Heart Failure with Reduced Ejection Fraction Flashcards
what does preload improve?
Cardiac contractions
What is the main determiner of filling volumne?
How much pressure is on venous side of the heart
What is the cardiac function curve?
CO dependent on CVP
What is the vascular function curve?
CVP dependent on CO
What are 4 common causes of LVF?
chronic ischemic heart disease
arterial hypertension
cardiomyopathy
valve dysfunctions
What are 2 common causes of RVF?
pulmonary hypertension
left ventricular failure
What are symptoms of LVF?
dyspnoea
pulmonary fluid retention
What causes pulmonary fluid retention in LVF?
oedema, increase pulmonary venous & capillary pressure due to increased transcapillary filtration of fluid into interstitial tissue of lung
What are symptoms of RVF?
Swelling of feet, ankles & legs
fluid in abdominal cavity
Why does subcutaenous oedema worsen in the day?
increased CVP & salt & water retention lead to increased transcapillary filtration of fluid & retention of fluid
What is HFREF characterized by?
Reduction in myocardial contractility
How do you calculate ejection fraction?
stroke volume/EDV x 100
What is the reduction in myocardial contractility compensated by?
Increased preload
What 3 things increase preload?
Reduced ejection fraction
increased sympathetic activity -> increase venous tone
increased salt & water retention (RASS)
What does chronically increased preload lead to?
distension of heart resulting in further reduced cardiac function
What happens to CO in decompensated HF?
CO is permanently reduced
What does CO fail to increase normally during HF during exercise?
reduced SV due to reduced contractility
impaired response to sympathetic stimulation
What is Ca2+ cycling?
plasma membrane of cardiac myocytes is invaginated into T-tubules which contact SR (main store of Ca2+)
What happens in contraction coupling in failing cardiac myocytes?
Reduced Ca2+ pumping into DR by SERCA
impaired/leaky SR Ca2+ release channels
fall in sensitivity of troponin
upregulation of Na+Ca2+ exchangers
downregulation of K= channels
impaired ATP supply
switch from FA to glucose as chief energy substrate
What does impaired conduction & excitation issues cause?
Arrhythmias
How does the sympathetic system enhance cardiac muscle contractility?
Through cAMP signaling pathways -> stimulate VG Ca2+ channels through phosphorylation of channel inhibitor protein Rad
Which NT affects cAMP?
Noradrenaline
What facilitates communication between receptor and specific targets like PLN/SERCA?
B1 adrenoreceptor-cAMP microdomain in subcellular compartments
What part of cAMP signaling gets disrupted in HF?
Subcellular compartment -> loss of PDE type 4
