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Ann Thorac Surg 2002;74:1139-1143
© 2002 The Society of Thoracic Surgeons

Original article: cardiovascular

The Heartflo device for distal coronary anastomoses: clinical experiences in 60 patients

Sven Martens, MDa*, Markus Dietrich, MDa, Mirko Doss, MDa, Anton Moritz, MD, PhDa, Gerhard Wimmer-Greinecker, MD, PhDa

a Department of Thoracic and Cardiovascular Surgery, University Hospital J.W. Goethe, Frankfurt am Main, Germany

Accepted for publication May 29, 2002.

* Address reprint requests to Dr Martens, Klinik für Thorax-, Herz und Thorakale Gefäßchirurgie, Klinikum der J.W. Goethe Universität, Theodor Stern Kai 7, 60590 Frankfurt am Main, Germany
e-mail: martens.herz{at}gmx.de


   Abstract
Top
 Abstract
Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
 References
 
Background. The Heartflo anastomotic device automates the suturing process with simultaneous delivery of 10 standard polypropylene sutures through the graft and the coronary vessel wall to construct the anastomosis. We performed clinical testing in 60 patients undergoing coronary artery bypass grafting.

Methods. One automated distal coronary anastomosis was initially placed in each patient, the other anastomoses were created with standard running sutures. After a "flat foot"-shaped prototype was deployed in 30 patients (group I), the design of the foot was modified and deployment of the new device performed in the next 30 patients (group II).

Results. In group I, automated anastomoses were completed in 16 patients (53%) using 1.7 ± 1 additional stitches. In 26 group II patients (86%), a hemostatic anastomosis using 1.2 ± 1 additional stitches was achieved. Anastomoses were completed in 19.0 ± 3 minutes in group I and in 15.6 ± 2 minutes in group II.

Conclusions. We have shown the feasability of coronary anastomoses using the Heartflo device. The modified version improved tissue capture, resulting in a higher rate of completed anastomoses. Because anastomotic time is still prolonged, an easier suture management is mandatory in the next developmental step.


   Introduction
Top
 Abstract
 Introduction
Material and methods
 Results
 Comment
 Acknowledgments
 References
 
In coronary artery bypass grafting, distal coronary anastomoses are currently performed with running sutures or, to a limited extent, interrupted techniques, which are more time consuming. Interrupted suture lines achieve a more ideal anastomotic configuration with minimal deformity and less narrowing of the anastomotic contour [1, 2]. An automated suturing device for distal coronary anastomoses may also reduce the dependency on surgical skills, which is a prognostic factor for long-term patency. The device must be simple to use and provide precise, repeatable, and effective technical results. The key element is the spaced placement of the sutures between the target and the graft vessels. Any imprecision may lead to occlusion or compromised flow [3]. Because minimal invasive coronary operations through limited incisions and beating heart operations carry a substantial risk for reduced anastomotic quality [4], anastomotic devices should be made available for minimally invasive or totally endoscopic use.

The Heartflo anastomotic device (Perclose/Abbott Labs, Redwood City, CA) is a micromechanical suturing device for coronary artery bypass grafting. It automates the suturing process by a simultaneous delivery of 10 interrupted sutures through the graft and the vessel wall. End-to-side anastomoses of vein grafts to coronary arteries, and side-to-side anastomoses of vein grafts or internal thoracic arteries (ITA) to coronary arteries are possible. Shennib and colleagues [3] published their early experiences in animals in 2000. Tozzi and associates [5] and our group [6] reported preliminary clinical experiences with the Heartflo suturing device. We started our first clinical trial (group I) in April 2000. Because a modification of the foot of the device had shown improved tissue capture in bench testing and animal studies, a second series was started in June 2001.


   Material and methods
Top
 Abstract
 Introduction
 Material and methods
Results
 Comment
 Acknowledgments
 References
 
The Heartflo anastomotic device was constructed for use in end-to-side or side-to-side coronary anastomoses. In cases of poor tissue capture and persistent leakage, additional stitches are inserted using the conventional technique. Since first clinical application in 2000, the shape of the foot and the direction of the needles penetrating the coronary vessel were modified. Figure 1 shows the first version applied clinically, the "flat foot" (diameter of the foot, 1.5 mm). The profound revisions leading to the "V-drive" model are visualized in Figure 2. A hydraulically activated mechanism automates the delivery of 10 interrupted 7-0 polypropylene sutures. Because we almost exclusively used the end-to-side device (which was not available for internal thoracic artery grafts), we describe the procedure to create a coronary anastomosis using a vein graft.



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  		Fig 1. The Heartflo anastomotic device: the "flat foot" version.

 


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  		Fig 2. Modification of the foot from (A) flat foot to (B) V-drive.

 
The distal end of the vein is cut at a 45-degree angle. The first step of the anastomotic procedure is the insertion of the needle guide into the vein graft. The delivery mechanism deploys the 10 needles, each one attached to the end of a suture, and drives them through the vein graft into a silicone barrier where they are captured (Fig 3A). Afterward, the foot of the device is inserted into the coronary artery through a 5-mm arteriotomy (Fig 3B). The heel and the toe of the device have to be completely covered by tissue to achieve hemostasis. A hydraulically activated delivery mechanism simultaneously deploys the needles, which pull the cuff-fixed sutures through the coronary vessel wall. After separation of the needle holders, the ends of the 10 sutures are sorted and pulled to approximate the edges of the vein graft and the coronary artery (Fig 3C). To complete the anastomosis, each suture is tied conventionally (Fig 3D). Exact placement of the foot inside the coronary artery before deployment is essential for optimal tissue capture. The anastomoses created with the device are angled (45 degrees). The procedures followed in groups I and II were the same except for details regarding the suture management, which was facilitated in the "V-drive" group (group II).



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  		Fig 3. The anastomotic procedure. (A) Vein graft placed on needle guide. (B) Insertion of the device into coronary artery. (C) Approximation of vein graft and coronary artery. (D) The completed anastomosis.

 
Sixty patients undergoing elective operation were referred to our institution for coronary artery bypass grafting. They presented with 2- or 3-vessel disease. Patients were not selected for angiographic criteria as vessel size and degree of stenosis. Patients with severe depression of their left ventricular function (<25%) and emergency operations were excluded from the trial. All patients were operated on using cardiopulmonary bypass with cardioplegic arrest. The first prototype was applied in 30 patients (group I), and 30 patients were operated using the modified version (group II). One distal anastomosis was initially placed with the anastomotic device. Vessel selection for the automated anastomosis was guided by size and quality of the target vessel, and our policy of arterial revascularization of the left anterior descending coronary artery in all patients. Because suture management was more complicated in the "flat foot" group, we preferred to use a branch of the right coronary artery in most of these patients, as the exposure was more comfortable.

Coronary artery size was measured using standard probes of 1 to 2.5 mm. The target vessels were as follows: right coronary artery: group I (4 patients) and group II (5); distal branches of the right coronary artery: group I (21) and group II (11); obtuse marginal branch of the left coronary artery: group I (0) and group II (11); circumflex artery: group I (3) and group II (3); left anterior descending coronary artery: group I (2) and group II (0 patient). In 4 patients of group I, a side-to-side anastomotic device was applied, 2 patients received internal thoracic artery grafts to the left anterior descending coronary artery with this version. We discontinued its application because our initial experiences with the end-to-side device were more promising. Flow through the anastomoses was measured by application of cardioplegia through a delivery line connected to the vein graft; the pressure did not exceed 100 mm Hg. The other distal anastomoses were performed using standard running sutures (7-0 polypropylene for vein grafts, 8-0 for internal thoracic artery grafts). The same surgeon performed all interventions. The study was approved by our local ethics committee; informed consent was obtained from all patients.


   Results
Top
 Abstract
 Introduction
 Material and methods
 Results
Comment
 Acknowledgments
 References
 
Table 1 lists patients characteristics and perioperative data. In 16 group I patients, a patent anastomosis with a mean flow of 75 ± 24 mL/min was achieved. In 5 patients, no additional stitches were needed to achieve hemostasis. To complete the other anastomoses, 1.7 ± 1 additional stitches were needed. Anastomotic time was 19.0 ± 3 minutes. Mechanical failure occurred in the first 4 patients; reasons for not completing the other mechanical anastomoses were vessel related in 7 patients (target vessel too small or severe calcification at the anastomotic site, resulting in bad tissue capture) or problems related to the suture management and handling of the device (3 patients).


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  		Table 1. Patient Characteristics and Perioperative Data

 
In 26 group II patients, a hemostatic anastomosis (mean flow, 87 ± 25 mL/min) was achieved. In 9 patients, anastomoses were perfect and no additional stitches were needed. In 17 anastomoses there was minor leakage and 1.2 ± 1 conventional stitches were needed. The time from incision of the coronary artery to completion of the anastomosis was significantly shorter in group II compared with group I (15.6 ± 2 minutes, p = 0.0003). The reasons for not completing the automated anastomosis were related to the vessel quality (severe calcification) in 2 patients and mechanical problems (incomplete capture of the suture cuffs) in 2 patients. Coronary artery size ranged from 1.5 to 2.5 mm in the entire study group, but only in the modified foot group (group II), anastomoses with 1.5-mm vessels were successfully completed.

We had one noncardiac death in group II (a patient on chronic dialysis died 4 days after the operation). Another patient with history of several strokes showed prolonged recovery due to perioperative stroke with hemiparesis. One group I patient was reexplored for bleeding, not caused by a distal anastomosis. The clinical course during hospital stay was uneventful for all other patients, no myocardial infarction or other cardiac adverse event occurred in our study groups. Angiographies were performed on 6 patients at follow-up; all automated anastomoses were patent.


   Comment
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
Acknowledgments
 References
 
The development of alternative ways to construct graft-to-coronary anastomoses is characterized by a reduction of technical demand with respect to the total number of manual maneuvers [7]. Werker and Kon [8] reviewed different approaches to construct vascular anastomoses. Tissue approximation by means of stapling was introduced in 1908, when a stapling device for distal gastrectomy was presented. In the late 1940s, a group of Russian engineers and physicians developed a method of constructing end-to-end anastomoses for vascular surgery with a circular stapler. We have to distinguish three categories of approaches: anastomotic devices using micromechanical connectors, laser-assisted vascular anastomosis techniques, and adhesive bonding of donor and recipient vessel.

Nonpenetrating clips were introduced in vascular surgery in 1992 by the group of Kirsch [9] and used for coronary anastomoses in 1997 by the group of Nataf [10]. They reported clinical results in 10 patients. The anastomotic procedure took 15 minutes, the surgeon performed the eversion of the vessel wall while the assistant applied the clips. Limitations of this method were seen in calcified vessel walls. Heijmen and colleagues [11] reported the application of a one-shot anastomotic stapler on the beating heart in an animal model. Occlusion of the coronary arteries was limited to 3 minutes; the procedure was successful in 8 of 14 anastomoses with 12 clips applied circumferentially. Minimal intimal hyperplasia, more pronounced when compared with conventionally sutured anastomoses, was seen 28 days after the operation. Solem and coworkers [12] presented their results with a new device for performing quick sutureless vascular anastomoses by means of stent technology. Short-term results were encouraging, with equivalent flow through an anastomosis created in less than 3 minutes compared with a conventional anastomosis. The disadvantage of any technique using intraluminal stents is the possible impairment of long-term patency by in-stent stenosis. Gundry and coworkers [13] reported a different approach to create sutureless coronary anastomoses, using biological glue formulated from bovine albumin and glutaraldehyde. Follow-up showed intact anastomoses 1 year after the procedure. A possible disadvantage of this method is that glutaraldehyde is a toxic component.

The implication of using the same suture material (7-0 polypropylene) as in a conventional handsewn coronary anastomosis is interesting because it does not leave additional endovascular material behind. Endovascular material possibly induces intimal proliferation, as in stents [3]. Several investigators describe a better performance with interrupted suturing techniques in coronary anastomoses, leading to optimal internal configuration with minimal deformity and less narrowing of the anastomotic contour [1, 2]. The disadvantage of the interrupted suture lines created with the Heartflo device is that each pair of sutures has to be tied separately to complete the anastomosis, and suture management is time consuming with the current generation of devices.

Our clinical study has proved feasability of automated coronary anastomoses with the Heartflo device. Initially apparent mechanical problems with the "flat foot" anastomotic device (4 patients) were resolved, so that in next patients no device-related problems occurred. Use of the device in small coronary arteries was limited by the coronary artery size. The square shape of the foot (Fig 1) was cumbersome, therefore target vessels smaller than 1.8 mm could not be approached with the flat foot. Bad tissue capture was the most important reason for failure of the anastomotic device in our first series. The novel design (V-drive) applied in group II drastically improved our results. The modification of the foot shape and direction of needles penetrating the vessel wall led to improved tissue capture in group II. Coronary anastomoses with vessels of 1.5 mm inner diameter were successfully performed. The procedure was less time consuming, partly due to a simplified suture management. Significant reduction of bypass time as well as cross-clamp time in group II can also be contributed to the learning curve of the performing surgeon, because several steps of the anastomotic procedure were prepared before cardiopulmonary bypass.

The performance of the anastomotic device remains questionable in target vessels with extreme calcification or thin-walled vessels. In the majority of our applications, conventionally performed supplementary stitches were necessary to achieve hemostasis. Introduction of the device into the coronary vessel and correct angulation during release are the key elements of the procedure. Limitations for beating heart or endoscopic cases are evident, because tissue capture is highly dependent on visual control of the foot placement. It is important to mention that we did not preselect our study patients based on angiographic criteria or risk factors. Their target vessel quality is representative of the patients we operate on currently and in the future, and for whom anastomotic devices should be constructed.

Limitations of our study
We could not directly compare anastomotic quality of interrupted mechanical and conventionally handsewn anastomoses, because postoperative angiography was only performed in a minority of study patients. A comparison of the flow rates achieved using the device with conventionally sutured anastomoses would be misleading, because the coronary vessels grafted with the suturing device represent a positive selection.

We conclude that the Heartflo device for distal coronary anastomoses represents a promising step toward automated coronary anastomoses. Anastomotic suturing devices leave a minimum of endovascular material behind, an advantage with regard to intimal proliferation. Introduction of foreign material may reduce long-term patency of anastomoses created with other devices. Future developments should automate knot tying, or replace it. Our success rate in unselected patients undergoing coronary artery bypass grafting encourages the development of devices based on this prototype. The application through limited incisions, or in a totally endoscopic setting, seems not possible with the current model.


   Acknowledgments
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
References
 
We thank Carla Maupin and John Barret (Perclose Inc/Abbott Labs) for their assistance during the conduction of this study, and Friedrich W. Wolf for providing us with drawings of the anastomotic procedure. The study received financial support from Perclose Inc/Abbott Labs.


   References
Top
 Abstract
 Introduction
 Material and methods
 Results
 Comment
 Acknowledgments
 References
 

  1. Young J.N., MacMillan J.C., May I.A., Iverson L.I., Ecker R.R. Internal configuration of saphenous-coronary anastomoses studied by the cast-injection technique. J Thorac Cardiovasc Surg 1978;75:179-185.[Abstract]
  2. John L.C., Edmondson S.J., Rees G.M. Coronary artery anastomotic contour—a method for individual surgeons to assess their suture techniques. Eur J Cardiothorac Surg 1993;7:220-222.[Abstract/Free Full Text]
  3. Shennib H., Korkola S.J., Bousette N., Giaid A. An automated interrupted suturing device for coronary artery bypass grafting: automated coronary anastomosis. Ann Thorac Surg 2000;70:1046-1048.[Abstract/Free Full Text]
  4. Bonchek L.I., Ullyot D.J. Minimally invasive coronary bypass: a dissenting opinion. Circulation 1998;98:495-497.[Free Full Text]
  5. Tozzi P., Stumpe F., Ruchat P., Marty B., Corno A.F., von Segesser L.K. Preliminary clinical experience with the Heartflo Anastomosis device. Thorac Cardiovasc Surg 2001;49:279-282.[Medline]
  6. Martens S., Doss M., Moritz A., Wimmer-Greinecker G. Sutured coronary artery grafting utilizing the Heartflo anastomotic device: first clinical experiences. Thorac Cardiovasc Surg 2002;50:1-4.[Medline]
  7. Scheltes J.S., Heikens M., Pistecky P.V., van Andel C.J., Borst C. Assessment of patented coronary end-to-side anastomotic devices using micromechanical bonding. Ann Thorac Surg 2000;70:218-221.[Abstract/Free Full Text]
  8. Werker P.M.N., Kon M. Review of facilitated approaches to vascular anastomosis surgery. Ann Thorac Surg 1997;63:S122-S127.[Medline]
  9. Kirsch W.M., Zhu Y.H., Hardesty R.A., Chapolini R. A new method for microvascular anastomosis: report of experimental and clinical research. Am Surg 1992;58:722-727.[Medline]
  10. Nataf P., Kirsch W., Hill A.C., et al. Nonpenetration clips for coronary anastomosis. Ann Thorac Surg 1997;63:S135-S137.[Medline]
  11. Heijmen R.H., Hinchliffe P., Borst C. A novel one-shot anastomotic stapler prototype for coronary bypass grafting on the beating heart: feasibility in the pig. J Thorac Cardiovasc Surg 1999;117:117-125.[Abstract/Free Full Text]
  12. Solem J.O., Boumzebra D., Al-buraiki J. Evaluation of a new device for quick sutureless coronary artery anastomosis in surviving sheep. Eur J Cardio-thorac Surg 2000;17:312-318.[Abstract/Free Full Text]
  13. Gundry S.R., Black K., Izutani H. Sutureless coronary artery bypass with biologic glued anastomoses: preliminary in vivo and in vitro results. J Thorac Cardiovasc Surg 2000;120:473-477.[Abstract/Free Full Text]



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