Ann Thorac Surg 1995;59:535-537
© 1995 The Society of Thoracic Surgeons
How To Do It
Continuous and Stable Recording of the His Bundle Electrogram During Open Heart Operations
Masatoshi Ikeshita, MD,
Shigeo Yamauchi, MD,
Takashi Nitta, MD,
Tasuku Shoji, MD
Department of Thoracic and Cardiovascular Surgery, Nippon Medical School, Tokyo, Japan
Accepted for publication October 17, 1994.
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Abstract
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We describe a method for continuously recording the stabilized His bundle electrogram from the aortic root during open heart surgical procedures. This simple technique was useful in all surgical procedures for the oblation of supraventricular tachyarrhythmias in the region around the atrioventricular conduction system.
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Introduction
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In the past few years, several surgical techniques for the management of supraventricular tachycardia have been introduced into clinical use. Among them, dissection of the atrioventricular (AV) perinodal tissue, a technique developed by Ross and associates [1], and cryoablation of the perinodal tissue, a method developed by Holman [2] and Cox [3] and their colleagues, are being used to treat AV node reentrant tachycardia. The greatest advantage offered by both techniques is that they allow AV conduction to be preserved. It is of vital importance to prevent injury to the AV conduction system during the operation. Therefore, to prevent intraoperative damage to the beating heart and during cardiopulmonary bypass, continuous recording of the stabilized His bundle electrogram is necessary. We describe a method that permits continuous recording and observation of the His bundle electrogram.
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Method
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A catheter sheath similar to the type used for cardiac catheterization was modified as shown in Figure 1
. First this involved cutting an 8F catheter sheath diagonally and passing a dilator through it. The catheter sheath was then passed through a 4-cm-long Nelaton catheter, so that the end of the catheter sheath was free and protruded from the catheter. Both catheters were tied together at three points. This modification allowed the catheter to be secured as it was inserted through the ascending aorta.
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Fig 1. . Recording method for the His bundle electrogram. An 8F catheter sheath is inserted in the direction of the aortic valve through the ascending aorta. The distal tip of the catheter electrode, which is passed through the catheter sheath, is fixed at the noncoronary cusp. (LCC = left coronary cusp; MSV = membranous septum of the ventricle; NCC = noncoronary cusp; RCC = right coronary cusp.)
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The heart was exposed and the cannulas were inserted into the aorta and corresponding venous system before the start of extracorporeal circulation. A 4-0 Prolene (Ethicon, Somerville, NJ) pursestring suture was placed at the base of the aorta. Using the same percutaneous procedure used for routine cardiac catheterization, the modified catheter sheath was inserted through the pursestring suture. A double needle was inserted into the aorta at a 30-degree angle to the long axis of the aorta, and the inner needle was removed. A guidewire was inserted and the outer needle was then removed. The guidewire was passed through the dilator in the catheter sheath and the catheter sheath was inserted in the same direction. This positioned the end of the catheter sheath in the direction of the commissure of the right coronary and noncoronary cusps.
Afterward, the pursestring suture around the Nelaton catheter was tightened firmly to secure the catheter sheath. The dilator and guidewire were removed from the catheter sheath and the sheath was filled with heparinized saline solution.
A 7F bipolar electrode catheter curved at the electrode end was used for the His bundle electrogram recording. To place the electrode end and fix it near the commissure of the right coronary cusp and the noncoronary cusp, the electrode end was inserted in the direction of the right atrial appendage until a stable His bundle electrogram was recorded. With the signals below 40 Hz and above 500 Hz filtered out, an electrogram was recorded between the distal and second electrodes as the catheter was inserted and advanced until a fixation position was found. Generally, a clear and stable recording of the His bundle deflections could be obtained at that position (Fig 2). If the recordings were not sufficiently clear or stable, the quality of the recording could be improved by slightly changing the direction of the catheter.
When it is necessary to induce cardiac standstill, cardioplegic solution should be injected through the side orifice of the catheter sheath at a maximum flow rate of 800 mL • min-1.
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Comment
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Recording of the His bundle electrogram through the aortic root was first reported by Urthaler and associates [4] in 1975. They demonstrated that there is no difference between this recording and a His bundle electrogram obtained through the right side of the heart. This method has been widely used in experimental studies, but it has not been employed very often in clinical practice. Using this recording method, we were able to operate successfully on patients to ablate supraventricular tachyarrhythmias. All the surgical procedures were performed within the triangle of Koch and in the region around the AV conduction system on the beating heart under normothermic cardiopulmonary bypass with the aid of continuous and stable recording of the His bundle electrogram. This made it possible for the His electrogram to be checked at any time, thereby helping prevent injuries to the AV conduction system during the operation.
The major concern for cardiovascular surgeons during operations to treat tachyarrythmias, particularly in the setting of the Wolff-Parkinson-White syndrome in which there is a posteroseptal Kent bundle, and also in the setting of AV node reentrant tachycardia, is to prevent injury to the AV conduction system. In current practice, the AV conduction system and its direction of travel is identified during open heart operations mainly on the basis of anatomic findings. However, individual variability makes this practice unreliable. It might be possible to determine the position of both the AV node and the His bundle, as well as to estimate its direction, by means of an electrophysiologic investigation of the AV conduction system, or by endocardial His mapping performed under direct visualization of the beating heart during the procedure. However, it is difficult to operate and continuously monitor the state of the AV conduction system with electrophysiologic recordings. If continuous recording were possible during the operation, the Wenckebach phenomenon and a prolonged A-H interval, which usually indicate surgical injury to the AV node, could be easily detected and the operation stopped. In other words, those phenomena could serve as guides for a selective operation performed near the AV node.
Fujimura and associates [5] have reported good postoperative results from the surgical treatment of AV node reentrant tachycardia through the use of an anatomically guided procedure. Ross and colleagues [1], however, reported that it was necessary to refer to endocardial maps to prevent injury to the AV conduction system, but AV conduction was not monitored while they operated. Moreover, Cox and co-workers [3] reported that they employed the so-called ice-mapping technique during perinodal cryoablation. Good results have been reported for both of these surgical techniques.
The modification for continuous recording of the His bundle deflections we have described here can be used effectively with any of these surgical techniques because (1) the sutured electrode does not interfere with the surgical procedure itself and (2) it permits continuous observation of the AV conduction status, and therefore immediately detects prolongation of the A-H interval or a Wenckebach phenomenon, both of which indicate surgical injury to the AV node.
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Acknowledgments
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We are grateful to Dr Richard B. Schuessler and Dr James L. Cox for their English correction of the manuscript.
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Footnotes
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Address reprint requests to Dr Ikeshita, Department of Thoracic and Cardiovascular Surgery, Nippon Medical School, 1-1-5, Sendagi Bunkyo-ku, Tokyo 113, Japan.
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References
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- Ross DL, Johnson DC, Denniss AR, Cooper MJ, Richards DA, Uther JB. Curative surgery for atrioventricular junctional (``AV nodal'') reentrant tachycardia. J Am Coll Cardiol 1985;6:1383–92.[Abstract]
- Holman WL, Ikeshita M, Lease JG, Smith PK, Ferguson TB, Cox JL. Elective prolongation of atrioventricular conduction by multiple discrete cryolesions. A new technique for the treatment of paroxysmal supraventricular tachycardia. J Thorac Cardiovasc Surg 1982;84:554–9.[Abstract]
- Cox JL, Ferguson TB, Lindsay BD, Cain ME. Perinodal cryosurgery for atrioventricular node reentry tachycardia in 23 patients. J Thorac Cardiovasc Surg 1990;99:440–50.[Abstract]
- Urthaler F, James TN. A comparison of His bundle electrograms recorded from an aortic root and from a plaque sutured near the His bundle. J Lab Clin Med 1975;85:711–22.[Medline]
- Fujimura O, Guiraudon GM, Yee R, Sharma AD, Klein GJ. Operative therapy of atrioventricular node reentry and results of an anatomically guided procedure. Am J Cardiol 1989;64:1327–32.[Medline]
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Abstract
Introduction
