Cardiovascular principles Flashcards
What is shock
abnormality of the circulatory system which results in inadequate tissue perfusion and oxygenation
What can inadequate tissue oxygenation lead to (3)
anaerobic metabolism
Accumulation of metabolic waste products
Cellular failure
What are the four causes of inadequate perfusion
loss of blood volume
Sudden severe impairment of heart
Obstruction to circulation
Excessive vasodilation and abnormal distribution of flow
What are the four types of shock
hypovolemic
Cardiogenic
Obstructive
Distributive
What are the types of causes of hypovolemic shock (2)
haemorrhagic and non-haemorrhagic
What is Cardiogenic shock
sustained hypotension due to rudimentary cardiac contractility
What are the types of causes of Cardiogenic shock (4)
contractility
Mechanical
Arrhythmia
Cardiotoxicity
What is obstructive shock
physical obstruction of blood flow outside the heart
What are the types of causes of obstructive shock (2)
outflow
Venous return
How do hypovolemic, Cardiogenic, and obstructive shock decrease CO and BP (and therefore cause inadequate tissue perfusion)
By decreasing stroke volume
What is distributive shock
abnormal distribution of blood flow
What are the causes of distributive shock (2)
neurogenic
Vasoactive
How does neurogenic distributive shock lead to inadequate tissue perfusion
loss of sympathetic tone causes vasodilation
How does vasoactive distributive shock lead to inadequate tissue perfusion
Release of vasoactive mediators causes vasodilation and increase capillary permeability
How is shock managed (3)
high flow oxygen (saturation should be above 94%)
IV access
Fluid resuscitation
What is syncope
a non-traumatic form of a transient loss of consciousness
What are the characteristics of syncope (3)
rapid onset
Short duration
Spontaneous and complete recovery
What are the three types of syncope
neurocardiogenic
Postural hypotension
Cardiac syncope
What are the two causes of neurocardiogenic syncope
Vagal stimulation
Depression of sympathetic activity
How does vagal stimulation affect cerebral perfusion (3)
cardioinhibiton
Decreases heart rate
Decreases cardiac output
How does depression of sympathetic activity affect cerebral perfusion (3)
decreases SVR
Decreases venous return, stroke volume, and cardiac output
Mean arterial pressure is decreased
what can trigger vasovagal syncope (3)
pain
Prolonged standing
Emotional stress
What is syncope
A faint during or immediately after a trigger
What causes hypersensitive carotid sinus syndrome
hypersensitive baroreceptors
What are the three types of neurocardiogenic syncope
Vasovagal
Situational
Hypersensitive carotid sinus syndrome
In what demographic is HCSS more common
Elderly males
Postural/orthostatic hypotension description
Failure of the baroreceptors to respond to gravitational shifts in blood when moving from a horizontal to a vertical position
Describe cardiac syncope
transient loss of consciousness caused by a cardiac event which leads to a sudden drop in cardiac output
For which type of syncope is permanent cardiac pacing usually recommended
Hypersensitive carotid sinus syndrome
What is used to manage situational syncope (2)
avoiding dehydration
Lying down
What factors regulate coronary blood flow (3)
Physical, neural, and metabolic
What can overcome sympathetic tone
Metabolic hyperaemia during exercise
Why is resting blood flow low
sympathetic vasoconstrictor tone
Why may blood pool in lower limbs
if venous valves become incompetent
What results from blood pooling in lower limbs
varicose veins
Why is blood pooling in lower limbs not accompanied by a decrease in cardiac output
due to a chronic compensatory increase in blood volume
What is paracellular movement (2)
movement of substances through the cells themselves
Used by water
What is Transcellular movement (2)
movement of substances through the gaps between cells
Used by gases
How does protein movement occur (2)
some fenestrated capillaries facilitate protein movement
Pinocytotic vessels can facilitate protein movement
What types of pressure drive direction and magnitude of fluid movement (2)
hydrostatic pressure and osmotic pressure
Describe capillary hydrostatic pressure (3)
favour filtration
Product of arterial and venous pressures
Highest at the arterial end of a capillary
Describe interstitial hydrostatic pressure (2)
opposes filtration
Normally low because the lymphatic system draws fluid out of the interstitial space
Describe capillary oncotic pressure (2)
opposes filtration
Due to presence of proteins in the capillary lumen
Describe interstitial oncotic pressure (2)
Favours filtration
Due to presence of proteins in interstitial fluid
At which ends of a capillary are filtration and reabsorption more common
Filtration is more common at the arteriolar end
Reabsorption is more common at the venous end
Function of the lymphatic system
To return fluid from the interstitial fluid to the circulation via lymphatic capillaries
Which transport lymph towards the thoracic duct
When can blood flow be heart with a stethoscope
if external pressure is between systolic and diastolic pressure
When blood pressure exceeds external pressure and becomes turbulent
What does the first Korotkoff sound indicate
peak systolic pressure
What are the second third korotkoff sounds due to
turbulent spurts of flow which cyclically exceed cuff pressure
What does the fourth Korotkoff sound indicate
minimum diastolic pressure
What causes the first heart sound (auscultation)
closing of the mitral and tricuspid valves
What does the first heart sound signal
Beginning of systole
What causes the second heart sound
closure of aortic and pulmonary valves
What does the second heart sound signal
End of systole
Beginning of diastole
Why can the second heart sound split (3)
during inspiration intrathoracic pressure decreases, increasing venous return to the right side of the heart
Increased volume in the right ventricle increases right ventricular ejection time
Pulmonary component of the second heart sound is delayed compared to the aortic component
What is the third heart sound
an early diastolic low frequency filling sound occurring immediately after the second heart sound
Where is the third heart sound most clearly heard
the apex of the heart
When would a third heart sound be pathological
in an older patient - could be caused by left ventricular systolic dysfunction
What is the fourth heart sound
a late diastolic low frequency filling sound occurring before the first heart sound
What causes the fourth heart sound
atrial contraction causing a rapid flow of blood into a less compliant ventricle
Associated with myocardial ischaemia, hypertension, and aortic stenosis
Which heart sound is always pathological
4
Which type of murmurs coincides with the carotid pulse
systolic
What causes cardiac murmurs
Turbulent blood flow in the heart
Which type of murmur is always pathological
diastolic
Which type of systolic murmurs can be pathological (3)
ejection
Late-peaking
Pan-systolic
What are the general features of pathological murmurs (3)
radiation
Poor localisation
Associated abnormalities
Describe the events of a pacemaker potential (3)
slow depolarisation
Further depolarisation involving calcium ion influx
Repolarisation involving potassium ion efflux
What is the funny current
a mixed sodium and potassium inward current resulting in slow depolarisation
Describe the events of a myocardium action potential (5)
depolarisation (Na influx)
Transient K efflux
Ca influx
K efflux
Resting potential restored due to K efflux
Which type of cell has a plateau phase in the action potential
Myocardium
What occurs during the plateau phase of a myocardium action potential
calcium ion influx through L type calcium ion channels
What receptors are involved in sympathetic stimulation of th heart
beta one receptors
How does vagal stimulation affect the pacemaker potential
decreases the slope
Which medication poses the risk of hypokalaemia
thiazide and loop diuretics as they increase potassium excretion (step three of hypertension treatment)
what is an indirect effect of loop diuretics
venodilation
An inferior STEMI results in changes in what parts of an ECG
leads II, III, and AVF
An anterior STEMI leads to changes in which part of an ECG
Leads V1-V6
Which ECG leads are the precordial leads
V1-V6
Which artery supplies the anterior aspect of the myocardium
left anterior descending coronary artery
If a patient suffers from an anterior STEMI, which artery is likely to be involved
Left anterior descending coronary artery
Describe how hypertrophic cardiomyopathy arises
due to a mutation in sarcomeric genes
Inherited in an autosomal dominant pattern
What test would be used if an abdominal aortic aneurysm is suspected
ultrasound
How does ventricular fibrillation present on an ECG (3)
Random, irregular rhythm
with no identifiable QRS complexes or P waves
Wandering baseline
How is first degree heart block characterised on an ECG
prolonged PR interval (greater than 0.2 seconds)
What can hypertrophic cardiomyopathy cause in relation to the structure of the heart
Asymmetric Hypertrophy of the inter-ventricular septum
What type of murmur is associated with hypertrophic cardiomyopathy
systolic crescendo-decrescendo (ejection) murmur along left sternal border
What type of murmur is associated with aortic stenosis + where is it heard
ejection systolic (crescendo-decrescendo)
Heard at upper right sternal border
Possibly radiating to carotids
What is the most common causative agent of acute bacterial endocarditis
staphylococcus aureus
What is the most common causative agent(s) of subacute endocarditis (2)
Streptococcus viridans
Staphylococcus epidermidis
Symptoms of left sided heart failure (4)
Breathlessness
Paroxysmal nocturnal dyspnoea
Productive cough
Bi-basal crackles
Symptoms of right sided heart failure (3)
raised JVP
Hepatomegaly
Peripheral oedema
What murmurs is associated with aortic regurgitation + where is it heart
Diastolic decrescendo murmur
heard at the left lower sternal border
What are the symptoms of aortic regurgitation (2)
shortness of breath
dizzines
(as a result of regurgitation of blood back into the heart)
What conditions are associated with aortic regurgitation
Connective tissue diseases such as Marfan’s syndrome
