Cardiovascular (2) Flashcards
What is Heart Block?
- Impairment of the atrioventricular (AV) node impulse conduction
- Represented by the interval between P wave and QRS complex
What is first degree Heart Block?
- Prolonged conduction through the AV node
- PR interval > 0.2 seconds
- Asymptomatic first-degree heart block is relatively common and does not need treatment
What is second degree Heart Block (Mobitz type 1- Wenchebach)?
- Progressive prolongation of the PR interval until a dropped beat occurs
- The progressive prolongation of AV node conduction culminating in one atrial impulse failing to be conducted through the AV node
- The cycle then begins again
What is second degree Heart Block (Mobitz type 2)?
- Intermittent or regular failure of conduction through AV node
- PR interval is constant but the P wave is often not followed by a QRS complex
- Also defined by the number of normal conductions per failed or abnormal one (e.g. 2:1 or 3:1)
What is third degree Heart Block?
- Also known as complete heart block
- No relationship between atrial and ventricular contraction ( no association between the P waves and QRS complexes)
- Failure of conduction through the AV node leads to a ventricular contraction generated by a focus of depolarization within the ventricle (ventricular escape)
What is the aetiology of Heart Block?
- Most common cause: MI or ischaemic heart disease
- Infection e.g. rheumatic fever, infective endocarditis
- Drugs e.g. digoxin ,b-blockers, Ca2+ channel blockers
- Metabolic e.g. hyperkalaemia, cholestatic jaundice, hypothermia
- Infiltration of conducting system e.g. sarcoidosis, cardiac neoplasms, amyloidosis
What is the epidemiology of Heart Block?
- The majority of pacemakers implanted annually are for heart block
- First degree heart block is associated with increased risk of AF
What are the features of Heart Block?
- First degree and Mobitz 1: Usually asymptomatic
- Syncope
- Heart failure
- Regular bradycardia (30-50 bpm)
- Wide pulse pressure
- JVP: cannon waves in neck
- Variable intensity of S1
What are the signs of Heart Block on physical examination?
- Often normal
- Complete heart block:
a. Slow large volume pulse
b. JVP may show ‘cannon waves’ - Mobitz type II and third-degree block:
a. Signs of a reduced cardiac output (e.g. hypotension, heart failure)
What are the ECG findings for First degree Heart Block?
Prolonged PR interval (>0.2 s)
What are the ECG findings for Second degree Mobitz 1 (Wenchebach) Heart Block?
- Progressively prolonged PR interval, culminating in a P wave that is not followed by a QRS
- The pattern then begins again
What are the ECG findings for Second degree Mobitz 2 Heart Block?
- Intermittently a P wave is not followed by a QRS
- There may be a regular pattern of P waves not followed by a QRS (e.g. two P waves per QRS, indicating 2:1 block)
What are the ECG findings for Third degree (complete) Heart Block?
No relationship between P waves and QRS complexes
What are the investigations for Heart Block?
- ECG: different findings
- CXR: may show hilar lymphadenopathy, cardiac enlargement, pulmonary oedema
- Bloods:
a. TFTs: hypo or hyperthyroidism
b. Digoxin level: identify cause
c. Cardiac enzymes, troponin: may be elevated - Echocardiogram:
Ventricular dysfunction or hypertrophy, valvular disease, wall-motion abnormalities
What is the management for asymptomatic first-degree AV block or type I second-degree Heart Block?
- No specific treatment is required
- Patients are at low risk for progression to higher-degree AV block
What is the management for symptomatic chronic Heart Block?
- First line: stop all AV-nodal blocking medications: beta-blockers, non-dihydropyridine calcium-channel blockers, and digoxin
- While discontinuing these medicines may improve AV conduction, they are not likely to completely reverse a clinically significant AV block
- If severe: Permanent pacemakers should be considered (recommended in patients with third-degree heart block, advanced Mobitz type II and symptomatic Mobitz type I)
What is the management for acute Heart Block (e.g. secondary to MI)?
If associated with clinical deterioration, IV
Atropine (anti-muscarinic) and consider temporary (external) pacemaker
What are the complications of Heart Block?
- Asystole- cardiac arrest
- Heart failure
- Complications of any pacemaker inserted
What is the prognosis for Heart Block?
Mobitz type II and third-degree block (advanced) usually indicate serious underlying cardiac disease whereas first degree and Mobitz type I have a low risk
What is Hypertension?
- Defined as systolic BP >140mmHg and/or diastolic BP >90mmHg persistently/ measured on three separate occasions or
- A 24 hour blood pressure average reading >= 135/85 mmHg
What is malignant hypertension?
Defined as BP 200/ 130 mmHg
What can hypertension be divided into?
- Primary (around 90-95%):
a. Essential hypertension
b. No single disease causes the rise in BP, associated with ageing - Secondary:
a. A wide variety of endocrine, renal and other causes
What are the different secondary causes of hypertension?
- Renal disease:
a. Glomerulonephritis
b. Chronic pyelonephritis
c. Adult polycystic kidney disease
d. Renal artery stenosis - Endocrine causes:
a. Primary hyperaldosteronism
b. Phaeochromocytoma
c. Cushing’s syndrome
d. Congenital adrenal hyperplasia (11-beta hydroxylase deficiency)
e. Acromegaly - Other:
a. Glucocorticoids
b. NSAIDs
c. Pregnancy
d. Coarctation of the aorta
e. COCP
What are the presenting symptoms of Hypertension?
- Often asymptomatic
- If secondary, symptoms of the cause
What are the symptoms of hypertension if > 200/120 mmHg?
Headaches
Visual disturbance
Seizures
What are the signs of Hypertension on physical examination?
BP: measure on two to three different occasions before diagnosing hypertension and record lowest reading (>140/90mmHg)
Longstanding hypertension: retinopathy (retinal vascular changes)
What is the Keith–Wagner classification of retinopathy?
(I) ‘silver wiring’
(II) as above, plus arteriovenous nipping
(III) as above, plus flame haemorrhages and cotton wool exudates
(IV) as above, plus papilloedema
What are the investigations for Hypertension?
- 24 h blood pressure
Ensure no end organ damage: - Fundoscopy: to check for hypertensive retinopathy
- Urine dipstick: to check for renal disease, either as a cause or consequence of hypertension
- ECG: to check for left ventricular hypertrophy or ischaemic heart disease
Co-morbidities, Q-RISK: - HbA1c
- Lipids
How is hypertension staged?
- Stage 1:
Clinic BP >= 140/90 mmHg and subsequent ABPM daytime average or HBPM average BP >= 135/85 mmHg - Stage 2:
Clinic BP >= 160/100 mmHg and subsequent ABPM daytime average or HBPM average BP >= 150/95 mmHg - Severe hypertension:
Clinic systolic BP >= 180 mmHg, or clinic diastolic BP >= 120 mmHg
What is the lifestyle management of hypertension?
- A low salt diet is recommended, aiming for less than 6g/day
- Caffeine reduction
- Smoking cessation
- Less alcohol
- Lose weight
What is the management of Stage 1 hypertension (>140/90)?
- Antihypertensives if:
< 80 years of age AND any of the following apply;
a. target organ damage
b. established cardiovascular disease
c. renal disease
d. diabetes or a 10-year cardiovascular risk equivalent to 10% or greater - Consider anti-hypertensives: in addition to lifestyle advice for adults <60 with stage 1 hypertension and an estimated 10-year risk below 10%
What is the management of stage 2 hypertension?
Offer drug treatment
What is the management of hypertension in patients < 40 years?
Referral to exclude secondary causes
What is the first step of anti-hypertensive treatment?
- If < 55-years-old or T2DM: ACE inhibitor or a Angiotensin receptor blocker (ACE-i or ARB)
- If ≥ 55-years-old or black/ African- Caribbean: Calcium channel blocker
What is the second step of anti-hypertensive treatment?
- If already on ACE-i or ARB: add a Calcium channel blocker or a thiazide-like Diuretic
- If already on Calcium channel blocker: add an ACE-i or ARB (preferred in black/ African-Carribeans) or a thiazide-like Diuretic
What is the third step of anti-hypertensive treatment?
Add a third drug:
usually a thiazide diuretic
What is the final step of anti-hypertensive management?
- NICE define step 4 as resistant hypertension and suggest either adding a 4th drug or seeking specialist advice
- First confirm elevated clinic BP with ABPM or HBPM
assess for postural hypotension - Discuss adherence
- If potassium < 4.5 mmol/l: add low-dose spironolactone
- If potassium > 4.5 mmol/l add an alpha- or beta-blocker
What are the target blood pressures for patients on anti-hypertensives?
- Age < 80 years:
Clinic: 140/90 mmHg
ABPM: 135/85 mmHg - Age > 80 years:
Clinic: 150/90 mmHg
ABPM: 145/85 mmHg
What is the most common cause of secondary hypertension?
Primary hyperaldosteronism
What is Mitral Regurgitation?
The retrograde flow of blood from LV to left atrium during systole (second most common valve disease after aortic stenosis)
What is the aetiology of mitral regurgitation?
- Regurgitation leads to a less efficient heart as less blood is pumped through the body with each contraction
- As the degree of regurgitation becomes more severe, the body’s oxygen demands may exceed what the heart can supply and as a result, the myocardium can thicken over time
- While this may be benign initially, patients may find themselves increasingly fatigued as a thicker myocardium becomes less efficient, and eventually go into irreversible heart failure
What are the causes of mitral regurgitation?
- Post- coronary artery disease or post-MI
- Mitral valve prolapse: deformity of the mitral valve leaflets: valve does not close properly and allows backflow
- Infective endocarditis: When vegetations from the organisms colonising the heart grow on the mitral valve, it is prevented from closing properly
- Rheumatic fever: While this is uncommon in developed countries, rheumatic fever can cause inflammation of the valves
- Congenital
What are the risk factors for mitral regurgitation?
- Female sex
- Lower body mass
- Age
- Renal dysfunction
- Prior MI
- Prior mitral stenosis or valve prolapse
- Collagen disorders e.g. Marfan’s Syndrome and Ehlers-Danlos syndrome
What are the symptoms of mitral regurgitation?
- Largely asymptomatic
- Symptoms develop later due to failure of the left ventricle, arrhythmias or pulmonary hypertension
- Presents as fatigue, shortness of breath and oedema
What are the signs of mitral regurgitation on examination?
- Pansystolic murmur described as “blowing”
- It is heard best at the apex and radiating into the axilla
- S1 may be quiet as a result of incomplete closure of the valve
- Severe MR may cause a widely split S2
What are the investigations for mitral regurgitation?
- ECG: may show a broad P wave, indicative of atrial enlargement
- CXR: Cardiomegaly may be seen with an enlarged left atrium and ventricle
- Echocardiography: crucial to diagnosis and to assess severity*