Diagnostic value of electrocardiographic abnormalities observed in subjects accidentally exposed to cold

Clements, Stephen D.; Hurst, J. Willis

doi:10.1016/0002-9149(72)90178-6

Cited by 86 publications

(28 citation statements)

References 15 publications

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“…Our findings of hypothennia-induced prolongations of the electrocardographic QRS-and QTc-intervals in conjunction with bradycardia are in accordance with observed electrocardiographic abnormalities observed in patients who had been accidentally exposed to cold, except that atrial fibrillation also occured in the human subjects (Clements & Hurst 1972). It has been shown in pithed rats that isoprenaline can produce a pronounced P-adrenoceptor down-regulation which caused a reduction of mainly the positive ino-and chronotropic effects of the (+)-isomer of dobutamine which acts agonistic on both Pl-and P2-adrenoceptors, whereas the action of the (-)-isomer of dobutamine was not affected because this is mediated by al-adrenoceptors (Hayes el al.…”

Section: Discussionsupporting

confidence: 91%

Myocardial Effects of Adrenaline, Isoprenaline and Dobutamine at Hypothermic Conditions

Riishede

Nielsen‐Kudsk

1990

Pharmacology & Toxicology

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Abstract:The pharmacodynamic myocardial effects of adrenaline, isoprenaline and dobutamine were studied in isolated, perfused and spontaneously beating rabbit hearts at hypothermic conditions. Cardiac contraction amplitude increased from the control value at 37" set equal to 100% to about 165% at 22". whereas contraction velocity decreased to 52%, frequency to 30% and oxygen consumption to about 19%. At 22" all drugs produced pronounced positive inotropic and chronotropic effects. Em-values related to contraction velocity, frequency and oxygen consumption were for isoprenaline 152, 98 and 136%, respectively, for adrenaline 127, 100 and 198% and for dobutamine 120, 86 and 165%, respectively. The corresponding ECSO-values decreased and a marked left-shift of the log-concentration response curves was observed as an expression of increased myocardial sensitivity to the drugs. Em for contraction velocity for dobutamine was distinctly reduced at 32 and 27" and for adrenaline at 27" in comparison to the increase seen at 22 and 37". Em for oxygen consumption showed for all drugs an increase at decreasing temperatures. The frequency-corrected QTc-interval decreased slightly to moderately during exposure to the drugs at hypothermic conditions. None of the drugs caused arrhytmias during the experiments. Coronary flow rate decreased only moderately at the higher drug concentrations at decreased temperatures. Dobutamine and adrenaline at 37" and isoprenaline at 37 and 22" caused an increase of Em for oxygen consumption that was slightly less than proportional to the increase of Em for contraction velocity.Hypothermia may influence mammalian receptors in a way that causes changes in receptor responsiveness to stimulation, possibly because of changes in ionic composition due to ion-pump shut-down (Karow 1977). Martinez & McNeill (1 977) in isolated electrically driven rat left atrial preparations found that hypothermia in itself caused an increase in contractile strength. Mori et al. (1979), Broadley (1980), Chess-Williams et al. (1 984) and Chess-Williams & Broadley (1 985) confirmed this observation and demonstrated that there is a higher agonist (but not antagonist affinity and increased sensitivity to some P,-receptor adrenergic inotropic drugs (including isoprenaline) at lower temperatures. In order to extend these in vitro investigations on excised heart muscle preparations we have used the isolated but intact rabbit heart as an experimental model for comparing the cardiac ino-, chrono-, dromo-and bathmotropic effects of adrenaline, isoprenaline and dobutamine at hypothermic conditions. A basic aim for the study has been to evaluate a rational experimental basis for the use of these drugs in resuscitative treatment of cardiovascular shock at decreased body temperatures. In the isolated spontaneously beating rabbit heart it was possible to determine the drug effects on the following relevant dynamic parameters: contraction amplitude and velocity, beating frequency, coronary flow rate, oxygen consumption, and electrocardi...

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Section: Discussionsupporting

confidence: 91%

Myocardial Effects of Adrenaline, Isoprenaline and Dobutamine at Hypothermic Conditions

Riishede

Nielsen‐Kudsk

1990

Pharmacology & Toxicology

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“…In our patients, 39 the mean vector illustrating the Osborn wave was directed to the left and parallel with the frontal plane or slightly anterior. This led to the view that the left anterior portion of the left ventricle was cooled more than other parts of the left ventricle.…”

Section: Genesis Of the Osborn Wavementioning

confidence: 58%

Naming of the Waves in the ECG, With a Brief Account of Their Genesis

Jw¹

1998

Circulation

175

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“…These deflections (also known as Osborn waves) may appear in hypercalcaemia and in patients predisposed to early repolarisation 2. Possible mechanisms include altered myocardial repolarisation and depolarisation rates during cooling1 3 or altered epicardial action potential morphology resulting in a voltage gradient across the ventricular wall 2. The amplitude of J waves increases with the severity of hypothermia and they are consistently seen below 25°C.…”

Section: Discussionmentioning

confidence: 99%