WEEK 5 - HEART AND LUNG PROBLEMS INTERLINKED Flashcards
cardiac conduction - SA and AV nodes, pace + process
SA node - made of pacemakers cell, spontaneously triggers an electronic signal through the atrial myocardium 60-100bpm (Sinus rhythm)
- conduction followed by influx of calcium, leading to muscle contraction
0.4 second pause between AV node activation
AV node - relays electronic signal through the Bundle of His through the ventricular myocardium via the Purkinje fibres.
- also made of pacemaker cells, firing every 40-60bpm
Heart failures types (not L+R)
Systolic HF:
- cant pump with enough force
- smaller and weaker myocardium, thinner muscle walls
- common sign - fluid build up in the lungs (congestion)
Diastolic HF
- cant fill with enough blood
- myocardium is larger, limiting the volume capacity for blood in the ventricles
- common sign - fluid build up in venous system (feet, abdomen)
Causes of L+R sided heart failure (3 factors)
Right
- Afterload - pulmonary hypertension (COPD, Left HF, pulmonary embolism, idiopathic hypertension)
- Contractility - myocardial infarction, infection, drug use (cardiomyopathies)
-
Preload
- increased load - hypervolemia (too much fluid in body e.g. IV drip), tricuspid and pulmonary valve regurgitation, shunting
- decreased load - tricuspid stenosis, hypovolemia
Left
- Afterload - systemic hypertension, aortic/aortic valve stenosis (narrowing)
- Contractility - myocardial infarction, infection, drug use (cardiomyopathies)
-
Preload
- increased load - hypervolemia (too much fluid in body e.g. IV drip), mitral and aortic valve regurgitation
- decreased load - mital stenosis, anaemia, hypovolemia
Valve heart disease: description
One or more of the valves in the heart are not functioning properly. Dysfunctional valves disrupt the cycle of blood through the heart and blood vessels surrounding it, which could cause heart failure
valve disease types (4)
- Stenosis - valves become thick/stiff, or conjoin together. The opening is now narrowed (stenosis). This allows for less blood flow through the valve than normal.
- Regurgitation - the valve flaps are unable to close properly, causing leaking back flow of blood.
- Prolapse - the valve flaps become stretched out and limp. This can cause regurgitation.
- Atresia - the valve is not formed. Blood flow is blocked between heart chambers.
valve disease risk factors (4)
- older age
- infections (e.g blood infection)
- MI
- hypertension, diabetes
chronic bronchiectasis –> HF
- bronchiectasis = blockage of alveoli = vasoconstriction of pulmonary arterioles
- leads to back log of blood = hypertension
- right ventricle must work harder to prevent back log = RV hypertrophy (cor pulmonale)
pulmonary oedema - effect on ventilation
- caused by excess fluid in the lungs.
- this fluid collects in the air sacs and and rather than the cell wall of the alveoli being one cell thick, it is much thicker due to the fluid
- this makes gaseous exchange more difficult, making the person hypercapnic and hypoxic.
- limited blood supply to the brain
- causes confusion
- delerium
- loss consciousness
- dyspnoea (air hunger)
- tight chest
mitral valve prolapse
Disallows the mitral valve to close properly, causing back up of blood in the left ventricle
- symptoms
- chest pain
- fatigue
- heart palpatation
- causes heart to dilate, can lead to heart failure
orthopnea
Orthopnea is a medical term to describeshortness of breath that occurs while lying flat and is relieved by sitting or standing.
In lying, left side heart failure causes decrease SV and allows blood to pool in the centre of the chest through the lungs. Leads to paroxysmal nocturnal dyspnoea (orthopnea during the night).
Dyspnoea
A feeling of not being able to get enough air.
Driven by peripheral chemoreceptors in the aortic arch and carotid body sensitive to changes in PaO2 and PaCo2.
Hypoxia or hypercapnia is then fed back to the brain stem.
Also driven by central chemoreceptors in the medulla sensitive to changes in cerebrospinal fluid hydrogen ions or C02.
how does LSHF cause RSHF
- left ventricle pumps less blood into the body
- the redued BF causes blood to back up behind the left ventricle, into the left atrium, lungs and eventually into the right ventricle
- the back up increased blood pressure, requiring the right side to pump harder to mantain
- the back up of blood in the lungs requires the right side to pump harder to prevent edema.
- Therefore there is more resistance through the pulmonary arteries
right sided heart failure (tension back up into the periphery) - signs
signs
- fatigue
- increased peripheral venous pressure
- ascites - fluid around the peritoneal (lines abdominal cavity)
- could make breathing painful
- enlarged liver and spleen
- vascular structures - full of vessels
- distended jugular veins - backlog in the superior vena cava
- anorexia and complaints of gastro-intestinal distress
- swelling in hands and fingers
- dependent edema
- cor pulmonale
