Term
| How long does each cardiac cycle last? |
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Definition
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Term
| How is the cardiac cycle divided? |
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Definition
0.1s = atrial systole
0.3s = ventricular systole
0.4s = diastole |
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Term
| Describe the valves during diastole |
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Definition
The heart is at rest.
- AV valve is open as atrial pressure is higher than ventricular pressure and blood returning from the lungs passively fills the ventricles.
- Semilunar valve is closed as the pressure in the aorta exceeds ventricular pressure |
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Term
| When do the AV valves close? |
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Definition
| When atrial pressure is exceeded by vetricular pressure (due to ventricular muscle contracting), the AV valves close and this causes the LUB sound. |
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Term
| As ventricular contraction continues, pressure within the ventricles continues to rise until... |
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Definition
| ...it exceeds aortic pressure; the aortic semi-lunar valve will then be pushed open by the greater pressure in the ventricle compared to the aorta and blood is ejected from the ventricles |
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Term
| During ventricular ejection phase, aortic pressure usually reaches... |
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Definition
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Term
| What causes the closure of the semi-lunar valves? |
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Definition
- ventricular pressure falls
- blood beings to flow back down the aorta into the ventricles
DUP sound |
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Term
| What is the dicrotic notch |
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Definition
| a brief rise in aortic pressure as blood rebounds off the closed valve susps |
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Term
| What occurs in the atria during ventricular contraction? |
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Definition
Atria have been in diastole
blood returning from the lungs have been collecting in the atria |
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Term
| What happens when atrial pressure exceeds ventricular pressure? |
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Definition
| the AAV valves open and passive part of ventricular filling begins which completes the cycle |
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Term
| Describe the isovolumic phase of contraction |
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Definition
AV valve is closed
Aortic semilunar valve is closed
blood volume doesn't change |
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Term
| Describe the isovolumic phase of relaxation |
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Definition
AV valve is closed
Aortic semilunar valve is closed
no blood entering or leaving the ventricle |
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Term
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Definition
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Term
| What is the MAP on the left side of the heart? |
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Definition
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Term
| What is the relationship between vessel diameter and arterial pressure? |
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Definition
| as vessel diameter decreases, arterial pressure falls |
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Term
| Where is the steepest drop in arterial pressure? what does this suggest? |
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Definition
| the arterioles - they offer the greatest resistance to blood flow |
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Term
| What is the average MAP in the pulmonary circuit? |
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Definition
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Term
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Definition
| plaque building up along the inner walls of the arteries of the heart, which narrows the arteries and reduces blood flow to the myocardium. |
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Term
| What does limitation of blood flow to the heart cause? what could this lead to? |
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Definition
| ischaemia (cell starvation due to lack of oxygen) of the myocardial cells. This could lead to myocardial infarction (death of myocardial cells) or angina pectoris ('tightening' chest pain) |
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Term
| What are the risk factors of CAD? |
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Definition
- high blood cholesterol
- smoking
- diabetes
- genetic predisposition
- hypertension
- obesity
- sedentary lifestyle |
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Term
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Definition
1. in severe cases, patients usually present with chest pain/acute heart attack
2. it is usual practice to inject patients with streptokinase to break up blood clots
3. once stable, angiography is used to detect blockages in coronary arteries |
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Term
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Definition
| a protein secreted by several species of streptococci that can bind and activate human plasminogen and by doing so can degrade many blood plasma proteins |
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Term
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Definition
| a medcial imaging technique used to visualise the inside, or lumen, of blood vessels and organs of the body, with particular interests in the arties, veins and the heart chambers. Traditionally done by injecting a radio-opaque contrast agent into the blood vessel and imaging using x-ray based techniques such as fluoroscopy |
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Term
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Definition
| an abnormal narrowing in a blood vessel (or other tubular organ) |
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Term
| What are the two routine procedures to treat CAD? |
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Definition
1. Percutaneous Transluminal Coronary Angioplasty (PTCA)
2. Coronary Artery Bypass Graph (CABG) |
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Term
| Describe the procedure of PTCA |
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Definition
1. balloon catheter with uninflated balloon is threaded to obstructed area in artery
2. when balloon is inflated, it stretches arterial wall and squashes atherosclerotic plaque
3. after lumen is widened, balloon is deflated and catheter is withdrawn
4. a stent is often placed at the site of blockage to permanently open the artery |
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Term
| What are the problems with PTCA? |
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Definition
1. balloon inflation can indue ischaemia in the heart
2. damage to vessel may lead to closure of artery again in the following months (stent is inserted to prevent this) |
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Term
| Describe the procedure of CABG |
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Definition
1. arteries/veins from elsewhere in the patient's body are grafted to the coronary arteries to bypass atherosclerotic narrowings and improve the blood supply to the coronary circulation supplying the myocardium
2. it is common to use saphenous vein from the leg
3. it is routine to have between 2-4 grafts to bypass blocked arteries |
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Term
| What are the problems with CABG? |
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Definition
1. open chest surgery
2. involves stopping the heart
3. risk of restenosis |
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Term
| Name 3 congenital heart defects |
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Definition
1. Ventricular septal defect (VSD)
2. Coarction of the aorta
3. Tetralogyof Fallot |
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Term
| What is VSD? what does it cause? |
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Definition
a defect (usually a hole) in the ventricular septum (the wall dividing the left and right ventricles).
De/oxygenated blood can therefore mix between the right and left ventricles, respectively. |
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Term
| What is coarction of the aorta? |
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Definition
aorta narrows in the area where the ductus arteriosus inserts.
a coarction increases the work load on the LV which can lead to hypertrophy in the LV |
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Term
| What is a Tetralogy of Fallot? |
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Definition
| involves 4 anatomical abnormalities (however only 3 are always present) |
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Term
| What are the 4 anatomical abnormalities? |
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Definition
1. stenosis of the pulmonary trunk
2. stenosis of the pulmonary valve
3. ventricular septal defect
4. aorta arises from both ventricles
ALL THESE DEFECTS CAN BE CORRECTED SURGICALLY. |
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