Patho & Pharmo 2 Heart Failure Wk 3
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What is heart failure?
When the heart fails to maintain cardiac output at required levels because of diminished ventricular ejection by either the right or left ventricle.
If one side of the heart fails will it effect the other?
Yes, maybe not straight away but eventually
Which side of the heart is doing the most work?
Left, and left sided heart failure is more common
What is systolic dysfunction?
Systolic dysfunction is a decrease in the cardiac contractiability hindering the hearts ability to eject blood from the LV.
What is diastolic dysfunction?
Diastoloic dysfunction is an abnormality in ventricular relaxation and filling
What is right sided heart failure?
Failure to move unoxygenated blood from the venous system into the pulmonary circulation, eventually causing backup in the systemic venous circulation. Decreaseing the forward flow.
What is left sided heart failure?
Failure to move oxygenated blood from the pulmonary circulation into the arterial circulation with eventual backup of blood in the lungs. Resulting in poor circulation of oxygenated blood in the body.
Name some syndromes that may reduce the pumping ability of the heart?
- Coronary Artery disease
- Dilated cardiomyothpathy
- Valvular heart disease
What is congestive cardiac failure caused by?
Vascular congestion - This starts with pulmonary congestion leading to pulmonary odema and dyspnoea (shortness of breath). Therefore systemic congestion occurs leading to tissue odema (lower limbs)
Why is Coronary Heart Disease (CHD) the most common cause of heart failure (HF)?
As it involves AS of the coronary arteries. Decreased O2 to the myocardium decreasing the strenght of contraction leading to HF
Why would anaemia cause HF?
Anaemia is a low amount of RBC. The RBC are responsible for carrying the oxygen to the body. The symptoms of Anaemia are fatigue, shortness of breath. All these symptoms will require more work from the heart.
What is Polycythemia?
Polycythemia is an elevated RBC count. If the patient had COPD there would be reduced gas exchange causing the kidney to kick in and release Renin-Angiotensin-Aldosterone therefore increasing BV.
What is preload?
Preload is the volume or loading conditions of the ventricle at the of diastole. It is the volume of blood stretching the heart muscle during heart rest and is normally determined by venous return.
What is Afterload?
Afterload is the force that the contracting heart muscle must generate to eject the blood from the filled heart. The main components are systemic vascular resistance and ventricular wall tension. Enough pressure must be generated to first open the aortic valve and then move blood out of the ventricle and into the systemic circulation.
Describe the manifestations of Right sided heart failure?
- Congestion of the peripheral tissues
- Causing dependent edema and ascites
- Possible liver congestion - signs related to impaired liver function
- GIT congestion - Anorexia, GI distress, weight loss
Describe the manifestations of left sided heart failure?
- Decreased cardiac output - causing activity intolerance and signs of decreased tissue perfusion.
- Pulmonary congestion leading to impaired gas exchange. Cyanosis and signs of hypoxia.
- Pulmonary edema - Orthopnea (difficulty breathing whilst lying down). Cough with frothy sputum. Paroxysmal nocturnal dyspnea (shortness of breath and coughing that normally occur at night)
What is the process of LHF?
- Decreased ventricular ejection
- Increased atrial pressure
- Increased pulmonary venous pressure
- Increased pulmonary capillary pressure
- Pulmonary oedema
- Decreased gas exchange
What is the process of RHF?
- Decreased ventricular ejection
- Increased right atrial pressure
- Blood pooling in the systemic venous system
- Increased venous pressure
- Increased capillary pressure
- Increased fluid exudates from capillaries
- Pitting oedema lower limbs, ascities (fluid accumulation in abdominal cavity)
What are the 4 classes of HF?
- Class 1 - (Mild) No limitation to physical activity
- Class 2 - (Mild) Slight limitation to physical activity
- Class 3 - (Moderate) Marked limitation of physical activity, resulting in fatigue, plapurtations or dyspnoea
- Class 4 (Severe) Unable to carry out physical activity without discomfort. Even at rest symptoms of cardiac insufficiency.
What is the Frank-Starling Mechanism?
The stroke volume of the heart increases in response to an increase in the volume of blood filling the heart. The increased volume of blood stretches the ventricular wall, causing cardiac muscle to contract more forcefully. The stroke volume may also increase as a result of greater contractility of the cardiac muscle during exercise, independent of the end-diastolic volume. The Frank-Starling mechanism appears to make its greatest contribution to increasing stroke volume at lower work rates, and contractility has its greatest influence at higher work rates.
What are the pharmalogical goals for MI?
- Restore blood supply
- Reduce myocardial oxygen supply
- Control any dysrhythmias
- Reduce post-MI complications
- Control MI pain
When restoring blood supply with the use of thrombolytics what needs to be considered?
Thrombolytics have a narrow margin of safety as it can also prevent good clots (mirco bleeds) which are helpful clots and can be life threatening.
Name two restrictions for streptokinase?
- Must be administered within 6 hours
- Only two doses can be given due to an increase in haemorrhagic episodes.
- It can cause an immune response due to it being an bacterial protein (non human)
- Activates plasmin as it is the bodies own off switch, it dissolves fribrin
Why is Alteplase different from Streptokinase?
- Its a tissue plasminogen activator - It will only act on tissues that have clots lodged in them and will not affect futrue clotting mechanism.
- It is the human form
- It can be given multiple times
- It is very expensive $1400 per dose
How can you reduce myocardial O2 demand?
- Beta blocker B1 receptor blocker is specific for the heart.
- Release of Noradrenaline inhibits calcium release
- Decreasing stroke volume
- Decrease HR
- Reduce amount of O2 the heart needs
What is the word link for a B1 blocker
lol - Atenolol or carvedilol
Name the four classes of adnormal rhythums?
- Class 1 - Local anaethetic agent might be useful (dual action) lethmacain shuts off sodium channels slowing down the synioaterial nodes
- Class 2 - B Blocker might be indicated lower O2 demand
- Class 3 - Excitability of the heart - Potassium channels blockers
- Class 4 - Calcium channel blockers reduced contractiability if a hypertensive situation.
When thinking about reducing MI complications, what needs to be considered?
- What was the trigger for the MI
- Plaque build up
- Occlusion - due to AS
What is the bonus of dipridamole?
- Dual effect
- Antiplatlet drug
- Coronary vasodilator - smooth muscle - Dilation
- More of a follow up not acute phase
Explain the thromboxane cycle?
Thromboxane cycle refers to impairment of platelet adhesiveness.
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