Resuscitation, 20 (1990) 25-29 Elsevier Scientific Publishers Ireland Ltd.
Comparison
of two different electrodes delivery of dc-shocks
25
for the
J. Jakobsson”, I. odmanssonb and R. Nordlanderb Department of Anaesthesiology’, Dandev& Hospital and Division of Cardiology. Department of Medicin@, Karolinsko Hospital, Karolinska Institute& Stockholm (Sweden) (Received September 15th, 1989; accepted January 3lst, 1990)
Twenty-six consecutive patients with atrial fibrillation, planned for elective cardioversion were randomised to cardioversion with ordinary or self-adhesive electrodes. The two types of electrodes were found equally efficient for conversion to sinus rhythm. With the self-adhesive electrodes there was a tendency towards the need for a lesser number of DC-shocks and a lower cumulated energy. The post-cardioversion maximal serum creatine kinase activity adjusted for number of shocks was significantly lower when the self-adhesive electrodes were used, indicating a lesser degree of skeletal muscle damage. DC-conversion - Electrodes - Creatine kinase - Isoenzymes
INTRODUCTION
Electrical direct current conversion is frequently used for treatment of tachyarrhythm& In experimental animals both internal and external countershocks have’ been found to produce myocardial lesions. The degree of damage has been shown to be inversly related to the paddle size and the time interval between shocks and directly related to the administered energy [ 11. In human studies, ECG-changes and release of myocardial specific isoenzymes have indicated some degree of myocardial damage after cardioversion. However, these results are conflicting and the major part of enzyme release after cardioversion have been considered to originate from skeletal muscle damage [2]. The use of self-adhesive electrodes has increased after the introduction of semiautomatic external defibrillators [3]. These electrodes are fixed to the anterior chest wall by adhesive material, which theoretically may limit the current leakage, thus increasing the effective energy as well as reducing damage to surrounding tissues [4]. The aim of this study was to compare self-adhesive electrodes with conventional electrodes with regard to conversion rate, energy requirement and enzyme release as an indicator of muscle damage during elective cardioversion. A secondary aim was to get an opinion by the responsible physician about the practical handling of these electrodes. Address all correspondence and reprint requests to: J. Jakobsson, Department of Anaesthesiology and Intensive Care, Danderyds Hospital, S-182 88 Danderyd, Sweden. Printed and Published in Ireland
MATERIALS AND METHODS
Twenty-six consecutive patients with atrial fibrillation, planned for elective cardioversion were randomised according to date of birth to cardioversion with conventional paddle electrodes or self-adhesive electrodes. The self-adhesive electrodes (Fast-Patch Disposable Defibrillation Electrodes, Physio Control, Redmond, WA, USA) had an electrode area of 82 cm* , which was identical with the area of the conventional paddles. The electrodes were placed in identical front-front positions with both systems. One electrode was placed at the upper right side of the sternum and the other at the site of the apical beat. The manual electrodes were firmly pressed to the chest wall with a gelled so called Defipad 3 M between the electrode and the skin in order to increase the contact. An ordinary defibrillator with a syncronized mode (Life Pak 8, Physio Control, Redmond, WA, USA) was used for the delivery of DCshocks. The cardioversion was performed during light anaesthesia after intravenous administration of diazepam. No intramuscular injections were given before or during the 24-h observation period after the cardioversion. Two hundred Joules were used for the first shock, a second and third shock with 300 J and a fourth with 360 J were given, if needed. Cardioversion was unsuccessful if atrial fibrillation persisted after four shocks with a cumulated energy of 1160 J. Blood samples for enzyme analysis of serum creatine kinase (S-CK) and serum creatine kinase isoenzyme B (S-CK-B) were taken immediately before cardioversion and 2, 4, 10, 20 and 28 h thereafter. The samples were centrifuged within 1 h of collection and stored at - 80°C until they were analyzed. S-CK and S-CK-B were determined according to the standards of the Scandinavian Enzyme Committee (SCE), with and without the immunoinhibitor antibody to creatine kinase Msubunit at a reaction temperature of 37OC. S-CK-B results were corrected for residual adenylate kinase activity in the serum. The results were reported as S-CK-B subunits activity and were not multiplied by the factor two for expressing them as ‘CK MB’ activity [5]. An ECG was recorded and blood pressure measured before and immediately after the shock. Statistics All data are presented as mean value f standard deviation unless otherwise stated. For statistical analyses two-tailed students t-test was used for parametric variables and two-tailed Fischer exact test for proportions. A P-value of less than 0.05 was considered to be statistically significant. The study was approved by the Ethics Committe of the Karolinska Hospital and informed consent was given by the patients. RESULTS
Twenty-six patients, 18 men and 8 women, with a mean age of 59 f 8 years,were given a total of 59 DC-shocks. The median duration of atrial fibrillation was 4
21 Table I.
Characteristics of patients given DC-shocks with conventional or self-adhesive electrodes. Conventional electrode group (?I = 15)
Self-adhesive electrode group (n = 11)
Age (Y=N
60+
Sex M/F Weight (kg) Median duration of atria1 fibrillation (months) Range (months) Digitalis (n)
9/6 72 f 12 5
59* 7 9/2 74 f 13 4
8
l-18 12
l-8 10
months, with a range of l-18 months. All patients had normal serum levels of sodium and potassium before cardioversion. There were no differences between the groups with regard to conventional patient characteristics (Table I). Twenty-four patients were successfully converted to sinus rhythm after one or more shocks. Thirteen of the 15 patients with conventional electrodes and all 11 patients with the self-adhesive electrodes converted. The number of shocks and cumulated energy is illustrated in Fig. 1. Eight of eleven patients with self-adhesive electrodes converted after the first shock of 200 J, but only five of fifteen were successfully converted by the first shock when the conventional electrodes were used (Fig. 1). No cardio-
8-
6-
1
2
3
4
Number of DC-shocks Fig. 1. Number of DC-shocks given for conversion to sinus rhythm in the two groups. Two hundred Joules were used for the first shock, 300 J for the second and third and 360 J for the fourth shock. Grey bars indicate conventional electrodes, hatched bars indicate the self-adhesive group.
depressent effects, such as asystole or postconversion hypotension were seen. The postconversion heart rate was the same in the two groups. No ECG-changes were seen in either group. The two patients in the conventional electrode group that were not possible to convert even after four shocks with a cumulated energy of 1160 J had a duration of atrial fibrillation of 4 and 18 months, respectively. The enzyme activity peaked within the observation period and the highest value. obtained during that period was defined as the maximal enzyme activity. S-CK increased from 66 + 36 (mean & S.D.) U/l to 1464 rt 528 U/l in the group with conventional electrodes and from 72 f 48 U/l to 600 -+ 456 U/l in the self-adhesive group. The maximal S-CK values did not not differ between the groups (P = 0.23). The maximal value was then adjusted for the number of DC-shocks by dividing this value with the number of shocks. The adjusted maximal S-CK value with conventional electrodes was 780 2 540 U/l and with adhesive electrodes 378 f 240 U/l (P = 0.04). The S-CK-B activity increased two-fold in both groups but with no difference between the groups. DISCUSSION
The clinical use of self-adhesive electrodes has increased after the introduction of semi-automatic external defibrillators. These electrodes are fixed to the anterior chest wall by adhesive material surrounding, and thus isolate the electrode surface from the surrounding skin. Theoretically, the fixation and isolation obtained by the adhesive material may limit the current leakage, thereby increasing the effective energy and protecting the surrounding tissues from electrical damage [4]. In order to investigate these potential advantages with self adhesive electrodes we randomized patients with chronic atrial fibrillation to elective cardioversion with conventional or self adhesive electrodes. We found a high conversion rate, 24 out of 26 patients were successfully converted to sinus rhythm. There were no differences between the groups in regard to the number of shocks or the cumulated energy needed. With the self-adhesive electrodes, however, there was a tendency towards a higher conversion rate after the first shock and the need for a lower cumulative energy requirement. The matter of myocardial or skeletal muscle damage in connection with cardioversion has been debated. However, the major part of the enzyme release after cardioversion has been considered to originate from the skeletal muscle and histological studies have confirmed this assumption [2]. In the present study there was a tendency towards a higher release of S-CK in the conventional electrode group. As the enzyme release after cardioversion has been shown to be positively correlated to the number of DC-shocks given [6], the maximal S-CK value was adjusted for this number. After this adjustment the maximal S-CK value in the conventional electrode group was significantly higher than in the self-adhesive group. The proportion of S-CK-B in relation to S-CK was less than 3 per cent in both groups indicating a skeletal muscle origin for the enzyme release [7]. Thus, there seems to be a more extensive skeletal muscle damage per shock in the group converted with conventional electrode paddles as compared to the self-adhesive electrodes.
29
The clinical importance of this finding is uncertain, but it still seems reasonable to use as few shocks and as low energy as possible for cardioversion with the purpose of limiting the number of potentional side effects with cumulative high energy levels. There were no cardiodepressant effects in the form of asystole, bradycardia or hypotension after the shocks in either of the groups. One obvious limitation of the present study is the small number of patients. However, even without the adjustment for number of DC-shocks there was a tendency towards a difference in maximal S-CK between the groups. Concerning the number of shocks and the cumulated energy no difference was found between the groups, which of course might be due to a beta error due to the small number of patients. Our results though indicate that self-adhesive electrodes are fully equal to ordinary paddle electrodes in terms of efficiency together with a lower enzyme release per shock, indicating less skeletal muscle damage. Concerning the safety aspects, the self-adhesive electrodes reduce the risk of accidental contact between the patient and the person delivering the shock. The system was found to be practical and easy to handle by the responsible physicians. The only drawback with the 6 self-adhesive electrodes was an increased cost. However, a cost-benefit analysis is outside the aim of this paper. In our opinion the self-adhesive electrodes are an interesting alternative to conventional electrodes, not only in connection with semi-automatic defibrillators, but also for elective cardioversions. REFERENCES 1 C.F. Dahl, G.A. Ewy and E.D. Warner, Myocardial necrosis from direct current countershock: effect of paddle electrode size and time interval between discharges, Circulation, 50 (1974) 956-961. 2 A. Ehsani. A.E. Gordon and B.E. Sobel, Effects of electrical countershock on serum creatine phosphokinase (CKP) isoenzyme activity, Am. .I. Cardiol., 37 (1976) 12-18. 3 J. Jakobsson. 0. Nyquist and N. Rehnquist, Energy requirement for early defibrillation, Eur. Heart J., 10 (1989) 551-554. 4 GA. Ewy, Deflbrillators, defibrillation and cardioversion, Chap 21. In: Cardiac Arrhythmias. Editor: B. Phibbs. St Louis, CV Mosby, 1972, p. 188. 5 W. Gerhardt, J. Waldenstrom, M. Horder, S. Hofvendahl, R. Billstrom, L. Ljungdahl, H. Berning and P. Bagger, Creatine kinase and creatine kinase B-subunit activity in serum in cases of suspected myocardial infarction, Clin. Chem., 28 (1982) 277-283. 6 L. Ljungdahl, Serum creatine kinase B-subunit activity in acute myocardial infarction. Thesis, Lund University, Lund, 1978. 7 W. Gerhardt, S. Hofvendahl and L. Ljundahl, Diagnostic approach in suspected acute myocardial infarction. In: Clinical Enzymology Symposia. Editors: A. Burlina and L. Galzigna, Piccin Medical Books, 1984, pp. 319-332.
Comparison
of two different electrodes delivery of dc-shocks
25
for the
J. Jakobsson”, I. odmanssonb and R. Nordlanderb Department of Anaesthesiology’, Dandev& Hospital and Division of Cardiology. Department of Medicin@, Karolinsko Hospital, Karolinska Institute& Stockholm (Sweden) (Received September 15th, 1989; accepted January 3lst, 1990)
Twenty-six consecutive patients with atrial fibrillation, planned for elective cardioversion were randomised to cardioversion with ordinary or self-adhesive electrodes. The two types of electrodes were found equally efficient for conversion to sinus rhythm. With the self-adhesive electrodes there was a tendency towards the need for a lesser number of DC-shocks and a lower cumulated energy. The post-cardioversion maximal serum creatine kinase activity adjusted for number of shocks was significantly lower when the self-adhesive electrodes were used, indicating a lesser degree of skeletal muscle damage. DC-conversion - Electrodes - Creatine kinase - Isoenzymes
INTRODUCTION
Electrical direct current conversion is frequently used for treatment of tachyarrhythm& In experimental animals both internal and external countershocks have’ been found to produce myocardial lesions. The degree of damage has been shown to be inversly related to the paddle size and the time interval between shocks and directly related to the administered energy [ 11. In human studies, ECG-changes and release of myocardial specific isoenzymes have indicated some degree of myocardial damage after cardioversion. However, these results are conflicting and the major part of enzyme release after cardioversion have been considered to originate from skeletal muscle damage [2]. The use of self-adhesive electrodes has increased after the introduction of semiautomatic external defibrillators [3]. These electrodes are fixed to the anterior chest wall by adhesive material, which theoretically may limit the current leakage, thus increasing the effective energy as well as reducing damage to surrounding tissues [4]. The aim of this study was to compare self-adhesive electrodes with conventional electrodes with regard to conversion rate, energy requirement and enzyme release as an indicator of muscle damage during elective cardioversion. A secondary aim was to get an opinion by the responsible physician about the practical handling of these electrodes. Address all correspondence and reprint requests to: J. Jakobsson, Department of Anaesthesiology and Intensive Care, Danderyds Hospital, S-182 88 Danderyd, Sweden. Printed and Published in Ireland
MATERIALS AND METHODS
Twenty-six consecutive patients with atrial fibrillation, planned for elective cardioversion were randomised according to date of birth to cardioversion with conventional paddle electrodes or self-adhesive electrodes. The self-adhesive electrodes (Fast-Patch Disposable Defibrillation Electrodes, Physio Control, Redmond, WA, USA) had an electrode area of 82 cm* , which was identical with the area of the conventional paddles. The electrodes were placed in identical front-front positions with both systems. One electrode was placed at the upper right side of the sternum and the other at the site of the apical beat. The manual electrodes were firmly pressed to the chest wall with a gelled so called Defipad 3 M between the electrode and the skin in order to increase the contact. An ordinary defibrillator with a syncronized mode (Life Pak 8, Physio Control, Redmond, WA, USA) was used for the delivery of DCshocks. The cardioversion was performed during light anaesthesia after intravenous administration of diazepam. No intramuscular injections were given before or during the 24-h observation period after the cardioversion. Two hundred Joules were used for the first shock, a second and third shock with 300 J and a fourth with 360 J were given, if needed. Cardioversion was unsuccessful if atrial fibrillation persisted after four shocks with a cumulated energy of 1160 J. Blood samples for enzyme analysis of serum creatine kinase (S-CK) and serum creatine kinase isoenzyme B (S-CK-B) were taken immediately before cardioversion and 2, 4, 10, 20 and 28 h thereafter. The samples were centrifuged within 1 h of collection and stored at - 80°C until they were analyzed. S-CK and S-CK-B were determined according to the standards of the Scandinavian Enzyme Committee (SCE), with and without the immunoinhibitor antibody to creatine kinase Msubunit at a reaction temperature of 37OC. S-CK-B results were corrected for residual adenylate kinase activity in the serum. The results were reported as S-CK-B subunits activity and were not multiplied by the factor two for expressing them as ‘CK MB’ activity [5]. An ECG was recorded and blood pressure measured before and immediately after the shock. Statistics All data are presented as mean value f standard deviation unless otherwise stated. For statistical analyses two-tailed students t-test was used for parametric variables and two-tailed Fischer exact test for proportions. A P-value of less than 0.05 was considered to be statistically significant. The study was approved by the Ethics Committe of the Karolinska Hospital and informed consent was given by the patients. RESULTS
Twenty-six patients, 18 men and 8 women, with a mean age of 59 f 8 years,were given a total of 59 DC-shocks. The median duration of atrial fibrillation was 4
21 Table I.
Characteristics of patients given DC-shocks with conventional or self-adhesive electrodes. Conventional electrode group (?I = 15)
Self-adhesive electrode group (n = 11)
Age (Y=N
60+
Sex M/F Weight (kg) Median duration of atria1 fibrillation (months) Range (months) Digitalis (n)
9/6 72 f 12 5
59* 7 9/2 74 f 13 4
8
l-18 12
l-8 10
months, with a range of l-18 months. All patients had normal serum levels of sodium and potassium before cardioversion. There were no differences between the groups with regard to conventional patient characteristics (Table I). Twenty-four patients were successfully converted to sinus rhythm after one or more shocks. Thirteen of the 15 patients with conventional electrodes and all 11 patients with the self-adhesive electrodes converted. The number of shocks and cumulated energy is illustrated in Fig. 1. Eight of eleven patients with self-adhesive electrodes converted after the first shock of 200 J, but only five of fifteen were successfully converted by the first shock when the conventional electrodes were used (Fig. 1). No cardio-
8-
6-
1
2
3
4
Number of DC-shocks Fig. 1. Number of DC-shocks given for conversion to sinus rhythm in the two groups. Two hundred Joules were used for the first shock, 300 J for the second and third and 360 J for the fourth shock. Grey bars indicate conventional electrodes, hatched bars indicate the self-adhesive group.
depressent effects, such as asystole or postconversion hypotension were seen. The postconversion heart rate was the same in the two groups. No ECG-changes were seen in either group. The two patients in the conventional electrode group that were not possible to convert even after four shocks with a cumulated energy of 1160 J had a duration of atrial fibrillation of 4 and 18 months, respectively. The enzyme activity peaked within the observation period and the highest value. obtained during that period was defined as the maximal enzyme activity. S-CK increased from 66 + 36 (mean & S.D.) U/l to 1464 rt 528 U/l in the group with conventional electrodes and from 72 f 48 U/l to 600 -+ 456 U/l in the self-adhesive group. The maximal S-CK values did not not differ between the groups (P = 0.23). The maximal value was then adjusted for the number of DC-shocks by dividing this value with the number of shocks. The adjusted maximal S-CK value with conventional electrodes was 780 2 540 U/l and with adhesive electrodes 378 f 240 U/l (P = 0.04). The S-CK-B activity increased two-fold in both groups but with no difference between the groups. DISCUSSION
The clinical use of self-adhesive electrodes has increased after the introduction of semi-automatic external defibrillators. These electrodes are fixed to the anterior chest wall by adhesive material surrounding, and thus isolate the electrode surface from the surrounding skin. Theoretically, the fixation and isolation obtained by the adhesive material may limit the current leakage, thereby increasing the effective energy and protecting the surrounding tissues from electrical damage [4]. In order to investigate these potential advantages with self adhesive electrodes we randomized patients with chronic atrial fibrillation to elective cardioversion with conventional or self adhesive electrodes. We found a high conversion rate, 24 out of 26 patients were successfully converted to sinus rhythm. There were no differences between the groups in regard to the number of shocks or the cumulated energy needed. With the self-adhesive electrodes, however, there was a tendency towards a higher conversion rate after the first shock and the need for a lower cumulative energy requirement. The matter of myocardial or skeletal muscle damage in connection with cardioversion has been debated. However, the major part of the enzyme release after cardioversion has been considered to originate from the skeletal muscle and histological studies have confirmed this assumption [2]. In the present study there was a tendency towards a higher release of S-CK in the conventional electrode group. As the enzyme release after cardioversion has been shown to be positively correlated to the number of DC-shocks given [6], the maximal S-CK value was adjusted for this number. After this adjustment the maximal S-CK value in the conventional electrode group was significantly higher than in the self-adhesive group. The proportion of S-CK-B in relation to S-CK was less than 3 per cent in both groups indicating a skeletal muscle origin for the enzyme release [7]. Thus, there seems to be a more extensive skeletal muscle damage per shock in the group converted with conventional electrode paddles as compared to the self-adhesive electrodes.
29
The clinical importance of this finding is uncertain, but it still seems reasonable to use as few shocks and as low energy as possible for cardioversion with the purpose of limiting the number of potentional side effects with cumulative high energy levels. There were no cardiodepressant effects in the form of asystole, bradycardia or hypotension after the shocks in either of the groups. One obvious limitation of the present study is the small number of patients. However, even without the adjustment for number of DC-shocks there was a tendency towards a difference in maximal S-CK between the groups. Concerning the number of shocks and the cumulated energy no difference was found between the groups, which of course might be due to a beta error due to the small number of patients. Our results though indicate that self-adhesive electrodes are fully equal to ordinary paddle electrodes in terms of efficiency together with a lower enzyme release per shock, indicating less skeletal muscle damage. Concerning the safety aspects, the self-adhesive electrodes reduce the risk of accidental contact between the patient and the person delivering the shock. The system was found to be practical and easy to handle by the responsible physicians. The only drawback with the 6 self-adhesive electrodes was an increased cost. However, a cost-benefit analysis is outside the aim of this paper. In our opinion the self-adhesive electrodes are an interesting alternative to conventional electrodes, not only in connection with semi-automatic defibrillators, but also for elective cardioversions. REFERENCES 1 C.F. Dahl, G.A. Ewy and E.D. Warner, Myocardial necrosis from direct current countershock: effect of paddle electrode size and time interval between discharges, Circulation, 50 (1974) 956-961. 2 A. Ehsani. A.E. Gordon and B.E. Sobel, Effects of electrical countershock on serum creatine phosphokinase (CKP) isoenzyme activity, Am. .I. Cardiol., 37 (1976) 12-18. 3 J. Jakobsson. 0. Nyquist and N. Rehnquist, Energy requirement for early defibrillation, Eur. Heart J., 10 (1989) 551-554. 4 GA. Ewy, Deflbrillators, defibrillation and cardioversion, Chap 21. In: Cardiac Arrhythmias. Editor: B. Phibbs. St Louis, CV Mosby, 1972, p. 188. 5 W. Gerhardt, J. Waldenstrom, M. Horder, S. Hofvendahl, R. Billstrom, L. Ljungdahl, H. Berning and P. Bagger, Creatine kinase and creatine kinase B-subunit activity in serum in cases of suspected myocardial infarction, Clin. Chem., 28 (1982) 277-283. 6 L. Ljungdahl, Serum creatine kinase B-subunit activity in acute myocardial infarction. Thesis, Lund University, Lund, 1978. 7 W. Gerhardt, S. Hofvendahl and L. Ljundahl, Diagnostic approach in suspected acute myocardial infarction. In: Clinical Enzymology Symposia. Editors: A. Burlina and L. Galzigna, Piccin Medical Books, 1984, pp. 319-332.
