Heart Failure (Fri 20th)

Question 1

Heart Failure

Answer 1

The heart pumps insufficiently to maintain adequate perfusion of tissues.

Question 2

Causes of HF

Answer 2

1. Cardiac causes: Ischaemic HD, arrhythmia, valve disease

2. Extra-cardiac causes: hemorrhagic shock, hypertension, anaemia, viral myocardium.

Question 3

Ischaemic Heart Disease

Answer 3

IHD is the most common cause of heart failure and leading killer in Western population. Risk factors include age, gender, socioeconomic status, diet, smoking, alcohol, diabetes, physical inactivity and hypertension

Question 4

Ischaemia

Answer 4

Lack of oxygenated blood, resulting in poor oxygen availability, nutrients and inadequate removal of metabolites. Most cases due to reduction in coronary blood flow, due to artery narrowing due to atherosclerosis.

Question 5

Necrosis

Answer 5

Tissue death

Question 6

Order of severity in Ischaemic Syndromes:

1. Angina Pectoris

Answer 6

1. Angina Pectoris: chest pain, and in back, jaw and left arm. Feels like strangling in chest. Transient, pain goes away 15s- 15m. Does not cause necrosis. Chemo-receptors pick up metabolites not sufficiently removed by blood flow and transmit the pain message via C-fibres and sympathetic afferents. Treatment needed to improve blood flow and decrease work of the heart. Endothelial cells make nitric oxide and goes to muscle cells, to form cyclic GMP, which relaxes the muscle. β-blockers- less work by heart

Question 7

Order of severity in Ischaemic Syndromes:

2. Myocardial Infarction

Answer 7

2. Myocardial Infarction: during heart attack, ischaemia causes necrosis of heart tissue, which can not be regenerated. Most common form is trans-mural (right across wall of chamber). In ECG, the hallmark of MI is a pathological Q wave. Use surgery, stents to remove blockage and drugs like blood thinners and statins.

Question 8

What are the compensatory responses of the body in CHF?

Answer 8

1. Body tries to use the Starling effect to contract properly and prevent pooling, but heart eventually becomes overstretched, and this decreases performance.
2. Sympathetic – but in the long-term this is not involved
3. Compensation by the kidneys. This produces a hypervolaemia which leads to an increase in Cardiac Output (see kidney course). However, although this improves cardiac output, it doesn’t stop the decline in heart itself.

Question 9

Order of severity in Ischaemic Syndromes:

3. Chronic Heart Failure

Answer 9

3. Chronic Heart Failure: Progressive myocardial damage over many decades. History of angina and MI. Increase in blood pooling in the chambers of the heart. Pressure increase in atria, transmitted back to venous system, and back to capillaries. This means in the venous end of capillary the pressure is increased, causing fluid leaving the capillary and into the lung.
   Left sided HF can cause pulmonary oedema and so breathing difficulties. If have left sided HF, patient needs to be kept upright. Cardinal sign of L sided heart failure can’t sleep lying down, due to fluid. R. sided HF causes oedema in liver and ankles/legs. Treatments involve diuretics like thiazides, to pee out excess fluid. Also use ACE ( angiotensin converting enzyme) inhibitors which reduce fluid retention and reduce plaque in blood vessels. This will lower after-load/BP. Another treatment is to use drugs that have a positively ionotropic effect (increase the strength of contractions). EG) Glyosides to increase calcium ion concentration in cells and β1-adrenagonists, such as dobutamine.