CAD, HF, Acute CS & AF Flashcards
What is the role of GTN?
- Vasodilator, given for angina pectoris
- Causes venous dilatation to reduce cardiac preload
- Decreasing cardiac oxygen demand
- GTN is metabolised into NO in smooth muscle cells
What are the adverse effects of Nitrate drugs?
- venous pooling
- leads to postural hypotension, from supine to sitting position
- dizziness and headaches
What are the types of Angina?
- Stable angina (most common)
- Unstable Angina
- Prinzmetal Angina
What is stable angina?
- Most common type of angina
- Induced by exercise, heavy meals, cold and emotional stress
- Controlled well by GTN & other anti-anginal drugs
What is unstable angina?
- Occurs at rest
- May be induced by little exercise or stress
- Occurs due to possible thrombus formation on ruptured atheromatous plaque
- Causing partial occlusion of CA
-Patient at risk of full occlusion of CA and MI
What is prinzmetal angina?
- rare form of angina
- spasm of CA’s
- may occur in patient’s with minimal atherosclerotic damage and rarely progresses to MI
Why is GTN administered as sublingual, skin patch or buccal spray and NOT as a tablet to swallow?
- Absorption of the drug in the gut will lead to metabolisation by the liver
- Limits the drug availability
Can a patient with Asthma be prescribed with Beta Blockers for angina (non-selective & selective)?
-No
- B- blockers have affinity for both B1 (cardiac) & B2 receptors (airways) on bronchial muscles
- This can lead to bronchoconstriction
- Even selective B- blockers can have some effect
What is the mechanism of action of Beta Blockers e.g. Propranolol?
- act on B1 and B2 receptors
- cause vasoconstriction & bronchoconstriction
- Block sympathetic effects on B1 & B2 receptors
- Causes small reduction in HR and CO; little effect on BP
- May be beneficial for some angina patients; reduces the response of B1 receptors to sympathetic stimulation during exercise, stress etc.
- Selective & Non-selective B-Blockers
How can you distinguish between Angina & MI?
- Angina goes away after rest and taking medication e.g. GTN
- MI patient still presents with symptoms
- Pain, pallor, sweating, nausea, hypotension with shock suggest complete occlusion of CA
- MI patient will have increased Troponin I & T with increased creatine phosphokinase
What is the MOA of Calcium Channel blockers (CCB’s)?
- Block L type Ca channels of vascular smooth muscles
- Reduces Ca concentration in smooth muscles
- Leads to dilation of arteries due to reduced contractile activity
- CCB’s mainly act on arteries
- Dihydropyridines, e.g. Nifedipine, is useful for CA dilation
- Commonly used for prinzmetal angina
What ECG changes will be expected in Angina?
- ST segment depression
- Severe Angina may present with ST segment elevation for short duration
What is Angina Pectoris?
- Paroxysmal attacks of retrosternal chest discomfort, tightness, or pressure due to myocardial ischemia
- Pain may radiate to left arm, chin and jaw area
- Narrowed CA’s may not be able to dilate upon exercise, stress, cold etc
- Therefore, increased oxygen demand of cardiac muscles are not met, leading to ischemia
What is heart failure?
-heart is unable to pump enough blood
-Unable to meet the metabolic needs
- Ventricular dysfunction results in low cardiac output
-congestion of blood (backward failure) and poor systemic perfusion (forward failure)
-Disturbance of tissue fluid management; increased venous pressure
- therefore swelling of ankles is presented in patients
What is the significant underlying cause of Heart Failure?
Hypertension- leads to increased afterload which causes hypertrophy of ventricles and increased O2 consumption
- reducing cardiac efficiency
