Flashcards in Drug Treatment of Cardiovascular Disease Deck (19)
How can the vascular endothelium be dilated to reduce blood pressure?
Substances such as endothelin and nitric oxide
How can the vascular endothelium be constricted to reduce blood pressure?
Substances such as catecholamines
What is angina?
The pain or discomfort arising from ischaemia of myocardial muscle generally due to atherosclerotic obstruction of coronary blood vessels
How is angina treated?
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
How may nitrates be used in the treatment of angina?
Have a dilatory effect so work to reduce preload, reducing the work of the heart
How may beta-1 adrenoreceptor antagonists (beta blockers) be used to treat angina?
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
How may calcium channel blockers be used to treat angina?
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
Name three treatments for hypertension
ACE inhibitors, calcium channel blockers and diuretics
Describe how ACE inhibitors can treat hypertension
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
Describe how calcium channel blockers can reduce hypertension
Block calcium entry to the vascular smooth muscle and myocardial cells (interrupting excitation-contraction coupling) in order to prevent constriction --> cause vasodilation
Describe how diuretics can reduce hypertension
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
Describe heart failure
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
What are the main causes of heart failure?
Ischaemic heart disease as well as valve defects and dysrhythmias
What is preload proportional to?
What is afterload proportional to?
Systemic vascular resistance
How can afterload be reduced?
ACE inhibitors (as angiotensin II is responsible for stimulating vasoconstriction)
How can preload be reduced?
Diuretics - inhibit water reuptake and therefore reduce the total blood volume
Describe the mechanism of action of digoxin in the treatment of heart failure
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