**4. Electrocardiography in Paediatric myocardial infarction**

The 12-lead ECG is an integral part of the evaluation of coronary artery disease [16]. Elevation of the J point which joins the QRS and the ST segment is the first finding of myocardial ischaemia [7]. Compared to baseline, an elevation of 1–2 mm is seen in the J point and the ST segment in myocardial ischaemia. An elevation of >2 mm should rouse suspicion of MI (**Figures 1** and **2**). When ST elevation is determined, there should be a progression through differential diagnosis of benign early repolarisation, pericarditis, MI, bundle branch block and left ventricle aneurism [18]. While pathological ST elevation does not show variability, J point and ST elevation seen in early repolarisation in healthy adults is generally corrected with isoproteronol infusion or exercise [19].

The presence of PR segment depression is an ECG finding which is valuable in the differentiation of myopericarditis from MI in favour of myopericarditis [18]. The positive predictive value of PR depression seen in chest and extremity derivations has been determined to be 96.7% [19].

T-wave alterations generally accompany ST segment alterations in AMI. Initially, T-waves may be long and sharp (hyperacute T-wave). These changes determined on ECG show myocardial injury (**Figure 3**). ST depression may reflect the reciprocal effect of the region in the derivation corresponding to approximately 180° [7]. The standard leads does not show ST segment elevation in patients with true posterior wall MI. Instead ST elevation, ST segment depression may be seen as a reciprocal change in V4R-V2 on the ECG [20, 21].

Electrocardiographic findings that show recent MI are pathological Q-waves. A long Q-wave from 3 small squares (0.12 secs) in whichever derivation should be evaluated as pathological Q. In addition, broad Q-wave in V1 and V2 may be seen in patients with left ventricle hypertrophy. In short, the evaluation of anamnesis, physical examination and laboratory findings together with the ECG findings is important for every patient.

**Figure 2.** Coronary angiography revealed total occlusion of the left anterior descending [LAD] and distal circumflex

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**Figure 3.** In this patient with aortic stenosis, ST depression on V4–6 and negative T wave show that coronary ischemia.

(CX) coronary arteries (red arrows).

Generally pathological Q-waves are seen to emerge within the first 12–48 hours on at least 2 adjacent leads, and when they are present at inferior, lateral or anterior derivations, they have

**Figure 1.** 2–3 mm ST elevations in DII, DIII, aVF, V5, and V6 leads of electrocardiography show that myocardial infarction.

**4. Electrocardiography in Paediatric myocardial infarction**

96.7% [19].

104 Myocardial Infarction

The 12-lead ECG is an integral part of the evaluation of coronary artery disease [16]. Elevation of the J point which joins the QRS and the ST segment is the first finding of myocardial ischaemia [7]. Compared to baseline, an elevation of 1–2 mm is seen in the J point and the ST segment in myocardial ischaemia. An elevation of >2 mm should rouse suspicion of MI (**Figures 1** and **2**). When ST elevation is determined, there should be a progression through differential diagnosis of benign early repolarisation, pericarditis, MI, bundle branch block and left ventricle aneurism [18]. While pathological ST elevation does not show variability, J point and ST elevation seen in early repolarisation in healthy adults is generally corrected with isoproteronol infusion or exercise [19].

The presence of PR segment depression is an ECG finding which is valuable in the differentiation of myopericarditis from MI in favour of myopericarditis [18]. The positive predictive value of PR depression seen in chest and extremity derivations has been determined to be

T-wave alterations generally accompany ST segment alterations in AMI. Initially, T-waves may be long and sharp (hyperacute T-wave). These changes determined on ECG show myocardial injury (**Figure 3**). ST depression may reflect the reciprocal effect of the region in the derivation corresponding to approximately 180° [7]. The standard leads does not show ST segment elevation in patients with true posterior wall MI. Instead ST elevation, ST segment

Electrocardiographic findings that show recent MI are pathological Q-waves. A long Q-wave from 3 small squares (0.12 secs) in whichever derivation should be evaluated as pathological Q. In addition, broad Q-wave in V1 and V2 may be seen in patients with left ventricle hypertrophy. In short, the evaluation of anamnesis, physical examination and laboratory findings

Generally pathological Q-waves are seen to emerge within the first 12–48 hours on at least 2 adjacent leads, and when they are present at inferior, lateral or anterior derivations, they have

**Figure 1.** 2–3 mm ST elevations in DII, DIII, aVF, V5, and V6 leads of electrocardiography show that myocardial infarction.

depression may be seen as a reciprocal change in V4R-V2 on the ECG [20, 21].

together with the ECG findings is important for every patient.

**Figure 2.** Coronary angiography revealed total occlusion of the left anterior descending [LAD] and distal circumflex (CX) coronary arteries (red arrows).

**Figure 3.** In this patient with aortic stenosis, ST depression on V4–6 and negative T wave show that coronary ischemia.

got extremely high value for the diagnosis of MI [1, 21]. However, in Paediatric patients, the determination of Q-wave in just one derivation could even be sufficient to determine MI [21]. While these Q-waves show infarct of the myocardial wall, high R waves in V1 and/or V2 (negative Q-waves) may represent true posterior wall MI. On the ECG of approximately half of cases, pathological Q-waves have a tendency to regress with time. In newborn infants, the presence of Q-waves in derivations DII, DIII and AVF may be normal. Furthermore, if ECG leads are placed on the upper part of the chest, Q-waves can be incorrectly shown in V5–6 that can cause misinterpretation of an integral part of the evaluation of coronary artery disease [16]. Elevation of the J point that joins the QRS and the ST segment is the first finding of myocardial ischaemia [7]. Compared to baseline, an elevation of 1–2 mm of the J point and the ST segment can be determined in myocardial ischaemia. An elevation of >2 mm should rouse suspicion of MI [7].

In the adult guidelines of MI criteria, it is stated that there should be ECG changes in more than one lead [23]. However, in Paediatric cases, when there are ECG changes in one derivation, there should be suspicion of MI [3]. Moreover, the observation on ECG of more than one of these changes, such as ST elevation, Q-wave changes, ST depression or T-wave inversion

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An increase in the level of enzymes released into circulation from cells exposed to injury is important in the diagnosis of MI. These enzymes are creatine kinase myocardial band (CK-MB) and troponin [7, 10]. In all Paediatric cases thought to have myocardial damage, the troponin level should be examined. Values more than 2 ng/ml value are especially more valuable for cardiac origin [17]. Even in cases of mild damage in myocardial cells, an increase in enzyme levels may be seen [19]. In addition, the events causing an increase in troponin levels must be known

The increasing experience with echocardiography [echo] in recent decades has greatly facilitated the diagnosis of acute myocardial infarction [AMI], as echo is an inexpensive, readily available, ambulatory, non-invasive method [24]. **Echo is useful, not only in the diagnosis of AMI but also in prognosis, the monitoring of complications and in follow-up.** In Paediatric AMI patients, echo provides very valuable information in the determination of segmentary wall movement abnormalities and in the diagnosis of CHD, pericarditis, myocarditis, Kawasaki disease, cardiomyopathy, aortic stenosis and ALCAPA which often accompanies chest pain. In adult studies, abnormal wall movement findings have been determined in 91% of patients applied with echo in the early stage in

**6. Echocardiographic evaluation of Paediatric acute myocardial** 

should more strongly suggest MI diagnosis.

**5. Cardiac enzymes**

(**Table 3**) [6].

**infarction**

Acute heart failure Cardiac contusion Myopericarditis Pulmonary embolism

Strenuous exercise Sympatomimetic drugs Tachyarrhythmia

**Table 3.** Non-coronary events which increase troponin.

Sepsis

When the clinician has suspicions on the resence of pathological Q-wave, ECG in deep inspirium can be helpful. There is a change in the voltage of the Q-waves in physiological cases while there is no change of voltage at deep inspirium in pathological Q waves [7]. Towbin et al. reported that the presence of Q-waves wider than 35 msn on ECG was the most valuable finding for MI and a diagnosis of transmural MI diagnosis should not be made in patients with no Q-wave abnormalities [2].

Towbin et al. evaluated the ECG and clinical findings in the pre-MI records of 37 patients who died because of MI. In this retrospective study, it was reported that findings of MI were determined on the pre-mortem ECG records of 28 children who suffered fatal acute MI, while it was reported in 9 cases who died because of chronic MI [3]. It was also reported by the same authors that when MI was determined in a hypertrophic heart, the infarction was determined at the hypertrophic ventricle. This showed that in PMI, the presence of hypertrophy was a risk factor for MI. At least one of the criteria shown in the **Table 2** was determined to be present in 30 patients included into the study by Towbin et al [2]. Furthermore, no finding was determined on ECG in approximately 19% of the cases in that study, ECG was not sufficient to make a diagnosis of PMI alone. The evaluation of the patient should be made together with the anamnesis, physical examination, ECG and laboratory data.

Furthermore, Nakanishi et al. showed that deep Q-waves were a good marker for MI in Kawasaki patients. It was also determined in the same study that T-wave inversion in derivations II, III and AVF showed MI in the inferior wall [22].

**Table 2.** Electrocardiographic findings significant for MI in children, as reported by Towbin et al.

**<sup>1.</sup>**New appearance of wide Q waves >35 ms in duration

**<sup>2.</sup>**Increased amplitude or duration [>35 ms] of pre-existing Q waves

**<sup>3.</sup>**New onset Q waves in serial tracings

**<sup>4.</sup>**Q waves notching

**<sup>5.</sup>**ST segment elevation [≥2 mm] and prolonged QT interval corrected for heart rate [>440 ms] with any other criteria.

In the adult guidelines of MI criteria, it is stated that there should be ECG changes in more than one lead [23]. However, in Paediatric cases, when there are ECG changes in one derivation, there should be suspicion of MI [3]. Moreover, the observation on ECG of more than one of these changes, such as ST elevation, Q-wave changes, ST depression or T-wave inversion should more strongly suggest MI diagnosis.
