Chapters Archive – Page 19 of 22

Figure 1. The component of the cardiac conduction system and the vascular supply. RCA = right coronary artery. LAD = Left anterior descending coronary artery. LCX = left circumflex coronary artery.

Supraventricular and intraventricular conduction defects in myocardial ischemia and infarction

Conduction defects caused by myocardial ischemia and infarction Bradycardia and conduction defects, such as bundle branch block, fascicular block and AV block, are common in…

Figure 2. The electrocardiographic natural course in STEMI (ST elevation myocardial infarction).

The ECG in assessment of myocardial reperfusion

The ECG in the assessment of myocardial reperfusion The ECG is an invaluable tool to assess whether an occlusion has been resolved and blood flow…

Figure 1. Pathological R-wave progression is indicative of previous myocardial infarction.

Other ECG changes in ischemia and infarction

Pathological R-wave progression Normal R-wave progression implies that the R-wave amplitude increases gradually from V1 to V5 and then diminishes again in V6. Refer to…

Figure 1. Examples of STE-ACS (STEMI). Note that these patients presented with pathological Q-waves, which means that these ECGs were recorded several hours after symptom onset or those are signs of old infarction.

ECG signs of myocardial infarction: pathological Q-waves & pathological R-waves

Pathological Q-waves are evidence of myocardial infarction Myocardial infarction – particularly if extensive in size – typically manifests with pathological Q-waves. These Q-waves are wider and…

Figure 1. Posterolateral (posterior, inferobasal) transmural ischemia causes reciprocal ST-segment depressions in V1–V3 (ocasionally V4). Leads V7–V9 must be placed to reveal the ST-segment elevations.

ST elevation myocardial infarction (STEMI) without ST elevations on 12-lead ECG

ST elevation myocardial infarction (STEMI) without ST segment elevations on 12-lead ECG This chapter covers situations in which the 12-lead ECG does not exhibit ST segment…

Figure 1. Types of ST segment elevations on ECG.

ST segment elevation in acute myocardial ischemia and differential diagnoses

ST segment elevation in acute myocardial ischemia ST segment elevations with straight (horizontal, upsloping, or downsloping) or convex ST segment strongly suggest acute transmural ischemia…

Figure 1. (A) The relation between the action potential and the ECG curve. Myocardial ischemia primarily affects the repolarization, which is reflected on ST-T changes on the ECG. (B) Note that the reference level for measuring deviation (elevation or depression) of the ST segment is the PR segment (the terminal portion of the PR interval). (C) and (D) Shows how to measure the magnitude of ST segment elevation and ST segment depression. The J 60 point is located 60 ms after the J point.

ECG in myocardial ischemia: ischemic changes in the ST segment & T-wave

ECG in acute myocardial ischemia: ischemic ST segment & T-wave changes This chapter discusses typical and atypical changes in the ST segment and the T-wave…

Figure 3. STE-ACS (STEMI) is caused by a complete occlusion, which means that there is no flow in the artery. The ischemia will affect all layers of the myocardium, from the endocardium to the epicardium (in the region supplied by the occluded artery). This type of ischemia, which affects all myocardial layers, is referred to as transmural ischemia.

Factors that modify the natural course in acute myocardial infarction (AMI)

Factors that modify infarct size and the natural course in acute myocardial infarction (AMI) The traditional distinction between NSTE-ACS (NSTEMI, Non-STEMI) and STE-ACS (STEMI) is slightly…

The right ventricle is supplied by the right marginal artery (r. marginalis dx), which originates from the right coronary artery (RCA). The RCA also supplies the inferior left ventricular wall in over 90% of all individuals. Hence, a proximal occlusion (in the RCA) which cuts off blood flow to the right ventricle, will also affect the inferior wall of the left ventricle in 90% of the cases.

The left ventricle in myocardial ischemia and infarction

Acute myocardial infarction (AMI) always affects the left ventricle Myocardial infarction is virtually synonymous with left ventricular infarction. All myocardial infarctions affect the left ventricle. Right…

Figure 1. Acute myocardial infarction is usually initiated by rupture or erosion of a vulnerable (unstable) atherosclerotic coronary plaque.

Diagnostic Criteria for Acute Myocardial Infarction: Cardiac troponins, ECG & Symptoms

Acute Myocardial Infarction: Definition & Criteria Acute myocardial infarction is the most severe complication of coronary artery disease. The most common initiating mechanism is rupture…