Cardiovascular Flashcards
Enzyme that statins inhibit?
HMG Co A reductase
Changes to the ECG in an exercise street test when the patient has angina?
ST segment depression
What do you do if a GP diagnoses a patient with unstable angina
Send to A&E it is a medical emergency (acute coronary syndrome)
Main difference in STEMI and NSTEMI?
STEMI - lumen is completely blocked
NSTEMI - the lumen is partially blocked
Treatments for STEMI and NSTEMI?
STEMI - Thrombolysis or PCI
NSTEMI - no thrombolysis but PCI could be useful
Features of cardiac pain?
Triggered by exercise and relieved at rest
Heavy, pressing or tight
Breathless, nausea
Radiates to arms
In a normal ECG are leads I, II and III positive or negative?
Leads I, II and III should be positive
What interval on an ECG do you use to assess heart rate?
RR interval
Possible causes of chest pain?
MI Angina GORD Aortic Dissection PE Pericarditis Musculoskeletal costochondritis
Types of heart block?
1st degree - enlarged PR interval
2nd degree:
Mobitz type I - PR interval gradually enlarges then skips a beat
Mobitz type II - Intermittent non-conducting p waves, some do some don’t
3rd degree - bundle branch block, no communication between SAN and AVN at all, random p waves
Signs of ventricular tachycardia?
Widened QRS
What is the ECG sign in ischaemia and in a previous infarction?
Ischaemia - ST elevation
Infarction - ST depression
What is a vulnerable plaque?
A plaque with a large risk of rupture
Initial pharmacological treatment for a STEMI?
Aspirin, Clopidogrel, B-blocker, atorvastatin, LMW heparin, ACE inhibitor
Other treatment for STEMI?
PCI
What is classified as an acute coronary syndrome?
STEMI, NSTEMI, unstable angina
Three physiological buffers, which has the biggest buffering capabilities?
Bicarbonate (is regulated to produce acid-base changes)
Proteins (mostly haemoglobin) carry a negative charge and will accept H+, has the most capacity but is not regulated
Phosphate buffer
What enzyme catalyses the reaction forming carbonic acid and bicarbonate?
Carbonic anhydrase
Where is bicarbonate formed, how?
In the red blood cell, the reaction is catalysed by carbonic acid, CO2 reacts with O2 to form H2CO3, which bissociates to form bicarbonate (HCO3) and H+ (which is buffered by haemoglobin).
How is acid secreted?
CO2 is blown off in the lungs and metabolic acids are excreted in the kidney
What primarily drives the impulse to breathe?
Acid/base balance driven by CO2 in the medulla
What substances are detected in the peripheral and in the central chemoreceptors?
Central - CO2
Peripheral - H+
What’s the Haldane effect?
The fact that during the passage of blood through the lungs O2 is taken up by red blood cells (makes them a stronger acid) This promotes the excretion of CO2
What two measurements of blood gas data show metabolic acidosis/alkalosis and what two show respiratory acidosis/alkalosis
Respiratory - High CO2 suggests respiratory acidosis
Metabolic - negative BXS suggests metabolic acidosis
Causes of metabolic acidosis?
Uraemia/renal disease
Lactic acidosis
Ketoacidosis
Poisoning
Diarrhoea
What is the Base excess?
The amount of bicarbonate that must be added to the blood to return it to standard pH - so therefore indicates that the bicarbonate concentration is above or below the amount expected
What is standard bicarbonate?
the plasma bicarbonate concentration at a paCo2 of 5.3 (by pumping 5.3 pco2 through a blood sample) and full O2 sats
Three layers of the vascular endothelium?
Tunica intima (inner)
Tunica media
Tunica adventitia
Some roles of the vascular endothelium?
Interface between blood body tissues
Control of blood coagulation
Mediates inflammatory response
Regulates vascular tone
Two key endothelial factors?
NO
Endothelins
Three types of NO synthase and where they are located, and whether they are constituently produced?
eNOS - endothelium (constituently)
nNOS - neurones (constituently)
iNOS - smooth muscle + macrophages (cytokine activated)
Action of NO?
Vasodilator
anti-thrombogenic/anti-atherogenic
Inhibits: cell growth, cell adhesion, platelet aggregation
How does NO reduce blood pressure?
Increase veno/vaso-dilatation (less preload)
Increasing Na+ and H2O excretion in the kidney (less blood volume)
Decreasing vascular remodelling
What happens when superoxide ions (O2-) react with NO, what causes superoxide anions to be formed?
Forms peroxinitrite (ONOO-)
This stops NO’s vasodilatory properties
Smoking forms superoxide anions
Two main drugs that act in the NO pathway?
Nitrates - e.g. GTN, acts as NO
Phosphodiesterase inhibitors (type V) e.g. sildenafil, Prevents the breakdoen of cGMP
Endothelin production pathway?
Stimulation of endothelin gene
preproendothelin
proendothelin
endothelins - by endothelin converting enzyme
The two endothelin receptors and their actions?
ETa - mediates vasoconstriction
ATb - mediates vasodilatation via NO
Actions of endothelin?
Vasoconstriction through ET receptors
Constriction of renal afferent arteriole
Prothrombogenic
Mitotic (promotes cell growth)
Role of enothelins in the kidney?
Decrease GFR (constriction of afferent arteriole)
Natriuresis:
- decrease proximal tube reabsorption
- inhibition of aldosterone
- promotes synthesis of ANP and BNP
Diuresis:
- opposes ADH action
What can ET antagonists be used for?
Pulmonary hypertension
Definitions of compliance, concordance and adherence?
Compliance: degree to which the patient obeys instructions of doctor
Concordance: Patient and doctor working together towards treatment aims
Adherence: The extent to which the patients behaviour corresponds to the AGREED recommendations of the doctor
What’s self-efficacy?
Personal confidence in ability to successfully perform a behaviour
What’s creative/intelligent non-adherance?
Deliberate decisions to stop/change treatments taken
What is blood pressure determined by?
CO (cardiac output)
Total peripheral resistance (TPR)
CO x TPR
Factors determining Cardiac Output?
Contractility, Afterload and Heart rate
Factors determining Peripheral resistance?
Vagal tone, Viscosity, Vessel length
Two types of fibre that respond to stretch of arteries in carotid body and aortic arch (baroreceptors)?
What will firing of the fibres then increase and decrease?
A fibres, C fibres
PNS output will increase
SNS output will decrease
What is the definition of hypertension?
Rise in BP without an increase in CO
Two categories of hypertension?
Primary - 95%
Secondary - 5%
What are some causes of secondary hypertension?
Renal hypertension: issues with the RAAS pathway
Endocrine tumour
Pre-acclampsia in pregnancy
Common environmental causes of essential hypertension?
High salt intake
Obesity, high calorie diet
High alcohol intake
Normal osmotic pressure?
290 mosmol/l
Two types of fluids to give to patients?
Crystalloids - salt/glucose and water
Colloids - suspesion (water and protein) and salts
What fluid space do colloids and crystalloids stay in?
Crystalloids - to the interstitial
colloids - the intravascular (vascular system) due to proteins
Valves of the heart?
Tricuspid (left AV valve)
Pulmonary
Bicuspid (mitral valve)
Aortic valve
Warfarin mechanism of action?
Vit. K inhibitor
