Heart Failure Flashcards
ventricular stroke volume is dependent on which three factors
preload
afterload
contractility
how is preload approximated
by measuring ventricular end-diastolic volume
what is preload
ventricular wall tension at the end of DIASTOLE
what is afterload
ventricular wall tension during SYSTOLE
how is afterload approximated
systolic arterial/ventricular pressure
what is ventricular end-systolic volume dependant on/
afterload and contractility but not preload
how is ventricular wall stress estimated and what is its relationship to wall thickness and chamber radius
Laplace’s relationship
wall tension is proportional to radius and inversely proportional to wall thickness
besides the side of heart failure, heart failure can be divided into two categories. Name them and briefly describe them
PRESERVED ejection fraction or DIASTOLIC dysfunction- abnormality in ventricular filling
REDUCED ejection fraction or SYSTOLIC dysfunction - an abnormality in ventricular filling from impaired contractility or increased afterload
name 5 conditions which impair ventricular filling
conditions which impair early diastolic relaxation (as this is an active process) or increase the stiffness of the ventricular wall
- left ventricular hypertrophy
- restrictive cardiomyopathy
- transient myocardial ischaemia
- myofibrosis
- pericardial constriction or tamponade
name three things which impair contractility of the ventricles
coronary artery disease (MI/transient ischaemia)
chronic volume overload (mitral or aortic regurg)
dilated cardiomyopathies
name two conditions which can increase afterload in heart failure
aortic stenosis
uncontrolled HTN
describe two conditions which are non-cardiac in origin which cause heart failure
inadequate perfusion (severe haemorrhage)
increased metabolic demand (hyperthyroid)
outline three pathophysiological processes which occur in cardiac muscle leading to decrease in contractility
- change in gene expression (from adult to foetal)
- less efficient energetics
- impaired calcium handling (impair calcium release –> systolic dysfunction; impaired pumping of calcium outside of the cell impairs relaxation)
name three mechanisms of heart failure compensation
the Frank-Starling mechanism
neurohormonal adaptations
ventricular hypertrophy and remodelling
all of these mechanisms eventually become maladaptive
how does the Frank-Starling compensatory mechanism restore cardiac output
reduced stroke volume leads to incomplete ventricular emptying
on the next cardiac cycle this means the diastolic volume is increased.
This means that there is an increased stretch in the heart muscle and therefore increased contraction
which three neurohumoral alterations help compensate heart failure
- the adrenergic nervous system
- RAAS
- incr production of ADH
what are the three immediate effects from activation of the sympathetic nervous system in the context of heart failure compensation
increased contractility
increased heart rate
increased vasoconstriction (via alpha receptors in arteries and veins)
how does venous vasoconstriction increase cardiac output
it increases the venous return to the heart (increasing preload) which leads to increased stroke volume
what are the stimuli for renin release from the juxtaglomerular cells in the kidney in heart failure patients
1) decreased renal perfusion following reduced CO
2) decreased salt delivery to macula densa
3) direct stimulation of beta-2 receptors in juxtaglomerular apparatus via the sympathetic nervous system
name two ways angiotensin II increases the intravascular volume
1) at the hypothalamus it stimulates thirst
2) increases aldosterone secretion at the adrenal cortex
when is BNP released
it is not normally detected but is released when the ventricular myocardium undergoes haemodynamic stress
what is endothelin-1 and what is its significance in heart failure
a potent vasoconstrictor from endothelial cells
in heart failure endothelin-1 levels correlate with adverse outcomes
how does chronic volume overload alter the ventricular musculature
it results in ECCENTRIC hypertrophy - addition of new sarcomeres in series
this impairs filling as the wall become stiffer
how does chronic pressure overload alter the ventricular musculature
it results in CONCENTRIC hypertrophy - addition of new sarcomeres in parallel
this alters the wall tension owing the Laplaces law as the ventricle becomes thicker
what causes constant fatigue in heart failure
mishandling of calcium in skeletal muscle
list some factors which precipitate symptoms in patients with chronic compensated heart failure
increased metabolic demand (fever, infection, anaemia, tachycardia, hyperthyroidism, pregnancy)
increased circulating volume (XS Na, XS fluid administration, renal failure)
Increased afterload (HTN, AS, PE)
impaired contractility (negative ionotropic medications, MI, ethanol ingestion)
medication non-compliance
Bradycardia
list some of the symptoms of left sided heart failure
dyspnoea
orthopnoea
paroxysmal nocturnal dyspnoea
fatigue
list some of the symptoms of right sided heart failure
peripheral oedema
RUQ discomfort from hepatomegaly
how might aortic regurg develop in heart failure
from cardiomegaly distorting the valve orifice but the valve leaflets remain unchanged
what is the first symptom of pulmonary oedema
paroxysmal nocturnal dyspnoea- respiratory chemoreceptors are less responsive during sleep
at which pulmonary pressure can transudation of fluid into the pulmonary interstitium occur
20mmHg
what is PND
severe breathlessness which awakens the patietn from sleep 2-3 hours after going to bed
how does haemoptysis occur in heart failure
from engorged bronchial veins
what causes anorexia in heart failure
oedema in the gastrointestinal tract
what are the clinical signs of left sided heart failure
diaphoresis (sweating) tachycardia and tachypnoea pulmonary rales loud P2 S3/4 gallop
which gallop rhythm is associated with systolic dysfunction
S3 gallop (early diastolic sound) caused by abnormal filling of a dilated chamber
which gallop rhythm is associated with diastolic dysfunction
S4 gallop (late diastolic sound) cuased by forceful atrial contraction into a stiff ventricle
which type of diuertic would be used immediately in acute heart failure
loop as they have a strong effect and quicker onset
they work by inhibiting reabsorption from the loop of Henle
how do thiazide diuretics work
inhibit Na reabsorption in the DCT
what are the side effects of thiazide (and related diuretics)
electrolyte disturbance (decr Na and K)
Gout (incr urate)
Hyperglycaemia
Derranged lipids
how does nitroglycerine work in the treatment of acute heart failure
reduces preload, afterload and increases stroke volume
what are the commonest causes of heart failure
IHD
HTN
valve disease
Cardiomyopathy
what is cardiac cachexia
weightloss and anorexia commonly seen in HF
Caused by metabolic changes, gut congestion, reduced intake, inflammation
is a predictor of survival
which heart sound is pathognomonic of heart failure
gallop rhythm
What is Osler-Weber-Rendu disease also known as and what does it cause
hereditary haemorrhagic telangiectasia
there is vascular dysplasia and AVMs in the lungs liver and CNS
what are the main differential diagnoses for heart failure
liver disease
nephrotic syndrome
what is Eisenmenger’s syndrome
left to right shunt causing pulmonary hypertension leading to a cyanotic heart defect
which two drugs used in the treatment of heart failure can cause gynaecomastia
spironolactone
digoxin
which is the only ACEI used in paediatric cardiology
Captopril
which protein is lacking in hereditary angioedema and why is this relevant to heart failure
C1esterase inhibitor is lacking
can’t tolerate ACEI or ARBs
Kerley’s B lines are a specific sign of what
pulmonary oedema
can be caused by anything causing lymphatic obstruction eg sarcoidosis
what is the bat wing appearance
a sign of pulmonary oedema on CXR
would what a giant v-wave on jugular venous pressure be suggestive of
tricuspid regurgitation
what would cannon a-waves in a jugular venous pressure be suggestive of
complete heart block
