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Effect of Intravenous Adrenaline on Electrocardiogram, Blood Pressure, and Serum Potassium

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Effect of Intravenous Adrenaline on Electrocardiogram, Blood Pressure, and Serum Potassium Br Heart J: first published as 10.1136/hrt.49.1.90 on 1 January 1983. Downloaded from Br Heart J 1983; 49: 90-3 Effect of intravenous adrenaline on electrocardiogram, blood pressure, and serum potassium A D STRUTHERS, J L REID, R WHITESMITH, J C RODGER From the University Department ofMateria Medica, and Department ofBiochemistry, StobhiU General Hospital, Glasgow, and Medical Unit, Monklands and District General Hospital, Airdrie, Lanarkshire SUMMARY Increased catecholamines after myocardial infarction may contribute to the development ofarrhythmias. We have infused adrenaline intravenously in nine normal volunteers to levels similar to those seen after myocardial infarction. Adrenaline caused an increase in systolic blood pressure, a decrease in diastolic blood pressure, and an increase in heart rate. Adrenaline also produced a decrease in T wave amplitude and an increase in the QTc interval. The serum potassium fell dramatically during the adrenaline infusion from a control value of 4*06 mmot/l to 3-22 mmol/l. Hypokalaemia after myocardial infarction is associated with an increased incidence of ventricular arrhythmias. Thus, circulating adrenaline may increase the frequency of arrhythmias both directly via changes in ventricular repolarisation and indirectly via adrenaline induced hypokalaemia. Hypokalaemia is not uncommonly observed in the All subjects gave their informed consent to the acute phase of myocardial infarctionl 2 when it is investigation which had the approval of the hospital's associated with serious ventricular arrhythmias.3 We research and ethical committee. have found that in this circumstance hypokalaemia is Subjects were investigated in the morning after a http://heart.bmj.com/ transient, it resolves without potassium supplements, standard light breakfast. Intravenous cannulae were and it cannot be attributed solely to diuretic therapy.4 inserted into the antecubital veins of both arms. After In addition, it is not the result either ofhaemodilution an initial rest period of 90 minutes, the subjects or of increased urinary excretion of potassium. As received three consecutive 90 minute infusions (Braun plasma catecholamine levels are increased in acute Perfusor VI) of 5% dextrose containing 1 mg/ml myocardial infarction5 6 and intravenous adrenaline ascorbic acid. The infusions contained, in sequence, infusion in dogs can lower the serum potassium,7 we 0, 0 01, and 0-06 ,ug/kg per min of 1-adrenaline (Anti- considered that the transient hypokalaemia of acute gen Ltd, Roscrea, Ireland) and the volume of dextrose on September 30, 2021 by guest. Protected copyright. myocardial infarction might be a consequence of delivered during each infusion period was 82-5 ml. increased circulating catecholamines. The present Blood pressure, heart rate, and the electrocardio- study was undertaken to examine this hypothesis; the gram were observed at 30 minute intervals for 90 aim was to infuse adrenaline intravenously in normal minutes before and up to 120 minutes after the infu- subjects to the plasma levels observed in acute sions. During each infusion, recordings were made at myocardial infarction and to investigate the effects on five minute intervals for the first 15 minutes and at 30 serum potassium and on the electrocardiogram. minute intervals thereafter. Blood pressure was meas- ured with a semiautomatic sphygmomanometer Subjects and methods (Bosomat). The electrocardiogram was displayed con- tinuously on an oscilloscope and was recorded at 50 Nine normal male volunteers aged 22 to 31 (mean 26) mm/s on a polygraph (Grass Model 7D) at the inter- was measured years were investigated. They were on no drug vals indicated above. The QT interval where a They had no symptoms or signs of car- from the onset of the Q wave to the point therapy. T wave crossed disease and the resting electrocardiogram, tangent to the descending limb of the diovascular to the chest radiograph, and serum electrolytes were nor- the base-line. QTc was calculated according mal. Bazett formula.8 Blood for serum electrolytes was taken at 30 minute and after the infusion and at the 60th Accepted for publication 7 October 1982 intervals before 90 Br Heart J: first published as 10.1136/hrt.49.1.90 on 1 January 1983. Downloaded from Adrenaline and electrocardiogram, blood pressure, and serum potassium 91 and 90th. minutes of each. Samples were collected in p<0O001) and a decrease in diastolic blood pressure plain glass bottles: they were allowed to stand at room (-14+9 mmHg; p<0.002). temperature and were centrifuged within 30 minutes. Electrolytes were measured on a Technicon SMA 6/60 SERUM POTASSIUM (Fig. 1) using standard methods. The mean of the values after 60 and 90 minutes of Samples for plasma adrenaline were taken at the each infusion have been compared. The low dose end of each infusion. They were collected into chilled infusion produced a small (p<0.05) drop in serum heparinised tubes, centrifuged at 4°C, and stored at potassium. During the high dose infusion, serum -70°C until assay. Assay was by the radioenzymatic potassium for the gr6up fell from 4-06+0 14 to method of Da Prada and Zurcher.9 3*22±0-26 mmolI (p<0.0001); 90 minutes after stop- ping the infusion, the serum potassium had returned Results to baseline. Plasma adrenaline levels during the 0-06 jig/kg per 4.5' min (high dose) adrenaline infusion were 5-5± 1-7 nmol. These levels are similar to the peak adrenaline levels found by Karlsberg et al. 10 in their study of patients after acute myocardial infarction. As it was our aim to simulate the effects of adrenaline at the _ 40 E plasma levels encountered in acute myocardial infarc- E tion, only the findings during the control and high dose infusion are considered in detail in this report. the control infusion and during the E 3.5 The results during aS high dose infusion have been compared by paired t iI test. HAEMODYNAMIC EFFECTS 30- Dextrose Adrenaline The mean of the observations at the 30th, 60th, and "---i 90th minutes of the control and high dose infusion 0 100 200 300 400 500 have been compared. The haemodynamic responses Time (minutes) to infused adrenaline were as expected, with an Fig. 1 Changes in serum potassiun (mean ±+ SD) produced by http://heart.bmj.com/ increase in both heart rate (+7±9 beats/min; p<005) infusion of5% dextrose containing 0, 0.01, and 0-06 pglkg per and systolic blood pressure (+11+6 mmHg; min adrenaline in nine normal subjects. Before During 4 ts StS f- A:II,4'S 6 ;, JX '' S:' ;,rt ff on September 30, 2021 by guest. Protected copyright. ., A, '0f' SiS '; 000f';000;ffff .S ff fEf fff: k; fitS ':03-5}Si:t ¢,S- :: :. f: --Wt :g:2 is; i:; :: ::: ,7: ::.C;. .ii: :i: ::-;-:: rS s03 isC :: s:/ si S;; : aS 1'SXx_ -4' Fig. 2 Single lead electrocardiogram (50 minIs) before infuision and during the 006 pg/kg per mni adrenaline infutsion in three normal subjects. Infutsion produces decreased T wave amplitude,iti ' i.fI-SU Ft'waves4S- ' i; j(case ' :S i;3), ' -'ST ;d: segment displacement (cases 2 and 3) and QT prolongation.:*, i(QT . iincreases ...7:frm - -037 s to 041 sin case I andfrom 0-32 s to 036 sin case 2.)7:.5V:X.t Br Heart J: first published as 10.1136/hrt.49.1.90 on 1 January 1983. Downloaded from 92 Struthers, Reid, Whitesmith, Rodger ELECTROCARDIOGRAM (Fig. 2) adrenaline (0.1 and 0 3 ug/kg per min) on the elec- All subjects remained in stable sinus rhythm through- trocardiogram of normal subjects. They did not look out the infusions. for changes in the QT interval, but, as in the present study, they did observe U waves, a decrease in T wave T waves amplitude, and displacement of the ST segment. The findings at the 90th minute of each infusion have Abildskov16 studied the effect of infused adrenaline been compared. With the high dose infusion, T wave on the QT interval of dogs. He found that this was amplitude decreased in eight subjects and increased in prolonged by rapid injection but shortened by slow one; the mean decrease for the group was -2-5±1*9 infusion of adrenaline. mm (p<0 002). With the low dose infusion, T wave This study has shown that the levels of plasma amplitude decreased in five subjects; the mean adrenaline observed in acute myocardial infarction decrease for the group was -0-61±0*86 mm can in normal subjects produce changes in ventricular (p<0.05). repolarisation which are reflected in T wave flattening and QT prolongation. Though our subjects remained U waves in sinus rhythm, these adrenaline induced abnor- Three subjects developed U waves during the high malities of repolarisation could, in theory, predispose dose adrenaline infusion; no U waves developed dur- to arrhythmias. 17 Prolongation of the QT in particular ing the low dose infusion. may be relevant to the genesis of arrhythmias during the acute phase of myocardial infarction.18 QT interval It has been suggested that T wave flattening and ST The findings at the 90th minute of each infusion have segment displacement in asymptomatic men with been compared. The low dose infusion increased the unobstructed coronary arteries are the result of QT interval in five subjects; for the group, QT increased sympathetic activity and our results are in increased from 0-36±0-02 s to 0 37±0 03 s (p<0.05). line with this. 1920 The electrocardiographic changes With the high dose infusion, the QT interval which we have observed may therefore be mediated increased in eight subjects and was unchanged in one; directly by the effects of adrenaline on beta for the group, QT increased from 0*36+0-02 s to adrenoceptors, by the hypokalaemia induced by 0A40±0 05 s (p<0-01).
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