Myocardial Infarction (Cardiac Diseases)

Question 1

STEMI

Answer 1

• complete occlusion of large vessel –> massive MI

- S-T segment elevated myocardial infarction

Question 2

NSTEMI

Answer 2

• branch fully occluded or large vessel partially occluded

Question 3

etiology

Answer 3

• atherosclerosis plaque (most likely)
• thrombus
• unexplained vasospasm in coronary artery
• severed vessel, hemorrhage (least likely)

Question 4

pathophysiology

Answer 4

• atherosclerosis (vessel unable to dilate d/t damage/max dilation) –> complicated lesion –> ischemia –> cardiac hypoxia –> anaerobic metb (prod lactic acid) –> metabolic acidosis (fixed acid)
• acidosis –> arrhythmias (ireg HR) d/t dec O2 –> inability to pump –> MI

Question 5

transmural infarction

Answer 5

• ST elevation, entire ventricle wall –> result of a proximal occlusion in artery = STEMI

Question 6

subendocardial infarction

Answer 6

• ST depression, inner part of ventricle wall –> result of distal occlusion or partial proximal occlusion = NSTEMI

Question 7

manifestations

Answer 7

• result of atherosclerosis, MI comes on suddenly
• acute, severe chest pain (“crushing”)
• pain radiates to left arm, neck, jaw
• anxiety and stress (inc HR & BP)
• tachycardia
• nausea & vomiting (result of severe pain)

Question 8

Dx

Answer 8

• ECG tracing: ST segment elevated/depressed, T inversion (should be upwards), abn Q wave, loss of R wave
• angiogram
• serum markers

Question 9

serum markers

Answer 9

• heart cells die and release proteins into blood
• troponin I & T (indicates heart muscle cell death & heart arrack)
• myoglobin (indicates muscle cell death)
• creatine kinase ; CKMB (enzyme)

Question 10

Tx

Answer 10

• thrombolytics
• anticoagulants
• antiarrhythmias
• morphine PRN
• O2 (for ischemia)

Question 11

Tx post stabilization

Answer 11

• IV diuretic (dec blood volume to dec workload on heart)
• inotrope (alter force of muscle contractions)
• vasodilators
• revascularization Sx (re-establish perf) : angioplasty, bypass