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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
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