L19- Cardiac Failure and Angina Flashcards
Which rceptors are primarily respinsable for the sympathetic increase of heart contractions?
Beta-1 receptors
What are the additional effects of beta blockers?
Blooc can flow through the coronary vessels during diastole, B blockers prolong diastole so theat more O2 can get to heart.
hat are the principal and secondary effecs of beta blockers in relieving angina of effort?
Principal- reduction in cardiac work, reducing O2 demand.
Secondary- making diastole longer, improving blood flow to cardiac muscle
Which 2 drugs can be used for angina, bind to the alpha subunit of the L type Ca channel?
Verapamil = use dependent block
Nifedipine = NOT use dependent block
What can verapamil treat?
dysrhythmias and angina and hypertension
How does the use dependence determine the mechanisms of ca blockers in angina treatment?
verapamil = use dependent. more potent on the heart than vasuclar smooth muscle. so reduces cardiac output
nifedipine= not use dependent. more potent on vascular smooth muscle than heart. so causes vasodilation.
Which drugs reduce risk of thrombosis?
Anti- coagulents eg heparin and aspirin
Which drugs relieve symptoms of angina?
beta blockers
organic nitrates
calcium antagonists
Which drugs relieve pain after an MI?
Opioids eg morphine
What;s a symptom of heart failure?
Oedema. Build up of fluid at the extremities. eg fat ankles
WHat is hypertrophy?
When the muscle thickness increases in the heart and the ventricles can’t fill as well.
WHat is dilated cardiomyopathy?
When the chambers become enlarged, filling more than normal and can’t pump as much
What are 3 causes of heart failure?
- chronic hypertension
- ischaemia
- heart valve disorders
What’s wrong with the compensatory mechanisms the body uses to deal with short term heart failure?
Blood pressure rises
Salt and water are retained
vasoconstriction
these end up causing more work for the heart and just make it aaall worse!!
What is a classification system for chronic heart failure?
left- left side failing
right- right side failing
forward- failure for pushing blood out heart
backward- failure for blood going back into the heart
What type of heart failure causes:
- problems in the lungs
- oedema in the rest of the body?
- lef-sided backwards
- right-sided backwards
What are the symptoms for:
- forward failure?
- backwards failure?
- tiredness, preipheral cyanosis, salt and water retention
- breathlessness, engorgement of liver, oedema of legs and ankles
What are 3 strategies for treating congestive heart failure?
- reduce cardiac work
- reduce pulmonary congestion and peripheral oedema
- increase cardiac output
How do you reduce cardiac workload?
- rest
- ACE inhibitor (reduce preload and afterload)
- Organic nitrate
How do you reduce oedema in tissue and lungs?
- diet- reduce salt
- Thiazide diuretics
- loop diuretics
How do you increase cardiac output?
With a positive inotropic agent.
eg Digoxin.
Improved quality of life but not survival
Where does digoxin come from?
Fox Gloves.
Digitalis lanata (digit finger)
What are the 4 parts in digoxin?
a glycone- determines pharmodynamic properties
lactone
steroid- lipid soluble
sugar residues - water soluble
Which drug has a positive inotropic effect on the heart without increasing oxygen demands?
Digoxin
What is the mechanism of digoxin?
Not understood. believed to involve the sodium potassium pump
What does digoxin do at pharmaceutical doses and toxic doses?
pharma- increases vagus nerve activity
toxic- increases sympathetic tone, causing arrhythmias. and inhibits na k atpase
When is digoxin used?
- To treat heart failure with atrial fibrillation and dysrhythmias
- Heart failure when diuretics and ACE inhibitors used and still have symptoms.
What;s the problemo with digoxin?
Low therapeutic index. small window. causes nausea and blurred vision.
How is digoxin toxicity treated?
Withdrawing it and trying to control the arrhythmias. Propranalol or phenytoin for the arhythmias,. KCl for hypokalaemia.
Name three other treatments for congestive heart failure?
- Phosphodiesterase inhibitors (PDE) ed milrinone
- B1- AGONIST eg dobutamine
- B1 ANTAGONIST WHEN BROUGHT IN SLOWLY eg carvedilol and metoprolol
(as well as digoxin)