Basic Science applied to medicine

1. If I were not an atheist, I would believe in a God who would choose to save people on the basis
of the totality of their lives and not the pattern of their words.
-Isaac Asimov
INTRODUCTION
● Natriuretic peptide system
○ Salt and water handling
○ BP regulation
○ Influence myocardial structure and function
● BNP
○ 1st identified in the brain
○ Released primarily from the heart, particularly the ventricles
○ Prohormone proBNP produces
■ BNP
● 32 amino acid
● Biologically active
■ N-terminal pro-BNP (NT-proBNP)
● Biologically inert
● 76 amino acid
● ANP
○ Released from the atria
○ In response to volume expansion
● ANP and BNP is increased in heart failure in response to the high ventricular filling
pressures
PHYSIOLOGIC ROLE IN HF
● Diuresis
● Natriuresis
● Inhibit RAAS
● Inhibit Endothelin secretion
● Inhibit systemic and renal sympathetic activity
- Created with love
by Dr. Eashan Srivastava

2. If I were not an atheist, I would believe in a God who would choose to save people on the basis
of the totality of their lives and not the pattern of their words.
-Isaac Asimov
ASSAY INTERPRETATION
● Plasma BNP
○ Concentrations can vary with
■ Assay used
■ Age - Increases with age
■ Sex - F>M
■ BMI - lower in obese
■ Increased in CKD
○ T50 = 20 minutes
● Plasma N-terminal pro-BNP
○ In normal subjects
■ [BNP] = [NT-proBNP]
○ CHF
■ [NT-proBNP] >> [BNP]
○ Increased in CKD
○ T50 = 60 min
BNP
Breathing Not Properly study
● Plasma BNP >100 pg/mL diagnosed HF with a high sensitivity, specificity, and predictive
accuracy
● Was better than NHANES and Framingham criteria for the diagnosis of HF
● BNP correlated with NYHA functional class
● Correlated with prognosis
● Also raised in HFpEF
Discordance between BNP and symptoms
Not all patients with symptomatic HF have high plasma BNP concentrations and not all
asymptomatic patients have low values.
- Created with love
by Dr. Eashan Srivastava

3. If I were not an atheist, I would believe in a God who would choose to save people on the basis
of the totality of their lives and not the pattern of their words.
-Isaac Asimov
Summary of BNP
● The utility of BNP in differentiating cardiac vs noncardiac causes of dyspnea = ​uncertain
● Clinical use
○ Evaluation of patients presenting with dyspnea of uncertain etiology
○ <100 pg/mL = very high negative predictive value for HF
○ 100-400 pg/mL = Not very sensitive or specific
○ >400 = Highly specific
● Limitations
○ High plasma BNP concentration does not exclude other DD’s
○ Plasma BNP levels are normal in some patients with CHF
○ Not useful in guiding management
N-TERMINAL PRO-BNP
● Role in HF
○ Raised in Acute decompensated HF
○ < 300 pg/mL = excluding CHF with a negative predictive value of 98%
○ C​​orrelates with prognosis
COMPARISON OF PLASMA BNP AND N-TERMINAL PRO-BNP
● Limited data available
● NT-pro-BNP had greater prognostic value than BNP levels for all-cause mortality.
- Created with love
by Dr. Eashan Srivastava

4. If I were not an atheist, I would believe in a God who would choose to save people on the basis
of the totality of their lives and not the pattern of their words.
-Isaac Asimov
BNP OR NT-proBNP AS GUIDE TO THERAPY
● BNP and NT-proBNP fall after effective chronic treatment of HF
● Conflicting data
● Randomized trials studying the effect of BNP- or NT-proBNP guided therapy have shown
mixed results, although the weight of the evidence suggests a mortality benefit
● Value of serial BNP measurement in guiding management of acute HF has not been
established
ATRIAL NATRIURETIC PEPTIDE
● Primarily released from the atria in response to volume expansion
● Mid-regional pro-atrial natriuretic peptide (MR-proANP) is non inferior to BNP
- Created with love
by Dr. Eashan Srivastava