B-type Natriuretic Peptide

B-type Natriuretic Peptide ●​ Released mainly by ventricular myocardium ○​ Once heart wall is stretched ○​ Pressure ○​ Volume overload ●​ NT-proBNP test ○​ Inactive fragment ○​ Longer half-life Physiologic ●​ Increase in Natriuresis and diuresis ○​ dumping salt and water ●​ Increased level of vasodilation ○​ Decreasing afterload ●​ Decrease in RAAS with decrease in sympathetic tone ●​ As a result of BNP there will be reduced in volume and overall workload of cardiac Usage ●​ Evaluation of dyspnea ○​ Heart failure or non-cardiac cause? ○​ ex) ■​ COPD ■​ Pneumonia ○​ Risk and prognosis of heart failure ■​ Higher the level = worse outcome ■​ Monitoring response ●​ Could help ●​ Clinical imaging will matter more Interpretation and levels ●​ High BNP/NT-proBNP ○​ Support on heart failure ○​ Volume overload ○​ Not specific ●​ Low BNP/NT ○​ Heart failure is less likely to happen BNP = stress signal. Stretched ventricle BNP increasing factors ●​ ●​ ●​ ●​ ●​ Acute coronary syndrome / IM Pulmonary embolism Pulmonary hypertension RV strain Renal failure ○​ Clearance reduced ●​ Atrial fibrillation ●​ Older age ●​ Sepsis and critical illness Factor on lowering BNP ●​ Obesity ○​ BNP being lower ●​ Early HF presentation ○​ Lower level of BNP could be seen ○​ Rises afterwards BNP vs NT-proBNP ●​ Both are used for cardiac wall stress ●​ NT-proBNP ○​ Longer half life ○​ Higher in number ○​ Affects kidney function ●​ Different cutoff ⇒ interpretation with local reference range BNP ●​ B-type Natriuretic Peptide ○​ Hormone produced mainly on ventricles of heart ○​ Released once heart muscle stretches by increase in pressure ■​ Volume overload ○​ BNP assists in cardiac ■​ BP regulation ■​ Blood volume ■​ Fluid balance Physiological Role ●​ Reduce stress on heat ○​ Promotion of vasodilation ■​ Widening of blood vessel ○​ Increase in excretion of sodium contents in urine ■​ Natriuresis ○​ Increase urine production ■​ Diuresis ○​ Reduction of blood volume + blood pressure ●​ Decrease cardiac workload Source ●​ BNP produced in ventricle of heart ○​ Ventricle wall stretched ○​ Increase in pressure of heart 1.​ Ventricular stretch a.​ Trigger b.​ Increase in blood volume c.​ Increase in ventricular pressure 2.​ BNP gene activation a.​ Mechanical stress signal will activate intracellular pathway b.​ BNP gene activated c.​ production of pre-proBNP 3.​ Hormone Processing a.​ Pre-proBNP b.​ ProBNP c.​ BNP i.​ Activated + NT-proBNP (inactive byproduct) 4.​ BNP released to blood a.​ Kidney b.​ Blood vessels c.​ Adrenal glands d.​ Brain Cx ●​ BNP could be used to diagnose + monitor heart failure ●​ Elevation of BNP level could indicate few smx (associated) ○​ Heart failure ○​ Acute Coronary Syndrome ○​ Pulmonary Hypertension ●​ High BNP = worse cardiac function BNP blood test ●​ Measures concentration of BNP in blood ○​ BNP < 100pg/ml ■​ Heart failure unlikely ○​ BNP 100-400pg/ml ■​ Possible heart failure ○​ BNP >400pg/ml ■​ Strong suggestive for heart failure ●​ Level of BNP might vary by laboratory