T waves morphology

Measurement of QT interval Definition of the end of the T wave. Changes in T wave morphology and occurrence of U waves (these may be important warning signs and precede the occurrence of TdP) Errors in manual measurement in QT interval Variability in the heart rate (need to correct the QT value for heart rate) Lack of reliable correlation between readings from Holter recordings and standard ECG Lack of standardization of automated ECG readings (computerized methods are often unreliable) Need for a central core laboratory to analyze data... 

Occasionally, the first change observed in an anteroseptal infarction, even extensive, is the increase in the T-wave amplitude in the right precordial leads, due to the acute subendocardium ischaemia in a heart without much prior ischaemia. This T-wave morphology may be interpreted as pseudonormal, and it should be readily recognised and differentiated from the normal T wave. In this case the recording of evolutionary ECG is mandatory (Figure 8.7). 

Furthermore, the meticulous study of the QRS complex or the T-wave morphology of the PVC allows for suspicion of an old infarction (qR morphology, with a wide q wave or slurred QS complex, with a sometimes symmetric T wave). 

Electrophysiological responses Action potential duration (QT interval) Repolarization (T wave morphology) Excitability Risk of arrhythmia... 

Hanton G, Yvon A, Racaud A (2008). Temporal variability of QT interval and changes in T wave morphology in dogs as markers of the clinical risk of drug-induced proarrhythmia. J Pharmacol Toxicol Methods 51(3) 194—201. 

Assessment of T-wave morphology may also provide relevant information. Vincente and colleagues (Vicente et al. 2015) noted that patients with LQT2 can develop flat, asynunetric, and notched T waves while also noting that we do not know how additional block of calcium or late sodium channels, which decrease... 

Vicente J, Johannesen L, Mason JW et al (2015) Comprehensive T wave morphology assessment in a randomized clinical study of dofetilide, quinidine, ranolazine, and verapamil. J Am Heart... 

Acute cardiotoxicity is seen in approximately 1 % of cancer patients. The cardiotoxicity manifests as acute pericarditis/myocarditis. Characteristics include a transient decline in indices of myocardial contractility as seen by the employment of echocardiography and the combination of alterations in the ST segment and T-wave morphology in conjunction with prolongation of the QT interval as seen on the ECG. Early-onset chronic cardiotoxicity, which is dose dependent, has been reported in 1.6-2.1% of patients late-onset cardiomyopathy is observed in up to 5 % of patients (Curighano et al. 2012). 

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