Skip to main content
NCBI home page
British Heart Journal logoLink to British Heart Journal
. 1995 Jun;73(6):523–526. doi: 10.1136/hrt.73.6.523

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

T M Davis 1, B Singh 1, K E Choo 1, J Ibrahim 1, J L Spencer 1, A St John 1
PMCID: PMC483913  PMID: 7626350

Abstract

OBJECTIVE--To investigate changes in the electrocardiographic QT interval during rapidly induced, sustained hypocalcaemia in healthy volunteers. DESIGN--Serial rate corrected QT measurements were made during and after a variable rate trisodium citrate infusion designed to "clamp" the whole blood ionised calcium concentration 0.20 mmol/l below baseline for 120 min. SUBJECTS--12 healthy teetotallers aged 19- 36 years who were not receiving medication known to influence calcium homoeostasis. MAIN OUTCOME MEASURES--Whole blood ionised calcium concentration and QaTc intervals (onset of the Q wave to T wave apex divided by the square root of the RR interval). RESULTS--Mean (SD) ionised calcium concentration decreased from 1.18 (0.03) mmol/l preinfusion to values close to target (0.98 mmol/l) between 10 and 120 min. The QaTc interval lengthened from a baseline of 0.309 (0.021) to a maximum 0.343 (0.024) s0.5 at 10 min before returning to a stable level from 15 to 120 min (0.334 (0.023) and 0.330 (0.023) s0.5 respectively). The change from baseline of both variables expressed as a ratio (delta QaTc/ delta [Ca2+]) was greater during rapid induction of hypocalcaemia (at 5 and 10 min) than at other times during and after the infusion (P < 0.02). CONCLUSIONS--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.

Full text

PDF
523

Selected References

These references are in PubMed. This may not be the complete list of references from this article.

  1. Ahmed R., Hashiba K. Reliability of QT intervals as indicators of clinical hypercalcemia. Clin Cardiol. 1988 Jun;11(6):395–400. doi: 10.1002/clc.4960110607. [DOI] [PubMed] [Google Scholar]
  2. Ahmed R., Kiya F., Kitano K., Takagi H., Hashiba K. Effects of combined changes in serum calcium and potassium on QT interval. A study by Holter electrocardiographic monitoring during hemodialysis. Jpn Heart J. 1987 Nov;28(6):813–828. doi: 10.1536/ihj.28.813. [DOI] [PubMed] [Google Scholar]
  3. Ahnve S. Correction of the QT interval for heart rate: review of different formulas and the use of Bazett's formula in myocardial infarction. Am Heart J. 1985 Mar;109(3 Pt 1):568–574. doi: 10.1016/0002-8703(85)90564-2. [DOI] [PubMed] [Google Scholar]
  4. Anselmo J., Martins J., Matos L., Boavida J., Carreiras F., Correia G., Lima e Silva F., Pereira E., Corrêa J. C. Hipoparatiroidismo crónico: revisão de 5 casos clínicos. Acta Med Port. 1991 Mar-Apr;4(2):83–86. [PubMed] [Google Scholar]
  5. Colletti R. B., Pan M. W., Smith E. W., Genel M. Detection of hypocalcemia in susceptible neonates: The Q-oTc interval. N Engl J Med. 1974 Apr 25;290(17):931–935. doi: 10.1056/NEJM197404252901703. [DOI] [PubMed] [Google Scholar]
  6. Giacoia G. P., Wagner H. R. Q-oTc interval and blood calcium levels in newborn infants. Pediatrics. 1978 Jun;61(6):877–882. [PubMed] [Google Scholar]
  7. Grant F. D., Conlin P. R., Brown E. M. Rate and concentration dependence of parathyroid hormone dynamics during stepwise changes in serum ionized calcium in normal humans. J Clin Endocrinol Metab. 1990 Aug;71(2):370–378. doi: 10.1210/jcem-71-2-370. [DOI] [PubMed] [Google Scholar]
  8. Howland W. S., Schweizer O., Carlon G. C., Goldiner P. L. The cardiovascular effects of low levels of ionized calcium during massive transfusion. Surg Gynecol Obstet. 1977 Oct;145(4):581–586. [PubMed] [Google Scholar]
  9. Ladenson J. H., Miller W. V., Sherman L. A. Relationship of physical symptoms, ECG, free calcium, and other blood chemistries in reinfusion with citrated blood. Transfusion. 1978 Nov-Dec;18(6):670–679. doi: 10.1046/j.1537-2995.1978.18679077948.x. [DOI] [PubMed] [Google Scholar]
  10. Lind L., Hvarfner A., Pollare T., Lithell H., Ljunghall S. Fasting insulin, calcium metabolism and the electrocardiogram in hypertensive subjects. J Intern Med. 1992 Oct;232(4):335–339. doi: 10.1111/j.1365-2796.1992.tb00594.x. [DOI] [PubMed] [Google Scholar]
  11. Nekvasil R., Stejskal J., Tuma A. Detection of early onset neonatal hypocalcaemia in low birth weight infants by Q-Tc and Q-oTc interval measurement. Acta Paediatr Acad Sci Hung. 1980;21(4):203–210. [PubMed] [Google Scholar]
  12. Nelson N., Illés L. The Q-oTc and Q-Tc interval and ionized calcium in newborns. Clin Physiol. 1989 Feb;9(1):39–45. doi: 10.1111/j.1475-097x.1989.tb00954.x. [DOI] [PubMed] [Google Scholar]
  13. Rosenqvist M., Nordenström J., Andersson M., Edhag O. K. Cardiac conduction in patients with hypercalcaemia due to primary hyperparathyroidism. Clin Endocrinol (Oxf) 1992 Jul;37(1):29–33. doi: 10.1111/j.1365-2265.1992.tb02279.x. [DOI] [PubMed] [Google Scholar]
  14. Rumancik W. M., Denlinger J. K., Nahrwold M. L., Falk R. B., Jr The QT interval and serum ionized calcium. JAMA. 1978 Jul 28;240(4):366–368. [PubMed] [Google Scholar]
  15. Saikawa T., Tsumabuki S., Nakagawa M., Takakura T., Tamura M., Maeda T., Ito S., Ito M. QT intervals as an index of high serum calcium in hypercalcemia. Clin Cardiol. 1988 Feb;11(2):75–78. doi: 10.1002/clc.4960110205. [DOI] [PubMed] [Google Scholar]
  16. Schouten E. G., Dekker J. M., Meppelink P., Kok F. J., Vandenbroucke J. P., Pool J. QT interval prolongation predicts cardiovascular mortality in an apparently healthy population. Circulation. 1991 Oct;84(4):1516–1523. doi: 10.1161/01.cir.84.4.1516. [DOI] [PubMed] [Google Scholar]
  17. Schwarz P., Sørensen H. A., Momsen G., McNair P., Transbøl I. Normal pattern of parathyroid response to blood calcium lowering in primary hyperparathyroidism: a citrate clamp study. Clin Endocrinol (Oxf) 1992 Oct;37(4):344–348. doi: 10.1111/j.1365-2265.1992.tb02336.x. [DOI] [PubMed] [Google Scholar]
  18. Schwarz P., Sørensen H. A., Transbøl I., McNair P. Induced hypocalcaemia controlled by a citrate clamp technique, and the intact parathyroid hormone response obtained. Scand J Clin Lab Invest. 1990 Dec;50(8):891–897. doi: 10.3109/00365519009104958. [DOI] [PubMed] [Google Scholar]
  19. Yunes-Zarraga J. L., Velez-Meza V., Velázquez-Quintana N. Problemas de diagnóstico en hipocalcemia neonatal. Bol Med Hosp Infant Mex. 1989 Mar;46(3):185–190. [PubMed] [Google Scholar]

Articles from British Heart Journal are provided here courtesy of BMJ Publishing Group

RESOURCES