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. 2009 Feb 3;22(6):413–416. doi: 10.1002/clc.4960220609

Paradoxical behavior of the QT interval during exercise and recovery and its relationship with cardiac memory

Federico Moleiro 1,✉, Francesca Misticchio 1, Jose M Torres 1, Moises Pulido 1, Milagros Luque 1, Ana Rodriguez 1, Ivan Mendoza 1, Julio Guerrero 1, Victor Ruesta 1, Agustin Castellanos 2, Robert J Myerburg 2
PMCID: PMC6656178  PMID: 10376181

Abstract

Background: Few studies have dealt with the behavior of the corrected (QTc) and uncorrected QT intervals during exercise and recovery.

Hypothesis: Based on previously published dynamics of the QT interval during treadmill testing, this study attempted to reevaluate the computer‐proposed underlying mechanisms of these dynamics and to determine whether the so‐called memory phenomenon could be operative in some subjects without evidence of structural heart disease.

Methods: This study included 42 unmedicated healthcare volunteers, 23 men and 19 women aged between 20 and 42 (mean 31.7) years. All had normal physical examinations, x‐rays, and transthoracic echocardiograms. The electrocardiograms were also normal with 12‐lead QT interval dispersions of <90ms.

Results: During exercise and recovery, the behavior of the QT intervals permitted the categorization into two groups. In Group 1 (31/42; 73.8% of subjects) the uncorrected QT interval showed a biphasic pattern consisting of a gradual decrease during incremental exercise followed by a gradual increase during recovery. In contrast, the QTc interval had a triphasic pattern resulting from a slight increase during the early phase of exercise, a gradual decrease at the highest rates, and a final increase during recovery as the rate slowed to control values. In Group 2 (11/42; 36.2% of subjects) the behavior was considered as paradoxical since the uncorrected QT interval displayed in a triphasic pattern whereas the QTc interval yielded a tetraphasic pattern due to the fact that both showed a second decrease during recovery while the rate was decreasing.

Conclusions: Analysis of dynamics behavior of the QTc and the uncorrected QT intervals during exercise showed that some normal subjects had a paradoxical behavior which, because of its temporal relation to the phases of exercise, could be an expression of the so‐called memory phenomenon.

Keywords: QT interval, exercise testing, cardiac memory, computer model, ventricular repolarization, action potential duration

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References

  • 1. Gulrajani RM: Computer simulation of action potential duration changes in cardiac tissue. IEEE Comp Cardiol 1987; 244: 629–632 [Google Scholar]
  • 2. Carmeliet E: Repolarization and frequency in cardiac cells. J Physiol 1977; 73: 903–923 [PubMed] [Google Scholar]
  • 3. Boyett MR, Jewell BR: A study of the factors responsible for rate‐dependent shortening of the action potential in mammalian ventricular muscle. J Physiol 1978; 285: 359–380 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 4. Boyett MR, Fedida D: Changes in the electrical activity of dog cardiac Purkinje fibers at high heart rates. J Physiol 1984; 350: 361–391 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 5. Elharrar V, Surawicz B: Cycle length effect on restitution of action potential duration in dog cardiac fibers. Am J Physiol 1983; 244: H782–792 [DOI] [PubMed] [Google Scholar]
  • 6. Pulido M, Moleiro F, Castellanos A, Torres JM, Ruesta V, Myerburg RJ: Paradoxical behavior of QT intervals during exercise (abstr). PRHSJ 1997; 16 (suppl A): 163 [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 7. Bazett HC: An analysis of the time relationship of electrocardiograms. Heart 1920; 7: 353–370 [Google Scholar]
  • 8. Coghlan JG, Madden B, Norell MN, Ilsley CDJ, Mitchell AG: Paradoxical early lengthening and subsequent linear shortening of the QT interval in response to exercise. Eur Heart J 1992; 13: 1325–1328 [DOI] [PubMed] [Google Scholar]
  • 9. Kligfield P, Kevin GL, Okin PM: QTc behavior during treadmill exercise as a function of the underlying QT heart‐rate relationship. J Electrocardiol 1996; 28: 206–210 [DOI] [PubMed] [Google Scholar]
  • 10. Kligfield P, Kevin GL, Okin PM: QT interval heart‐rate relation during exercise in normal men and women: Definition by linear regression analysis. J Am Coll Cardiol 1996; 28: 1547–1555 [DOI] [PubMed] [Google Scholar]
  • 11. Perkiömäki JS, Huikuri HV, Koistinen J, Mäkikallio T, Castellanos A, Myerburg RJ: Heart rate variability and dispersion of QT interval in patients with vulnerability to ventricular tachycardia and ventricular fibrillation after previous myocardial infarction. J Am Coll Cardiol 1997; 30 (5): 1331–1338 [DOI] [PubMed] [Google Scholar]
  • 12. Mirvis DM: Spatial variation of QT intervals in normal persons and patients with acute myocardial infarction. J Am Coll Cardiol 1985; 5 (3): 625–631 [DOI] [PubMed] [Google Scholar]
  • 13. Coumel P, Maison‐Blanche P, Badilini F: Dispersion of ventricular repolarization. Reality? Illusion? Significance? Circulation 1998; 97: 2491–2493 [DOI] [PubMed] [Google Scholar]
  • 14. Ahvine S, Vallin H: Influence of heart rate and inhibition of autonomic tone on the QT interval. Circulation 1982; 65: 433–435 [DOI] [PubMed] [Google Scholar]
  • 15. ZaZa A, Malfatto G, Schwartz PJ: Sympathetic modulation of the relation between ventricular repolarization and cycle length. Circ Res 1991; 68: 1191–1203 [DOI] [PubMed] [Google Scholar]
  • 16. Cappato R, Alboni P, Pedroni P, Gilli G, Antonioli G: Sympathetic and vagal influences on rate‐dependent changes of QT interval in healthy subjects. Am J Cardiol 1991; 68: 1188–1193 [DOI] [PubMed] [Google Scholar]
  • 17. Chialvo DR, Michaels DC, Jalife J: Supernormal excitability as a mechanism of chaotic dynamics of activation in cardiac Purkinje fibers. Circ Res 1990; 66: 525–545 [DOI] [PubMed] [Google Scholar]
  • 18. Shvilkin A, Danilo P Jr, Wang J, Burkhoff D, Anyukhovsky E, Sosunov EA, Hara M, Rosen MR: Evolution and resolution of long‐term cardiac memory. Circulation 1998; 97: 1810–1817 [DOI] [PubMed] [Google Scholar]
  • 19. Litovsky SH, Antzelevitch C: Rate dependence of action potential duration and refractoriness in canine ventricular endocardium differs from that of epicardium: Role of the transient outward current. J Am Coll Cardiol 1989; 14: 1053–1066 [DOI] [PubMed] [Google Scholar]
  • 20. Costard‐Jäckie A, Goetsch B, Antz M, Franz MR: Slow and long‐lasting modulation of myocardial repolarization produced by ectopic activation in isolated rabbit hearts: Evidence for cardiac “memory.” Circulation 1989; 80: 1412–1420 [DOI] [PubMed] [Google Scholar]
  • 21. Elharrar V, Surawicz B: Cycle length effect on restitution of action potential duration in dog cardiac fibers. Am J Physiol 1983; H782–H792 [DOI] [PubMed]
  • 22. Coumel P, Fayn J, Maison‐Blanche P, Rubel P: Clinical relevance of assessing QT dynamicity in Holter recordings. J Electrocardiol 1997; 27 (suppl): 62–66 [DOI] [PubMed] [Google Scholar]

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