Heart Failure

Question 1

What is Biventricular heart failure?

Answer 1

Both right and left sided heart failure

Question 2

What is systolic heart failure?

Answer 2

• if ejection fraction <40% called systolic heart failure

- ventricles can’t pump hard during systole

Question 3

What is diastolic heart failure?

Answer 3

• not enough blood fills the ventricles during diastole
• reduced preload

both result in blood backing up into lungs = congestion and fluid build-up

Question 4

What causes left sided heart failure?

Answer 4

Usually systolic problem…

• ischaemic heart disease from coronary atherosclerosis = scar tissue created due to damage to myocardium cannot contract as forcefully
• long standing hypertension = if arterial pressure increases in systemic circulation - harder for left side to pump blood out, so compensates by ‘bulking up’ = hypertrophy. increased muscle mass requires more oxygen and squishes other coronaries
• dilated cardiomyopathy = heart chamber dilates or grows to attempt to fill with more blood (preload) and increase contraction = wall becomes thin + weak

Diastolic problem….

• long standing hypertension
• Aortic stenosis (narrowing of aortic valve opening)
• hypertrophic cardiomyopathy
• restrictive cardiomyopathy = heart muscle gets stiffer + less compliant

When the heart doesn’t pump out as much blood = decreased blood flow to kidneys = activates renin-angiotensin aldosterone System = fluid retention = fills heart more during diastole + increases preload = increases contraction strength.
• With fluid retention, some can leak into tissues from blood vessels leading to fluid build up

When heart can’t pump out enough blood a backup of blood seen in lungs. A back up of blood in capillary beds + pulmonary veins increases the pressure in the pulmonary artery. And can result in fluid moving from blood vessels to the institiual space causing pulmonary oedema (congestion).

In the alveoli in the lungs, all this extra fluid makes O2 + CO2 exchange a lot harder = dyspnoea, orthopnea (allows venous blood to more equally flow back from the legs + gut to heart + into pulmonary circulatory system. Crackles can be heard on the lungs when there is fluid in the lungs.

Question 5

What causes right sided heart failure?

Answer 5

Often caused by left-sided heart failure
- increased pulmonary pressure from fluid build up from left sided HF makes harder for right to pump blood into = biventricular

isolated right sided HF

• Left to right cardiac shunt = e.g. atrial septal defect
• enables blood to flow from the higher pressure on left side to the lower pressure right side = increases fluid volume on right side = hypertrophy
• Chronic lung disease (hard to exchange oxygen)- Due to hypoxia = pulmonary arterioles constrict raising the pulmonary blood pressure = makes harder for right side to pump against = hypertrophy + heart failure

In right sided heart failure, fluid is backed up to the body

Sign of systemic vein congestion = jugular venous distension

When fluid backs up to liver + spleen, fluid can move into interstitial space within these organs = become enlarge (hepato spleno megly)

• If liver is congested for long periods of time = develop cirrhosis+ liver failure
• Excess interstitial fluid around liver + spleen can move out into peritoneal space = fluid builds up = ascites
• Fluid that builds up in interstitial space of soft tissue of legs causes pitting oedema = Normally found in legs, as gravity causes fluid to pool

Question 6

What is the treatment for HF?

Answer 6

Initial

• Exercise = increases hearts efficiency = increases pumping ability
• Dietary changes = reduce salt, lowers BP
• Medications
  
  • ACE inhibitors = helps dilate blood vessels
  • Nitrates + hydralazines = lowers pressure
  • Beta blockers = inhibit action of SNS

Late stage

• medications
  
  • diuretics e.g. aldosterone inhibitors, treats congestion
  • CCB (diastolic HF) = dilated arteries = reduces BP + HR
  • Digoxin = increases strength of muscle contractions + lowers HR

Medical devices + surgery

• ventricular assist device (VAD) - helps ventricles
• Cardiac resynchronised therapy = pacemaker / defib
• surgery e.g. stents, coronary artery bypass, complete heart transplant