Block 13 - Cardiorespiratory systems (cardio) Flashcards
What is the progression of heart disease? (5)
Asymptomatic > Stable angina > Acute coronary syndrome (unstable angina > AMI) > Heart failure > Death
Explain the timeline of atherosclerosis (4)
- Fatty streak augmented by smooth muscle and platelets > inflammation
- Fibrous cap forms on top > vessel enlargement
- Core becomes necrotic which increases inflammation
- Cap thins and ruptures > thrombus formation
What does an ECG look like in a patient who has just exercised and has stable angina?
ST depression
What is acute coronary syndrome?
Progression from unstable angina to acute myocardial infarction
What is the pain like in angina?
‘central tight chest pain’
What does an ECG look like in a patient with unstable angina?
- Normal
- ST elevation
- No ST elevation
What is the difference between an ‘interval’ and a ‘segment’ on an ECG?
Intervals are bigger and overlap peaks
Segments are smaller and are between peaks
What happens to the ECG when you block a coronary artery (5 stages)
- peaked T wave (min)
- ST elevation (min>hr)
- loss of R wave and Q wave formation (hr>day)
- T wave inversion
- T wave normalisation but persisting Q wave (month)
What happens if you block the LAD or RCA?
Which has the worse prognosis?
LAD: reduced supply to the L ventricle (worse prognosis)
RCA: reduced supply to the inferior wall of L ventricle and R ventricle
(right coronary artery)
What ECG change can an NSTEMI have which is worse?
ST depression
What protein is measured in the blood to diagnose a heart attack?
Troponin
6 other causes of increased troponin
PE AF Sepsis Hypertension Aortic or brain haemorrhage Renal dysfunction
How do you die from an MI?
Arrhythmia
Explain the pathophysiology behind a myocardial rupture
A hinge forms at the edge of the infarct zone
Breakage of this causes bleeding into the pericardial sac
What is a false aneurysm?
When the rupture is incomplete and heals itself
How are ruptures diagnosed?
ECHO
What is the mitral valve made from?
What is the blood supply to the 2 muscles?
Which muscle has less chance of rupturing?
Mitral valve made from 2 leaflets controlled by papillary muscles
Posteromedial muscle supplied by PDA from RCA
Anterolateral muscle supplied by LAD and LC (dual)
How do patients present with a papillary muscle rupture?
Hypotension, Shock, Pulmonary oedema
Mid-late systolic murmur
How do patients present with an interventricular septum rupture?
Haemodynamic compromise
Harsh, loud and holosystolic murmur as blood shunted from L to R
What is left ventricular dysfunction?
4 symptoms
Large infarct causes lasting damage
SOB, peripheral oedema, orthopnoea, PND
How is left ventricular dysfucntion diagnosed?
NTProBNP
What does the New York Heart Classification classify?
Explain the 4 classes
Classifies how bad the left ventricular dysfunction is
- No symptoms on normal activity (normal exercise)
- Symptoms on normal activity (slight limitation)
- Symptoms on less than normal activity (exercise limitation)
- Symptoms at rest (no activity without discomfort)
What is sudden cardiac death?
Death due to ventricular fibrillation (VF)
What is the difference between myocytes and pacemaker cells?
Myocytes = atria and ventricles
Depolarise after stimulation
Intrinsic ability to send impulses
Pacemaker = SAN, AVN and conducting tissue
What are the 4 stages of the cardiac action potential?
Phase 0: Inflow of Na > rapid depolarisation
Phase 1: Na channel closure > rapid repolarisation then Cl in and K out
Phase 2: Plataeu, delay repolarisation due to slow inward Ca and K out
Phase 3: 2nd repolarisation by K out and Ca in
Phase 4: Resting membrane potential
Draw the cardiac action potential
See image in revision folder
How is resting membrane potential in the heart maintained?
Increased intracellular K so it diffuses out
Negative intracellular ions cannot penetrate membrane > slight negative charge at rest
K out of Na/K ATPase (active)
Na/Cl exchange (passive)
What are the stages of the nodal action potential?
Phase 0: Depolarisation (Ca comes in)
Phase 3: Repolarisation (slow increase in K out and inactivation of Ca in)
Phase 4: Spontaneous depolarisation (slow Na in)
Draw the nodal action potential
See image in revision folder
What 2 stimuli do the SAN AND AVN respond to?
Neural and hormonal
Where is the AVN and what is its protective role?
Base of inter-atrial septum, only connection across the annulus fibres
Prevents high atrial rates > ventricles
What are the annunuls fibres?
Provide insulation between the atria and ventricles
What are the conduction velocities of the:
- His and purkinje
- Ventricular and atrial muscles
- AVN
- His and purkinje: fastest (2-5ms)
- Ventricular and atrial muscles: (1ms)
- AVN: slowest (0.05ms) - time for atrial to fill
What is the intrinsic rate of the:
- SAN
- Bundle of His
- Purkinje cells
- SAN: 105bpm
- Bundle of His: 40bpm
- Purkinje cells: 15bpm
What happens to the heart rate at rest?
Vagal inhibition predominates to slow the heart down from 105bpm
What is the heart rate in complete heart block?
Why?
Annulus fibre conduction is blocked so bundle of his predominates and the heart rate is 40bpm
What is the absolute refractory period?
Phase 0-3
No way to stimulate heart
What is the relative refractory period?
What is the clinical significance?
Phase 3-4
At the T wave - this is when you shock the heart
How long should the P-R interval be?
What happens?
0.12-0.20 seconds
3-5 small boxes
(AVN > Atrial conduction)
How long should the QRS interval be?
What happens?
0.08-0.12 seconds
2-3 small boxes
(ventricular conduction and contraction)
How long should the QT interval be?
What happens?
0.30-0.46 seconds
12 small boxes
(repolarisation of ventricles)
Which interval is dependent on heart rate?
How do you calculate corrected heart rate?
QT interval
QTc = QT/√RR
When does QT = QTc?
60 bpm
How many milliseconds is:
- a small square
- a large square
- 1 minute
- a small square: 40ms
- a large square: 200ms
- 1 minute: 300 x 200 = 60,000ms
How do you calculate heart rate on an ECG?
300/number of squares
Define bradycardia and tachycardia
What is normal heart rate for an adult and child?
Bradycardia is less than 60bpm
Tachycardia is more than 100bpm
Normal is between 60 and 100 (children = 100-120)
What drugs increase/decrease sympathetic and parasympathetic activity?
(and thus increase or decrease heart rate)
Decrease PNS (increase heart rate): Atropine Increase SNS (increase heart rate): Adrenaline, Salbutamol Decrease SNS (decrease heart rate): Beta blockers
What does the ECG look like in sinus bradycardia?
Regular QRS
P wave in front of every QRS
Normal AV delay
What happens to the ECG in asystole? (2 stages)
No QRS = ventricular standstill
No waves = total asystole
3 treatments for asystole
CPR and Adrenaline
Pacemaker
First degree heart block:
- ECG
- Symptoms
Regular QRS
P wave but prolonged PR
Asymptomatic and normal pulse
Symptoms (dizzy and faint) = BAD
What are the 2 types of second degree heart block?
Mobitz type 1 (wenkebach)
Mobitz type 2
Mobitz type 1 (wenkebach)
- ECG
- Treatment
Regular QRS
Progressive PR prolongation until the P wave fails
No treatment unless symptomatic
Mobitz type 2
- ECG
- Progression
Regular QRS
Not all P waves followed by QRS
Monitored as easily progresses to type 3
Third degree heart block:
- Another name
- ECG
- Management
Complete heart block
Wider QRS (generated from ventricles so 30-35bpm)
No P waves or relationship between P and QRS
ICU
Another name for tachy-brady syndrome
Sinus sick syndrome
What causes sinus arrest?
Does it always need treating? (e.g.)
SAN failure
No atrial depolarisation > ventricular asystole + sinus arrest
Common when sleeping
What causes left bundle branch block?
What does the ECG look like?
Poor left ventricle function WiLLiaM - V1 looks like a V (W) - V2 looks like an M - L = left
What happens in right bundle branch block?
What does the ECG look like?
R ventricle strain (lung disease/congenital) MaRRoW - V1 looks like an M - V2 looks like a W - R = right
3 ways to treat sinus bradycardia?
Fitness
Remove drugs
Treat cause
4 examples of drugs which cause sinus bradycardia
Beta blocker, Digoxin, Amiodarone, Diltiazem
4 examples of physiological causes of sinus bradycardia
Hypothyroidism, Hyperkalemia, Hypothermia, Vasovagal
What is a common cause of heart block?
Recent MI which has blocked the right coronary artery (blood supply to the AVN)
What does the ECG look like generally in a bundle branch block?
Wide, double peaked QRS
T wave inverted
What does the ECG look like in supraventricular (atrial) tachycardia?
Regular QRS
Less than 120msec apart
What does the ECG look like in ventricular tachycardia
Regular QRS
More than 120msec apart
What does the ECG look like in atrial fibrillation
Irregular QRS
Less then 120msec apart
What is the diagnosis if the QRS complexes are irregular and more than 120msec apart?
Atrial fibrillation
But ventricular fibrillation if in short bursts and the patient ill
What are the 3 mechanisms of tachycardia?
Atria send impulses quickly
Accessory circuit from the purkinje fibres to the AVN
Short circuit within the AVN
How does adenosine aid with the diagnosis?
Blocks the AVN so slows the rate if supraventricular but has no affect if it is ventricular
6 symptoms of a 2nd / 3rd degree heart block
Faint, Dizzy, Lightheaded, Fatigue, SOB, Chest pain
What happens in atrial flutter with variable block?
How fast do the atria and ventricles beat?
What does the ECG look like?
Regular atrial activity and ventricle beat after every few p waves
Atria rate = 300bpm
Ventricle rate = less than 300bpm
ECG = saw tooth apperance
What happens in atrial flutter with 2:1 AV conduction?
How fast do the atria and ventricles beat?
What is the heart rate?
2 flutter waves for every QRS complex
Atria rate = 280bpm
Ventricle rate = 140bpm
HEART RATE = 150bpm
What is the heart rate in atrial flutter with 4:1 AV conduction
75bpm
How do you treat atrial flutter?
Often reverts on its own but likely to recur > AF
Shock into sinus rhythm and anticoagulate
What is the ECG like in atrial fibrillation?
No P waves
Irregularly irregular QRS (narrow complex)
How do you treat atrial fibrillation?
Rhythm control via cardioversion (electrical or IV flecinide if a stable left ventricle and structurally normal heart)
Ensure you give anticoagulants before shocking if they’ve been in AF for a while
Ventricular tachycardia:
- Another name
- Heart rate
- ECG
- Associated with ___ (2)
Broad complex tachycardia
Fast heart rate
QRS more than 120ms
Associated with sudden death or ventricular fibrillation
Ventricular fibrillation:
- Heart rate
- ECG
- Treatment
Heart rate = 300-600bpm (irregular)
No P waves
Shock
Torsades de pointes:
- Another name
- ECG
- Treatment
Polymorphic ventricular tachycardia
Wide QRS, unstable R-R, axis shift at isoelectric line
Reverses itself
6 causes of torsades de pointes
Heart block Bradycardia Na/Mg Long QT (congenital) Class 1 anti-arrhythmic drugs Antidepressant overdose
5 things that can cause sinus tachycardia
How is it treated?
Hyperthyroidism, Anxiety, Heart failure, Hypovolemia, Sepsis
Investigate and remove the cause
How do you treat stable ventricular tachycardia? (3)
IV Na and Mg
IV Amiodarome
Cardioversion
How do you treat stable supra-ventricular tachycardia?
If it doesn’t self revert:
IV Adenosine
Vagotonic manoevures
Give 4 examples of vagotonic manoevures
Valsalva manoeuvre
Child in cold shower
Right carotid massage (stimulates the AVN)
Ocular pressure
6 methods of managing arrhythmia
Treatable cause Vagotonic manoeuvres DC cardioversion Pacemaker Surgery Drugs
What changes in the ECG when there are atrial ectopic beats?
Is it concerning?
P wave is earlier
No concern
What happens in a junctional ectopic beat?
What does it cause
Conduction from AVN
Causes bradycardia
What changes in the ECG when there are ventricular
ectopic beats?
What causes them normally
Broad wave
No bundle branch block
Coffee
DC shock (4) vs Drugs (3)
Shock is immediate but doesn’t always work, needs a GA and drugs after to stop reversal
Drugs can take a while to act and have side effects but are needed to prevent reversal
What is Pouiseuille’s law?
Explains the relationship between the flow rate, pressure, resistance and fluid viscosity
Define pressure
What needs to change to increase the pressure?
Pressure = CO x resistance
SO either CO or resistance increases
What happens in the early phase of primary hypertension?
Increased CO and blood volume increase
unknown why
What happens in the chronic phase of primary hypertension?
Normal CO and blood volume
Blood pressure is increased due to increased systemic vascular resistance due to abnormal vasculature
(smaller lumen and thickened walls)
What happens to vascular tone in primary hypertension?
5 reasons why
Vascular tone increases
- Increased Na and H2O
- Increased sympathetic activity
- Increased ANG2
- Alcohol
- Selection pressures
What exactly activates RAAS?
Increased pressure in the afferent arteriole
2 changes to the endothelium in diabetics with primary hypertension
Oxygen free radical damage
NO impaired in the endothelium
4 changes to the vessels in secondary hypertension
Increased CO
Increased systemic vascular resistance
Increased blood volume
Increased neurohormonal activation
Causes of secondary hypertension
Renal artery stenosis, Chronic renal disease, Conn’s syndrome, Pneochromocytoma, Coarctation of the aorta
Cushing’s, Pregnancy, Alcohol, Thyroid, Sleep apnoea, SAME (syndrome of apparant mineralocorticoid excess)
What chronic renal disease do many diabetics suffer from?
Diabetic neuropathy
How do you diagnose Conn’s syndrome?
Another name for it?
Increased bp, Decreased K
Decreased renin : Increased aldosterone
Primary hyperaldosteronism
What is pheochromocytoma
What are the 2 different effects?
Is it curable?
An curable adrenal medullary tumour which secretes catecholamines
- alpha-mediated effect: vasoconstriction
- beta-mediated effect: increased CO
How do you diagnose coarctation of the aorta?
Feel the radial and popliteal arteries at the same time
5 changes to the heart caused by secondary hypertension
Accelerated coronary atheroma Concentric LV hypertrophy Fibrosis Increased peripheral resistance Reduced flow in vessels (thicker vessels > epicardial 'small vessel' disease > reduced blood flow to heart)
Which artery does accelerated coronary artheroma not occur in?
Why?
Not in the pulmonary artery (unless pulmonary arteriole hypertension)
Define concentric and eccentric
Concentric = IN Eccentric = OUT
Explain what happens in a dissecting aortic aneurysm
The aorta wall tears causing the intima to be stripped from the media
This forms a ‘false lumen’
Eventually the false lumen (media) is completely stripped away = life treatening
What can hypertension cause to happen in the brain?
Thrombotic stroke
Haemorrhagic stroke
What are the 2 stages of hypertensive retinopathy?
What is it a sign of?
Early - Artery Vein nipping
Late - exudates, haemorrhages, pappiloedema
Poorly controlled hypertension
What is the eye the only place you can see?
Only place you can visibly see small vessels
What does hypertension do to the kidney?
Accelerates glomerular loss (reduces kidney function)
Define accelerated (malignant) hypertension
Recent elevation of blood pressure associated with organ damage and cerebral changes
What happens in accelerated (malignant) hypertension
Normal auto-regulation of blood through the brain is lost as cerebral arteries dilate so pressure exceeds homeostatic control
4 impacts of accelerated (malignant) hypertension
Papilloedema (increased ICP)
Necrosis of small arteries
Damage to RBC as vessels obstructed by fibrin
Loose capacity to think
3 risk factors of accelerated (malignant) hypertension
Men, Smokers, Secondary hypertension
Define pre-load
Pressure in the VENTRICLE just before the heart starts to contract
Define after-load
What is it altered by?
Pressure once the AORTIC VALVE has opened AGAINST WHICH the heart has to eject blood
(altered by the blood vessels)
4 changes to the heart muscle in heart failure
Heart is the same size in systole and diastole
Heart dilated so can’t pump hard
Heart doesn’t contract simultaneously
Heart pulled around by contractions
What does heart failure increase the risk of? (2)
Sudden death due to rhythm disturbance
More MI’s
Define acute heart failure
Accumulation of fluid in the wrong place, secondary to the heart malfunctioning
Define carcinogenic shock
Acute heart failure caused by a large heart attack wiping out a large proportion of heart muscle
What does starling’s law state?
The increased load on the heart, the harder it works
What happens when you exercise? (in relation to starling’s law)
Increased venous return > heart pumps more blood
What happens to the starling curve during heart failure?
The curve moves down and to the right
The heart needs a higher pre-load to maintain the same level of ventricular work
What is starling’s relation?
The forces that govern whether fluid remains or leaves a vessel
What can the alveolar capillary membrane do to reduce oedema?
Thicken
Why does blood pressure increase in heart failure?
The heart views it as a haemorrhage situation so preserves blood flow to organs by increasing pressure
What does the sympathetic system do?
When is this activated (2)
Increases heart rate and blood pressure
Sweaty, cold and clammy
Heart attack or pulmonary oedema
8 things which may cause pulmonary oedema
Acute ischaemia or infarction (e.g. coronary artery) Arrhythmia Environment (stress, drugs, salt) Hypertension Infection Lack of compliance Papillary muscles detach from valve (mitral regurg) Pulmonary embolism
6 symptoms of anasacra
Ascites Gradual weight gain Pitting oedema Pleural effusion Raised JVP Reduced muscle mass
What has to happen to the CO for oedema to form?
Explain
CO decreases
Decreased renal perfusion > RAAS
3 characteristic of chronic heart failure
Symptoms
Evidence of cardiac dysfunction at rest (imaging)
Treatment response
What is VE/VCO2?
How does this differ from normal in heart failure?
Minimum ventilation/CO2 production
In heart failure you need to breathe more to get rid of the same amount of CO2
What are the 4 mechanisms of chronic heart failure?
- Haemodynamic
- Neurohormonal
- Peripheral
- Metabolic
What is the law of laplace?
Tension = (Pressure in chamber X Radius of chamber)
/ thickness of wall
Define tension
What changes in heart failure
Amount of work the heart does before it contracts
In heart failure, the heart is dilated (increased radius) so has to contract more to overcome tension
What happens to stroke volume and ejection fraction in heart failure
The heart pumps the same amount of blood per beat (same stroke volume) but has a reduced ejection fraction so pumps less blood out
Give 5 examples of neurohormonal systems which are activated in chronic heart failure
ADH, Adrenergic, Endothelin, RAAS, Natriuretic peptides
What does aldosterone produce which is bad in heart failure?
Fibrosis
What are the 2 types of Natriuretic peptides?
What do they do?
A and B
Inhibit RAS, reduce aldosterone, reduce endothelin, reduce catechols
How are neurohormonal systems activated in chronic heart failure?
Neuroendocrine activation > Fluid retention, Vasoconstriction, Apoptosis and LVH > Heart failure > Neurohormonal activation
What are the 2 types of skeletal muscle?
Type 1: Aerobic and slow
Type 2: Anaerobic and fast
Explain the ergoreflex and how it is affected in heart failure
Ventilation increases with exercise and decreases without
Trapping exercise metabolites inside the body causes ventilation to remain high (but a slight decline)
In heart failure, you breathe more for a given amount of exercise (VE/VCO2) so there is no slight decline and ventilation remains higher
Define catabolic and anabolic hormones
Catabolic break down
Anabolic build up
What happens to catabolic and anabolic hormones in heart failure?
Increased catabolic
Resistance to anabolic
2 types of ventilation support
CPAP: Continuous Positive Airways Pressure
IPPV: Invasive Positive Pressure Ventilation
4 treatments for anasacra?
Bed rest (Heparin to reduce clots) Fluid restriction Diuretics Mechanical support e.g. dialysis if patients struggling
What happens when you recover from pulmonary oedema or anasacra?
You are treated for chronic heart failure
What are the 5 classes of adrenergic receptors?
A1: postsynaptic > vasoconstriction A2: presynaptic > -ve feedback B1: cardiac > inotropy B2: peripheral > vasodilation B3: metabolic
What is the aim of chronic heart failure treatment?
Reduced heart rate > reduced death