Heart failure Flashcards
Heart failure, what is it
- heart can’t supply enough blood to meet the metabolic demands of the body
- many of the ischemic diseases and valvular diseases can lead to inability of the heart to function properly, causing HF -> and death
List the different types of HF
- Systolic HF
- Diastolic HF
- RHF
- LHF (LHF+Systolic HF / LHF + Diastolic HF)
- Low CO HF
- High CO HF
What is the CO
- the volume of blood the heart squeezes out each minute = CO
CO usually around 5L/min
CO = HR x SV
What’s normal CO, normal HR, normal SV
normal CO = 5L/min
normal HR = around 70bpm
normal SV = around 70ml of blood per beats
What is the ejection fraction
Ejection fraction: expressed as a percentage, of how much blood the left ventricle pumps out with each contraction.
EF = SV / Total volume
Ejection fractions measures:
- between 50 and 70%: normal EF
- between 40 and 50%: borderline
- below 40%: Systolic HF
What is Systolic HF, and how is the EF altered
- heart can’t pump hard enough and send enough blood to maintain the metabolic demands, EF is diminished (less than 40%)
What is Diastolic HF
- the heart squeezes hard enough, but is not filling enough the left ventricle
How is the EF changed in diastolic HF ?
- the heart doesn’t fill enough (reduced preload), so the SV will be low, but the total volume will also be lowered, so the EF remains normal
Ex: 44ml / 69ml = 64%
LHF + Systolic HF, def
- usually due to systolic (pumping) dysfunction, most of the time because of damage to the myocardium
LHF + Systolic HF: state the different causes that could lead to LHF+Systolic HF
- ischemic heart disease
- long standing HTN
- dilated cardiomyopathy
LHF + Systolic HF: C: Ischemic heart disease
- Ischemic heart disease
.Coronary atherosclerosis -> less blood to the myocardium -> damaged myocardium
.Complete coronary artery blockage -> heart attack (MI)-> scar tissue formation -> no more contracting function to the affected area
LHF + Systolic HF: C: Long standing HTN
- Long standing HTN: makes it harder for the LV to pump blood -> causes LV hypertrophy -> requires more O2 to the muscles + squeezes coronary arteries (making it even harder for the blood/O2 delivery) -> leads to weaker contraction -> systolic failure
LHF + Systolic HF: C: Dilated cardiomyopathy
- Dilated cardiomyopathy: chambers grow in size -> attempt to fill the ventricles with larger amount of blood (preload) -> stretches the muscle wall -> increases the contraction strength (via the frank starling mechanism) -> over time the muscle wall gets thinner and weaker -> becomes so thin -> causes systolic HF
LHF + Diastolic HF: causes
- long standing HTN
- aortic stenosis
- hypertrophic cardiomyopathy (genetic)
- restrictive cardiomyopathy
LHF + Diastolic HF: long standing HTN, aortic stenosis, hypertrophic cardiomyopathy
- Long standing HTN, aortic stenosis, hypertrophic cardiomyopathy -> all lead to concentric hypertrophy -> less room for filling -> diastolic HF
LHF + Diastolic HF: C: restrictive cardiomyopathy
- restrictive cardiomyopathy: wall is stiffer and less compliant -> wall can’t stretch out and fill blood -> can lead to diastolic HF
HF body compensatory mechanism (kidney)
- as the heart doesn’t pump out much blood -> there’s a decrease of blood to the kidneys -> which stimulates the renin-angiotensin-aldosterone system -> causing fluid retention -> which fills the heart a bit more during diastole and increases its preload -> which increases its contraction strength (because of the frank-starling mechanism)
However, in long term, because of more fluid retention in the blood vessels -> leads to a large portion leaking in the tissues -> contributes to fluid buildup in the lungs and other parts of the body -> worsen the symptoms of heart failure
LHF: signs and symptoms
- pulmonary edema (congestion): because the blood can’t go forwards -> back up in veins and capillaries -> fluid goes to the interstitial space
- Dyspnea: extra fluid in the alveoli makes the O2/CO2 exchange harder
- Orthopnea: difficulty breathing when laying flat
- crackles (rales) upon auscultation (because of the extra fluid)
LHF: T
- medications to help improving the blood flow:
.ACEi -> dilates blood vessels
.Diuretics -> reduces fluid build up
Right HF: C
- most commonly due to LHF -> which in this case will cause biventricular HF
- isolated RHF can be due to a left to right shunt: arterial septal defect, ventricular septal defect
- Chronic lung disease -> makes O2 exchange harder -> in response to hypoxia, pulmonary arterioles contract -> which increases pulmonary BP -> causes hypertrophy + HF, called COR pulmonale
Right HF: compensatory mechanism
- increased fluid volume on R side -> causes concentric hypertrophy, leads to:
.myocardial ischemia -> systolic dysfunction
.Smaller volume filling -> less compliant -> diastolic dysfunction
Right HF: signs and symptoms
RHF -> blood backs up in the body -> congestion in systemic vein circulation
- Jugular vein distention
- Hepatosplenomegaly, painful
- congested liver over a long period of time causes cirrhosis and liver failure (cardiac cirrhosis)
- ascites: fluid excess found near the surface of the liver and spleen can go in the peritoneal space
- pitting edema: fluid that backs up in the interstitial space of the tissues of leg -> tissue is swollen and when pressure is applied to it, leaves a pit
Right HF: T
- ACEi
- Diuretics
Arrhythmias as a complication of heart failure
- HF gets either stretched and thinner, or thicken and becomes ischemic -> either ways -> heart cells get irritated -> can cause arrhythmias
Arrhythmias -> ventricles can’t contract synchronically -> less blood pumped out -> worsen the situation
Heart failure: Diagnosis
- medical history
- physical examination: BP, HR, auscultation, depends on which type of HF is present
- blood test: Brain Natriuretic peptide (hormone secreted by the ventricles) can be used as a screening test for HF, cardiac markers, CRP
- ECG
- Echocardiography, doppler echocardiography: look for -> SV, EF, EDV, wall motion, valvular damage
- Angiography
