Cardiac Cycle

Question 1

Ventricular isovolumic systole corresponds to which wave on a normal jugular venous pulse tracing?

Answer 1

“c” wave — increase in right atrial pressure during right ventricular isovolumic systole (contraction); due to bulging of the tricuspid valve into the right atrium.

Question 2

Describe the “y” descent on JVP (jugular venous pulse) tracing in patients with tricuspid stenosis.

Answer 2

“y” descent — decrease in right atrial pressure following the peak of the “v” wave; due to tricuspid valve opening.
Absent “y” descent — cardiac tamponade
Slow “y” descent — tricuspid stenosis
Rapid (prominent) “y” descent occurs in:
1. Constrictive pericarditis
2. Severe right heart failure
3. Tricuspid regurgitation

Question 3

What is the longest part of the cardiac cycle?

Answer 3

Reduced ventricular filling (diastasis) is the longest part of the cardiac cycle, and precedes atrial systole.

Question 4

Describe the “y” descent on JVP (jugular venous pulse) tracing in patients with tricuspid regurgitation.

Answer 4

“y” descent — decrease in right atrial pressure following the peak of the “v” wave; due to tricuspid valve opening.
Absent “y” descent — cardiac tamponade
Slow “y” descent — tricuspid stenosis
Rapid (prominent) “y” descent occurs in:
1. Constrictive pericarditis
2. Severe right heart failure
3. Tricuspid regurgitation

Question 5

Describe the “y” descent on JVP (jugular venous pulse) tracing. What causes it?

Answer 5

“y” descent — decrease in right atrial pressure following the peak of the “v” wave; due to tricuspid valve opening.

Question 6

Describe the “y” descent on JVP (jugular venous pulse) tracing in patients with cardiac tamponade.

Answer 6

Absent “y” descent — cardiac tamponade

Question 7

What marks the beginning of the rapid ventricular ejection phase of the cardiac cycle?

Answer 7

Rapid ventricular ejection is the period of ventricular contraction after the aortic and pulmonic valves have opened, when the ventricles are ejecting blood into the pulmonic and systemic circulations.

Question 8

Describe the “x” descent on JVP (jugular venous pulse) tracing in patients with tricuspid regurgitation.

Answer 8

Absent “x” descent — tricuspid regurgitation

Question 9

In addition to an absent “x” descent and a prominent (rapid) “y” descent, tricuspid regurgitation may result in which other characteristic finding on jugular venous pulse tracing?

Answer 9

“v” wave — increase in right atrial pressure during late ventricular systole due to right atrial filling against a closed tricuspid valve. Peak of “v” wave usually corresponds with (or occurs just after) the T wave on EKG.
Large (giant) “v” (or “cv”) waves can occur due to tricuspid regurgitation

Question 10

Late ventricular systole corresponds to which wave on a normal jugular venous pulse tracing?

Answer 10

“v” wave — increase in right atrial pressure during late ventricular systole due to right atrial filling against a closed tricuspid valve. Peak of “v” wave usually corresponds with (or occurs just after) the T wave on EKG.

Question 11

Describe the “x” descent on JVP (jugular venous pulse) tracing. What causes it?

Answer 11

“x” descent — decrease in right atrial pressure following the peak of the “c” wave; due to atrial relaxation as well as the downward displacement of the tricuspid valve during ventricular systole

Question 12

What causes the first heart sound?

Answer 12

The first heart sound (S1) is the sound of the atrioventricular valves closing, and occurs at the beginning of isovolumetric ventricular contraction. Normally, the mitral valve closes before the tricuspid, which is why the second heart sound may be split.

Question 13

In addition to a slow “y” descent, tricuspid stenosis may result in which other characteristic finding on jugular venous pulse tracing?

Answer 13

Large (giant) “a” waves indicate the right atrium is contracting against increased resistance to right ventricular filling. Giant “a” waves may be seen with:

1. Tricuspid stenosis
2. Right ventricular hypertrophy
3. Pulmonic stenosis
4. Pulmonary hypertension
5. Right atrial myxoma

Question 14

What causes the fourth heart sound?

Answer 14

The fourth heart sound (S4) is a low frequency diastolic sound that occurs during the late diastolic filling phase (the atrial kick). Decreased ventricular compliance or increased diastolic volume generates this low frequency vibration.

Question 15

What causes the fourth heart sound?

Answer 15

The fourth heart sound (S4) is a low frequency diastolic sound that occurs during the late diastolic filling phase (the atrial kick). Decreased ventricular compliance or increased diastolic volume generates this low frequency vibration.

Question 16

A 39-year-old patient presents to the ER with lower extremity edema and increased dyspnea on exertion. On exam, a “S3” heart sound is auscultated. This finding is:

AIndicative of a hypertrophic ventricle 
BFound in aortic stenosis 
CFound at the beginning of systole 
DIndicative of increased filling pressure 
EFound in congenital heart disease

Answer 16

A S3 heart sound occurs at the beginning of diastole after S2 and is lower in pitch than S1 and S2. It is not of valvular origin and is also not consistent with congenital heart disease. It is most likely due to increased filling pressures from a failing and dilated left ventricle, such as in CHF. An S4 heart sound is sometimes heard in a stiff/hypertrophic ventricle. Patients with aortic stenosis may have a systolic “crescendo-decrescendo” ejection murmur that is heard loudest at the 2nd intercostal space on the right. Patient with hypertrophic cardiomyopathy also present with a systolic “crescendo-decrescendo” ejection murmur that is loudest at the 2nd intercostal space on the right. However, as opposed to the murmur in aortic stenosis which increases with increased blood volume in the left ventricle, the HOCM murmur increases with decreased blood volume in the left ventricle. Therefore the HOCM murmur will increase with the valsalva maneuver and decrease on squatting. The opposite is true for the aortic stenosis murmur. Patients with congential heart disease may present with various types of murmurs depending on their particular disease.

The third heart sound (S3) is the sound of rapid blood flowing into the ventricles.

Question 17

Atrial systole corresponds to which wave on a normal jugular venous pulse tracing?

Answer 17

“a” wave — increase in right atrial pressure during atrial contraction (i.e., atrial systole)

Question 18

What causes the second heart sound?

Answer 18

The second heart sound (S2) is the sound of the aortic and pulmonic valves closing. Normally, the aortic valve closes before the pulmonic.

Question 19

Regarding the cardiac cycle, which of the following statements is false?

AThe dicrotic notch represents opening of aortic valve
BIsovolumic relaxation occurs in diastole
CThe “a wave” represents atrial contraction
DIsovolumic contraction occurs in systole
EThe “v wave” represents increased atrial pressure

Answer 19

The dicrotic notch is the notch in the aortic pressure curve caused by closure of the aortic valve. The sudden closure of the aortic valve causes a momentary elevation in blood pressure. Also, this point represents the end of systole and the beginning of diastole. When compared to an EKG tracing, the dicrotic notch occurs during the midpoint of the T wave. All of the other statements are true.
Dicrotic notch – notch in aortic pressure curve caused by closure of aortic valve

Question 20

When is the reduced ventricular ejection phase of the cardiac cycle?

Answer 20

Reduced ventricular ejection follows rapid ventricular ejection. The slowing of ventricular ejection is a result of the decreasing volume of the ventricle, according to the length-tension relationship described by the Frank-Starling Equation.

Question 21

What marks the beginning of the rapid ventricular filling phase of the cardiac cycle?

Answer 21

Rapid ventricular filling begins when the atrial pressure equals the ventricular pressure, at which point the mitral and triscuspid valves will open and the ventricles will begin to fill.

Question 22

What is isovolumetric ventricular contraction in the cardiac cycle?

Answer 22

Isovolumetric ventricular contraction is the period when the ventricles are contracting, but before the aortic and pulmonic valves have opened.

Question 23

Atrial fibrillation may result in which characteristic finding on jugular venous pulse tracing?

Answer 23

Absent “a” wave — characteristic of atrial fibrillation due to a lack of coordinated atrial contraction

Question 24

What marks the beginning of the isovolumetric ventricular relaxation phase of the cardiac cycle?

Answer 24

Isovolumetric ventricular relaxation begins with repolarization of the ventricles, at which point the aortic and pulmonic valves close.

Question 25

Cannon “a” waves on JVP (jugular venous pulse) tracing most commonly occur in patients with…? What are cannon “a” waves caused by?

Answer 25

Cannon “a” waves (i.e., large “a” waves with a sharp ascent and descent) are caused by the right atrium contracting against a closed tricuspid valve, which most commonly occurs during junctional arrhythmias (e.g., 3rd degree (complete) heart block)

Question 26

What is atrial systole?

Answer 26

Atrial systole is the activation of the atria, pumping atrial blood into the ventricles.

Question 27

Describe the “x” descent and “y” descent on JVP (jugular venous pulse) tracing in patients with cardiac tamponade.

Answer 27

Rapid (prominent) “x” descent occurs in:

1. Constrictive pericarditis (also has a prominent “y” descent)
2. Cardiac tamponade (absent “y” descent)