Cardiology Flashcards
What is atrial fibrillation?
AF is an irregular atrial rhythm between 300-600bpm
The AV node is unable to transmit beats as quickly as this, and thus does so intermittently, resulting in an irregular ventricular rhythm. This irregular stimulation of the ventricles reduces cardiac output by up to 20%, as well as allowing stasis of blood in the heart chambers.
What are the causes of atrial fibrillation?
Primary/Lone AF (younger than 60 years no clinical or echocardiographic causes found)
Secondary
- Cardiac
* Valve disease (mitral)
* Ischaemic heart disease
* Hypertension
* Heart failure
* Myocardial infarction - Pulmonary
* Pulmonary embolism
* Pneumonia - Other
* Alcohol
* Thyrotoxicosis
* Deranged electrolytes (K+ and Mg2+)
What is the epidemiology of AF?
It is present in:
- 5% of the over 65’s
- 10% of over 70’s
- 15% of all stroke patients
- Stroke is a major complication of AF (see below)
What are the signs and symptoms of AF?
- Palpitations
- Irregularly irregular pulse
- Pulse deficit
- Chest pain/dyspnoea
What would you see on ECG
- No p waves
- Irregularly irregular rhythm
How would you manage AF?
The mainstays of treatment are:
Conservative
- Manage risk factors (CHADVASC)
Medical
- Anticoagulation: heparin, apixaban, dabigatran, rivaroxaban, warfarin
- Rate control: beta-blocker (not sotalol) or rate limiting CCB (verapamil, diltiazem)
- Rhythm control: cardioversion, beta blocker, dronedarone, amiodarone
Surgical
- Ablation
When would you use apixaban in AF?
people with nonvalvular atrial fibrillation with 1 or more risk factors such as:
- prior stroke or transient ischaemic attack
- age 75 years or older
- hypertension
- diabetes mellitus
- symptomatic heart failure
When would you use dabigatran in AF?
people with nonvalvular atrial fibrillation with one or more of the following risk factors:
- previous stroke
- transient ischaemic attack
- systemic embolism
- left ventricular ejection fraction below 40%
- heart failure NYHA 2 or above
- age 75 years or older
- age 65 years or older with diabetes mellitus, coronary artery disease or hypertension
When would you use rivaroxaban in AF?
people with nonvalvular atrial fibrillation with one or more risk factors such as:
- congestive heart failure
- hypertension
- age 75 years or older
- diabetes mellitus
- prior stroke or transient ischaemic attack
When do you do electrical cardioversion for AF without anticoagulating?
Acute
When would you NOT offer rate control for AF?
- whose atrial fibrillation has a reversible cause
- who have heart failure thought to be primarily caused by atrial fibrillation
- with new‑onset atrial fibrillation
- with atrial flutter whose condition is considered suitable for an ablation strategy to restore sinus rhythm
- for whom a rhythm control strategy would be more suitable based on clinical judgement
When would you consider digoxin monotherapy for AF?
people with non‑paroxysmal atrial fibrillation only if they are sedentary (do no or very little physical exercise)
Which type of cardioversion should you perform for AF?
Acute, haemodynamically stable - rate and rhythm control
Chronic: must anticoagulate first, electric
When would you give a pill in the pocket?
People who
- have no history of left ventricular dysfunction, or valvular or ischaemic heart disease and
- have a history of infrequent symptomatic episodes of paroxysmal atrial fibrillation and
- have a systolic blood pressure greater than 100 mmHg and a resting heart rate above 70 bpm and
- are able to understand how to, and when to, take the medication
When do you use ablation and pacing?
Refractory AF
What is dilated cardiomyopathy?
Dilated cardiomyopathy is a disorder of heart muscle characterized
by LV and/or RV dilation and impairment of systolic function, in the
absence of significant coronary artery disease.
What causes dilated cardiomyopathy?
- Inherited (may account for > 25 %of cases)
- Myocarditis (Infective: coxsackie B, HIV, Chagas. Autoimmune. Toxic: alcohol, chemotherapy, antipsychotics)
- Metabolic (haemochromatosis, thyrotoxicosis, diabetes, pregnancy)
- Nutritional (vitamin defi ciencies — thiamine (beri-beri))
- Persistent tachycardia (tachymyopathy)
What are the symptoms and signs of dilated cardiomyopathy?
- Atypical chest pain
- LV dysfunction (exertional dyspnoea, syncope and fatigue)
- RV failure (peripheral edema, elevated JVP)
- basal lung crackles
- MR and TR
- Tachycardia unresponsive to breathing
What forms the cardiomyopathy screen?
- Renal function
- Liver function tests (LFTs)
- Serum ferritin, iron, transferrin, B 12, and folate
- Thyroid function
- Viral serology
- Infective screen (HIV, hepatitis C, enteroviruses)
- Autoantibodies
Consider TTN gene testing (25% idiopathic familial cases)
How is DCM diagnosed?
- Clinical
- ECG: tachycardia, AF, ventricular ectopics, bundle branch block, non-specific T-wave changes, poor R wave progression in anterior chest leads
- CXR: ABCDE of heart failur
- ECHO (gold standard): biatrial and biventricular enlargement, impaired systolic and diastolic function
- Consider exercise testing (functional) and ambulatory ECG (paroxysmal AF, non-sustained VT)
What are the complications of DCM?
- Intramural thrombus
- Arrhythmias
- Valve regurgitation
- Emboli
How do you treat DCM?
Conservative
- Follow up
- Manage risk factors
Medical
- Symptomatic: loop diuretics
- Prognostic: ACEI, potassium sparing diuretics (amiloride/spironolactone), beta-blockers, warfarin/aspirin anticoagulation
Surgical
- Cardiac resynchronization therapy (if wide QRS, EF
