| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Ann Thorac Surg 1998;66:1029-1031
© 1998 The Society of Thoracic Surgeons
a Division of Cardiothoracic Surgery, Duke University Medical Center, Durham, North Carolina, USA
Address reprint requests to Dr Duhaylongsod, Duke University Medical Center, Box-3457 Med Ctr, Durham, NC 27710
e-mail: (duhay001{at}mc.duke.edu)
Presented at "Facts and Myths of Minimally Invasive Cardiac Surgery: Current Trends in Thoracic Surgery IV," New Orleans, LA, Jan 24, 1998.
Abstract
Background. Because of smaller incisions and limited exposure, less invasive operations on the mitral valve can be arduous and time-consuming. This study examined the feasibility of a mechanical suturing device to facilitate less invasive mitral replacement.
Methods. Five mongrel dogs underwent limited left thoracotomy. After conventional cardiopulmonary bypass and cardioplegia, the mitral valve was exposed through a left atriotomy. After excision of the anterior leaflet, subannular sutures were placed using a mechanical suturing device. This device simultaneously passes two ends of a pledgeted 2-0 braided suture through the valvular annulus, then mechanically grasps both needles on the atrial aspect. Hence, a mattress suture is accomplished one-handed in a single continuous motion. This procedure was repeated around the entire annulus. A mechanical valve was seated and the sutures were tied and cut.
Results. All mechanical valves were implanted successfully. In the 4 animals in which it was attempted, cardiopulmonary bypass was successfully weaned. No evidence of perivalvular leak was observed by echocardiography.
Conclusions. These data establish the feasibility of a mechanical suturing device for operations on the mitral valve. The device is easily mastered, maintains precise spacing between sutures, and permits rapid placement of mattress sutures. We predict widespread application for both less invasive and conventional valve operations.
Early results suggest that video-assisted thoracoscopic or less invasive mitral and aortic valve operations can be accomplished safely in carefully selected patients. These methods may benefit patients through less morbidity, shorter length of stay in the intensive care unit and hospital, and more rapid return to normal activity [1–3]. Because of smaller incisions and limited exposure, however, less invasive operations on the mitral valve can be arduous and time-consuming. At this institution, the experience with port-access mitral valve repair or replacement though a limited right thoracotomy has demonstrated that cardiopulmonary bypass (CPB) and aortic cross-clamp times were significantly increased compared with conventional median sternotomy (mean ± standard deviation; 212 ± 53 and 133 ± 49 minutes, versus 157 ± 36 and 104 ± 28 minutes, respectively) [4]. Chitwood and colleagues [1] have reported a similar experience using a video-assisted approach to operations on the mitral valve. In their series, the CPB and aortic cross-clamp times were 183 ± 7.2 and 136 ± 5.7 minutes, respectively, compared with 116 ± 4.4 and 92 ± 3.6 minutes, respectively, after conventional median sternotomy. Although the explanation for the observed differences is multifactorial, one aspect of the operation that contributes significantly is the inherent difficulty in placing annular mattress sutures through a limited incision. This study examined the feasibility of a mechanical suturing device to facilitate less invasive mitral replacement in an animal model.
Material and methods
All animals received humane care in compliance with the Institutional Animal Care and Use Committee at Duke University and the "Guide for the Care and Use of Laboratory Animals" published by the National Institutes of Health (NIH publication 85-23, revised 1985).
Five mongrel dogs weighing 20 to 25 kg were sedated with ketamine (15 to 25 mg/kg IM), anesthetized with thiopental sodium (10 to 15 mg/kg IV), and endotracheally intubated. Anesthesia was maintained with 2% to 3% isoflurane using an Ohio V5 mechanical ventilator and anesthesia machine (Ohio Medical Products, Madison, WI). Respiratory rate, end-tidal CO2, inspired %O2, and inspired and expired isoflurane concentrations were monitored using a Capnomac infrared spectrophotometer (Datex, Helsinki, Finland). Periodic arterial blood gas samples were obtained to guide ventilator management. Surface electrocardiogram and femoral artery pressure were continuously monitored. Each dog was placed on conventional CPB with aortic and bicaval cannulation and cardioplegic arrest. The mitral valve was approached through a limited left thoracotomy and left atriotomy. The anterior leaflet of the mitral valve was resected. Subannular sutures were placed using the mechanical suturing device (United States Surgical Corp, Norwalk, CT). This device has a handle, a toggle switch, a 17-cm-long shaft that is angled, and a twin needle-grasping mechanism with proximal and distal jaws (Fig 1). This latter feature gives the device an appearance of a "cobra head." To prepare for subannular suture placement, both needles were set in the distal jaw (Fig 2). The needles were then passed into the desired location of the mitral annulus from the ventricular aspect. By squeezing the handles together and flipping the toggle switch (Fig 3) both needles were transferred from the distal to the proximal jaw (Fig 4). The device can simultaneously pass both ends of a pledgeted 2-0 braided suture through the annulus, 3 mm apart, then mechanically grasp both needles on the atrial aspect. Hence, a mattress suture was accomplished one-handed in a single continuous motion (Fig 5). This process is repeated around the annulus. Sutures were then cut and passed through the cuff of the mechanical valve using a unique French-eye needle (United States Surgical Corp). The mechanical valve was seated and the sutures were tied in the usual fashion. The left atrium was closed with 4-0 polypropylene. The animals were then separated from CPB and the cannulas were removed. Intraoperative epicardial echocardiography was used to assess valve function and perivalvular leak when the animals came off CPB and the cannulas were removed.
|
|
|
|
|
All mechanical valves were implanted successfully. The bypass times were 58 ± 4 minutes (range, 50 to 62 minutes). The cross-clamp times were 28 ± 5 minutes (range, 24 to 40 minutes). The time to place the sutures was about 10 minutes. In the 4 animals in which it was attempted, CPB was successfully weaned. In the 1 that was not weaned from CPB, the failure to wean was because of catastrophic bleeding from the aortic cannula connection site, which had become disrupted before weaning from CPB. Recovery of left ventricular function was uniformly excellent. There was no evidence of perivalvular leak by transepicardial echocardiography.
Comment
Less invasive or video-assisted mitral valve operations can be accomplished through a variety of innovative incisions, including a hemisternotomy, a minithoracotomy, and a parasternal incision, using the techniques of intraaortic balloon occlusion, transthoracic aortic cross-clamping, or ventricular fibrillation [5–8]. These approaches may offer distinct advantages over conventional mitral valve operations through a median sternotomy, such as reduced postoperative morbidity, a shorter intensive care unit and hospital length of stay, and a more rapid return to work. Because of smaller incisions and limited exposure, however, less invasive operations on the mitral valve can be arduous and time-consuming. In particular, excision of native valvular tissue, suture placement, prosthetic valve positioning, and knot tying represent aspects of the operation that are less than ideal with current less invasive techniques. Indeed, at this institution, the duration of cardiac ischemia and CPB were significantly longer in patients undergoing less invasive mitral valve operations through a limited right thoracotomy than in those undergoing procedures through a conventional incision [4].
The mechanical suturing device employed in this study improves the precision and speed of suture placement through the limited exposure provided by a less invasive incision. The mechanical suturing device simultaneously passes two ends of a pledgeted 2-0 braided suture through the annulus, then mechanically grasps both needles on the atrial aspect. Hence, a mattress suture is accomplished one-handed in a single continuous motion. Alternatively, the direction that the needles are transferred can be reversed (from proximal to distal jaw) to permit placement of supraannular pledgeted sutures. Although the device functioned exceptionally well in these studies, the mitral valve complex of a healthy canine differs in many aspects from a patient with valvular heart disease. Clinical experience is therefore required to assess performance of the device under conditions of severe fibrosis, calcification, and deformity in both mitral and aortic valves.
In summary, these data establish the feasibility of a mechanical suturing device for operations on the mitral valve. This device is easily mastered, maintains precise spacing between sutures, and permits rapid placement of mattress sutures. We predict widespread application for both less invasive and conventional valve operations using the mechanical suturing device.
Footnotes
The study was supported in part through an unrestricted educational grant from United States Surgical Corporation, Norwalk, CT.
References
This article has been cited by other articles:
|
|
 |
|
  X M Mueller, H T Tevaearai, P Chaubert, C-Y Genton, and L K von Segesser Does laser injury induce a different neovascularisation pattern from mechanical or ischaemic injuries? Heart, June 1, 2001; 85(6): 697 - 701. [Abstract] [Full Text]
|
|
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| ANN THORAC SURG | ASIAN CARDIOVASC THORAC ANN | EUR J CARDIOTHORAC SURG |
| J THORAC CARDIOVASC SURG | ICVTS | ALL CTSNet JOURNALS |
