7 Flashcards
What is the cardiac afterload
Ventricular contraction and blood ejection against arterial resistance
What is the cardiac preload
Ventricular relaxation and filling of the heart via main capacitance veins
What is heart failure
Cardiac output insufficient to meet circulatory needs of the body
What are typical symptoms of heart failure
Breathlessness, ankle swelling and fatigue
What is usually the cause of heart failure
Ischaemia to the myocardium
What are two major types of heart failure
Systolic failure - contractility or force of contraction reduced
Diastolic failure - stiffening and inadequate relaxation
What are two major causes of heart failure
Ischaemic heart disease
Hypertension
What is the formula for EF
SV/EDV
What is occurs to the EF during heart failure
SV decrease and EDV increases
What is a case where EF can be normal yet the ventricle in failure
Diastolic dysfunction caused by hypertrophy
What occurs in right ventricular heart failure (3)
1) Right ventricle does not pump forward
2) Pressure in systemic circulation increases
3) Congestion in veins and leads to peripheral oedema
What occurs in left ventricular heart failure (3)
1) Left ventricle does not pump forward
2) Pressure in pulmonary circulation increases
3) Congestion within pulmonary veins leading to pulmonary oedema
What are some consequences of heart failure (5)
1) Cardiac output reduced
2) Reduced EF
3) Fluid retention
4) Vasoconstriction
5) Cardiac hypertrophy and fibrosis
What compensatory mechanisms are activated
SNS
RAAS
“hormonal” - atrial natriuretic factor, endothelin
What drugs work indirectly to decrease workload of heart (6)
ACEI ARB Diuretics Aldosterone antagonist B blockers Nitrates
What drugs work directly to stimulate the heart (2)
Inotropic agents
B1-agonists
How do ACEI and ARB treat heart failure
Decreased vasoconstriction
Decrease oedema
How do diuretics and aldosterone antagonists treat heart failure (2)
Decreased oedema
Decreased BP
(but increase raas)
How do B blockers treat heart failure (3)
Decreased HR
Decreased cardiac workload
Decreased RAAS
What is the first line treatment for heart failure
ACEI
When are cardiac stimulants useful
Patients with atrial fibrillation
What is the MOA of digoxin
Inhibits Na/K/ATPase
Decreases Na/Ca2+ exchange
Increases intracellular Ca2+
What are side effects of digoxin and its low TI (4)
Nausea
Vomiting
Bradycardia
Arrhythmia
What are three effects of digoxin (Lanoxin)
1) Positive inotropic on the heart
2) Reduce serum renin and aldosterone level
3) Increases parasympathetic tone on the heart
