4/6/2023 0 Comments Ivcd with st elevation![]() ![]() LBBB is associated with secondary ST- T wave abnormality which leads to deviation of ST segment in the opposite direction to major QRS deflection (Figure 7). However, after acute STEMI or cardiac surgery, focal pericarditis may lead to localized STE with ST depression in leads other than AVR and V1 and can be confused with a STEMI (Ariyarajah & Spodick, 2007). Stage 2 pericarditis may involve PR depressions. Diffuse nature of STE differentiates it from STEMI due to an occlusion of a single coronary artery. Diffuse STE with reciprocal ST depressions in leads AVR and V1 are hallmark features of stage 1 pericarditis (Figure 6). Moreover, LVH may present in combination with early repolarization or intraventricular conduction delay and more than one pattern of NISTE may be seen in the same patient. It is of utmost importance that it be differentiated from left main territory ischemia pattern (STE in AVR and V1, ST depression in precordial and inferior leads) It has to be kept in mind that patient with LBBB and LVH do not have the usual cutoffs for STE (Thygesen, et al., 2007). ![]() Concomitant ST elevation in AVR may also be seen. Common associated findings include QRS voltage fulfilling criteria for LVH and a ST depression in the lateral leads I, aVL, V5 and V6. It is observed most commonly in leads V1 – V3 (same leads as the normal variant pattern) (Figure 5). The patterns do occur simultaneously in many patients. “Normal variant” and “early repolarization” patterns are considered to be the same by some investigators. Lack of QRS voltage criteria for left ventricular hypertrophy (LVH) and absence of concomitant ST depressions in lateral leads differentiates it from NISTE associated with LVH. It is observed more frequently in young African American and Hispanic males. Leads V1- V3 most commonly demonstrate the normal variant pattern (Wang, et al., 2003) (Figure 4). Their limited distribution in leads V1- V3 serves as a distinguishing feature (Nasir et al., 2004). Another etiology that can be confused with J point notching is epsilon waves (observed only in leads V1- V3) in Arrhythmogenic right ventricular dysplasia. Hyperkalemia is another cause of ST elevation but is accompanied by widening of QRS interval and changes in PR segment. QT interval prolongation is seen with hypothermia whereas hypercalcemia is usually associated with QT interval shortening (Nishi, Barbagelata, Atar, Birnbaum, & Tuero, 2006). Osborne waves may also be seen in hypercalcemia and nervous system disorders. Bradycardia and tremor are frequently seen with hypothermia. Prominent J point notching- also known as Osborne waves may be seen transiently in hypothermia (Spodick, 2006), and should not be confused with benign early repolarization. However, there is recent data to suggest its association with fatal arrhythmias, especially if there is STE of > 0.2 mV (Haissaguerre et al., 2008 Myerburg & Castellanos, 2008 Nam, Kim, & Antzelevitch, 2008 Tikkanen, et al., 2009). Early repolarization NISTE was previously thought to be benign in etiology given nearly 5% prevalence in normal population (Klatsky, Oehm, Cooper, Udaltsova, & Armstrong, 2003 Tikkanen et al., 2009). The underlying pathophysiology associated with early repolarization still remains a matter of controversy as some investigators consider it not to be secondary to early repolarization of the ventricle (Mirvis, 1982). Comparison with previous ECGs can serve as a valuable tool. Occasionally, T wave inversions may also be observed in precordial leads which are believed to be associated with juvenile T waves and should not be confused with ischemia. Hence, dynamic nature of ST segment is not always a reliable indicator of ischemia. in many cases and decreases in amplitude or even resolves with hyperventilation and tachycardia. ![]()
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