Heart failure Flashcards
define Cardiac output
the amount of blood the heart pumps in 1 min
Define stroke volume
the volume of blood pumped out of the heart with each cardiac contraction
Define ejection fraction
the proportion of the blood ejected with each heart beat - normal value 50-70%
What is the normal cardiac output at rest?
4-8L
How do we work out the EF?
SV/EDV all x100
Define heart failure
- a complex clinical syndrome in which the heart is incapable of maintaining a cardiac output adequate to accomodate metabolic requirements and the venous return
What is chronic heart failure?
long term, gradual, reduction in heart failure
What is acute heart failure?
sudden decompensation in heart function
What is HFrEF?
heart failure with a reduced ejection fraction - systolic dysfunction
What is HFpEF?
heart failure with a preserved ejection fraction- diastolic dysfunction
What is LV dysfunction?
systolic- impaired contractility/ejection, approx 2/3 of HF patients have systolic dysfunction
Diastolic- impaired filling/relaxation
Describe the prevelance of HF
-increases with age
-HF accounts for approx 2% of all hosp bed stays and 5% of all medical emergency admissions
1 in 35 people aged 65-74 years
1 in 15 people aged 75-84 years
1 in 7 people aged >= 85 years
What causes HF?
-the loss of critical quantity of functioning myocardial cells after injury to the heart due to
-IHD
-hypertension
-idiopathic cardiomyopathy
-infections ( viral myocarditic, Chagas’ disease)
-toxins
-valvular disease
-prolonged arrhythmias
What are the classes of HF according to the NYHA?
I- no symptoms, ordinary activity
II- slight limitations of physical activity, comfortable at rest, but ordinary physical activity results in fatigue, palpitations, dyspnea or angina
III-marked limitation of physical activity, comfortable at rest, less that ordinary physical activity results in fatigue, palpitation, dyspnea or anginal pain
IV-unable to carry out any physial activity without discomfort, symptoms of cardiac insufficency may be present at rest
What are the stages/ classification of HF according to the AHA?
A-high risk- hypertension, CAD, diabetes, HX of cardiomyopathy
B- Aymptomatic LVD- previous MI, LV systolice dysfunction, assymotimatic valvular disease
C-symptomatic HF- known structural heart disease, SOB, fatigue, reduced excersise tolerance
D-Refractory End stage HF- marked symptoms at rest despite maximal medical therapy
What is inotropy?
contractility (Increased or decreased)
Define the Frank-starling law of the heart
the force of tension developed in a muscle fibre depends on the extent to which the fiber is stretched, increased quantities of blood flow into the heart, increases preload, heart walls stretch
What are some determinants of ventricular function?
-preload
-contractility
-afterload
-HR
-Cardiac output
-synchronised LV contraction, Wall integrity, valvular competence
-stroke volume
What factors can cause LV dysfunction?
-volume overload
-pressure overload
-myocardium loss
-imparied contractillity uncoordinated
What happens to the heart as a result of LV dysfunction <40% ?
-decreased cardiac output leads to hypoperfusion
-increased end systolic volume, end diastolic volume leads to pulmonary congestion
What are some symptoms of LV dysfunction- systolic and diastolic?
-dyspnea on exertion
-paroxysmal nocturnal dyspnea
-tachycardia
-cough
-haemoptysis
-fatigue
What are some physical signs of LV dysfunction- systolic and diastolic?
-Basilar rales
-pulmonary oedema
-S3 gallop-systolic dysfunction
-pleural effusion
-Cheyne-strokes respiration
What are some symptoms of RV failure?
-abdominal pain
-anorexia
-nausea
-bloating
-swelling
What is basilar rales?
lung sounds- listen for basal crackles
What are some physical signs of RV failure - systolic and diastolic?
-peripheral oedema
-jugular venous distention
-abdominal jugular reflux
-hepatomegaly
what is cheynes- stokes respiration?
very irregular breathing, disarrangement of body oxygen saturations
What are some consequences of decreased MAP?
-decreased cardiac output x total peripheral resistance
What is hepatomegaly?
liver enlargement
What are some compensatory mechanisms for HF?
-Frank- Starling mechanism
-Neurohormonal activation
-Ventricular remodeling
Describe the Neurohormonal activation mechanism
-SNS
-RAAS
-Vasopressin- ADH
What is the equations for increased MAP?
Increased MAP = (increased SV X increased HR) x increased TPR
Describe the RAAS system
-angiotensinogen
-angiotensin 1- angiotensin 2
AT II receptor:
-systemic vasoconstriction
-oxidative stress
-sodium and water retention
-proteinuria
-LV remodelling
-Vascular remodelling
-sympathetic augmentation
What is ventricular remodelling?
alterations in the heart size, shape and structure and function brought about by the chronic haemodynamic stresses experienced by a failing heart
Name 3 known types if neurohormones/ natriuretic peptides
-Atrial natriuretic peptides (ANP)
-brain natriuretic peptide ( BNP/NT-PRO-BNP
-C type natriuretic peptide ( CNP)
Describe ANP
-predominantly found in atria- diuretic and vasodilatory properties
Describe BNP/NT-pro-BNP
-predominatly found in cardiac ventricles
-diuretic and vasodilatory properties
-used as a marker to detect, diagnose and monitor HF severity
Describe CNP
-predominantly found in the CNS
-limited natriuretic vasodilatory properties
Describe the HF cycle
1-LV dysfunction
2-decreased cardiac output and BP
3-Frank-Starling remodelling, neurohormonal activation
4-increased cardiac output via increased contractility and HR. Increased BP via vasoconstriction and increased blood volume
5-increased cardiac workload, increased preload and afterload
What are some neurohormonal responses to impaired cardiac performance?
-salt and water retention
-vasoconstriction
-sympathetic stimulation
What are some long and short term effects of salt and water retention on the heart ?
short-augement periods
long-pulmonary congestion, anascara
What are some long and short term effects of vasocontrcition on the heart?
short-maintains BP for perfusion of vital organs
long-Exacerbates pump dysfunction (excessive afterload), increases cardiac energy expenditure
What are some long and short term effects of sympathetic stimulation on the heart?
short- increased HR and ejection
long-increased energy expenditure
