Cardiovascular drugs 1 Flashcards
AF - pathophysiology
The pathogenesis of AF is now thought to involve an interaction between initiating triggers, often in the form of rapidly firing ectopic foci located inside one or more pulmonary veins, and an abnormal atrial tissue substrate capable of maintaining the arrhythmia. Structural heart disease underlies many cases of AF. Pulmonary vein triggers may play a dominant role in younger patients with relatively normal hearts and short paroxysms of AF, whereas an abnormal atrial tissue substrate may play a more important role in patients with structural heart disease and persistent or permanent AF.
What is fibrosis and loss of atrial muscle mass related to
- Ageing
- Chamber dilatation
- Inflammation
- Genetic
AF - risk factors
- Hypertension
- Valvular heart disease
- Coronary artery disease
- Cardiomyopathy
- Congenital heart disease
- Previous cardiac surgery
- Pericarditis
- Lung disease - PE, Pneumonia, COPD
- Hyperthyroidism
- Alcohol
AF - classification
Lone AF
Paroxysmal (<7 days)
Persistent (>7 days)
Permanent (>7 days ± Cardioversion)
AF - clinical features
Asymptomatic Palpitations SOB Chest pain Syncope Pre-syncope Heart failure
AF - Treatment
- Rate control
- Rhythm control
- Anticoagulation
Should treatment be focused on rhythm or rate control
<48hrs duration - Rhythm
>48hrs duration - Rate control
When is rhythm control preferred
- Symptom improvement
- Younger patient
- Heart failure related to AF
- Adequacy of rate control
AF - Acute without heart failure rate control
1st line - Beta blocker or CCB(Diltiazem, verapamil)
2nd line - Add digoxin
AF - Acute with heart failure rate control
1st line - digoxin, amiodarone
2nd line - amiodarone
AF - Permanent or paroxysmal rate control
1st line - beta blocker or CCB
2nd line - Add digoxin
AF - Rhythm control - acute cardioversion, normal heart
- Flecainide, sotalol
AF - Rhythm control - acute cardioversion, abnormal heart
- Amiodarone
AF - Rhythm control - maintain sinus rhythm, normal heart
- Flecainide, sotalol
AF - Rhythm control - Maintain sinus rhythm, abnormal heart
- Amiodarone
PDE3 inhibitors
Activation of the sympathetic nervous system releases the neurotransmitter norepinephrine and increases circulating catecholamines (epinephrine and norepinephrine) which bind primarily to beta1-adrenoceptors in the heart that are coupled to Gs-proteins.
This activates adenylyl cyclase to form cAMP from ATP.
Increased cAMP, through its coupling with other intracellular messengers, increases contractility (inotropy), heart rate (chronotropy) and conduction velocity (dromotropy).
Cyclic-AMP is broken down by an enzyme called cAMP-dependent phosphodiesterase (PDE). The isoform of this enzyme that is targeted by currently used clinical drugs is the type 3 form (PDE3). Inhibition of this enzyme prevents cAMP breakdown and thereby increases its intracellular concentration
Non-cardioselective beta blockers
- Propanolol
- Carvedilol
- Sotalol
Cardioselective beta blockers
- Atenolol
- Bisoprolol
- Esmolol
- Metoprolol
- Nebivolol
Vasodilatory beta blockers
- Labetalol
- Carvedilol
Rate limiting CCBs
- Verapamil
- Diltiazem
Dihydropyridine CCBs
- Amlodipine
- Nifedipine
- Felodipine
- Lercanidipine
- Nimodipine