Patients may also manifest signs of sinus node dysfunction, such as sinus bradycardia, sinus pauses, sinoatrial exit block and sinus arrest. The conduction block may develop either as a step-wise progression from 1st degree heart block via Wenckebach to complete heart block (in 50% of cases) or as abrupt onset of second or third-degree heart block (in the remaining 50%). Bezold-Jarisch reflex = increased vagal tone secondary to ischaemia.This artery arises from the RCA 80% of the time, hence its involvement in inferior STEMI due to RCA occlusion. Ischaemia of the AV node due to impaired blood flow via the AV nodal artery.There are two presumed mechanisms for this: Up to 20% of patients with inferior STEMI will develop either second- or third-degree AV block. These differences allow for electrocardiographic differentiation between RCA and LCx occlusion.īradycardia and AV Block in inferior STEMI
The injury current in LCx occlusion is directed inferiorly and leftward, producing ST elevation in the lateral leads I and V5-6 The LCx territory covers the lateral part of the inferior wall and the left posterobasal area.The injury current in RCA occlusion is directed inferiorly and rightward, producing ST elevation in lead III > lead II (as lead III is more rightward facing)
While both RCA and LCx occlusion may cause infarction of the inferior wall, the precise area of infarction and thus ECG pattern in each case is slightly different: Occasionally, a “type III” or “wraparound” left anterior descending artery ( LAD), producing the unusual pattern of concomitant inferior and anterior ST elevation.Dominant left circumflex artery (LCx) in 18%.Dominant right coronary artery (RCA) in 80% of cases.Inferior STEMI can result from occlusion of any of the three main coronary arteries:
0 kommentar(er)
