myocardial ischemia 心脏内科廖国宏医师.ppt
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Pseudonormalization: previously flattened or inverted T waves may revert to upright
Posterior wall MI
- enhanced R waves in the anterior chest leads (augmented depolarization forces anteriorly, which are now less opposed by posterior forces)
requirements by exercise, tachycardia, or emotion leads to a transitory imbalance. - responsible for most episodes of chronic stable angina. Supply ischemia - reduction of O2 supply 2nd to increased coronary vascular tone or by platelet aggregates or thrombi - responsible for MI and most epiห้องสมุดไป่ตู้odes of unstable angina.
- the only ECG changes may be T wave inversion or ST elevation in leads I & aVL.
A relationship between the number of ECG leads showing ST elevation and mortality (pts with 8 or 9 of 12 leads with ST elevation have 3-4 times the mortality of those with only 2 or 3 leads with ST elevation)
- occurs with 30% inferior wall MI.
RV MI
- V3R to V5R, ST segment and evolution of q waves.
- occurs with 30% LV inferior-posterior wall MI.
High lateral wall MI
MYOCARDIAL ISCHEMIA
心臟內科 廖國宏醫師
• Definition of Ischemia
Ischemia results from both an increase in O2 demand and a reduction in supply.
Demand ischemia - coronary obstruction, myocardial O2
Often accompanied by acute onset of dyspnea and diaphoresis.
Physical exam.- insensitive and nonspecific; S4; MR murmur; systolic bulge may be palpated; S3; elevated jugular veins (RV diastolic P.); lung crackles (LV filling P. - LV function depressed)
Pain pattern with myocardial ischemia
Differential diagnosis of chest pain according to location
12-Lead ECG Variations in AMI and Angina
Baseline
Ischemia—tall or inverted T wave (infarct), ST segment may be depressed (angina)
• Ischemic ECG
Loss of R waves may be the only ECG evidence for the presence of permanent myocardial damage.
Non-Q MI : infarctions with ST depression do not evolve q waves, which represent discrete regions of irreparably damaged tissue.
• Signs and Symptoms
Most commonly manifested as constant substernal chest tightness or pressure.
Typically Lt-sided and may radiate to the throat and jaw or the Lt shoulder, interscapular, or perceived in the epigastrium.
Injury—elevated ST segment, T wave may invert
Infarction (Acute)—abnormal Q wave, ST segment may be elevated and T wave may be inverted
Infarction (Age Unknown)—abnormal Q wave, ST segment and T wave returned to normal
A “pure” posterior MI manifest by tall R waves in Leads V1 & V2 with ST segment depression in Leads V2-4.
•Conduction Disturbance
Ranging from PR interval to bundle br. block & CAVB.
Posterior wall MI
- enhanced R waves in the anterior chest leads (augmented depolarization forces anteriorly, which are now less opposed by posterior forces)
requirements by exercise, tachycardia, or emotion leads to a transitory imbalance. - responsible for most episodes of chronic stable angina. Supply ischemia - reduction of O2 supply 2nd to increased coronary vascular tone or by platelet aggregates or thrombi - responsible for MI and most epiห้องสมุดไป่ตู้odes of unstable angina.
- the only ECG changes may be T wave inversion or ST elevation in leads I & aVL.
A relationship between the number of ECG leads showing ST elevation and mortality (pts with 8 or 9 of 12 leads with ST elevation have 3-4 times the mortality of those with only 2 or 3 leads with ST elevation)
- occurs with 30% inferior wall MI.
RV MI
- V3R to V5R, ST segment and evolution of q waves.
- occurs with 30% LV inferior-posterior wall MI.
High lateral wall MI
MYOCARDIAL ISCHEMIA
心臟內科 廖國宏醫師
• Definition of Ischemia
Ischemia results from both an increase in O2 demand and a reduction in supply.
Demand ischemia - coronary obstruction, myocardial O2
Often accompanied by acute onset of dyspnea and diaphoresis.
Physical exam.- insensitive and nonspecific; S4; MR murmur; systolic bulge may be palpated; S3; elevated jugular veins (RV diastolic P.); lung crackles (LV filling P. - LV function depressed)
Pain pattern with myocardial ischemia
Differential diagnosis of chest pain according to location
12-Lead ECG Variations in AMI and Angina
Baseline
Ischemia—tall or inverted T wave (infarct), ST segment may be depressed (angina)
• Ischemic ECG
Loss of R waves may be the only ECG evidence for the presence of permanent myocardial damage.
Non-Q MI : infarctions with ST depression do not evolve q waves, which represent discrete regions of irreparably damaged tissue.
• Signs and Symptoms
Most commonly manifested as constant substernal chest tightness or pressure.
Typically Lt-sided and may radiate to the throat and jaw or the Lt shoulder, interscapular, or perceived in the epigastrium.
Injury—elevated ST segment, T wave may invert
Infarction (Acute)—abnormal Q wave, ST segment may be elevated and T wave may be inverted
Infarction (Age Unknown)—abnormal Q wave, ST segment and T wave returned to normal
A “pure” posterior MI manifest by tall R waves in Leads V1 & V2 with ST segment depression in Leads V2-4.
•Conduction Disturbance
Ranging from PR interval to bundle br. block & CAVB.