Ischemia and Infarction 2.3

Criteria for right ventricular infarction -not all needed on one ECG for definitive dx

1. Inferior Wall MI 2. ST segment elevation greater in lead III than II 3. ST elevation in V1 (possibly extending to V5 to V6) 4. ST depression in V2 (unless elevation extends, as in #3) 5. ST depression in V2 can't be more than 1/2 ST elevation in aVF 6. More than 1 mm of ST elevation in right-sided leads (V4R to V6R)

Occlusion of the Left anterior descending artery

Anterior infarction involves the anterior surface of the left ventricle caused by occlusion of the _____ ______ __________ ECG changes: Mid V3-V4

V3 to V6 possibly: 1, aVL

Anterolateral MI infarct ECG changes

Leads V1 to V4

Anteroseptal MI infarct ECG changes

V2 to V5 usually: V1, V6, 1, aVL (V1-V6, 1, avL)

Anteroseptal MI with lateral extension infarct ECG changes

Leads II, III, aVF

Anteroseptal MI with lateral extension infarct RECIPROCAL ECG changes

I, II, III, aVF, avL, V2 to V6

Apical infracts causes direct changes in leads.....

pattern of distribution

Cells die along the _____ _______ __________ of a branch, perfusing that section of myocardium

Non-Q wave:

Infarct is... small enough to not produce visible Q wave, big enough to cause area of ST depression or T wave abnormalities

Occlusion of Right coronary artery

Inferior infarction: involves the diaphragmatic surface of the heart. caused by occlusion of the ________ ___________ ____________ ECG changes seen in the inferior leads: II, III, and aVF.

Leads II, III, aVF, V5, V6 may include leads I and aVL (if high laterals are involved) ST changes can occur in V2 to V4

Inferolateral MIs present with ECG changes in.... may include which leads? ST changes can occur in _____ to ____

reversible

Ischemia and injury are ________

Occlusion of the left circumflex artery.

Lateral infarction involves the left lateral wall of the heart. occlusion of the ______ ________ __________ ECG Changes occur in left lateral leads I, aVL, V5, and V6.

Cardiogenic shock

Left main coronary artery Lose 40% of LV wall --> need ________ ___________

Left anterior descending artery (LAD) Left circumflex artery (LCX)

Left main coronary artery divides into

Infarction ECG

NOT generate any action potentials; electrically neutral Acts like electrical "window" in wall of myocardium ▪ An electrode can look through and see opposite wall ▪ Unopposed, positive vector produces Q wave Dead tissue

most likely Anterior ischemia or non Q wave MI

Normal R:S ratio, thin R wave, flipped T with ST depression =

Collateral Circulation

Overlap of areas of perfusion supplied by different arteries along endocardium allows some areas of endocardium to be supplied by two different branch systems

Diffuse

Oxygen from ventricles can _________ into cells of nearby tissue

Occlusion of the right coronary artery would MOST likely result in:

Posterior infarction involves the posterior surface of the heart caused by occlusion of the _______ _________ _________ rarely occur in isolation, usually accompany an inferior infarction or, less commonly, a lateral infarction. no leads directly overlying the posterior wall. diagnosis made by looking for reciprocal changes in the anterior leads = a tall R wave in leads V1, V2, or V3.

V7 to V10

Posterior leads aid in diagnosing posterior wall MIs Posterior leads show ST elevation Flipped T waves Q waves Direct changes in leads...

Reciprocal Changes

Refers to "mirror image" that occurs when two electrodes view same MI from opposite angles

right ventricle AV hypotension

Right coronary arteries infarcts results 1. severe _______ ventricle dysfunction 2. _____ nodal block 3. _______________

Right Posterior Descending

Right main coronary artery divides into

V4R, V5R, V6R

Right sided leads aid in diagnosis of right ventricular infarction Right-sided leads show ST elevation in a right-side infarct Direct changes occurring in right ventricle are clearly seen in leads....

RVH with strain

ST depression tall R wave asymmetric flipped T wave (rather than a upright symmetric t wave like the carousel ponies)

Occlusion of the Left anterior descending artery

Septal infarction caused by the occlusion of the _____ _____ __________ ECG changes: Proximal V1-V2

Right posterior descending artery

Supplies ▪ AV node ▪ Proximal bundle branches ▪ Inferior-posterior LV wall ▪ Basal portion of septum

Right coronary artery

Supplies ▪ Right ventricle and right atrium ▪ Part of the septum ▪ AV node via posterior descending artery (90%) ▪ Inferior wall

left anterior descending artery

Supplies 40-50% of the left ventricle > 50% of the septum Variable amounts of the lateral wall Bundle of HIS & Bundle branches Proximal occlusion potentially fatal

left circumflex artery (LCX)

Supplies ▪ Posterior wall ▪ Parts of the lateral wall ▪ Possibly the inferior wall

Left main coronary artery

Supplies 70% of the LV Loss of this artery results in death -unless extensive collaterals from the RCA

Q wave infarcts

What type of infarct is associated with higher incidences of acute mortality, increased tissue damage, and development of congestive heart failure

Inferior MIs

Which MIs are commonly associated with additional involvement of lateral wall, posterior wall, and right ventricle

Every infarct

Which infarcts have a high chance (about 40%) of arrhythmia leading to sudden cardiac death

left anterior descending artery

Widow Maker

acute infarcts

_______ ________ tend to involve more than one region: ▪ Inferoposterior ▪ Anteroseptal with lateral extension ▪ Posterolateral

Carousel Ponies

if you see this on ECG BAD NEWS indicative of a posterior MI ▪ ST depression makes a saddle; T wave is back of saddle ▪ Upright T wave is critical criteria for correct diagnosis

irreversible

infarcts (cell death) is _________

Ischemia ECG

more negative than surrounding normal tissue ST depression and T wave flipped Repolarization occurs along abnormal pathway (ST depression becomes ST elevation)

Injury ECG

more positive than surrounding tissue ST elevation and T wave flipped Does not repolarize completely

Myocardial Infarction how the process starts

myocardial cell is oxygen deprived --> anaerobic metabolism (produce energy w/o oxygen) --> acidosis created (ineffective) --> cell suffers injuries and will die if normal circulation and oxygenation are not restored

Apical Infarct

occurs when a large right coronary artery dominant system infarcts

Posterior wall MI

see reciprocal changes in V1 and V2 -Tall and fat R wave -ST depression -Upright T wave in leads V1 and V2

additional posterior leads of V7 to V9

If you see a posterior wall MI and an anterior wall MI is occurring acutely you will have ST segment depression so you order additional .......

Right Ventricular MI Decrease venous return = no blood pressure

In what type of MI does blood gets back almost exclusively by venous return? What does Nitrates, beta blockers, diuretics and morphine do? No venous return = No _______ ___________

demand supply

Increase in ____________ Decrease in ____________ can cause ischemia and or injury to develop

RIGHT SIDED LEADS

VERY IMPORTANT TO KNOW THIS ANY TIME YOU SEE AN INFERIOR INFARCT OBTAIN ____ ____ _____

POSTERIOR LEADS

VERY IMPORTANT TO KNOW THIS obtain _____ _________ in any patient with ST depression in V1 to V3 not associated with RBBB

thebesian veins

Vessels arise directly from ventricles

septum lateral wall or both

anterior infarction rarely presents by itself Commonly occurs with infarcts of _____ _______ _______

Infarct

cellular death and tissue necrosis permanent loss of myocardium and subsequent loss of function