed in 7 patients in whom surgical risk was deemed excessive because of comorbidities. Echocardiographic median aortic valve area increased from 0.7 +/- 0.1 cm2 (interquartile range) to 1.8 +/- 0.8 cm2 (interquartile range). There were no intraprocedural deaths. At a follow up of 87 +/- 56 days, 6 of 7 patients remain alive and well.

CONCLUSIONS

This initial experience suggests that transapical aortic valve implantation without cardiopulmonary bypass is feasible in selected patients with aortic stenosis.

[Percutaneous cardiac valve replacement: a review]

Surgery is no longer the only technique to replace a cardiac valve. New percutaneous procedures allow aortic or pulmonary valve implantation. Even if the feasibility of these procedures has been proved, cases reported are very rare and selected. This emergent technology is still at an early stage of development and new prospective studies will be necessary to evaluate these procedures correctly before concluding their clinical benefit. At this time surgery remains the gold standard in terms of cardiac valve replacement.

Percutaneous aortic valve implantation retrograde from the femoral artery

BACKGROUND

Percutaneous aortic valve implantation by an antegrade transvenous approach has been described but is problematic. Retrograde prosthetic aortic valve implantation via the femoral artery has potential advantages. Percutaneous prosthetic aortic valve implantation via the femoral arterial approach is described and the initial experience reported.

METHODS AND RESULTS

The valve prosthesis is constructed from a stainless steel stent with an attached trileaflet equine pericardial valve and a fabric cuff. After routine aortic balloon valvuloplasty, a 22F or 24F sheath is advanced from the femoral artery to the aorta. A steerable, deflectable catheter facilitates manipulation of the prosthesis around the aortic arch and through the stenotic valve. Rapid ventricular pacing is used to reduce cardiac output while the delivery balloon is inflated to deploy the prosthesis within the annulus. Percutaneous aortic prosthetic valve implantation was attempted in 18 patients (aged 81+/-6 years) in whom surgical risk was deemed excessive because of comorbidities. Iliac arterial injury, seen in the first 2 patients, did not recur after improvement in screening and access site management. Implantation was successful in 14 patients. After successful implantation, the aortic valve area increased from 0.6+/-0.2 to 1.6+/-0.4 cm2. There were no intraprocedural deaths. At follow-up of 75+/-55 days, 16 patients (89%) remained alive.

CONCLUSIONS

This initial experience suggests that percutaneous transarterial aortic valve implantation is feasible in selected high-risk patients with satisfactory short-term outcomes.

Rapid pacing to facilitate transcatheter prosthetic heart valve implantation

OBJECTIVES

We describe the technique of, and our experience with, rapid ventricular burst pacing to facilitate transcatheter heart valve implantation.

BACKGROUND

Endovascular therapeutic procedures frequently require the precise placement of implantable devices. The precision of transcatheter device deployment may be hampered by cardiac motion or the effects of intravascular flow. Burst pacing is associated with a reduction in stroke volume, cardiac output, transvalvular flow, and cardiac motion.

METHODS

Rapid pacing was used in 40 consecutive patients with severe aortic stenosis undergoing implantation of catheter-delivered prosthetic valves. Clinical, procedural, and hemodynamic records were reviewed.

RESULTS

A mean of 5 +/- 2 burst pacing sequences at rates of 150-220 min(-) (1) were used during balloon valvuloplasty and valve deployment. The duration of pacing required during valve deployment was 12 +/- 3 sec. Pacing was relatively well tolerated when cautiously used with judicious recovery intervals and pressor support. Rapid pacing was associated with a rapid and effective reduction in systemic blood pressure, pulse pressure, transvalvular flow as well as cardiac and catheter motion.

CONCLUSIONS

Rapid pacing is a relatively reliable technique to facilitate precise transcatheter deployment of prosthetic heart valves and other endovascular therapeutic devices.

Use of a Covered Stent Modification to Produce a Transcatheter Valve: Laboratory and Animal Testing

Stent-based transcatheter valves continue to require large sheaths inappropriate for deployment in children. Low-profile covered stent valves (CSVs) were constructed by removing triangular sections from two sides of partially expanded Palmaz P308 stents before covering the stents with 0.1 mm polytetrafluoroethylene. Valves were carefully crimped onto balloon catheters and deployed in a pulsatile flow loop. With fixed afterload and pump output, flow, degree of stenosis, effect on pulse pressure, and ease of deployment were determined for each valve. In vivo transcatheter feasibility studies were then performed by disabling the aortic valve of two 25-kg pigs, and deploying transcatheter CSVs into their descending aorta. All transcatheter valves deployed consistently via sheaths three French sizes larger than the recommended sheath for their balloon and none created significant obstruction. With the bicuspid and supravalvar CSVs, the flow was 64% and 79% (respectively) of a commercially available valve. Angiograms revealed excellent acute CSV function after deployment with only mild regurgitation and without significant obstruction to systolic flow. Although long-term testing is required, a modified CSV design may have utility in low-profile pediatric transcatheter valve replacement.