Cardiac Cycle

Question 1

T/F electrical events initiate the mechanical events

Answer 1

T

Question 2

Types of contraction inc radial muscle

Answer 2

. Isometric: contraction where force is generated in absence of change in fiber length (isovolumetric in heart)
. Isotonic: contraction where a dec. in fiber length occurs in absence of change in force (change in volume in absence of change in pressure)

Question 3

Type of contraction with valve in opening

Answer 3

. Begins as isometric contraction then becomes an isotonic contraction
. Change in volume begins when pressure inside exceeds outflow pressure and then valve opens which allows volume displacement to begin
. When valves close, the ventricles are contracting isometrically
. When valves open the outflow valves open and outflow begins so contractions are nearly isotonic

Question 4

Afterload

Answer 4

. Resistance against which the chamber is contracting or pumping
. With a large afterload (excessively high diastolic aortic pressure) the afterload Ed contraction would eventually become a purely isometric contraction
. With no afterload, the contraction would be purely isotonic

Question 5

Phases of ventricular contraction

Answer 5

. Systole Isovolumetric ventricular contraction (AV valves and aortic and pulmonary valves closed)
. Systole Ventricular ejection: blood flows out of ventricle (AV valves closed, aortic and pulmonic valves open)
. Diastole isovolumetric ventricular relaxation (All valves closed)
. Diastole ventricular filling w/ atria relaxed, then ventricular filling w/ atria contraction (AV valves open, others closed)

Question 6

Isovolumetric contraction phase

Answer 6

. Ventricle contract following depolarization
. Begins shortly after QRS complex
. Bother valves are closed to pressure inc. but volume doesn’t change

Question 7

Ventricular ejection phase

Answer 7

. Pressure in ventricles then exceeds diastolic pressure in aorta (LV) Or pulmonary a. (RV) and outflow valves open and blood ejected
. Has initial rapid ejection followed by reduced ejectionphase
. Initially ventricular pressure continues to rise
. Pressure in LV and aorta is identical in ejection (true for right side too)

Question 8

Isovolumetric relaxation phase

Answer 8

. At end of ejection phase the initial fall in ventricular pressure occurs due to loss of significant volume of blood in ventricles
. Outflow valves close as pressure gradient reverses approx. coinciding w/ onset of ventricular relaxation
. Closure of outflow valves is onset of diastole
. During isovolumetric relaxation both set of valves are closed
. Ventricular pressure declines rapidly w/o a change in volume

Question 9

Ventricular filling phase

Answer 9

. Rapid filling phase: during rapid filling, ventricular pressure in than than atrial pressure so process is passive, it is rapid bc the pressure gradient favors rapid movement
. Reduced filing phase: as ventricles fill, intraventricular pressure inc. that leads to slowing of filling, process still passive
. Atrial contraction (atrial systole): active, follows atrial depolarization, accounts for 20-30% of ventricular filling volume, may inc. during exercise

Question 10

Similarities in cardiac cycle of R and L ventricles

Answer 10

. Same phases

. Sequence of valves opening and closing

Question 11

Difference between cardiac cycle of L and R ventricles

Answer 11

. Pressure in pulmonary circulation lower than systemic so afterload for RV is lower than for LV
. Systole of LV beings slightly before contraction of RV begins
. Pulmonic valve opens before aortic valve due to difference in afterload
. Pulmonic valve closes after aortic valve closes bc of difference in afterload too

Question 12

S1 heart sound

Answer 12

. Produced by closing of AV valves at onset of systole
. Closure of mistral precedes tricuspid by 0.01 sec
. Results from vibration of valves immediately after closure from ventricular pressure exceeding atrial pressure
. Intensity enhanced w/ shorter PR interval, mild mitral stenosis, high CO
. Intensity diminished w/ long PR interval, and mitral regurgitation

Question 13

S2 heart sound

Answer 13

. Occurs during diastole
. Assoc. w/ closure of semilunar valves when pressure in ventricles fal below pressure in corresponding great a.
. Sounds from recoil of blood from closed valves back into aa. Causing reverberation
. Aortic valve closes before pulmonic so it has aortic and pulmonic component sounds

Question 14

Physiological split

Answer 14

. 2nd heart sound in S2 from A2 and P2
. Interval btw A2 and P2 varies w/ respiration
. Inc. w/ pulmonary stenosis

Question 15

Physiological split during inhalation

Answer 15

. Chest expands, intrathoracic pressure becomes more neg., blood flow inc. returning to right side of heart
. Inc. filling enhances RV EDV and stroke volume
. Causes inc. in ventricular emptying time during ejection phase, delaying closure of pulmonic valve
. Neg. intrathoracic pressure enhances capacity of pulmonary vv. Reducing venous return to LV
. Causes shorter LV ejection and early closure of aortic valve

Question 16

Physiological split during expiration

Answer 16

. Intrathoracic pressure becomes less neg.

. Pulmonic and aortic valve closing occurs at approx. same time and split narrows or disappears

Question 17

Paradoxical split

Answer 17

A2 follows P2

. Occurs w/ left bundle branch block or severe aortic stenosis

Question 18

Extra systolic heart sounds

Answer 18

. Usually heard as clicks
. Ejection click: early is systole shortly after S1, indicate pulmonic stenosis or dilation or aorta or pulmonary a.
. Click in mid-late systole due to bulging of prolapsed mitral or tricuspids into corresponding atrium

Question 19

Extra diastolic heart sounds

Answer 19

. Opening snap: after S2 w/ mitral or tricuspid stenosis
. S3: during rapid filling phase, sound from excessive oscillation of blood back and forth btw ventricular walls as blood rushes in from atria hitting leaflets, mark of CHF or mitral/tricuspid regurgitation
. S4: late diastole, sound from atrial contraction into stiff ventricle from hypertrophy or ischemia

Question 20

Most murmurs are due to ____

Answer 20

Valvular lesions

. Can be caused by septal defects or patent ductus arteriosis

Question 21

Systolic murmurs

Answer 21

. Aortic/pulmonic stenosis
. Mitral/tricuspid insufficiency
. Interventricular septal defects

Question 22

Aortic or pulmonic valve stenosis

Answer 22

. Narrowing of valve leading to turbulent flow
. Blood flow in normal directions hrough small opening
. Intensity varies w/ rate of blood flow
. Exhibits crescendo-decresendo intensity
. Pressure gradient across stenosis valve

Question 23

Mitral/tricuspid insufficiency

Answer 23

. Regurgitation of blood through incompetent valves leading to turbulent flow
. Valves won’t completely close so blood is forced back into atrium from high pressure in ventricle

Question 24

Interventricular septal defects

Answer 24

. Patent (unsealed) openings btw ventricles
. Less common
. Blood flows from LV to RV through opening due to high LV pressure

Question 25

Diastolic murmurs

Answer 25

. Mitral stenosis: narrowing of AV valve on left side causes turbulent flow
. Aortic insufficiency: regurgitation go blood through incompletely closed aortic valve causing turbulent flow

Question 26

Continuous murmurs

Answer 26

. Occurs throughout all of systole and diastole
. Most common cause is patent ductus arteriosus
. Blood flow occurs from aorta to pulmonary a. Throughout cardiac cycle since aortic pressure is always higher than pulmonary a.

Question 27

To and fro murmurs

Answer 27

. Occurs during parts of systole and diastole

. An outflow valve is both stenosis and insufficient

Question 28

Murmur grading scale

Answer 28

1: barely audible only w/ stethoscope w/ cardiologist
2: faint but immediately audible w/ stethoscope
3: moderately loud w/ no thrill
4: loud w/ thrill
5: thrill and loud enough to be heard w/ slight touch of stethoscope’s rim on chest
6: thrill and so loud can be heard w/o stethoscope