QT間期

QT間期
	心電圖顯示用切線法計算的 QT 間期
ICD-10-PCS（英語：ICD-10 Procedure Coding System）	R94.31
ICD-9-CM	89.52
MeSH	D004562
MedlinePlus	003868

QT間期是描述心電圖波形中，Q波開始到T波結束的時間，該電位變化時間近似於從心室開始收縮到結束舒張的時間^[1]。QT間期過長或過短可能代表心律異常和心源性猝死的風險較高。^[1]可能造成QT間期異常的原因包含遺傳疾病（如長QT綜合症）、^[2]藥物（如索他洛爾或替洛利生）、血液電解質失衡（如低鉀血症）或激素失衡（如甲狀腺功能減退症）等。^[3]

測量[編輯]

QT間期最常在II導聯中測量，用於評估系列心電圖，I和V5導聯是II導聯的可比替代品。通常避免使用導聯III、aVL和V1來測量QT間期。^[4]QT間期的準確測量是主觀的，因為T波的末端並不總是明確定義，通常會逐漸與基線融合。^[5]心電圖複合波中的QT間期可以通過不同的方法手動測量，例如閾值法，其中T波的終點由T波的分量與等電基線合併的點或切線法確定，其中T波的終點由從最大下坡點處的T波外推到等電基線的切線的交點確定。^[6]

隨着具有同時12通道記錄的數字心電圖的可用性增加，QT測量也可以通過「疊加中位搏動」方法完成。在疊加中位心搏法中，為12條導聯中的每條導聯構建中位ECG複合波。12個中位心搏相互疊加，QT間期是從Q波的最早開始到T波的最新偏移量或從Q波開始的最大收斂點到T波偏移量測量的。^[7]

心率校正[編輯]

QT間期隨心率而變化，隨着心率的增加，QT間期縮短。這些變化使得比較在不同心率下測量的QT間期變得更加困難。考慮到這一點，從而提高QT測量的可靠性，可以使用各種數學公式對QT間期進行心率（QTc）校正，該過程通常由現代心電圖記錄儀自動執行。

巴澤特公式[編輯]

最常用的QT校正公式是巴澤特公式（Bazett's formula），^[8]該公式以得名自英國生理學家亨利·庫斯伯特·巴澤特（Henry Cuthbert Bazett），^[9]計算心率校正的QT間期（QTcB）。

巴澤特的公式是基於1920年的一項研究的觀察結果。巴澤特的公式通常以返回QTc的形式給出，該QTc以量綱可疑的單位（秒的平方根）為單位。巴澤特公式的數學正確形式是： $QTc_{B}={QT \over {\sqrt {RR \over 1{\text{ s}}}}}$

其中QTcB是針對心率校正的QT間期，RR是從一個QRS波群開始到下一個QRS波群開始的間隔。這個數學上正確的公式以與QT相同的單位返回QTc，通常為毫秒。^[10]

在該公式的一些流行形式中，假設QT以毫秒為單位測量，而RR以秒為單位測量，通常從心率（HR）推導出為60/HR。因此，結果將以每平方根毫秒的秒數為單位。^[11]但是，使用此公式報告QTc會產生「關於測量原始QT和RR的單位的要求」。^[10]

在這兩種形式中，巴澤特的非線性QT校正公式通常被認為是不準確的，因為它在高心率時過度校正，而在低心率時校正不足。^[11]巴澤特校正公式是最適合新生兒的QT校正公式之一。^[12]

弗里德里西亞公式[編輯]

弗里德里西亞提出了一種使用RR的立方根的替代校正公式^[13]： $QTc_{F}={QT \over {\sqrt[{3}]{RR \over 1{\text{ s}}}}}$

薩吉公式[編輯]

弗雷明漢校正公式（Framingham correction），又稱為薩吉公式（Sagie's formula）。該公式源自於弗雷明漢心臟研究（英語：Framingham Heart Study），使用了超過5000名受試者的長期隊列數據，被認為是一種更好的方法。^[14]^[15]

$QTlc=1000\left({\frac {QT}{1000}}+0.154(1-RR)\right)$

同樣，這裡QT和QTlc以毫秒為單位，而RR以秒為單位。

參見[編輯]

參考文獻[編輯]

^ ^1.0 ^1.1 Postema, Pieter G.; Wilde, Arthur A. M. The measurement of the QT interval. Current Cardiology Reviews. 2014-08, 10 (3) [2022-06-20]. ISSN 1875-6557. PMC 4040880 . PMID 24827793. doi:10.2174/1573403x10666140514103612. （原始內容存檔於2022-08-02）.
^ Long QT syndrome - Symptoms and causes. Mayo Clinic. [2022-06-20]. （原始內容存檔於2022-07-26）（英語）.
^ Nachimuthu, Senthil; Assar, Manish D.; Schussler, Jeffrey M. Drug-induced QT interval prolongation: mechanisms and clinical management. Therapeutic Advances in Drug Safety. 2012-10, 3 (5) [2022-06-20]. ISSN 2042-0986. PMC 4110870 . PMID 25083239. doi:10.1177/2042098612454283. （原始內容存檔於2022-08-03）.
^ Panicker, Gopi Krishna; Salvi, Vaibhav; Karnad, Dilip R.; Chakraborty, Saikat; Manohar, Deepak; Lokhandwala, Yash; Kothari, Snehal. Drug-induced QT prolongation when QT interval is measured in each of the 12 ECG leads in men and women in a thorough QT study. Journal of Electrocardiology. 2014-03, 47 (2) [2022-06-20]. ISSN 1532-8430. PMID 24388488. doi:10.1016/j.jelectrocard.2013.11.004. （原始內容存檔於2022-07-02）.
^ Panicker, Gopi Krishna; Karnad, Dilip R.; Joshi, Rajesh; Shetty, Sheetal; Vyas, Niraj; Kothari, Snehal; Narula, Dhiraj. Z-score for benchmarking reader competence in a central ECG laboratory. Annals of Noninvasive Electrocardiology: The Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc. 2009-01, 14 (1). ISSN 1542-474X. PMC 6932360 . PMID 19149789. doi:10.1111/j.1542-474X.2008.00269.x.
^ Panicker, Gopi Krishna; Karnad, Dilip R.; Natekar, Mili; Kothari, Snehal; Narula, Dhiraj; Lokhandwala, Yash. Intra- and interreader variability in QT interval measurement by tangent and threshold methods in a central electrocardiogram laboratory. Journal of Electrocardiology. 2009-07, 42 (4) [2022-06-20]. ISSN 1532-8430. PMID 19261293. doi:10.1016/j.jelectrocard.2009.01.003. （原始內容存檔於2022-07-11）.
^ Salvi, Vaibhav; Karnad, Dilip R.; Panicker, Gopi Krishna; Natekar, Mili; Hingorani, Pooja; Kerkar, Vaibhav; Ramasamy, Arumugam; de Vries, Michiel; Zumbrunnen, Troy; Kothari, Snehal; Narula, Dhiraj. Comparison of 5 methods of QT interval measurements on electrocardiograms from a thorough QT/QTc study: effect on assay sensitivity and categorical outliers. Journal of Electrocardiology. 2011-03, 44 (2) [2022-06-20]. ISSN 1532-8430. PMID 21238976. doi:10.1016/j.jelectrocard.2010.11.010. （原始內容存檔於2022-06-18）.
^ Bazett, H. C. AN ANALYSIS OF THE TIME-RELATIONS OF ELECTROCARDIOGRAMS.. Annals of Noninvasive Electrocardiology. 1997-04, 2 (2) [2022-06-20]. ISSN 1082-720X. doi:10.1111/j.1542-474X.1997.tb00325.x. （原始內容存檔於2022-07-10）（英語）.
^ Roguin, Ariel. Henry Cuthbert Bazett (1885-1950)--the man behind the QT interval correction formula. Pacing and clinical electrophysiology: PACE. 2011-03, 34 (3) [2022-06-20]. ISSN 1540-8159. PMID 21091739. doi:10.1111/j.1540-8159.2010.02973.x. （原始內容存檔於2022-07-08）.
^ ^10.0 ^10.1 Molnar, J.; Weiss, J. S.; Rosenthal, J. E. The missing second: what is the correct unit for the Bazett corrected QT interval?. The American Journal of Cardiology. 1995-03-01, 75 (7) [2022-06-20]. ISSN 0002-9149. PMID 7864010. doi:10.1016/s0002-9149(99)80603-1. （原始內容存檔於2020-08-06）.
^ ^11.0 ^11.1 Salvi, Vaibhav; Karnad, Dilip R.; Panicker, Gopi Krishna; Kothari, Snehal. Update on the evaluation of a new drug for effects on cardiac repolarization in humans: issues in early drug development. British Journal of Pharmacology. 2010-01, 159 (1) [2022-06-20]. ISSN 1476-5381. PMC 2823350 . PMID 19775279. doi:10.1111/j.1476-5381.2009.00427.x. （原始內容存檔於2022-07-04）.
^ Stramba-Badiale, Marco; Karnad, Dilip R.; Goulene, Karine M.; Panicker, Gopi Krishna; Dagradi, Federica; Spazzolini, Carla; Kothari, Snehal; Lokhandwala, Yash Y.; Schwartz, Peter J. For neonatal ECG screening there is no reason to relinquish old Bazett's correction. European Heart Journal. 2018-08-14, 39 (31) [2022-06-20]. ISSN 1522-9645. PMID 29860404. doi:10.1093/eurheartj/ehy284. （原始內容存檔於2022-06-20）.
^ Fridericia, L. S. The duration of systole in an electrocardiogram in normal humans and in patients with heart disease. 1920. Annals of Noninvasive Electrocardiology: The Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc. 2003-10, 8 (4) [2022-06-20]. ISSN 1082-720X. PMC 7328879 . PMID 14516292. doi:10.1046/j.1542-474x.2003.08413.x. （原始內容存檔於2022-07-10）.
^ Vandenberk, Bert; Vandael, Eline; Robyns, Tomas; Vandenberghe, Joris; Garweg, Christophe; Foulon, Veerle; Ector, Joris; Willems, Rik. Which QT Correction Formulae to Use for QT Monitoring?. Journal of the American Heart Association. 2016-06-17, 5 (6) [2022-06-20]. ISSN 2047-9980. PMC 4937268 . PMID 27317349. doi:10.1161/JAHA.116.003264. （原始內容存檔於2022-08-05）.
^ Sagie, A.; Larson, M. G.; Goldberg, R. J.; Bengtson, J. R.; Levy, D. An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study). The American Journal of Cardiology. 1992-09-15, 70 (7) [2022-06-20]. ISSN 0002-9149. PMID 1519533. doi:10.1016/0002-9149(92)90562-d. （原始內容存檔於2022-07-16）.

外部連結[編輯]

Corrected QT Interval (QTc). MDCalc. [2022-06-20]. （原始內容存檔於2022-01-20）（英語）.

[eurekaselect-1] 1.0 ^1.1 Postema, Pieter G.; Wilde, Arthur A. M. The measurement of the QT interval. Current Cardiology Reviews. 2014-08, 10 (3) [2022-06-20]. ISSN 1875-6557. PMC 4040880 . PMID 24827793. doi:10.2174/1573403x10666140514103612. （原始內容存檔於2022-08-02）.

[2] Long QT syndrome - Symptoms and causes. Mayo Clinic. [2022-06-20]. （原始內容存檔於2022-07-26）（英語）.

[3] Nachimuthu, Senthil; Assar, Manish D.; Schussler, Jeffrey M. Drug-induced QT interval prolongation: mechanisms and clinical management. Therapeutic Advances in Drug Safety. 2012-10, 3 (5) [2022-06-20]. ISSN 2042-0986. PMC 4110870 . PMID 25083239. doi:10.1177/2042098612454283. （原始內容存檔於2022-08-03）.

[4] Panicker, Gopi Krishna; Salvi, Vaibhav; Karnad, Dilip R.; Chakraborty, Saikat; Manohar, Deepak; Lokhandwala, Yash; Kothari, Snehal. Drug-induced QT prolongation when QT interval is measured in each of the 12 ECG leads in men and women in a thorough QT study. Journal of Electrocardiology. 2014-03, 47 (2) [2022-06-20]. ISSN 1532-8430. PMID 24388488. doi:10.1016/j.jelectrocard.2013.11.004. （原始內容存檔於2022-07-02）.

[5] Panicker, Gopi Krishna; Karnad, Dilip R.; Joshi, Rajesh; Shetty, Sheetal; Vyas, Niraj; Kothari, Snehal; Narula, Dhiraj. Z-score for benchmarking reader competence in a central ECG laboratory. Annals of Noninvasive Electrocardiology: The Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc. 2009-01, 14 (1). ISSN 1542-474X. PMC 6932360 . PMID 19149789. doi:10.1111/j.1542-474X.2008.00269.x.

[6] Panicker, Gopi Krishna; Karnad, Dilip R.; Natekar, Mili; Kothari, Snehal; Narula, Dhiraj; Lokhandwala, Yash. Intra- and interreader variability in QT interval measurement by tangent and threshold methods in a central electrocardiogram laboratory. Journal of Electrocardiology. 2009-07, 42 (4) [2022-06-20]. ISSN 1532-8430. PMID 19261293. doi:10.1016/j.jelectrocard.2009.01.003. （原始內容存檔於2022-07-11）.

[7] Salvi, Vaibhav; Karnad, Dilip R.; Panicker, Gopi Krishna; Natekar, Mili; Hingorani, Pooja; Kerkar, Vaibhav; Ramasamy, Arumugam; de Vries, Michiel; Zumbrunnen, Troy; Kothari, Snehal; Narula, Dhiraj. Comparison of 5 methods of QT interval measurements on electrocardiograms from a thorough QT/QTc study: effect on assay sensitivity and categorical outliers. Journal of Electrocardiology. 2011-03, 44 (2) [2022-06-20]. ISSN 1532-8430. PMID 21238976. doi:10.1016/j.jelectrocard.2010.11.010. （原始內容存檔於2022-06-18）.

[8] Bazett, H. C. AN ANALYSIS OF THE TIME-RELATIONS OF ELECTROCARDIOGRAMS.. Annals of Noninvasive Electrocardiology. 1997-04, 2 (2) [2022-06-20]. ISSN 1082-720X. doi:10.1111/j.1542-474X.1997.tb00325.x. （原始內容存檔於2022-07-10）（英語）.

[9] Roguin, Ariel. Henry Cuthbert Bazett (1885-1950)--the man behind the QT interval correction formula. Pacing and clinical electrophysiology: PACE. 2011-03, 34 (3) [2022-06-20]. ISSN 1540-8159. PMID 21091739. doi:10.1111/j.1540-8159.2010.02973.x. （原始內容存檔於2022-07-08）.

[elsevier-10] 10.0 ^10.1 Molnar, J.; Weiss, J. S.; Rosenthal, J. E. The missing second: what is the correct unit for the Bazett corrected QT interval?. The American Journal of Cardiology. 1995-03-01, 75 (7) [2022-06-20]. ISSN 0002-9149. PMID 7864010. doi:10.1016/s0002-9149(99)80603-1. （原始內容存檔於2020-08-06）.

[wiley-11] 11.0 ^11.1 Salvi, Vaibhav; Karnad, Dilip R.; Panicker, Gopi Krishna; Kothari, Snehal. Update on the evaluation of a new drug for effects on cardiac repolarization in humans: issues in early drug development. British Journal of Pharmacology. 2010-01, 159 (1) [2022-06-20]. ISSN 1476-5381. PMC 2823350 . PMID 19775279. doi:10.1111/j.1476-5381.2009.00427.x. （原始內容存檔於2022-07-04）.

[12] Stramba-Badiale, Marco; Karnad, Dilip R.; Goulene, Karine M.; Panicker, Gopi Krishna; Dagradi, Federica; Spazzolini, Carla; Kothari, Snehal; Lokhandwala, Yash Y.; Schwartz, Peter J. For neonatal ECG screening there is no reason to relinquish old Bazett's correction. European Heart Journal. 2018-08-14, 39 (31) [2022-06-20]. ISSN 1522-9645. PMID 29860404. doi:10.1093/eurheartj/ehy284. （原始內容存檔於2022-06-20）.

[13] Fridericia, L. S. The duration of systole in an electrocardiogram in normal humans and in patients with heart disease. 1920. Annals of Noninvasive Electrocardiology: The Official Journal of the International Society for Holter and Noninvasive Electrocardiology, Inc. 2003-10, 8 (4) [2022-06-20]. ISSN 1082-720X. PMC 7328879 . PMID 14516292. doi:10.1046/j.1542-474x.2003.08413.x. （原始內容存檔於2022-07-10）.

[14] Vandenberk, Bert; Vandael, Eline; Robyns, Tomas; Vandenberghe, Joris; Garweg, Christophe; Foulon, Veerle; Ector, Joris; Willems, Rik. Which QT Correction Formulae to Use for QT Monitoring?. Journal of the American Heart Association. 2016-06-17, 5 (6) [2022-06-20]. ISSN 2047-9980. PMC 4937268 . PMID 27317349. doi:10.1161/JAHA.116.003264. （原始內容存檔於2022-08-05）.

[15] Sagie, A.; Larson, M. G.; Goldberg, R. J.; Bengtson, J. R.; Levy, D. An improved method for adjusting the QT interval for heart rate (the Framingham Heart Study). The American Journal of Cardiology. 1992-09-15, 70 (7) [2022-06-20]. ISSN 0002-9149. PMID 1519533. doi:10.1016/0002-9149(92)90562-d. （原始內容存檔於2022-07-16）.

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