Lecture 21 - Disorders Of The Cardiovascular System Flashcards
When does heart failure occur
When the cardiac output is insufficient to perfuse the body tissues despite normal filling of the heart
What does heart failure normal result from
Coronary artery diseases, but also hypertension, vascular disease and cardiacmyopathy
What are the symptoms of heart failure
Breathlessness, reduced exercise tolerance, pulmonary oedema and fatigue
How is heart failure treated
Through drug therapy
What does drug therapy aim to do in heart failure
Reverse maladaptive changes and improve the cardiac output by the use of positive conotropic drugs
What is an oedema
An abnormal accumulation of fluid in the interstitium
What does an oedema result from
An imbalance between the rate of formation and absorption of interstitial fluid
What diseases can cause an oedema
Nephrotic syndrome, congestive heart failure and hepatic cirrhosis with ascites
What does nephrotic syndrome involve
A disorder of glomerular filtration, allowing albumin to appear in the filtrate
What is albumin in the filtrate known as
Proteinurea
What does congestive heart failure arise from
Reduced cardiac output
What are the aims of clinical management of heart failure
Reduce preload, reduce after load and to enhance contractility
What are used to reduce preload
Diuretics, aldosterone receptor antagonists, aquanetics, ACE inhibitors and venodilators
What are used in the reduction of afterload
ACE inhibitors
What is used to enhance contractility
Cardiac glycosides and calcium-sensitisers
What increases venous and capillary pressures
Expansion of blood vessels
What is hepatic cirrhosis with ascites
An increased in the pressure in the hepatic portal vein, combined with decreased production of albumin
What does hepatic cirrhosis with ascites cause
A loss of fluid into the peritoneal cavity and oedema
Along with Na+ and K+ was else is lost in the use of loop agents
Ca2+ and Mg2+
What is the indirect vasodilatory action of loop diuretics possibly caused by
An increased formation of vasodilating prostaglandins, decreased responsiveness to angiotensin II and noradrenaline or through the opening of K+ channels in resistance vessels
What are the adverse effects of loop diuretics
Potassium loss which causes the production of low serum potassium levels, a shift in the acid-base towards the alkaline side, a decreased volume of circulating fluid, hypotension, a depletion of calcium and magnesium and in increase in plasma uric acid
What is the production of low serum potassium levels known as
Hypokalaemia
What is a shift in the acid-base towards the alkaline side known as
Metabolic alkalosis
What is a decreased volume of circulating fluid known as
Hypovolaemia
What is an increase in plasma uric acid
Hyperuricaemia
What causes metabolic alkalosis
An increased H+ secretion from intercalated cells in the collecting tubule
How is hypokalaemia corrected
The concomitant us of potassium sparing diuretics or potassium supplements
What is spironolactone
An aldosterone receptor antagonist
What is spironolactone modulated by
Aldosterone levels
What does spironolactone competitively antagonise
The action of aldosterone at cytoplasmic aldosterone receptors
How does spironolactone gain access to the cytoplasm
Through the basolateral membrane
What is the function of spironolactone
It increases the excretion of Na+ and decreases the excretion of K+
Where is spironolactone well absorbed
In the G.I tract
What is the major use of potassium sparing diuretics
In conjunction with other agents that cause potassium loss
If potassium sparing diuretics are given alone what happens
They cause hypokalaemia
What are aldosterone antagonist used in the treatment of
Heart failure, primary hyperaldosteronism, resistant essential hypertension and secondary hyperaldosteronism
What is the syndrome name of primary hyperaldosteronism
Conn’s syndrome
What does secondary hyperaldosteronism result from
Hepatic cirrhosis with ascites
What is an example of a calcium-sensitiser
Levosimendan
What do calcium-sensitisers do
They bind to troponin C in cardiac muscle, sensitising it to the action of calcium
What effect do calcium-sensitisers have on vascular smooth muscle
It opens KATP channels causing vasodilation
What are calcium-sensiters used in the treatment of
Heart failure
