Potassium-Induced Cardiac Resetting Technique for Persistent Ventricular Tachycardia and Fibrillation After Aortic Declamping Go Watanabe, MD, PhD, Noriyoshi Yashiki, MD, PhD, Shigeyuki Tomita, MD, PhD, and Shojiro Yamaguchi, MD, PhD Department of General and Cardiothoracic Surgery, Kanazawa University Graduate School of Medical Science, Kanazawa, Japan We report a technique of injecting a high concentration replacement was performed using a 21-mm mechanical of potassium chloride into the aorta root to resolve valve. The aortic cross-clamping time was 45 minutes. refractory ventricular tachycardia after aortic declamp- Patient 2 was a 74-year-old man with bicuspid aortic ing, which occurs occasionally in open heart surgeries. valve. The valve area was 0.4 cm2 with severe calcifica- Using this technique, normal sinus rhythm can be re- tion. At normal sinus rhythm, echocardiography showed stored without the need for defibrillation and aortic left ventricular ejection fraction of 65%, and left ventric- clamping. ular wall thickness of 18 mm. The aortic valve replace- (Ann Thorac Surg 2011;91:619 –20) ment was performed using a 19-mm biological valve. The 2011 by The Society of Thoracic Surgeons aortic cross-clamping time was 65 minutes. Patient 3 was a 78-year-old woman with mitral insuf- ficiency after percutaneous transvenous mitral commis- surotomy. An electrocardiogram demonstrated atrial fi- Incardiacsurgeries,suchasvalvereplacement,ventric- brillation.Herpreoperativeleftventricularejectionfraction ular tachycardia (VT), and ventricular fibrillation (VF) was 68%. The mitral valve replacement was conducted may occur after removal of the aortic cross clamp. In most using a 27-mm biological valve. The aortic cross- of these cases, direct current defibrillation restored nor- clamping time was 59 minutes. In all three cases, coro- mal sinus rhythm, and the patients could be weaned off nary angiograms showed no stenosis. cardiopulmonary bypass. However, VT and VF occasion- All 3 patients underwent conventional open heart ally persisted, despite repeated defibrillations. In this ARTICLES surgery described as follows. The cardiopulmonary by- case, the only conventional measure is to administer pass was conducted at a body temperature of 32°C, with lidocaine, magnesium, and various anti-arrhythmic the arterial cannula placed in the ascending aorta and agents, and then repeat defibrillation again. However, venous cannulae in superior and inferior vena cavae. A repetitive defibrillations not only have the risk of dam- left ventricular vent was also inserted. The flow rate of aging the myocardium and lower cardiac function, but cardiopulmonary bypass was 3.2 L/min/body surface may also decrease the fibrillation threshold resulting in area. Blood cardioplegia was used based on the original greater susceptibility to further fibrillations Clini- method of Buckburg. Terminal warm blood cardioplegia cally, this situation is called the VT storm. Once entering was infused before aortic declamping. In all three pa- the spiral of the VT storm, it becomes difficult to exit tients, VF developed after removal of the aortic cross We encountered three cases of such a rare complication clamp. Defibrillation failed to resolve the VF. Another 5 and were able to resolve the VT storm using a simple to 10 defibrillations at 50 joules were given, also without technique. We describe the detailed procedures in this report. success. During this period, lidocaine, amiodarone, mag- nesium, pilsicainide, disopyramide, verapamil, and other drugs were administered. Thus, we tried the potassium- Technique induced cardiac resetting technique. Patients Potassium-Induced Cardiac Resetting Patient 1 was a 67-year-old man with aortic valve steno- Cardiopulmonary bypass was maintained at a normal sis. The valve area was 0.5 cm2 with severe calcification. body temperature (36°C). In all 3 patients, 20 mL (20 At normal sinus rhythm and echocardiography, the pa- mEq) of potassium chloride solution (Terumo, Tokyo, tient had a left ventricular ejection fraction of 70% and Japan) was infused slowly from the aortic root toward the left ventricular wall thickness of 15 mm. Aortic valve base of the heart. In the absence of cardiac pumping, potassium chloride reached a high concentration at the Accepted for publication July 21, 2010. aortic root, causing asystole within a short time. With the Address correspondence to Dr Watanabe, Department of General and potassium concentration maintained at a high level and Cardiothoracic Surgery, Kanazawa University Graduate School of Medi- in the absence of aortic cross clamping, the heart was cal Science, 13-1 Takara-machi, Kanazawa, 920-8640, Japan; e-mail:
maintained in an asystolic state for approximately 1 2011 by The Society of Thoracic Surgeons 0003-4975/$36.00 Published by Elsevier Inc doi:10.1016/j.athoracsur.2010.07.075 HOW TO DO IT WATANABE ET AL Ann Thorac Surg POTASSIUM-INDUCED CARDIAC RESETTING 2011;91:619 –20 minute. Then, a delayed heart beat re-started gradually gia is due to diversion of oxygen toward reparative at an idioventricular rhythm. With time, the wide QRS processes rather than expending it on electromechanical interval was normalized and the heart rate increased. The work of prolonged cardiopulmonary bypass. However, blood potassium level decreased slowly as a result of this method has some drawbacks; aortic clamping is ultrafiltration. When the level reached 5 mEq, the pa- prolonged with a risk of decreasing cardiac function, and tients were weaned from cardiopulmonary bypass. In all the optimal clamping time and amount of infusion are 3 patients, weaning was easy, and the postoperative not defined. The second method is to lower the temper- course was uneventful with no electrocardiograhic ature of the perfusate to reduce myocardial oxygen abnormalities. consumption. However, although hypothermia reduces myocardial oxygen consumption, it also predisposes VF. Therefore, the second method is not being used. In our method, cardiopulmonary bypass is conducted In patients with aortic stenosis, perioperative arrhythmia at normothermia. Without aortic clamping, we infuse a is a crucial factor that determines the prognosis. Myocar- high concentration of potassium to the aortic root. Tran- dial protection in the perioperative period, especially sient asystole is obtained, and VT and VF storm is during cardiopulmonary bypass, and management of successfully avoided when the heart beat re-starts. Our arrhythmia during reperfusion are important issues methods have several advantages. First, the aortic is not Shigemitsu and colleagues reported the postoperative clamped and the heart is perfused continuously with occurrence of VT storm. Although the incidence of a VT warm blood, thus preserving the cardiac function. Sec- storm complication is low, cardiac surgeons should al- ond, the heart is in a nonworking state with no increased ways bear it in mind and acquaint themselves with the oxygen consumption. The general myocardium and spe- techniques to resolve this problem. cialized myocardium of the conduction system recover The mechanism of VT storm remains unclear, and it is from a stunning state, and this is thoroughly reperfused not related to the time of aortic clamping or cardiopul- in a relaxed condition. Although this method was used in monary bypass, but it is associated with problems in the only three cases so far, our experience suggests that high protection of hypertrophied myocardium and reperfu- potassium-induced asystole under nonclamping and sion of the myocardium. The factors implicated in VT normothermic conditions is a useful method to reset the storm include anisotropic conduction of the myocardium and subendocardial ischemia in aortic stenosis natural heart rate. Furthermore, the body has already been rewarmed to 36°C during reperfusion, and VF at normal body temper- References ARTICLES ature consumes a large amount of oxygen and may progress to myocardial damage if untreated When VT 1. Shigemitsu O, Hadama T, Takasaki H, et al. Analysis of perioperative ventricular arrhythmias in valvular heart dis- and VF occurs during reperfusion after aortic declamp- eases by Holter ECG recording. Jpn Circ J 1991;55:951– 61. ing, direct current defibrillation is usually performed. 2. 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Needless valve replacement for aortic stenosis. Int J Cardiol 2004;97: 535– 41. to say, administration of anti-arrhythmic agents is impor- 5. Fontan F, Madonna F, Naftel DC, et al. Modifying myocardial. tant. If administration of lidocaine, magnesium, amioda- management in cardiac surgery: a randomized trial. Eur rone,and other anti-arrhythmics, followed by defibrilla- J Cardiothorac Surg 1992;6:127–37. tion succeeds to resolve VT and VF, then the problem is 6. Israel CW, Barold SS. Electrical storm in patients with an implanted defibrillator: a matter of definition. Ann Noninva- However, if VT and VF persists, then two methods are sive Electrocardiol 2007;12: 375– 82. 7. England MR, Gordon G, Salem M, et al. Magnesium admin- plausible. The first method is to cross clamp the aorta and istration and dysrhythmias after cardiac surgery. JAMA 1992; re-arrest the heart by infusing blood cardioplegia to the 268:2395– 402. aortic root Lazar and colleagues have shown that 8. Gadhinglajkar SV, Sreedhar R, Varma PK. Controlled aortic rearresting the heart with a brief, continuous infusion of root perfusion: a novel method to treat refractory ventricular blood cardioplegia results in more complete reversal arrhythmias after aortic valve replacement. J Cardiothor Vasc Anesth 2004;18:197–200. of ischemic damage than is possible with prolongation of 9. Lazar HL, Buckberg GD, Manganaro AJ, et al. Reversal of cardiopulmonary bypass alone. Lazar and colleagues ischemic damage with secondary blood cardioplegia. J Thorac suggested that better recovery with secondary cardiople- Cardiovasc Surg 1979;78:688 –97.
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