Acute Pericarditis:
- Inflammation of the pericardium
- May be caused by number of factors: viral/bacterial infection, metastatic tumors, collagen vascular diseases, MI, cardiac surgery, and uremia
ECG Changes w/ Acute Pericarditis:
- Early phase is characterized by ST segment elevation, due to inflammation of the epicardium, which accompanies inflammation of the overlying pericardium
- Can have generalized ST-T changes in both anterior and inferior leads
ECG Changes w/ Acute Pericarditis:
- Also affects the repolarization of the atria (PR segment)
- Leads to atrial current of injury with elevation in PR segment in aVR and depression of PR segment in other extremity / left-sided chest leads
- Can have T-wave inversions
Pericardial Effusion:
- Abnormal accumulation of fluid in the pericardial sac, can be due to pericarditis
- Other causes: myxedema (hypothyroidism), or rupture of heart (VSD)
- Can lead to cardiac tamponade: drop in SBP leading to PEA activity
Pericardial Effusion ECG:
- Can see low QRS voltages (<5-mm in the 6 extremity leads or < 10-mm in the chest leads V1-V6)
- Low voltage: Obesity (fat around heart), emphysema (air insulates heart), anasarca (generalized edema), pleural effusions
- Electrical alternans
Chronic Constrictive Pericarditis:
- Some conditions cause pericardial inflammation and can lead to fibrosis and calcification of the pericardial sac (cardiac surgery, trauma, infections, TB, viral infections, connective tissue diseases, sarcoid, uremia, and asbestosis)
Chronic Constrictive Pericarditis:
- Can present with HF, elevated neck veins/ascites. Can be mistaken for liver cirrhosis.
- Treatment: Pericardiectomy ('surgical stripping' of the pericardium to decrease intra-cardiac pressures.
** Not to use for clinical care, just educational material**
Thanks to these websites/journals for amazing graphics!
Hyperkalemia:
- Distinctive sequence of ECG changes affecting both depolarization (QRS) and repolarization (ST-T)
- First change: Narrowing and peaking of T-waves ('tented' or 'pinched' shape) and can become tall
Hyperkalemia:
- Further elevation: PR intervals become prolonged, P-waves may disappear. Will have intra-ventricular conduction delay, with widening of QRS complexes.
- Can lead to large, undulating (sine wave) pattern with asystole and cardiac death
Inferior Wall Infarction:
- Diaphragmatic portion of the LV
- Will see changes in leads II, III, and aVF
- May produce abnormal Q-waves in these leads
- Generally caused by occlusion of the RCA; less commonly can occur with a left circumflex coronary obstruction
Posterior Infarction:
- Occurs on the posterior (back) surface of the LV
- May be difficult to diagnose because characteristic abnormal ST elevations may no appear in any of the 12 conventional leads
- Tall R-waves and ST depressions can occur in V1 and V2
Q-wave:
- Can occur in any lead; indicates that the electrical voltages are directed away from that particular lead
- With a transmural infarction, necrosis of heart muscle occurs in a localized area of the ventricle
- New Q-waves usually appear within first day of MI
Anterior Wall MI:
- Can see loss of normal R-wave progression in the chest leads (normally should have a progression of height of R-waves from V1-V6)
- In antero-septal infarct, will lose small r waves in V1-V2 (septal depolarization from left to right) and have QS in V1-V2
Myocardial Ischemia:
- One of the most important things to evaluate on EKG
- If severe narrowing/complete blockage of a coronary artery causes blood flow to become adequate, ischemia of the heart muscle develops
- Can be transient (angina pectoris) or more severe (necrosis & MI)
Myocardial Ischemia
- LV consists of an outer layer (epicardium/sub-epicardium) and inner layer (sub-endocardium)
- Can have limit of ischemia to the inner layer or can affect the entire thickness of the ventricular wall (transmural ischemia)
Fascicular Blocks:
- Left bundle branch system: sub-divided into an anterior & posterior fascicle.
- Hemi-block does not widen the QRS complex markedly (compared to a RBBB or LBBB)
Left Anterior Fascicular Block (LAFB):
- Diagnosed by finding of a left axis deviation (-45 degrees or more negative)
- Delayed activation of more superior & leftward position of the LV
- Isolated finding is non-specific; can be seen w/ HTN, AV disease, CAD, and aging