Cardiovascular Flashcards
What is blood pressure normally controlled by?
Renin-angiotensin system
Describe how the renin-angiotensin system works
1) If renal perfusion is low, kidney juxtaglomerular cells convert pro-renin (present in blood) into renin
2) Renin converts angiotensinogen (secreted by liver) into angiotensin I
3) Angiotensin I is converted to angiotensin II by angiotensin-converting enzyme (ACE), released from lungs
4) Angiotensin II is potent vasoconstrictor + promotes adrenal glands to produce aldosterone
5) Aldosterone makes kidneys reabsorb sodium and water into blood (and excrete potassium to maintain electrolyte balance)
What are the stages of hypertension?
Stage 1: clinic blood pressure at least 140/90 and subsequent ABPM daytime average of at least 135/85
Stage 2: clinic BP >160/100; ABPM >150/95
Severe hypertension: >180 systolic; >110 diastolic
Accelerated hypertension: >180/110 with signs of papilloedema +/or retinal haemorrhage
What are some secondary causes of hypertension?
Renal disease
Endocrine diseases - Cushing’s, Conn’s, phaeochromocytoma, adrenal hyperplasia
Congenital disease - coarctation of the aorta
Pregnancy - pre-eclampsia
Drugs - oestrogen-containing contraceptives, steroids, NSAIDs, EPO
If the blood pressure is raised on a one-off reading, what is required to confirm the diagnosis?
ABPM or HBPM
Hypertension is confirmed if:
- Clinic BP of 140/90 PLUS
- ABPM/HBPM of >135/85
How do you do home BP monitoring?
Twice a day for 7 days
Each of BP recording must be done twice at least 1 minutes apart with patient seated
Discard readings for day 1
Take an average of the rest
What conditions can HTN cause?
Heart failure Coronary artery disease Stroke CKD Peripheral arterial disease Vascular dementia
It is the single biggest risk factor for cardiovascular disease and related disability - half of all MIs and CVA are associated with hypertension
What score is relevant to HTN?
QRISK3
Estimates 10-year risk of developing CVD
If over 20%, consider high risk and encourage patient to take statin
Between 10-20% is moderate risk; NICE recommends discussing with patient about starting a statin
What is the drug treatment of hypertension?
Step 1: <55 years - ACE inhibitor
> 55 years or black of any age - calcium channel blocker (if CCB not tolerated, use a thiazide diuretic instead)
Step 2: ACE inhibitor + calcium channel blocker
Step 3: ACEi + Ca channel blocker + thiazide diuretic
Step 4 (resistant hypertension): step 3 + further diuretic (e.g. spironolactone) or beta blocker
What is the mechanism of action of thiazides?
Inhibit sodium resorption at distal convoluted tubule by binding to Na/Cl co-transporter
This causes increased Na + K excretion
When are thiazides contraindicated?
Hyponatraemia - in the elderly, thiazides are a common cause of hyponatraemia
Hypokalaemia
Hypercalcaemia
Renal impairment
What is the mechanism of action of loop diuretics?
How do they compare to thiazides?
They inhibit resorption of sodium in ascending loop of Henlé
This causes increased Na+ and K+ excretion
Compared to thiazides:
- more potent
- shorter half-life
- better tolerated in patients with CKD
What is the mechanism of action of potassium-sparing diuretics?
Competitively inhibit aldosterone-dependant sodium-potassium exchange channels in the distal convoluted tubule
This action leads to increased sodium and water excretion, but more potassium retention
When are ACE inhibitors contraindicated?
Renal artery stenosis
What the side effects of ACE inhibitors?
Dry cough
Impotence
Hypotension - take the first one in bed at night
What is decubitus angina?
Occurs when lying down
Impaired left ventricular function due to severe coronary artery disease
What is the drug management of coronary artery disease?
20mg artovastatin to those with >10% risk of CV disease (calculated with QRisk3)
80mg artovastatin if previous MI, Hx of type 2 diabetes, current ACS symptoms (e.g. angina, total cholesterol >4, LDL>2)
What is the mechanism of action of statins?
Inhibit HMG Co-A reductase which limits the rate of cholesterol synthesis
How can you describe heart failure?
When the cardiac output is inadequate for the body’s metabolic requirements leading to peripheral hypoperfusion
What is high output cardiac failure?
What are some causes of high output heart failure?
This is when the heart is working at normal/increased rate but needs of the body are beyond that which heart can supply
AAPPTT
- Anaemia
- Arteriovenous malformation
- Paget’s disease
- Pregnancy
- Thyrotoxicosis
- Thiamine deficiency (wet Beri-Beri)
What is the difference between systolic and diastolic low output heart failure?
Systolic
- Inability of the ventricle to contract normally resulting in reduced cardiac output
- Ejection fraction <40%
Diastolic
- Inability of the ventricle to relax and fill normally causing increased filling pressures
- Ejection fraction >50%
What are some causes of systolic heart failure?
- Ischaemic heart disease
- Dilated cardiomyopathy
- Myocarditis
- Infiltration (e.g. in haemochromatosis or sarcoidosis)
How does left sided heart failure present?
Symptoms caused by pulmonary congestion…
- Shortness of breath on exertion
- Orthopnoea
- Paroxysmal nocturnal dyspnoea
- Nocturnal cough (± pink frothy sputum)
Failure of the left side of the heart causes blood to back up into the lungs, causing respiratory symptoms as well as fatigue due to insufficient supply of oxygenated blood
What are the signs and symptoms of right side heart failure?
Symptoms of venous congestion… • Ankle swelling • Weight gain • Abdominal distension and discomfort, • Anorexia/nausea.
Signs of venous congestion… • Raised JVP • Pitting ankle/sacral oedema • Tender smooth hepatomegaly • Ascites • Transudative pleural effusions (typically bilateral)
failure of the right ventricle leads to congestion of systemic capillaries, which generates excess fluid accumulation in the body
What is the blood pressure like in heart failure?
Low BP with narrow pulse pressure
What is the pulse like in left heart failure?
Pulse alternans - alternate strong and weak beats
What would you feel on palpation of heart failure?
Displaced apex beat - LV dilated
What would you hear on auscultation of LVF?
Gallop rhythm due to presence of S3
What investigations should be done in suspected heart failure if no previous MI? What levels indicate what?
B-type natriuretic peptide (BNP) - initial test
- It is released when the myocardium is stressed and is related to left ventricular pressure
- It distinguishes heart failure from other causes of dyspnoea
· High: >2000 pg/ml – urgent ECHO within 2 weeks
· Raised: 400-2000 pg/ml – 6 week referral for ECHO
Normal: <400 pg/ml – normal
ECHO - confirms the presence and degree of ventricular dysfunction
- <40% = HF with reduced ejection fraction
- > 40% with raised BNP = HF with preserved ejection fraction
What chest X-Ray signs do you see in pulmonary oedema?
A:Alveolaroedema (with ‘batwing’ perihilar shadowing)
B:Kerley Blines (caused by interstitial oedema)
C:Cardiomegaly(cardiothoracic ratio >0.5)
D: upper lobe blooddiversion (increased vasculature in the upper lobes)
E:Pleural effusions(typically bilateral transudates)
F:Fluid in the horizontal fissure
What is the criteria used to diagnose congestive cardiac failure?
Framingham criteria
1 major + 2 minor criteria
Major criteria:
- PND
- Crepitations
- Neck vein distention
- S3 gallop
- Hepatojugular reflex
- Cardiomegaly
- Increased CVP
- Weight loss >4.5kg over 5 days
Minor criteria:
- Bilateral ankle oedema
- Dyspnoea on normal exertion
- Tachycardia > 120bpm
- Nocturnal cough
- Hepatomegaly
- Pleural effusion
- Decreased vital capacity by 1/3
What is the management of acute heart failure (i.e. pulmonary oedema)?
- Sit the patient up
- High flow oxygen therapy via rebreathe mask
- IV furosemide 40mg (with further doses as necessary) and close fluid balance (aiming for a negative balance to reduce cardiac preload)
- IV diamorphine 2.5mg - vasodilator, alleviates distress and anxiety, small dose to reduce risk of respiratory depression
If systolic BP<100, send to ICU
What is the pharmacological management of chronic heart failure?
First line - ACEi + beta-blocker
- these improve mortality
- avoid ACEi in valve disease
- if intolerant of ACEi, give ARB
- hydralazine + nitrate in africans/caribbeans
Second line - add spironolactone if still symptomatic
Third line - consider digoxin if still symptomatic and in AF (it worsens mortality but improves mortality)
Loop diuretic to treat symptoms (but does not improve mortality)
What are some complications of heart failure?
Cardiogenic shock
AKI
Pleural effusion
CKD
What are the most common causes of AF?
Ischaemic heart disease
Hypertension
Valvular heart disease
Hyperthyroidism
Define the different types of AF:
1) Acute
2) Paroxysmal
3) Persistent
4) Permanent
- Acute - <48 hours
- Paroxysmal - < 7 days and is intermittent
- Persistent - >7 days but is amenable to cardioversion
- Permanent - >7 days and is not amenable to cardioversion
How do you investigate suspected paroxysmal AF?
ambulatory ECG
What are some symptoms of AF?
Often asymptomatic Palpitations Chest pain Dyspnoea Fatigue Light-headedness or syncope
What does an ECG of AF show?
Absent p waves
Irregular QRS complexes
Irregular RR intervals
What score is relevant to AF?
CHA2DS2VASc score - calculates the risk of stroke in AF
o Congestive HF/LVSD 1 o Hypertension 1 o Age ≥75 years 2 o Diabetes mellitus 1 o Stroke/ TIA/ thromboembolism Hx 2 o Vascular disease 1 o Age 65-74 years 1 o Sex category (female) 1
When should you consider anticoagulation in AF?
If their CHADSVASc score is greater than or equal to 2
What is the first line therapy for AF?
Rate control drugs such as:
Beta-blockers e.g. atenolol, bisoprolol (but not sotalol)
Calcium channel blockers e.g. verapamil or diltiazem
Digoxin (only consider in sedentary patients and heart failure)
What is the second line therapy for AF?
Rhythm control - consider if symptoms persist after rate control
Flecainide - Na+ channel blocker
Amiodarone (only given to older, sedentary patients)
Sotalol - beta-blocker with additional K+ channel blocker action
What is warfarin?
Vitamin K antagonist
What drugs reduce the concentration of warfarin in the body?
It is metabolised by the CYP450 system - concentration is reduced by CYP450 inducers
Carbamazepine Rifampicin Barbituates Phenytoin St John's wort
What drugs increase the concentration of warfarin in the body?
It is metabolised by the CYP450 system - concentration is increased by CYP450 inhibitors
Sodium valproate Ciprofloxacin Sulphonamide Cimetidine/omeprazole Antifungals Amiodarone Isoniazid Erythromycin/clarithromycin Grapefruit juice
What do NOACs do?
Inhibit factor Xa
What score is relevant to anticoagulation?
HAS-BLED score
Hypertension - 1 Abnormal renal and liver function - 1 point each Stroke - 1 Bleeding - 1 Labile INRs - 1 Elderly >65 - 1 Drugs or alcohol - 1 point each
Max 9 points
What conditions are NOACs contraindicated in?
Mitral stenosis
Chronic kidney disease
In which AF patients should rate control not be used as the first line strategy?
Those whose AF has reversible cause
Those who have heart failure due to AF
Those with new onset AF
For whom a rhythm control strategy is more suitable based on clinical judgement e.g. paroxysmal atrial fibrillation
What does catheter ablation do in AF?
Creates an electrically inexcitable ‘scar’ around the pulmonary veins which blocks pulmonary vein ectopics from entering the left atrium
When should you anticoagulate if performing cardioversion?
if AF>48hours, consider amiodarone 3 weeks before + 4 weeks after to eliminate clots that may have formed in heart
if AF<48hrs, can perform without cardioversion
What medication is commonly used for patients in AF who are also in heart failure or are hypotensive?
Digoxin