Cardiac Lab Findings & Disease Management

Question 1

Natriuretic peptide characteristics

Answer 1

• 3 related forms: atrial, B-type, and C-type
• Atrial natriuretic peptide: found in the atrium of the heart
• B-type natriuretic peptide: found mainly in the ventricles of the
heart
• C-type natriuretic peptide: peptides found in the endothelium

Question 2

B-type natriuretic peptide characteristics

Answer 2

• Found only in the cardiac ventricles
• Released in response to stretch, ↑ volume in the
ventricle
• BNP levels correlate with:
* Left ventricular end-diastolic pressure
* New York Heart Association (NYHA) classification
* Objective heart failure diagnosis in patients 55 or older

Question 3

BNP levels & indications (general)

Answer 3

• BNP levels tend to be higher in women, elderly
• BNP levels elevated in renal insufficiency
• BNP < 100 –> sensitive for non-HF cause

Question 4

Cardiac enzymes & characteristics

Answer 4

• Troponin (I and T)
– Regulatory proteins involved in actinmyosin
interaction
– specific to heart
– Released into bloodstream with
myocyte necrosis

Question 5

Dx of myocardial necrosis via cardiac enzymes

Answer 5

-ELEVATED TROPONIN = myocardial necrosis
-• Myocardial necrosis –> Troponin release within 3-12 hours, peaking in 18-24 hours
• Troponin felt to be more specific, remains elevated longer