CVS Pathophysiology Flashcards
What is cardiac failure?
- Heart cannot provide sufficient cardiac output for the metabolic needs of the body
- Aka Congestive Heart Failure (CHF) or Cardiac Heart Failure (CCF)
- Symptoms: increase venous pressure
(heart fails -> backlog of blood (congestion) -> increase venous pressure) - Diseases lead to CHF, not a diseases of its own
What are the common causes/etiology of CHF?
- Inappropriate work load
(volume or pressure overload) - Loss of muscle = cardiac muscle cells die
- Restricted/poor filling
(preload determines stroke volume. decrease blood in = decrease blood out = CHF
What causes volume overload?
- Regurgitant valve
- High output status
How does regurgitant valve cause volume overload?
Eg. aortic valve regurgitation
- Aortic valve becomes leaky/cannot close properly = aortic regurgitation
- Blood coming in from left atrium –> fills the left ventricle –> aortic valve leaky –> blood comes back into left ventricle –> causes heart to dilate and pump harder –> to accommodate to additional leaky volume –> chamber size increases –> muscle thickness –> hypertrophy
- Over a long period of time –> increase in chamber size and hypertrophy –> heart cannot last indefinitely as heart cannot handle the increase volume workload –> cardiac failure
How does pressure overload cause volume overload?
eg. hypertension (high bp)
- High BP –> causes heart to pump harder to push blood out –> causes heart chamber to thicken –> to compensate the high pressure –> after some time, heart give up –> cardiac failure
How does loss of muscle cause volume overload?
eg. Post Myocardial Infarction
- area of MI = area where blood supply cut off
- cells are dead in that area –> only surrounding cells can be use for contraction –> decrease pumping efficiency –> not enough blood coming out –> cardiac failure
How does restricted filling cause volume overload?
eg. pericardial diseases
- pericardium diseases –> heart is still good–> but pericardium thickens and shrinks –> compresses the heart chambers –> heart chambers become small –> blood cannot come in from SVC and IVC –> decrease blood in, decrease blood out –> cardiac failure
What are some examples of etiology of cardiac failure?
- Volume overload
> regurgitant valve
> high output status - Pressure overload
> systemic hypertension
> outflow obstruction
Loss of muscles > Post MI > Chronic ischemia > Connective tissue diseases > Infections
Restricted filling
> pericardial diseases
> restrictive cardiomyopathy
> tachyarrhythmia
What are the common causes of cardiac failure?
Most to least prevalent >CAD (coronary artery disease) > ischemic heart diseases (heart attacks) > hypertension > valvular heart disease > cardiomyopathies (muscle cell diseases) > pericardial diseases > arrhythmias > high-output conditions
What are high output conditions?
eg. anaemia
- low Hb –> low O2 –> heart compensate by pumping harder and faster –> causes high output state
- due to compensation
- long run –> heart give up –> CF
What are the causes of left sided heart failure?
- poor output -> less blood supply to the body -> body low of energy, low of oxygen
- blood congestion: blood coming from lungs into the left atrium –> cannot pump out of left ventricle to the rest of the body –> lungs and heart congested
- compensation: HF = decreased CO –> increase HR, increase contraction via ANS (sympathetic)
What are the symptoms of left sided heart failure caused by poor output of blood?
- fatigue (low blood to body, low metabolic needs = tired)
- cyanosis (blue, low blood supply to tissues, no oxygen)
- confusion (low oxygen to brain)
What are the symptoms of left sided heart failure caused by congestion of blood?
- exertional dyspnea (during exercise)
- paroxysmal nocturnal dyspnea (lies flat on bed –> blood distribute to lungs –>improve by standing)
- orthopnea (lungs fully congested)
- pulmonary congestion > cough > wheezes > blood-tinged sputum > tachypnea
What are the symptoms of left sided heart failure caused by compensation of low cardiac output?
- tachycardia
- restlessness
What causes right sided heart failure?
- mainly the backlog effect on SVC, IVC
(blood coming in from SVC and IVC –> into the right atrium –> flows to right ventricle –> but cannot be pumped out to the lungs –> blood gets congested –> whole body is congested –> except the lungs - when blood is congested –> forces water to come out of tissues –> leak into body –> body congested with water
- not caused by cardio problem, but lung problem –> CF
(eg. lung disease COPD –> blood cannot flow to lungs –> pulmonary vessel resistance -> heart work harder to push blood –> causes hypertrophy –> CF)
What are the symptoms of right sided heart failure?
- may be secondary to chronic pulmonary problems
- distended jugular veins
- anorexia and complaints of GI distress
- weight gain (by water)
- dependent edema (by gravity, water comes down to legs. if lie down -> water foes to back and face)
- enlarged liver and spleen
- ascites (water in abdomen)
- increased peripheral venous pressure
- fatigue
How does CF be classified on?
- Systolic Dysfunction
2. Diastolic Dysfunction
What happens during systolic dysfunction?
- enlarged ventricles fill with blood -> but ventricles pump out less than 40 - 50% of the blood
What happens during diastolic dysfunction?
- the stiff ventricles fill with less blood than normal -> but ventricles pump out about 60% of blood, but the amount may be lower than normal
- ejection fraction is normal = can pump well but does not receive enough blood
How does the heart maintain adequate tissue perfusion (compensation mechanisms)?
- Increase heart rate
- Vascular tone
- Circulating Volume
What is the role of the sympathetic nervous system when there is decreased cardiac output?
- increases contractility
- increases heart rate
- vasoconstriction
= increase cardiac output
What is the role of the renin-angiotensin system when there is decreased cardiac output?
- vasoconstriction
- increase circulating volume/ increase blood volume
- kidneys receive less blood –> release renin –> convert to angiotensinogen –> Angiotensin 2 –> produce vasoconstrictor –> increase BP
= increase venous return to heart
What is the role of the antidiuretic hormone when there is decreased cardiac output?
- increase circulating volume/increase blood volume
= increase venous return to heart
What can a chest x-ray result tell you about cardiovascular diseases?
- size and shape of the heart -> cardiomegaly (huge heart size)
> diameter of heart compared to diameter of chest –> cardiothoracic (CT) ratio must be less than 50% - evidence of pulmonary venous congestion (dilated or upper lobe veins –> perivascular edema
> dilated veins -> venous congestion of fluid on the base area - pleural effusion
> fluid leak into pleural space
What is an ECG?
- gold standard investigation
- assess chamber size –> look for dilation
- assess systolic function - lvEF
- assess valve structure and function
- assess BNP in blood (B-type natriuretic peptide)
> high sensitivity 89% and specificity 81% for CF
What is the treatment of CF?
- correction of reversible causes (treat the primary problems)
> ischemia/CAD (manage this first then manage CF)
> valvular heart diseases
> thyrotoxicosis
> anaemia
> arrhythmia
What is the management of CF?
- by action of drugs
> digoxin, inotrope drugs - drugs decreases preload –> increases contractility –> decreases afterload
