Ann Thorac Surg 1999;67:862-863
© 1999 The Society of Thoracic Surgeons
How To Do It
Angle-adjustable sheath for a dual-stage venous cannula
Kazuya Akiyama, MDa,
Arifumi Takazawa, MDa,
Tomohiro Maeda, MDa,
Toshimasa Akazawa, MDa,
Hideki Yamanishi, MDa
a Department of Cardiovascular Surgery, Iwaki Kyoritsu General Hospital, Fukushima, Japan
Accepted for publication July 29, 1998.
Address reprint requests to Dr Akiyama, Department of Cardiovascular Surgery, Iwaki Kyoritsu General Hospital, 16 Kusehara Uchigomimayamachi, Iwaki City, Fukushima 973-8555, Japan
 |
Abstract
|
|---|
The dual-stage venous cannula is widely used but can obstruct the surgeon’s view and interfere with operative procedures in the aortic root. We designed a new stainless steel sheath for a dual-stage venous cannula that enables the cannula to bend and maintain the appropriate angle for the surgical procedures. We suggest that operative procedures in the aortic root can be performed faster during safety cardiopulmonary bypass by use of a dual-stage venous cannula bent by application of this new sheath.
|
Introduction
|
|---|
The standard venous cannula used to establish cardiopulmonary bypass in an operation without incision of the right atrium is a straight dual-stage venous cannula. However, the straight dual-stage venous cannula inserted through the right atrial appendage often obstructs the surgeon’s view and interferes with surgical procedures in the aortic root. In addition, this type of cannula is prone to disturb venous return because of the displacement of the cannula. In this report, we describe a newly designed stainless steel sheath with a bellows-like configuration that enable the dual-stage venous cannula to bend and maintain the appropriate angle for the surgical procedure.
|
Device and technique
|
|---|
A stainless steel plate (no. 316) with a 0.3-mm thickness is electrically welded by arc welding into a bellows-like configuration for flexibility and to maintain the diameter of the lumen. Both the internal and external sides of the formed sheath are roughly polished after welding, and the external side is then finely polished. The internal diameter of the sheath is sized to fit the external diameter of a 46F dual-stage venous cannula (36F x 46F Wire-reinforced Venoatrial Catheter; Sarns 3M Health Care, Ann Arbor, MI). Insertion of a dual-stage venous cannula into the sheath enables maximal bending of the cannula up to 45 degrees without occluding the internal lumen (Fig 1).
View larger version (92K):
[in this window]
[in a new window]
|
Fig 1. Top panel shows an angle-adjustable sheath for a two-stage venous cannula. Bottom panel shows a dual-stage venous cannula inserted into the angle-adjustable sheath bent to 45 degrees.
|
|
Before venous cannulation, the cannula must be inserted into the sheath at the level of the proximal marker. After cannulation, the cannula is secured with an atrial pursestring suture and connected to the cardiopulmonary bypass machine. Then, during bypass, the sheath must be bent to the caudal direction, with careful attention paid to the flow rate change of venous return and arrhythmia. The ditch on the sheath is useful for fixing the venous cannula by tying it to the sternal retractor. The bending angle can be adjusted according to the situation in the various operative procedures. Insertion of the left venting catheter through the right upper pulmonary vein and distal anastomosis of the right coronary artery bypass graft can be performed by retraction of the angled venous catheter toward the assistant surgeon (Fig 2).
View larger version (155K):
[in this window]
[in a new window]
|
Fig 2. Operative position of angle-adjustable sheath and bent dual-stage venous cannula during aortic root replacement.
|
|
|
Comment
|
|---|
Establishment of cardiopulmonary bypass by a conventional straight dual-stage venous cannula is a simple and useful technique [1]. However, there are several problems. A large-sized cannula located between the operator, the heart, and large vessels often interferes with the surgeon’s view. Operative difficulties can often arise in cases such as aortic valve replacement, aortic root replacement, and proximal anastomosis during coronary artery bypass grafting using a saphenous vein graft or a free arterial graft. In addition, exposure of the proximal marginal branch of the left circumflex artery or the circumflex artery in the atrioventricular groove [2] cannot easily be achieved because the space occupied by a dual-stage venous cannula makes traction and rotating the back of the heart toward the right difficult. Longer tubing for venous return to the cardiopulmonary bypass machine increases the priming volume of the circuit. The instability of the position of the dual-stage venous cannula has a tendency to disturb venous return, and a longer return path to the machine makes the tube more prone to kinking. The angled dual-stage cannula was designed to help eliminate these disadvantages. A 45-degree dual-stage cannula and a 90-degree cannula [3–5] have been described previously and are commercially available.
Although an angled dual-stage venous cannula has several benefits, it also has two disadvantages. One of the difficulties involves insertion of the venous cannula because of its right-angled shape [6, 7]. Sharp-angled cannula insertion may be more difficult than insertion of the right-angled type. Insertion of a conventional cannula presents no difficulties because it has a straight shape, even if it will be bent after cannulation. The other problem is a possible mismatch between the cannula angle and the anatomically determined angle. The angle determined among the right atrial appendage, inferior vena cava, and caudal end of the sternotomy incision is not usually a constant value. So, the mismatch in the angle may cause distortion of the heart and inferior vena cava, that can result in tissue trauma and arrhythmia during cardiopulmonary bypass.
We use this sheath to bend venous cannulas and have established cardiopulmonary bypass in 50 consecutive cases of aortic valve replacement, aortic root replacement, and coronary artery bypass grafting. Although the external diameter of the sheath is 24 mm, or 75F, the sheath has not interfered with the surgeon’s view in our experience. A 10-minute reduction in mean aortic cross-clamping time was achieved by improvement of the surgeon’s view. Venous return and bypass flow rates in angled cannulas did not decrease markedly compared with these variables in straight cannulas and were sufficient in all patients when the 36F x 46F dual-stage venous cannula was used. Although we selected a cannula with wire coil reinforcement, a cannula without reinforcement is also thought to be effective because of the anticollapsable property of this sheath. Mean serum free hemoglobin levels after cardiopulmonary bypass was established in patients with use of the venous cannulas and straight cannulas were 43.5 and 39.6 mg/dL, respectively. Markedly increased hemolysis could not be detected despite the increased turbulent flow caused by the bent cannula. The sheath is not expensive and is clinically reusable.
In conclusion, use of the newly designed angle-adjustable sheath enabled the most effective use of the dual-stage venous cannula during safety cardiopulmonary bypass. In addition, the angle adjustability of the cannula is a useful feature that allows the surgeon to obtain a sufficient view for minimal incision cardiac operation.
|
Acknowledgments
|
|---|
We thank Mr Jun Kato of Tonokura Ikakogyo Co Ltd (Tokyo, Japan) for his cooperation in the manufacture of the angle-adjustable sheath.
|
References
|
|---|
-
Riley J.B., Hardin S.B., Winn B.A., et al. In vitro comparison of cavoatrial (dual stage) cannulae for use during cardiopulmonary bypass. Perfusion 1986;1:197-204.
-
Akiyama K., Hirota J., Ohkado A., et al. Coronary artery bypass grafting to the left circumflex artery in the atrioventricular groove. Kyobu Geka 1998;51:365-369.[Medline]
-
Lawrence D.R., Desai J.B. Forty-five-degree two-stage venous cannula: advantages over standard two-stage venous cannulation. Ann Thorac Surg 1997;63:253-254.[Abstract/Free Full Text]
-
Bugge M., Lepore V., Dahlin A. The "90° bent" two-stage venous cannula. Eur J Cardiothorac Surg 1995;9:526-527.[Abstract]
-
Souza L.S.S. Ninety-degree two-stage venous cannula. Ann Thorac Surg 1997;64:1523-1524.[Free Full Text]
-
Watanabe T., Abe T., Tanaka M., et al. Newly developed holder for a right-angled metal venous cannula. Ann Thorac Surg 1992;54:993-994.[Abstract]
-
Matsuzaki K., Nagano I., Tatewaki H., et al. A catheter-guided insertion of Pacifico’s venous cannula. Kyobu Geka 1996;49:813-814.[Medline]
This article has been cited by other articles:
|
|
|
|
 
K. Akiyama, A. Takazawa, N. Taniyasu, and H. Sato
Flexible Angle-Retaining Dual-Stage Venous Cannula
Asian Cardiovasc Thorac Ann,
December 1, 1999;
7(4):
331 - 332.
[Abstract]
[Full Text]
[PDF]
|
|
|
Top
Abstract
Introduction
