SACCM 42: Ventricular Failure and Myocardial Infarcion

Question 1

What is the function of cardiac troponin I? (cTnI)

Answer 1

inhibits actinomyosin ATPase –> prevents the interaction of myosin with actin bindin sites

this action is stopped when Ca binds to troponin C –> displaces cTnI –> conformational change of tropomyosin –> muscle contraction

Question 2

What is the primary predisposing factor of myocardial injury in dogs?

Answer 2

hypercoagulable state

Question 3

What are the three main components of the glycocalyx?

Answer 3

• Glycosaminoglycans (GAGs)
• Proteoglycans
• Glycoproteins

Question 4

What ECG changes are indicative of myocardial infarction in people?

Answer 4

ST elevation
pathologic Q waves
new conduction abnormalities e.g., bundle branch block/AV conduction delay

Question 5

What are the three proteins comprising the troponin complex?

Answer 5

troponin C, T, and I

Question 6

How soon after cardiac injury do circulating cardiac troponins increase and when do peak values occur?

Answer 6

within 2-4 hours after injury
peak values occur 18-24 hours after onset of symptoms

Question 7

How do troponin elevations compare between patients with actue myocardial injury (e.g., myocardial ischemia) and congestive heart failure/cardiomyopathy

Answer 7

acute myocardial injury: onset 2-4 hours after injury, peak 18-24 hours after, elevations lasting up to 14 days

cardiomyopathy: lower steady elevations rahter than spike

Question 8

List causes for troponin elevations besides myocardial injury

Answer 8

• renal disease
• sepsis
• infectious disease
• inflammatory process
• trauma
• extreme exercise