Presentation Transcript
Myocardial infarction(PYP imaging) :Myocardial infarction(PYP imaging)
Anatomy :Anatomy Myocardial Infarction
Left Ventricle
Areas affected
Anterior wall and septum
Inferior wall and posterior third of septum
Right ventricle
involved in 25% to 50 of pt with inferior wall infarction
Classification of infarction :Classification of infarction Thickness of necrosis
Transmural or Q wave- full thickness myocardial wall
Nontransmural, non-Q wave- less than full thickness of wall
Subendocardial infarction- less than one-half thickness of wall.
Slide 4:Coronary thrombosis
Present in half of infarcts
Intramural hemorrhage 40%
Most frequent arteries:
LAD (56%)
Right coronary (25%)
Circumflex (14%)
Tans mural infarction
Coronary artery spasm
Some primary cause of infarction Causes for Infarction
Physiology :Physiology Myocardial Infarction
Intramural infarctions
Reduced blood flow to center of infarction= endocardium
Slide 6:Technitium 99m pyrophosphate
Determinants of Uptake in infarction.
Blood Flow
Tc 99m PYP must reach damaged tissue to be taken up.
Highest concentration of 99mTc pyrophosphate occurs when local blood flow reduced by 20% to 40%
Flow reduces, concentration falls in regions of severely reduced flow
Concentration of pyrophosphate greater in epicardial than endocardial segments
PYP ratio of 18 to 20 infarcted tissue/ normal myocardium possible.
Slide 7:Extraction
Extraction fraction
Total amount tracer extracted decreases at low flow.
Calcium influx
Key role in T99m PYP binding acute infarction
Intracellular calcium phosphate and is present in 3 forms in cell:
Amorphous – uniformly
Crystalline
Hydroxyapatite- mitochondria
PYP binds to both amorphous and hydroxyapatite deposits
99mTc PYP concentration parallels calcium phosphate concentration.
Slide 8:Necrotic Tissue
Pyrophosphate
Acutely necrotic myocardium
Other Diseases unstable angina, multifocal lesions of necrosis and myocytolysis
Uptake in ventricular aneurysm
Timing :Timing Earliest uptake 4 hours after coronary artery occulsion
Peak uptake @ 48 hours
Diminish over next 5 to 7 days
Time course varies depending on:
Size of infarction
Extension of infarction
Slide 10:CAD
Slide 11:CAD
Slide 16:MI
Myocardial Infarction :Myocardial Infarction
Slide 18:PYP