238 - Heart Failure Flashcards
What is heart failure?
Failure to maintain cardiac output to meet the bodies O2 demands despite adequate venous return/pressures
What investigations can be done in ? Heart failure?
ECG - if normal - probably not HF CXR - specific signs Bloods - Brain Natiuretic peptide Echocardiocram Perfusion Scintigraphy
What sings are seen on CXR with someone with heart failure/
Cardiomegaly Pleural effusion Pulmonary oedema Kerley's B lines Pulmonary venous congestion
What function does testing Brain natiuretic peptide have?
Levels increase with myocardial wall stress
A low value has a high negative predictive value for HF
What might you seen on an echocardiogram in HF
LV or RV - dilated, reduced contractility
Valve lesions?
Mechanical dysfunction
What does perfusion scintigraphy do?
Looks for coronary artery disease
Stress heart with a drug - inject radioactive dye, scan with a gamma camera - shows blood flow + scarring
Heart failure can be classified many ways, what are they?
Left vs right sided
Systolic vs Diastolic
How output vs high output
Describe Left sided HF
Sympt, signs, why?
Pulmonary venous congestion
Sympt: Dyspnoea, orthopnoea, paroxysmal nocturnal dyspnoea, fatigue.
Signs: displaced apex beat, S3/S4/Gallop rhythm, basal insiratory crepitations
Why? 70% ischaemic heart disease
10% valvular heart disease
10% cardiomyopathy
Can be due to Bp, toxic, diabetic, sepsis
Describe Right sided heart failure
Systemic venous congestion
Symp: Peripheral oedema, Raised JVP, Hepatomegaly, ascites.
Why? Chronic lung disease -> Cor pulmonale, pulmonary hypertension, L-R cardiac shunts, chronic valvular disease
What is CCF?
Congestive Cardiac Failure
L and R heart failure combined
What heart sound is pathonemonic of heart failure?
a 3rd hear sound - sounds like gallop rhythm
Describe systolic HF
HF symptoms with Left ventricular systolic dysfunction and reduced pump function
a reduced ejection fraction of
Describe diastolic HF
HF symptoms with a preserved LV systolic function
Normal heart size but LA increased in size, LV wall thickened - so the ventricle can’t relax enough as it is too stiff -> less filling.
What is low output heart failure?
Most HF is low output
CO is reduced and fails to increase normally with exertion
Due to pump failure, excessive preload or chronic excessive afterload
What is high output heart failure?
Rare
When CO is normal or increased, but faced with very high needs - so failure because CO can’t meet those excessive needs.
A mimic of heart failure - eg. anaemia, septicaemia, liver failure, beri beri, AV shunt
- look for reversible causes
What lifestyle management options are there in heart failure?
Patient education key Monitor weight (for oedema) Sodium restriction Fluid restriction Reduce alcohol Moderate daily exercise
What disease modifying medication is available in heart failure?
1st) ACEinhibitor + Beta-Blokers
2nd) if intollerant try ARBs - angiotensin II receptor antagonists
3rd) if intollerant try Isorobide dinitrate + hydralazine
Then: If symptoms persist add in:
- Spironolactone
- Ivabridine
Which ACE inhibitors are used in HF?
Ramipril, captopril
What do ACEi do in HF?
They improve symptoms and improve LV function and increase survival + reduce hospitalisation
Who are ACEi contra-indicated in?
Severe AS/MS/LVOT
bilateral renal stenosis
Pregnancy
If Creat >220
What side effects do ACEi have? Why?
Hypotension
Cough (also blocks bradykinin which supresses cough normally)
Which B-Blockers are used in heart failure?
Bisoprolol
Cavedilol
Reduces mortality by 30%
Which ARBs are used in Heart failure?
Candestartan
Valsartan
- don’t give a cough s/e so good if can’t cope with ACEi
What does spironolactone do in HF?
A K+ sparing diuretic, acts as an aldosterone antagonist.
It is cardioprotective, and reduces mortality and hospitilisation
What is a side effect of spironolactone?
Gynecomastia
Breast pain
High K+
How does Ivabridine work?
Inhibits If channel in the sinus node - reduces HR.
Reduces hospitalisation but not mortality
Good for QoL
What are some symptom relieving medications that can be used in HF?
Loop diuretics (Furosemide, Bumetanide) - Act on ascending loop of henle
Digoxin - improves filling by slowing down conduction pathways in the AV node - reduces ventricular rate
What surgery could be done for someone with HF?
Cardiac resynchronisation - CRT-P
+ a defib - CRT-D
Synchronises inter and intra ventricular contraction in HF
What determins cardiac output?
CO = HR x SV
SV is determined by contractility + preload, and negatively affected by afterload.
What is afterload?
Ventricular wall tension during systole
Increases if arterial pressure increases
How do calcium changes damage muscle function in heart failure?
Normally Ca is released from stores and influx - which causes contraction. Ca is then pumped back out again into the stores by a co-transporter
In failure - There is reduced Ca movement, and reduced Ca in stores - so less is released. So there is less energy in each contraction.
There is also impaired reuptake after each contraction - so the muscle relaxes poorly
- so dysfunction in contraction and preload.
What is the cardiac function curve?
Flow plotted against central venous pressure - gives you CO as the curve.
Developed by starling - isolated heart-lung preparations.
- examined the effects of change in filling pressure on output.
Why is the curve that shape? The myocytes contract following an isometric length-tension curve - so same shape.
What are gyton curves?
Cardiac function curve with a venous return curve combined - Where they intersect is the CO.
In HF the heart compensates -what is the Frank starling mechanism ?
Frank starling mechanism - SV increases with increased volume of blood filling (end diastolic volume)
- this shifts the curve up slightly - helps increase CO in early heart failure
In HF the heart compensates - explain what happens to the ventrical
Ventricular hypertrophy and remodelling - concentric and eccentric hypertrophy increases the ventricular volume
BUT in longrun harmful
Why is ventricular hypertrophy bad in the long run in HF?
It causes decompensation
The failing heart has to push against increased total peripheral resistance.
Due to Laplace’s law - T=Pr/2
As the radius increases you require more tension to produce the necessary pressure.
The AV valve also becomes too small - get leakage
Describe the neurohumoral activation that occurs in heart failure
A reduced CO causes:
- Increase in sympathetic activation -> increase in contractility and HR - increase CO
- RAAS -> vasoconstriction: arteriolar increases Bp, venous increases venous return -> increases preload
- also redustribution of resting CO - more to brain
- ADH increases - increases circulating volume - increases venous return
Why do the neurohumoral adaptations in heart failure harmful in the long term?
Volume expansion -> oedema
R failure - Peripheral oedema
L failure - pulmonary oedema -> conjections on pul veins and cap
Ventricular arrythmias can also be caused by re-entry circuits (DAD mediated?)
