Lecture 6 - Feb 4 Flashcards
What are the two types of coronary dominance?
- Right coronary dominance
- Left coronary dominance
Right coronary dominance means the posterior descending artery (PDA) is a branch of the right coronary artery. Left coronary dominance means the PDA is a branch of the circumflex portion of the left coronary artery.
What percentage of people typically have right coronary dominance?
Approximately 75% of people
This statistic reflects the common anatomy of coronary arteries.
What is the role of the circumflex artery?
Curves around towards the back of the heart
The circumflex artery branches off the left coronary artery and can supply the PDA in some individuals.
In which situation is left coronary dominance considered a risk factor?
When the left coronary artery is responsible for supplying more heart tissue
This condition increases the risk of serious cardiac issues if the left coronary artery fails.
What happens to pulmonary artery pressure (PAP) during inspiration?
PAP is reduced
This reduction occurs due to the chest becoming more negative, which affects blood flow dynamics.
How does positive pressure ventilation affect cardiac output?
Initially increases, then may decrease
The initial increase in cardiac output occurs due to increased preload; however, prolonged positive pressure can impede venous return.
What is the expected effect of positive pressure ventilation on the right side of the heart?
Preload increases but afterload also increases
This results in a net effect that may not significantly change cardiac output for the right heart.
What structural change occurs in the heart due to aortic stenosis?
Thickening of the heart wall
This adaptation allows for more forceful contractions against a narrowed valve.
What happens to compliance of the ventricle with hypertrophy?
Compliance is reduced
This reduction makes it harder for the ventricle to fill with blood.
What is the relationship between the slope of the passive filling pressure curve and compliance?
A higher slope indicates reduced compliance
This means more pressure is needed to fill the heart with the same volume of blood.
True or False: The left side of the heart is thicker than the right side.
True
This is due to the left side having to pump against higher vascular resistance.
What happens to systemic blood pressure during early inspiration?
It decreases
This decrease is due to low pressure in the pulmonary veins affecting preload.
Fill in the blank: If the circumflex artery supplies the PDA, the patient has _______.
left coronary dominance
What occurs in the thorax when positive pressure ventilation is applied?
Thoracic pressure increases, impeding venous return
This can lead to difficulty in refilling the heart during the next cycle.
What is the effect of increased afterload on the right side of the heart during positive pressure ventilation?
It may negate the benefits of increased preload
This can lead to a situation where cardiac output does not increase significantly.
What is the average filling pressure in the cardiovascular system?
7 mmHg
This pressure is crucial for normal heart filling and cardiac output.
What does the slope of the line in pressure-volume relationships indicate?
The compliance of the systems
Compliance refers to the ability of the system (like the lungs or heart) to stretch and accommodate changes in volume.
How does a highly compliant ventricle behave during filling?
It requires relatively low pressures to fill with blood
A compliant ventricle has thin walls that easily stretch.
What happens to the slope of the pressure-volume loop during aortic stenosis?
The slope of phase one is higher than normal
This indicates that it is harder to fill the ventricle due to thicker walls.
What is the significance of a low compliance ventricle?
It fills faster than normal and reaches fullness quicker
This can lead to the third heart sound being audible.
What are the four possible heart sounds?
- 1st Heart Sound: AV Valves Closing
- 2nd Heart Sound: Aortic Valve Closure
- 3rd Heart Sound: Present in Heart Failure & Pediatric Population
- 4th Heart Sound: Should NOT be present in Healthy People
What causes the first heart sound?
Closure of the AV valves when intraventricular pressure exceeds atrial pressure
This sound lasts approximately 0.14 seconds and is low pitch.
What is the duration of the second heart sound?
0.11 seconds
This sound occurs after the ejection phase.
True or False: The fourth heart sound is audible in healthy individuals.
False
It is typically present when the atria work harder, such as in cases of mitral stenosis.