Drugs for Heart Failure Flashcards
(38 cards)
What is the definition of heart failure?
- an abnormality of cardiac structure or function leading to the failure of the heart to delivery oxygen at a rate that fulfills the requirements of the tissues in the body
Most patients with heart failure have ____
high blood pressure and an enlarged heart muscle and chamber
What happens to the ejection fraction during heart failure?
- it is low
- the percent of blood that is pumped from the body decreases, so the heart does not provide adequate perfusion to the body
What predisposing illness can lead to heart failure?
heart attacks
diabetes
other diseases
Explain the steps of the heart pumping blood to the body
- starts with ventricle diastole/isovolumetric relaxation
- ventricular filling occurs (ventricular diastole)
- atrial contraction/systole occurs
- isovolemic/isovolumetric contraction
- ventricular contraction (ventricular systole-first phase)
- ventricular ejection (ventricular systole- second phase)
What determines the function of the heart?
ejection fraction
What ejection fraction constitutes heart failure?
less than 50%
What is systole? Diastole?
Systole: ventricles contracting
Diastole: ventricles relaxing
Describe how ejection fraction is calculated?
ejection fraction = (amount of blood pumped out of ventricle/ total amount of blood in the ventricle)
How do cardiomyocytes respond to action potentials?
- respond by depolarizing the membrane
- starts by shortening of contractile proteins and ends with relaxation and return to resting state
- cardiomyocytes are interconnected in intercalated discs that respond to stimuli as a unit
What is echocardiography?
- sends sound waves into the body which are reflected at the interfaces between tissues
- return time tells us the depth of the reflecting surface
Force of muscle contraction is related to the amount of what?
cytosolic Ca
What triggers the release from SR and mitochondrial stores?
Ca coming from outside of the cell
How is muscle relaxation in the heart occur?
- achieved through removal of free Ca by the Na/Ca exchangers ad reuptake into SR and mitochondria
What are some of the risk factors and comorbidities that contribute to the development of HF?
- age
- smoking
- obesity
- hypertension
- coronary artery
- diseases like diabetes and dyslipidemia
What is the progression of heart failure?
- damage to cardiac myocytes and ECM leads to changes in the size, shape and function of the heart and cardiac wall stress
- these changes lead to systemic neurohormonal imbalance
- this may lead to fibrosis, apoptosis, hypertension, hypertrophy, cellular and molecular alterations, myotoxicity
- remodeling and progressive worsening of LV function
- hemodynamic alterations, salt and water retention
What is the physiological response to HF?
Slight decreases in bp is corrected by:
- increased sodium retention (slow benefit_
- with water retention this increases blood volume - activation of RAAS
- angiotensin- constricts arteries and veins (fast benefit)
- aldosterone- sodium retention (slow benefit) - sympathetic nerve activation
- increased HR
- increases contractility
– all of these work to correct the drop in blood pressure (initially the patient may be unaware of early heart failure)
Late in heart failure (decompensated), _____ are things that worsen the condition
the compensatory mechanisms
How is an increase in blood volume and constriction of veins detrimental in late stage heart failure?
- increased venous return stretches already overstretched ventricles
- the heart is no longer able to increase the force of contraction
- heart size enlarges and the muscle thickens (hypertrophy)
- venous pressure increases - edema - peripheral and pulmonary
How are overly increased constriction of arteries a detrimental thing in late stage heart failure?
- greatly increased peripheral resistance heart for the heart to empty against
- increased resistance to outflow more than the heart can now overcome
How does cardiac stimulation cause detrimental effects in late stage HF?
- little response to this- the heart has failed
- overstimulation of beta adrenergic receptors
- down regulation of these receptors
- increased fibrosis
- increased apoptosis (cell death)
What is the difference in the effect of right sided vs left sided heart failure?
Left sided failure: blood backs up into the lungs and the periphery
- pulmonary (edema)
- life threatening
- sitting-up helps
- more blood in lower veins
Ride sided failure: blood backs up into the periphery
- peripheral edema
What are the main symptoms of heart failure?
- shortness of breath
- shortness of breath at night
- need to sit to breath easily
- reduced exercise tolerance
- fatigue
- peripheral edema
- pulmonary edema
What are the main signs of heart failure?
- sweating
- increased heart rate
- elevated jugular venous pressure
- hepato-jugular reflux
- rapid breathing
- cardiac murmur
