Drug Treatment of Cardiovascular Disease

Question 1

How can the vascular endothelium be dilated to reduce blood pressure?

Answer 1

Substances such as endothelin and nitric oxide

Question 2

How can the vascular endothelium be constricted to reduce blood pressure?

Answer 2

Substances such as catecholamines

Question 3

What is angina?

Answer 3

The pain or discomfort arising from ischaemia of myocardial muscle generally due to atherosclerotic obstruction of coronary blood vessels

Question 4

How is angina treated?

Answer 4

Aim is to improve/restore coronary blood flow OR reduce the workload of the myocardium and hence the oxygen demand it requires –> as angina is often due to ischaemia of myocardium

Question 5

How may nitrates be used in the treatment of angina?

Answer 5

Have a dilatory effect so work to reduce preload, reducing the work of the heart

Question 6

How may beta-1 adrenoreceptor antagonists (beta blockers) be used to treat angina?

Answer 6

Activation of beta-1 receptor usually activates the sympathetic NS and adrenal glands (increasing heart rate, myocardial contractility and conduction through AVN). Therefore, beta blockers impede this activation to reduce the work of the myocardium and hence it’s required oxygen demand

Question 7

How may calcium channel blockers be used to treat angina?

Answer 7

Reduces Ca2+ influx through voltage gated channels on myocyte membrane –> reduced intracellular Ca2+ which reduces the contractility in myocytes and vascular smooth muscle which reduces oxygen demand due to improved supply in the coronary arteries and reduces work of the heart

Question 8

Name three treatments for hypertension

Answer 8

ACE inhibitors, calcium channel blockers and diuretics

Question 9

Describe how ACE inhibitors can treat hypertension

Answer 9

Interrupts RAAS system (prevents angiotensin I being converted to angiotensin II) which prevents sodium and water retention at the kidney as well as the stimulation of vascular smooth muscle constriction, vasodilation –> reduced BP

Question 10

Describe how calcium channel blockers can reduce hypertension

Answer 10

Block calcium entry to the vascular smooth muscle and myocardial cells (interrupting excitation-contraction coupling) in order to prevent constriction –> cause vasodilation

Question 11

Describe how diuretics can reduce hypertension

Answer 11

Thiazide-type are used to prevent the reabsorption of sodium (and water) in the distal tubule and early collecting duct in order to decrease intravascular volume, and decrease BP

Question 12

Describe heart failure

Answer 12

Severe failure of the heart to function properly; insufficient CO to delivery necessary blood flow to the tissues –> pulmonary congestion, difficulty breathing and peripheral oedema

Question 13

What are the main causes of heart failure?

Answer 13

Ischaemic heart disease as well as valve defects and dysrhythmias

Question 14

What is preload proportional to?

Answer 14

Venous return

Question 15

What is afterload proportional to?

Answer 15

Systemic vascular resistance

Question 16

How can afterload be reduced?

Answer 16

ACE inhibitors (as angiotensin II is responsible for stimulating vasoconstriction)

Question 17

How can preload be reduced?

Answer 17

Diuretics - inhibit water reuptake and therefore reduce the total blood volume

Question 18

Describe the mechanism of action of digoxin in the treatment of heart failure

Answer 18

Selectively binds to and inhibits myocyte Na+/K+ ATPase so that intracellular Na+ rises in the cells and Na+/Ca2+ exchange is altered to increase intracellular Ca2+ to improve contractility with depolarisation and may have direct action on conduction at AVN – decreases automaticity, slows the conduction velocity and slows HR

Question 19

What are the aims of treatment for heart failure?

Answer 19

Reduce preload and afterload in the heart