Week 5 - Cardiology Flashcards
Describe the flow of blood in secundum ASD
Shunts left to right when isolation (path of least resistance, from high to low pressure)
Describe catheter ablation in atrial fibrillation
- Identification of triggers for paroxysmal AF in the pulmonary veins
- Pulmonary vein isolation can be curative in up to 65-80% of patients with paroxysmal AF, 50-60% of patients with persistent AF
- Radiofrequency current (‘burning’) or cryo-ablation (‘freezing’)
- More effective in patients with structurally normal hearts or minimal heart disease
Describe the prevalence of hypertension
Increasing in prevalence (35-45%), estimated 1 billion worldwide
Describe the timing of coronary revascularisation in NSTEMI
Early coronary revascularisation (<24 hours) is of substantial benefit in high risk group. No benefit in lower risk groups.
Describe anticoagulation in AF
- Atrial fibrillation with mechanical heart valves or moderate/severe mitral stenosis - Warfarin
- All other atrial fibrillation - NOACs
Describe the classificaiton of endocarditis
- Native valve endocarditis - most common
- Endocarditis in IVDUs
- Prosthetic valve endocarditis - more difficult to treat, higher mortality
- Inserted for a variety of reasons, mainly to replace diseased valves
Describe the appearance of a normal ECG
Normal sinus rhythm, rate of 75bpm, normal waveform
How can the heart rate be determined from an ECG?
300 divided by the number of large squares between each QRS complex:
1 square = 300/min
2 squares = 150/min
3 squares = 100/min
4 squares = 75/min
5 squares - 60/min
6 squares = 50/min
OR - number of QRS complexes across ECG (10 sec) x 6
What signs may be seen on imaging in coarctation of the aorta?
Rib notching may be present on CXR due to retrograde flow from high pressure anterior intercostal arteries to low pressure posterior
What are the consequences of mitral regurgitation?
- Volume overload - LA/LV
- LV and LA dilatation
- Pulmonary hypertension
- Secondary right heart dilatation
- Atrial fibrillation
- What is the QRS rate?
- Normal (300/5 = 60 bpm)
- Are the QRS complexes regular?
- Yes
- Is the QRS broad or narrow?
- Usually narrow
- What is the P:QRS relation?
- 1:1
= Normal Sinus Rhythm
Describe the classificatino of heart failure
- New York Heart Association Functional Classification
- Method of describing functional limitations in heart failure
- Class I
- No symptoms and no limitation in ordinary physical activity e.g. shortness of breath when walking, climbing etc.
- Class II (mild)
- Mild symptoms (mild shortness of breath and/or angina) and slight limitation during ordinary activity
- Class III (moderate)
- Marked limitation in activity due to symptoms, even during less-than-ordinary activity e.g. walking short distance (20-100m). Comfortable only at rest.
- Class IV (severe)
- Severe limitations. Experiences symptom even while at rest. Mostly bedbound patients.
List the types of MI based on their cause
- Spontaneous MI due to a primary coronary event (coronary artery plaque rupture and formation of an intraluminal thrombus), ischaemia/necrosis or area supplied by artery (acute coronary syndrome) CORONARY ARTERY IS THE PROBLEM
- Increased oxygen demand or decreased oxygen supply
- Heart failure, sepsis, anaemia, arrhythmias, hypertension or hypotension (supply-demand imbalance)
- CORONARY ARTERY IS NOT THE PROBLEM
- Sudden cardiac death, often proven on autopsy
- Iatrogenic
- MI associated with percutaneous coronary intervention - angioplasty in coronary artery can cause infarction in area supplied by artery, arterial rupture/perforation can occur
- MI stent thrombosis (stent reocclusion) documented by angiography or PM
- MI associated with CABG
Compare amiodarone and dronedarone
- Dronedarone
- Same effect as amiodarone without iodine
- Less potent
Describe the components of tetralogy of fallot
- Ventricular septal defect
- Right ventricular outflow tract obstruction
- Often stenosis below the pulmonary valve due to large muscle mass
- Narrowing of the pulmonary valve and outflow tract or area below the valve that creates an obstruction (blockage of blood flow) from the right ventricle to the pulmonary artery
- Overriding aorta - aortic valve enlarged and appears to arise from both the left and right ventricles instead of the left ventricle as in normal hearts
- Right ventricular hypertrophy
Which antihypertensive should be used in which patients?
- Step 1
- Aged under 55 years - ACE inhibitor or low-cost angiotensin II receptor blocker
- Aged over 55 years or black person of African or Carribean origin of any age
- Calcium channel blocker
- Step 2
- ACE inhibitor or low-cost angiotensin II receptor blocker and calcium channel blocker
- Step 3
- ACE inhibitor or low-cost angiotensin II receptor blocker and calcium channel blocker and thiazide-like diuretic
- Step 4 - resistant hypertension
- ACE inhibitor or low-cost angiotensin II receptor blocker and calcium channel blocker and thiazide-like diuretic and consider further diuretic or alpha- or beta-blocker
- Take into account co-morbidities
- Beta-blockers in heart failure/asymptomatic coronary heart disease
- ACEI in heart failure
- ACEI in diabetes mellitus
- Often more than one drug will be required
What is seen on an ECG in pericarditis?
ST elevation in V1-6 - global ST elevation
= Pericarditis rather than STEMI
Describe the heart murmur heard in mitral stenosis
Low-pitched (‘rumbling’) mid-diastolic murmur, with pre-systolic accentuation in sinus rhythm due to atrial systole, best heard at the apex with patient lying on their left side
Describe the appearance of a STEMI on ECG
- STEMI shows elevation of J point - junction of the termination of the QRS complex and the beginning of the ST segment.
- Different ECG patterns in STEMI:
- ST elevation reflects occlusion of a coronary artery
- Occurs in regional patterns
- Posterior infarct
- Location means ST elevation not seen
- Left bundle branch block
- If NEW can indicate infarction
- If OLD can obscure ST elevation during an infarct
- Always ask senior advice as to whether to treat as a STEMI or not
- ST elevation reflects occlusion of a coronary artery
Describe the use of ACE inhibitors in heart failure
ACE inhibitors (e.g. enalapril, captopril) shown to improve outcomes compared with placebo (reduce mortality) in severe and less symptomatic patients.
Explain the complications of aortic valve disease including the effects on the L ventricle
- Aortic stenosis
- Angina, syncope, dyspnoea
- Sudden death, heart failure - surgical valve replacement considered even in absence of severe symptoms
- Aortic regurgitation
- LV dilatation, heart failure will eventually occur
- Challenge is to offer valve replacement before irreversible damage has occurred but delay appropriately in asymptomatic patients
Describe the modern techniques used for procedural intervention in valve dysfunction
- TAVI
- Reduces morbidity/mortality in those too unwell for conventional surgery
- Catheter from leg to aorta, inflate balloon w/ valve, valve expands
- Trials to prove its better than conventional
- Mitraclip
- Not well enough for mitral valve surgery, clips that keep mitral valve together
- Valvuloplasty
Describe the pathophysiology of endocarditis
- Vegetation = mass of platelets, fibrin, microcolonies of organisms, inflammatory cells and RBC debris
- Vegetation hard to penetrate - hard treat.
- Vegetation - biofilm = mass of organisms
- Commonly associated with infections of prosthetic devices e.g. valves, hip replacements
- Quorum Sensing:
- Ability to detect and respond to cell population density by gene regulation
- E.g. enables bacteria to restrict the expression of specific genes to the high cell densities at which the resulting phenotypes will be most beneficial
- Many species of bacteria use quorum sensing to coordinate gene expression according to the density of their local population
Why is heart failure important?
- Common - prevalence = 1-2% of population, may be increasing. Incidence - 1 in 5 lifetime risk of HF.
- Costly - 2% of all health care expenditure - mainly spent on hospital admissions (70% of expenditure on heart failure, also outpatient clinics and drugs)
- Disabling - associated with a worse quality of life than almost any other medical condition. Because of symptoms (dyspnoea, fatigue) and frequent deterioration leading to hospital admission. Unemployment due to poor health.
- Deadly - worse survival than most forms of cancer. 50% mortality within 5 years, is improving.