Ann Thorac Surg 2002;73:322-324
© 2002 The Society of Thoracic Surgeons
How to do it
Biologic glue-molded "bio-mini-paddle" electrode used for atrial and ventricular pacing and defibrillation
Hiroshi Kubota, MD*a,
Shinichi Takamoto, MDa,
Arata Murakami, MDa,
Yutaka Kotsuka, MDa,
Akira Furuse, MDb
a Department of Cardiothoracic Surgery, University of Tokyo, Tokyo, Japan
b Department of Cardiac Surgery, JR Tokyo General Hospital, Tokyo, Japan
Accepted for publication October 10, 2001.
* Address reprint requests to Dr Kubota, Department of Cardiothoracic Surgery, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, Tokyo, 113-8655, Japan
e-mail: kubota-tho{at}h.u-tokyo.ac.jp
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Abstract
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Atrial and ventricular dysrhythmias developing after cardiac operation further reduce cardiac output, posing a serious problem for postoperative management. We have developed a "bio-mini-paddle" electrode designed to be attached directly to the myocardium for atrial or ventricular defibrillation and pacing for intraoperative and postoperative cardiac management. We use fibrin glue for the paddle, which is biodegradable. The characteristics of this unique paddle were examined using mongrel dogs.
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Introduction
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Atrial and ventricular dysrhythmias developing after cardiac operation further reduce cardiac output, posing a serious problem for postoperative management. We have developed a "bio-mini-paddle" electrode designed to be attached directly to the myocardium for atrial or ventricular defibrillation and pacing for intraoperative and postoperative cardiac management. We use fibrin glue for the paddle, which is biodegradable. The characteristics of this unique paddle were examined using mongrel dogs.
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Technique
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How to make the bio-mini-paddle
First, the end of the platinum lead is fixed to the center of the mold. The lead is made of 25 wound platinum wires and is covered by a silicon tube. Each wire is 0.05 mm in diameter. In the final 1-cm tip portion of the lead, the platinum wire is exposed by cutting the silicon tube and unwinding it into a broom shape (Fig 1).
This broom-shaped portion is fixed to the mold. The translucent acrylic mold has a cylindrical groove in its center that is 20 mm in diameter and 10 mm in depth (Fig. 2).
Next, liquid A and liquid B of the biologic glue (Beliplast-P, Aventis Behring LLC, King of Prussia, PA) are prepared. Liquid A is made from fibrinogen, factor XIII, and aprotinin, and liquid B is made from thrombin powder and calcium chloride. Liquid A and liquid B are poured into the mold at the same time. One minute later, these liquids become a puddinglike solid material. The lead is gently pulled upward, and the lead and glue can be smoothly extracted from the mold (Fig 3).
This is the bio-mini-paddle.
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Fig 1. Platinum lead made by winding 25 strands of platinum wire having a diameter of 0.05 mm. The lead is covered with a silicone tube 2 mm in diameter and 50 cm long. The platinum wire is exposed for the final 1-cm tip portion of the lead, and unwound into a broom shape.
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Fig 2. Translucent acrylic mold to make the bio-mini-paddle has a cylindrical groove in the center. The diameter of the groove is 20 mm, the depth is 10 mm.
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The other end of the lead is connected to a stainless-steel needle, which can be pulled from the mediastinum through the skin to the outside. This needle can be connected to a pacemaker, fibrillator, or the defibrillator.
Characteristics of the bio-mini-paddle
Using the Impulse-3000 tester (DNI Nevada, Carson City, NV), the effective output with the bio-mini-paddle was tested. The actual delivered energy was 70% of the dial setting of the cardioverter-defibrillator FC 1400 (Fukuda Denshi, Tokyo, Japan).
The bio-mini-paddle gradually decreases its volume. Our experiment showed that the electrode decreased in size from the initial 20 mm to 18 mm in diameter and from 6 mm to 3.5 mm in thickness one week after implementation (Fig 4).
The reduction rate in volume was 47% (from 1.88 cm3 to 0.89 cm3).
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Fig 4. Bio-mini-paddle 1 week after implantation. The electrode has decreased in size from the initial 20 mm to 18 mm in diameter, and from 6 mm to 3.5 mm in thickness. The reduction in volume was 47%.
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Application of the bio-mini-paddle
Using 7 mongrel dogs, the threshold of atrial defibrillation or pacing and the threshold of ventricular defibrillation or pacing were examined. Atrial fibrillation was induced by burst stimulation to the atrium under the stimulation of bilateral vagus nerve with pulse width of 0.2 msec, 3 V at 10 Hz. As stimulation of the vagus nerve modifies the atrial potassium-channel receptor, atrial fibrillation can be easily induced by modifying the potassium-channel receptor, which shortens the atrial effective refractory period and elevates atrial vulnerability. When we measure the atrial thresholds, bio-mini-paddles were placed on the right atrium and the left atrial appendage. When we measure the ventricular thresholds, they were placed on the right ventricle and the left ventricle. Results are shown in Table 1.
Histopathologic change 7 days after shock delivery to both ventricles was also examined under various shock intensities. The myocardial damage was negligible until a shock intensity of 30 J given three times was read (the depth of the burn was 2.2 ± 0.5 mm). It did not cause any dysrhythmia or ST-T change on electrocardiogram.
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Comment
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At present, different devices and different electrodes are used to defibrillate or pace the atrium or ventricle. Our aim was to develop an electrode that would enable us to pace and defibrillate more conveniently. The results of our experiments were satisfying. Atrial or ventricular defibrillation and pacing thresholds were low enough and ventricular sensing threshold was high enough. All data suggest that the bio-mini-paddle can be applicable in clinical use. Some epicardial electrodes designed to treat postoperative dysrhythmias have been reported. Mehmanesh and colleagues [1] reported a temporary atrial patch electrode consisting of a polytetrafluoroethylene felt pad approximately 3 x 5 cm in size with three parallel stainless-steel defibrillation wire electrodes that allows low-energy defibrillation of episodes of atrial fibrillation. According to their report, the mean intraoperative atrial defibrillation threshold was 1.6 ± 1.4 J. The mean postoperative defibrillation threshold was 2.7 ± 2.1 J. The problem with their electrode is that foreign material remains after removing the metallic electrode portion. Our biologic glue can solve this problem. Fibrin glue is widely used to achieve hemostasis during cardiac operation. Because it is biodegradable, it will be absorbed within several weeks without any harm to the patient.
Cardiac tissue damage caused by shock delivery is also an important problem. Although low-energy internal cardioversion using a temporary electrode has also been reported, the degree of cardiac damage is still unclear. Cmolik and associates [2] reported successful atrial defibrillation with very low energy shocks delivered through temporary epicardial wire electrodes in mongrel dogs. The energy intensity was 0.42 ± 0.07 J. Liebold and coworkers [3] also reported successful treatment of postoperative atrial defibrillation with epicardial stainless-steel wire electrodes. They reported an overall success rate of 40 of 51 (78%), and the mean energy of the successful shocks was 5.8 ± 2.7 J. We question whether the small attachment area of the electrode to the epicardium causes burns to the atrium that would raise the threshold of pacing, sensing, and defibrillation. They described that there was no evidence of trauma from the multiple defibrillations after the hearts were excised. Our study also showed that there was no histopathologic changes in myocardium excised immediately after shock delivery, even at shock intensities of 30 J administered three times. However, the heart that was excised 1 week after the shock delivery (30 J, three times) showed superficial (2.2 mm in depth) degenerated myocardium in depth. Doherty and colleagues [4] reported cardiac damage after using different size paddles. Their conclusion was that use of different size paddles did not appear to affect the total number of cells damaged. This means that with large paddles, the injury was more superficial and extended over a wider area. Thus, to avoid deep myocardial injury, a certain size of attaching surface area should be required. They concluded that shocks less than 30 J delivered by a small paddle that is 20 mm in diameter are safe.
A fibrillator can also be connected to the bio-mini-paddles. It is useful in pediatric cardiac operation performed under induced ventricular fibrillation. Pediatric cardiac operation for atrial septal defect or ventricular septal defect is often performed through a small skin incision and subxyphoid incision without sternotomy. In such cases, the clip electrodes to induce ventricular fibrillation disturb the operative field and injure the myocardium. We also, believe it is difficult to insert conventional metallic paddles through a small skin incision. For these cases, the bio-mini-paddle can also be applicable. As small-weight mongrel dogs were used for our study, when we use bio-mini-paddle for adult humans clinically, we should consider that the thresholds shown in this experiment might change.
Our bio-mini-paddle electrode allows low-power atrial and ventricular defibrillation and is also suitable for atrial and ventricular pacing. This paddle has unique characteristics: it is easy to make, easy to use, harmless to the myocardium, and the material left in the pericardial space is biodegradable. Thus, this bio-mini-paddle may improve intraoperative and postoperative cardiac management.
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Acknowledgments
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This work was supported by Grant in Aid for Scientific Research of the Japanese Ministry of Education, 1999.
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References
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Mehmanesh H., Lange R., Hagl S. Temporary atrial electrode for the treatment of supraventricular tachycardia after cardiac operations. Ann Thorac Surg 1998;65:632-636.[Abstract/Free Full Text]
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Cmolik B.L., Ortiz J., Ayers G.M., Lee J.H., Geha A.S., Waldo A.L. Successful atrial defibrillation with very-low-energy shocks by means of temporary epicardial wire electrodes. J Thorac Cardiovasc Surg 1996;111:392-398.[Abstract/Free Full Text]
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Liebold A., Haish G., Rosada B., Kleine P. Internal atrial defibrillation—a new treatment of postoperative atrial fibrillation. Thorac Cardiovasc Surg 1998;46:323-326.[Medline]
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Doherty P.W., McLaughlin P.R., Billingham M., Kernoff R., Goris M.L., Harrison D.C. Cardiac damage produced by direct current countershock applied to the heart. Am J Cardiol 1979;43:225-232.[Medline]
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Abstract
Introduction
