Gökhan LAFÇI, Mahmut Mustafa ULAŞ, Kumral ERGÜN, Hikmet Selçuk GEDİK, Kerim ÇAĞLI

QT and P wave dispersion

Refrakter periyodun ve iletim hızının heterojenitesi re-entran aritmilerin temel mekanizmasını oluşturur.Ventriküler refrakteritenin heterojenitesini gösteren indekslerden biri yüzey elektrökardiyogramından (EKG) elde edilen QT dispersiyonudur. QT dispersiyonunu hesaplamada en çok kullanılan yöntem 12 derivasyonlu EKG'de en uzun ve en kısa QT intervalinin farkının alınıp hıza veya kullanılan derivasyon sayısına göre düzeltilmesidir.Anormal olarak artmış QT dispersiyonu bazı hastalıklarda (kardiyak ve nonkardiyak) aritmik ölüm riskini artırır. QT dispersiyonu bazı ilaçların etkinlik ve proaritmik potansiyeli hakkında da fikir veren basitpratiKucuz bir parametredir. Bu derlemede QT dispersiyonunun ölçümü, yorumu, klinik önemi ve diğer bir kavram olan P dispersiyonu anlatılmıştır.

QT ve P dispersiyonu

Heterogeneity in refractoriness and conduction velocity is the main mechanism of reentrant ar-rhythmias. One of the indexes which show the heterogeneity of ventricular refractoriness is QT dispersion, which is found in surface ECG leads. The most commonly used index to calculate this QT dispersion is the difference between the longest and shortest QT intervals on the 12 lead ECG, which is often adjusted for heart rate as well as number of leads sampled. Abnormally high QT dispersion has been correlated with risk of arrhythmic death in a variety of disorders (cardiac and noncardiac). Also, QT dispersion is an easy, practical and cheap parameter which has been correlated with efficacy and proarrhythmic potential of drug therapy. In this review, the measurement techniques, interpretation, clinical importance of QT dispersion and another related subject, P wave dispersion, are mentioned.

PDF

___

1. Horan LG, Flowers NC, Brody DA. Principal factor waveforms of the thoracic QRS complex. Circ Res 1964;XV:131-145.
2. Day CP, McComp LM, Campbell RWF. QT dispersion: an indication of arrhythmia risk in patients with long QT intervals. Br Heart J 1990;63:342-344.
3. Hnatkova K, Malik M, Yi G, Camm AJ. Adjustment of QT dispersion assessed from 12 lead ECGs for differentnumberofanalysed electrocardiographic leads: comparison of stability of differentmethods.BrHeartJ1994;72:390-396.
4. de Bruyne MC, Hoes AW, Kors JA, et al.QTc dispersion predicts cardiac mortality in the elderly. TheRotterdamStudy.Circulation1998;97:467-472.
5. Okin PM, Devereux RB, Howard B, et al.Assessment of QT interval and QT dispersion for prediction of all cause and cardiovascular mortality in American Indians. TheStrongHeartStudy. Circulation 2000;101:61-66.
6. Kautzner J, Yi G, Camm AJ, et al. Short and long term reproducibility of QT, QTc and QT dispersion measurement in healthy subjects. PACE 1994;17:928-937.
7. Kors JA, van Herpen G, van Bemmel JH. QT dispersion as an attribute of T loop morphology. Circulation 1999;99:1458-63.
8. Somberg JC, Molnar J. Usefulness of QT dispersion as an electrocardiographically derived index. Am J Cardiol 2002; 89:291-294.
9. Murray A, Mc Laughlin NB, Bourke JP, et al. Errors in manual measurement of QT intervals. Br Heart J 1994; 71:386-390.
10. Malik M, Bradford A. Human precision of operating a digitizing board:implications for electrocardiogram measurement. PACE 1998;21:1656-1662.
11. Davey PP, Bateman J, Mulligan IP et al. QT interval dispersion in chronic heart failure and left ventricular hypertrophy: relation to autonomic nervous system and Holter tape abnormalities. Br Heart J 1994;71:268-273.
12. Goldner B, Brandspiegel Hz, Horwitz L, et al. Utility of QT dispersion combined with the signal averaged electrocardiogram in detecting patients susceptible to ventricular tachyarrhythmia. Am J Cardiol 1995;76:1192-1194.
13. Macfarlane PW, on behalf of the WOSCOPS: QT dispersion-lack of discriminating power (abstr). Circulation 1998;98 Suppl:I-81.
14. Glancy JM, Garrat CJ, de Bono DP. Dynamics of QT dispersion during myocardial infarction and ischemia. Int J Cardiol 1996; 57:55-60.
15. Yap YG, Yi G, Guo XH, et al. Dynamic changes of QT dispersion and its relationship with clinical variables and arrhythmic events after myocardial infarction (abstr). J Am Coll Cardiol 1999;33 Suppl A:107 A.
16. Malik M, Velislav N, Batchvarov. Measurement, interpretation and clinical potential of QT dispersion. J Am Coll Cardiol 2000; 36:1749-1766.
17. Choi KJ, Lee CW, Kang DH. Change of QT dispersion after PTCA in angina patients. Ann Noninvas Electrocardiol 1999; 4:195-199.
18. Veglio M, Bruno G, Borra M, et al. Prevalance of increased QT interval duration and dispersion in type 2 diabetic patients and its relationship with coronary heart disease: a population-based cohort. J Intern Med 2002;251:317-324.
19. Beaubien ER, Pylypchuk GB, Akhtar J, et al.Value of corrected QT interval dispersion in identifying patients initiating dialysis at increased risk of total and cardiovascular mortality. Am J Kidney Dis 2002;39:834-842.
20. Papandonokis E, Tsoukas A, Christakos S QT dispersion as a noninvasive arrhytmogenic marker in acute myocardial infarction. Ann Noninvas Electrocardiol 1999;4:35-38.
21. Lee KW, Okin PM, KligfieldP,etal.PrecorfialQTdispersionandinducible ventricular tachycardia. Am Heart J 1997;134:1005-1013.
22. Brooksby P, Robinson PJ, Segal R et al.on behalf of the ELITE study group. EffectsoflosartanandcaptoprilonQTdispersioninelderly patients with heart failure. Lancet 1999;534:395-396.
23. Baranowski R, Malecka L, Poplawska W et al. Analysis of QT dispersion in patients with hypertrophic cardiomyopathy-correlation with clinical data and survival (abstr). Eur Heart J 1998; 19:Suppl:428.
24. Priori SG, Napolitano C, Diehl L et al. Dispersion of the QT interval. A marker of therapeutic efficacyintheidiopathiclongQTsyndrome. Circulation 1994;89:1681-1689.
25. Cui G, Sen L, Sager P, et al. Effectsofamiodarone,sematilideandsotalol on QT dispersion. Am J Cardiol 1994;74:896-900.
26. Sicouri S, Moro S, Litovsky S, et al. Chronic amiodarone reduces transmural dispersion of repolarization in the canine heart. J Cardiovasc Electrophysiol 1997;8:1269-1279.
27. Torres J, Tepper D, Flowers D, et al. QT prolongation and the antiarrhythmic efficacyofamiodarone.J AmCollCardiol1986;7:142-147.
28. Kose S, Iyisoy E,Barcin C, et al. Seasonal variation of P wave dispersion in healthy subjects. J Electrocardiol 2002; 35:307-311.
29. Dilaveris PE, Gialafus JE. P wave dispersion: a novel predictor of paroxysmal AF. Ann Noninvasive Electrocardiol 2001;6:159-165.
30. Szabo Z, Kabuk G, Fulop T, et al. Effectsofhaemodialysisonmaximum P wave duration and P wave dispersion. Nephrol Dial Transplant 2002;17:1634-1638.
31. Tukek T et al. Factors associated with the development of AF in COPD patients: the role of P wave dispersion. Ann Noninvasive Electrocardiol 2002;7:222-227.
32. Tsikouris JP, Kuger J, Song J et al. Changes in P wave dispersion and P wave duration after open heart surgery associated with the peak incidence of AF. Heart Lung 2001;30:466-471.
33. Ho TF, Chia EL, Yip WC, et al. Analysis of P wave and P dispersion in children with secundum ASD. Ann Noninvasive Electrocardiol 2001;6:305-309.
34. Özmen F, Atalar E, Aytemir K, et al. Effectsofballooninducedacute ischemia on P wave dispersion during PTCA. Europace 2001;3:299-303.
35. Tukek T, Atilgan D, Akkaya et al. Effectsofleftatrialsizeand function on P wave dispersion : a study in patients with paroxysmal AF. Clin Cardiol 2001;24:676-860.
36. Ozer N, Aytemir K, Ataler E, et al. P wave dispersion in hypertensive patients with paroxysmal AF. Pacing Clin Electrophysiol 2000;23:1859-1862.
37. Cui G, Kabashigawa J, Chung T, et al. Atrial conduction disturbance as an indicator of rejection after cardiac transplantation. Transplantation 2000;70:223-227.
38. Andrikopoulos GK, Dilaveris PE, Richter D, et al. Increased variance of P wave duration on the electrocardiogram distinguishes patients with idiopathic paroxysmal atrial fibrillation.PacingClinElectrophysiol 2000;23:1127-1132.
39. Dilaveris PE, Gialafos EJ, Sideris SK et al. Simple electrocardiographic markers for the prediction of paroxysmal idiopathic atrial fibrillation.AmHeartJournal1998;135:733-738.