CV&R Non-Anatomy Flashcards
What are 5 risk factors for atherosclerosis?
Age
Male
Family history
Smoking
Obesity
Hypertension
What are the 4 causes of chest pain ?
Cardiac
Respiratory
GI
Musculoskeletal
(+others)
What can cause cardiac chest pain ?
Ischaemia
Aortic dissection
Pulmonary embolism
Aortic stenosis
Pericarditis
Myocarditis
What are the two classifications of cardiac chest pain ?
Troponin positive
Troponin negative
What bare Troponin Positive cardiac conditions ?
Type 1 and 2 MI, SCAD, coronary spasm
What’s are Troponin Negative cardiac conditions ?
Angina (stable or unstable)
Cor spasm
Micro vascular/endothelial
What is the investigation pathways for cardiac conditions ?
Exercise tolerance test ( ETT) ——— stress echo, perfusion scan, CT coronary angiogram or stress perfusion cMR ———invasive coronary angiogram
What shows an ischaemia on an ECG ?
ST wave depression (during ETT)
What drug treatments can be used for angina ?
Beta blockers (-olol)
Calcium agonists (-dipine for smooth muscle + verapamil on the heart)
Nitrates (GTN spray)
What are the 3 acute coronary syndromes ?
Unstable angina - unstable plaque without myocardial necrosis
NSTEMI - thrombus without total vessel occlusion (ST depression)
STEMI - total vessel occlusion (ST elevation)
What are lipids ?
Water insoluble
3 classes = cholesterol, triglycerides, phospholipid
What is cholesterol a precursor to ?
Steroid hormones (oestrogen, testosterone, cortisol, aldosterone )
Endogenous vitamin D production
What is the structure of a lipoprotein ?
Central hydrophobic lipid core (triglycerides and cholesterol esters)
Surface layer of polar components (phospholipids + free cholesterol + apolipoproteins)
What is the LDL calculation ?
LDL = TOTAL CHOLESTEROL — HDL — TRIGLYCERIDES/5
Describe anticoagulant HEPARIN mechanism of action
Binds to and enhances antithrombin III, this bind to and inhibits clotting factors II,IX,XI and XII
Given intravenously or sub-cutaneously
Side effects = allergic reactions, haemorrhage, HIT, hyperkalaemia
Describe anticoagulant Warfarin mechanism of action
Structural Analogue of Vit K
Blocks vit. k reductase and therefore carboxylation
Blocks coagulation factor synthesis in the liver
Oral administration
Side effects = haemorrhage, crosses placenta and BBB (foetal haemorrhage)
Deceive aspirins use as an anti-thrombolytic agent
Used in low doses
It inhibits platelet synthesis, and COX irreversibly
Prevents re infarction (lowers risk by 20%)
Describe tissue plasminogen activator (t-PA) as a fibrinolytic ?
Enzyme produced by vascular endothelium
Only activate s plasminogen bound to fibrin (clot selective)
Side effects = haemorrhage
What are platelets derived from ?
Megokaryocytes in bone marrow
What normally suppresses platelet activation ?
Prostacyclin
Nitric oxide
Antithrombin III
What do fibrin strands enmesh ?
Erythrocytes and platelets
What is Von Willebrand disease ?
A deficiency in Von Willebrand factor (binds platelets to collagen)
What is Haemophilia A ?
Deficiency of factor VIII (8)
What is Haemophilia B ?
Deficiency of factor IX (9)
What is Haemophilia C ?
Deficiency of factor XI (11)
What digests fibrin I to soluble degradation products ?
Plasmin (activated by t-PA)
What is the treatment for venous thrombosis ?
Anticoagulants
What is the treatment for arterial thrombosis ?
Fibrinolytics (immediate)
Antithrombotics (long-term)
What is coronary steal ?
During vasodilation, When blood is diverted to already well perfumed areas
What do beta1-adrenoceptor blockers do ?
Competitive antagonists if adrenaline and noradrenaline at cardiac beta1-adrenoceptors
Decrease HR and SV, decrease myocardial O2 demand
What does Ivabradine do ?
Blocks Na current causing delay in SA node depolarisation
Decreases HR (not force), decreases myocardial O2 demand
What is after-load ?
Force against which LV contracts
What is pre-load?
Diastolic pressure that distends LV
What causes reduces after-load ?
Dilation of arteries
What causes reduced pre-load ?
Dilation of veins
What is the Bainbridge Reflex ?
Initiated by increased blood in atria
Causes stimulation of SA node
Stimulates barorecptors in the atria, causing increased SNS stimulation
What does P in the ECG wave show ?
Atrial depolarisation
What does P-Q show in ECG waves ?
Delay at AV node
What happens at Q of ECG wave ?
Conduction through bundle branches
What also happens at Q of ECG wave ?
Conduction through purkinje fibres
What happens at the QRS complex of ECG waves ?
Ventricular depolarisation
What happens at S-T of ECG waves ?
Plateau phase of re polarisation
What happens at T wave of ECG ?
Rapid Repolarisation
What causes a U wave to sometimes be present on an ECG ?
Repolarisation of Purkinje fibres
Which leads are unipolar ?
aVR
aVL
aVL
Chest leads 1-6
Which leads are bipolar ?
I = RA-LA
II= RA-LL
III= LA-LL
Which ECG leads are anterior ?
V1-V4
Which ECG leads are inferior ?
II , III, aVF
Which ECG leads are lateral ?
I, aVL, V5 + V6
What does a wave look like that is horizontal -ve to +ve from L to R ?
All positive wave
What does a wave look like that is horizontal -ve to +ve from R to L ?
All negative wave
What does an ECG wave look like that is -ve to +ve superiority to inferiorly ?
Positive and negative parts STANDARD PQRST ECG WAVE
How do you calculate HR from ECG ?
300/no. of big squares between each QRS
OR
No. of QRS complexes across ECG (10 seconds) x 6
What is normal angle for the QRS axis ?
-30 to +90 degrees (from limb lead I)
How do you find the QRS axis ?
By finding lead with most positive QRS complex
What shows left axis deviation ?
-30 to -90 degrees
Positive QRS in I
Negative in II and aVF
What shows normal axis ?
-30 to +90
Positive QRS in I and II
What shows right axis deviation ?
+90 to +180 degrees
Negative QRS in I
Positive QRS in aVF
What shows extreme axis deviation ?
+180 to -90 degrees
Negative QRS in I and II
Positive QRS in aVR
What do normal T waves show in relation to QRS ?
Same polarity
What is absolute risk ?
Incidence of disease in a given population
How do you calculate absolute risk ?
Number of new cases per population over a specified time
E.g. 1000 obese, 100 develop CAD in 1 year = 10/1000 pa = 0.1
How do you calculate relative risk ?
Compare the absolute risk of those who have the risk factor and those who don’t
Express as how many times greater or smaller among exposed
Case-control study calculation ?
(exposed have disease x not exposed don’t have disease) / (not exposed have disease x exposed that don’t have disease)
Attributable risk (AR)
AR = incidence of disease in exposed - incidence of disease in unexposed
AR% calculation ?
(AR/ incidence of disease in exposed ) x100
Population attributable risk (PAR) calculation
PAR = AR x prevalence of exposure
PAR% calculation
(PAR / incidence of disease in the population)x100
What are normal cholesterol ranges ?
TC = <5 mmol/L
HDL = >1 mmol/L
Non-HDL = <4mmol/L
TC to HDL ratio = <6
What is the pathophysiology of asthma ?
Loss of airway epithelium
Thickening of BM
Hypertrophy of smooth muscle layer
What are possible triggers of asthma ?
Inflammation - allergy, infection, exercise
Drugs - beta blockers, NSAIDs
Cold air + scents
What is the presentation of asthma ?
Bronchospasm = wheeze, dyspnoea, exercise intolerance
Inflammation = cough
What is the management of asthma ?
Bronchorelaxation = beta 2 agonists
Anti-inflammatories = corticosteroids, leukotrine receptor blockade, monoclonal antibodies (-mab)
What is the maximum peak flow rate ?
900L/minute
Achieved by firm but flexible airway walls
What are ways of airway narrowing ?
Dynamic = rapid muscle contraction, secretions
Fixed = smooth muscle bulk, thickening of BM
What is different about smooth muscle in asthma ?
There are mast cells present
What do the mast cells in smooth muscle in asthma cause ?
Variable airway calibre , leading to diurnal variation (nighttime or morning)
How to measure asthma via enhanced nitric oxide ?
Increased eosinophilic inflammation
Normal value 30ppb
Describe how spirometers can be used to measure asthma ?
Narrow airway relaxes in response to salbutamol (approx 15% improvement)
What are the 3 phases of asthma ?
1) smooth muscle only - triggered by mediator ,rare wheezy episodes
2) chronic inflammation- irritates smooth muscle, regular wheezy episodes
3) acute inflammation- viral infection, clinical exacerbations
Describe type 2 inflammation in asthma
Cells = lymphocytes, eosinophils and mast cells
Cytokines = IL-4, IL-5
Prostanoids = PGE2, Leukotrine D4
Immunoglobulins = specific IgE
What does histamine in asthma mast cell mediation cause ?
Smooth muscle contraction
What type of immune cell fights viruses ?
Neutrophils and lymphocytes
What type of immune cells fight parasitic infection ?
Eosinophils
What type of immune cells fight bacterial infection ?
Neutrophilic
What is the mechanism of action of B2 Agonists ?
Bind to B-2 adrenergic receptors activating a G protein
Cyclic AMP acts as a second messenger
Smooth muscles relaxes widening the airway
What is the main side effect associated with B-2 adrenoceptor agonists such as salbutamol) ?
Tremor
What is the partial pressure of O2 in alveoli ?
102
What is the partial pressure of CO2 in alveoli ?
40
What is the distance between alveoli and red blood cells ?
1-2um : includes type 1 alveolar epithelium, capillary endothelium and BM
How quickly do red blood cells pass through capillaries ?
Less than 1 second
For each mmHg of Po2 how much oxygen is there ?
0.003ml/100ml of blood
How many ml of O2 per litre of blood in the arteries ?
3ml O2/L blood
How do pH and temperature effect the oxygen dissociation curve ?
High pH or high temperature decrease oxygen affinity for Hb
At what O2 saturation does Hb affinity loss become steep ?
60mmHg
What is the respiratory exchange ratio ?
Ratio of expired CO2 to O2 uptake
What is the respiratory exchange ratio in normal conditions?
0.8
Which 3 forms is CO2 carried in the blood ?
Dissolved (7%)
Bound to Hb (23%)
Converted to bicarbonate (70%)
What is the bicarbonate equation ?
H2O + CO2 —> H2CO3 —> H+ + HCO3-
What is the V/Q ratio for lungs ?
0.8-1.2
What are possible V/Q ratios for individual alveoli?
V/Q > 1 = ventilation exceeds perfusion
V/Q < 1 = perfusion exceed ventilation
Where does the brain receive neural signals from for breathing control ?
Chemoreceptors: feedback on blood Po2, PCo2 and pH
Mechanoreceptors : feedback on mechanical status of lungs, chest wall and airways
Where in the brain controls breathing ?
Brainstem
Where are peripheral chemoreceptors found ?
Aortic arch and carotid sinuses
Which nerve do aortic chemoreceptors use ?
Vagus (X)
What nerve do carotid chemoreceptors use ?
Glossopharyngeal (IX)
Where do the nerves send chemoreceptor signal to in the brainstem ?
Nucleus Tractus Solitarius (NTS)
What chemoreceptors are responsible for hypoxia response ?
Peripheral
What chemoreceptors are responsible for hypercapnia or pH decrease responses ?
Central
What are central chemoreceptors?
Clusters of neurones in the brainstem
Which type of chemoreceptor plays a major role in moment to moment breathing ?
Central
What do mechanoreceptors do ?
Detect movement of the lung and chest wall
What nerve do mechanoreceptors signal through ?
Vagus (X)
What are the locations and functions of mechanoreceptors?
Airway smooth muscles = terminate inspiration
Airway epithelium = sigh or shortened expiration
What makes up the ventral respiratory group in the brainstem ?
Pattern and rhythm generating neurones
What do respiratory pattern generating neurones do ?
2 types : inspiratory and expiratory active during their respective phases of breathing
What do respiratory rhythm neurones do ?
Produce rhythmic output through the spinal nerves to respiratory muscles (diaphragm + intercostals) to produce rhythmic breathing
What are the 3 major components of acid-base regulation ?
Buffering
Ventilation
Renal regulation
What are buffers ?
Weak acids partially dissolved in solution
What is the Henderson hasselbach equation ?
CO2 + H2O —> H2CO3 —> HCO3 + H+
What is metabolic acidosis ?
Low HCO3 therefore low pH
What is metabolic alkalosis ?
high pH
What is respiratory acidosis ?
High CO2 therefore low pH
What is respiratory alkalosis ?
Low CO2 therefore high pH
What is the ADME pneumonic ?
Absorption
Distribution
Metabolism
Excretion
Which method of drug administration is preferred ?
Oral
Volume of distribution calculation ?
Dose (mg) / concentration ( mg/L-1)
How to calculate dose for individual ?
Typical weight adjusted volume x weight
Dose calculation?
Dose = concentration x volume
What is loading dose ?
A single dose which brings a drug to its target range
What is the clinical significance of first pass metabolism ?
Differences (due to age + gender)
Some drugs undergo more first pass metabolism than others
Impact peak drug concentrations
What is bioavailability?
The fraction of the drug that reaches systemic circulation after oral administration
F= effective dose after oral / effective does after IV
(F=%effective dose)
What are the routes of clearance of drugs ?
Total = renal + hepatic + other
What is clearance ?
The rate at which drug is removed from the body
What is clearance proportional to ?
Drug concentration
What is a drug-drug interaction ?
When a second drug alters the effects of the first drug
What are inhibitors ? (CYP450 enzyme)
They reduce clearance by inhibiting drug metabolism, increasing half life, meaning drug can accumulate with repeated dosing
What do inducers do ? (CYP450)
Accelerated clearance of drugs metabolised, shorter half life
What are the features of type 1 respiratory failure ?
Low O2 = <8kPa
Pneumonia
Cardiac failure
Pulmonary embolism
What are the features of type 2 respiratory failure ?
Low O2 = < 8kPa
High CO2 = >6kPa
Opiate overdose
Neuromuscular weakness
Advanced COPD
Severe respiratory fatigue
What are the symptoms of heart failure ?
Breathlessness
Ankle swelling (oedema)
Fatigue
What are the 3 goals of HF treatment ?
Relief of symptoms
Avoid admission or readmission
Prevent premature death
