Case 15 Flashcards
MOA of loop diuretics used in HF
Decrease NaCl and KCl reabsorption in thick ascending limb of loop of Henlé
Increasing excretion of salt and water
Reduces cardiac preload and afterload
Reducing pulmonary/ peripheral oedema
MOA of aldosterone antagonists used in HF
Block cytoplasmic aldosterone receptors in collecting tubules
increasing salt and water excretion
and reducing remodelling
MOA of ACEI used in HF
Inhibits angiotensin converting enzyme so angiotensin I is not converted to angiotensin II
Arteriolar/ venous dilation
Reduces aldosterone secretion
Reduces cardiac remodelling
MOA of ARB used in HF
Antagonise angiotensin II effects at AT1 receptor
Arteriolar/ venous dilation
Reduces aldosterone secretion
Reduces cardiac remodelling
MOA of B-blockers used in HF e.g. carvedilol
Competitively blocks B1 receptors
Reduces bp and heart rate
MOA of cardiac glycosides used in HF e.g. digoxin
Inhibits Na+/K+-ATPase resulting in reduced Ca2+ expulsion and increased Ca2+ stored in SR
MOA of natriuretic peptides used in HF e.g. nesiritide
Activates BNP receptors, increases cGMP
Vasodilation and diuresis
MOA of bipyridines used in HF e.g. milrinone
Phosphodiesterase type 3 inhibitor
Decreases cAMP breakdown
Vasodilator
Increases cardiac contractility
What is the central venous pressure if the JVP is visible when the patient is sat upright?
At least 10cmH2O - elevated venous pressure
How can the JVP be differentiated from the carotid pulse?
JVP - non palpable as low pressure
Arterial pulse - palpable
When do you get large/giant a waves?
Obstruction to active right ventricular filling during right atrial contraction
Pulmonary hypertension, pulmonic stenosis, tricuspid stenosis
When do you get cannon a waves?
Right atrial contraction against closed tricuspid valve
or simultaneous contraction of right atrium and right ventricle
AV dissociation - complete heart block or ventricular tachycardia
When are a waves absent?
Atrial fibrillation
When do you get large v waves?
Tricuspid regurgitation
What does the JVP reflect?
Right ventricular filling pressure
What is the normal range of central venous pressures and how is it measured?
5-9 cm H2O
Distance from right atrium to right internal JVP
Sternal angle used as reference point - 5cm above right atrium
Normal JVP is 0-4cm above sternal angle (can only really see 2cm or over as clavicle in the way)
What is the most accurate external reference point for the right atria?
Midaxillary line, 4th intercostal space = mid right atria
What happens to the JVP during inspiration?
Declines
What is Kussmaul’s sign?
JVP increases during inspiration
Caused by an inability of the heart to accommodate increased venous return caused by negative intrapleural pressure
What is classed as a positive abdominojugular reflux sign?
Increase in JVP of greater than 3cm H2O
That is sustained for longer than 15 seconds
What do the a, c, x, v and y waves represent?
a: right atrial contraction
c: tricuspid valve closes as ventricles contract
x: ventricular contraction
v: passive right atrial filling (tricuspid valve still closed)
y: tricuspid opens and blood fills right ventricle
What are the layers of a vessel? Which is breached first in formation of atherosclerotic plaque?
Intima, media, adventitia
Intima
What do chylomicrons do?
Carry triglycerides
From intestines
To skeletal muscle, adipose tissue and liver
What do VLDL do?
Carry triglycerides
From liver
To adipose tissue
