Dynamic assessment of the electrocardiographic QT interval during citrate infusion in healthy volunteers.

Davis, Timothy M. E.; Singh, Balbir; Choo, K. E.; Ibrahim, J.; Spencer, J L; John, Andrew St

doi:10.1136/hrt.73.6.523

Cited by 26 publications

(16 citation statements)

References 15 publications

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“…The most common pathological conditions associated with QT prolongation are electrolyte disturbance, including hypocalcaemia , hypokalaemia and hypomagnesaemia . In a study of amisulpride overdose hypokalaemia was significantly associated with patients with QT prolongation .…”

Section: Non‐drug Risk Factors and The Qt Intervalmentioning

confidence: 99%

Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

Isbister

Page

2013

Brit J Clinical Pharma

129

115

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There has been an increasing focus on drug induced QT prolongation including research on drug development and QT prolongation, following the removal of drugs due to torsades de pointes (TdP). Although this has improved our understanding of drug-induced QT prolongation there has been much less research aimed at helping clinicians assess risk in individual patients with drug induced QT prolongation. This review will focus on assessment of drug-induced QT prolongation in clinical practice using a simple risk assessment approach. Accurate measurement of the QT interval is best done manually, and not using the measurement of standard ECG machines. Correction for heart rate (HR) using correction formulae such as Bazett's is often inaccurate. These formulae underestimate and overestimate the duration of cardiac repolarization at low and high heart rates, respectively. Numerous cut-offs have been suggested as an indicator of an abnormal QT, but are problematic in clinical practice. An alternative approach is the QT nomogram which is a plot of QT vs. HR. The nomogram has an 'at risk' line and QT-HR pairs above this line have been shown in a systematic study to be associated with TdP and the line is more sensitive and specific than Bazett's QT c of 440 ms or 500 ms. Plotting the QT-HR pair for patients on drugs suspected or known to cause QT prolongation allows assessment of the QT interval based on normal population QT variability. This risk assessment then allows the safer commencement of drugs therapeutically or management of drug induced effects in overdose.

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Section: Non‐drug Risk Factors and The Qt Intervalmentioning

confidence: 99%

Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

Isbister

Page

2013

Brit J Clinical Pharma

129

115

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“…The toxic effects of citrate, including tetany, a reduction in blood pressure and prolonged electrocardiographic Q-T intervals, result from a decrease in blood ionized calcium (Ca 2+ ) levels caused by its chelating action (Dzik and Kirkley, 1988;Scheidegger et al, 1980;Corbascio and Smith, 1967;Davis et al, 1995;Nakasone et al, 1954). The decreased blood Ca 2+ level is thought to be related to the citrate infusion rate (Kahn et al, 1979), and significant changes in clinical signs, cardiovascular system and hemodynamic functions are induced at blood Ca 2+ levels below 0.8 mmol/l in swine and humans (Liu et al, 1992;Martin et al, 1990;Olson et al, 1977).…”

Section: Introductionmentioning

confidence: 99%

Effect of Whole Blood Clotting Time in Rats With Ionized Hypocalcemia Induced by Rapid Intravenous Citrate Infusion

et al. 2006

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-Although the toxic effects of citrate including hemodynamic and cardiovascular changes result from a decrease in ionized calcium levels in serum due to chelating action, these effects of citrate on blood coagulation have not yet been fully clarified. The present study examines whether serum citrate and ionized calcium levels affect whole blood clotting time in rats using the test tube method in which citrate is administered by rapid intravenous infusion. Citrate was infused via the tail vein into 10 rats at 3, 4 or 5 mmol/kg/hr for 1 hr, and then whole blood clotting time, serum citrate and ionized calcium levels were determined. Whole blood clotting time did not significantly change at citrate infusion rates of 3 and 4 mmol/kg/hr. However, at 5 mmol/kg/hr, whole blood clotting time was significantly prolonged by a factor of 2.1 relative to the untreated group, when the serum citrate level was 10.03 ± 1.39 mmol/l (59.0-fold higher than that in the untreated group) and the serum-ionized calcium level was 0.29 ± 0.02 mmol/ l (0.2-fold lower than that in the untreated group). These results suggest that whole blood clotting time is significantly prolonged in rats with severe ionized hypocalcemia.

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“…Hence, although rarely reported, hypocalcemia can be associated with ST segment elevation, mimicking an acute myocardial infarction or T wave abnormalities. 28 The QT interval prolongation is proportional to the degree of hypocalcemia; nevertheless, the QTc rarely exceeds 140% of normal. 26,27 Most commonly, the characteristic ECG manifestation of hypocalcemia is prolongation of the QT interval as a result of lengthening of the ST segment.…”

Section: Manifestations Of Hypocalcemiamentioning

confidence: 99%

Electrocardiographic Manifestations of Calcium Abnormalities

Chorin

Rosso

Viskin

2015

Ann Noninvasive Electrocardiol

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Dynamic assessment of the electrocardiographic QT interval during citrate infusion in healthy volunteers.

Abstract: The disproportionate prolongation of QaTc interval during prompt induction of hypocalcaemia suggests rate dependency which can be represented by a hysteresis relation between (ionised calcium, QaTc) coordinates. This finding may have clinical implications.

Cited by 26 publications

References 15 publications

Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

Drug induced QT prolongation: the measurement and assessment of the QT interval in clinical practice

Effect of Whole Blood Clotting Time in Rats With Ionized Hypocalcemia Induced by Rapid Intravenous Citrate Infusion

Electrocardiographic Manifestations of Calcium Abnormalities

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