PRESSURE CURVES IN CVS

Explanation:

Ans. C. Atrial contraction

[REF: Harrison’s Internal Medicine 17^th edition Chapter 220 Physical Examination of the Cardiovascular System, http://en.wikipedia.org/wiki/Jugular_ venous_pressure]

JVP WAVEFORM:

Classically three upward deflections and two downward deflections have been described.

1. The ” a ” wave corresponds to right Atrial contraction and ends synchronously with the carotid artery pulse. The peak of the ‘a’ wave demarcates the end of atrial systole.

2. The ” c ” wave corresponds to right ventricular Contraction causing the triCuspid valve to bulge towards the right atrium.

3. The ” x ” descent follows the ‘a’ wave and corresponds to atrial relaXation and rapid atrial filling due to low pressure.

4. The ” x’ ” (x prime) descent follows the ‘c’ wave and occurs as a result of the right ventricle pulling the tricuspid valve downward during ventricular systole. The x’ (x prime) descent can be used as a measure of right ventricle contractility.

5. The ” v ” wave corresponds to Venous filling when the tricuspid valve is closed and venous pressure increases from venous return – this occurs during and following the carotid pulse.

6. The ” y ” descent corresponds to the rapid emptYing of the atrium into the ventricle following the opening of the tricuspid valve.

ABNORMAL JVP:

1. Raised JVP, normal waveform

• Bradycardia

• Fluid overload

• Heart Failure 

2. Raised JVP, absent pulsation

• Superior vena cava syndrome

3. Large ‘a’ wave (increased atrial contraction pressure)

•  Tricuspid stenosis

•  Right heart failure

• Pulmonary hypertension

4. Cannon ‘a’ wave (atria contracting against closed tricuspid valve)

• Atrial flutter

• Premature atrial rhythm (or tachycardia)

• Third degree heart block

• Ventricular ectopics

• Ventricular tachycardia

5. Absent ‘a’ wave (no unifocal atrial depolarisation)

• Atrial fibrillation

6. Large wave (c-v wave)

• Tricuspid regurgitation

7. Slow ‘y’ descent

• Tricuspid stenosis

8. Parodoxical JVP (Kussmaul’s sign: JVP rises with inspiration, drops with expiration)

• Pericardial effusion

• Constrictive pericarditis 

• Pericardial tamponade

Explanation:

Answer is B (Bulging of Tricuspid valve)

The ‘c’ wave in JVP is a positive wave produced by the bulging of the tricuspid valve into the right atrium during right ventricular isovolumetric systole and by the impact of the carotid artery adjacent to the jugular vein.

Explanation:

Ans. B: Atrial contraction

Waves

* a – presystolic; produced by right atrial contraction

* c – bulging of tricuspid valve into the right atrium during ventricular systole (isovolumic phase)

* v – occurs in late ventricular systole; increased blood in right atrium from venous return

Descents

*  x – combination of atrial relaxation, downward movement of the tricuspid valve and ventricular systole

* y – tricuspid valve opens and blood flows in to the right ventricle 

Abnormal waveform causes

Dominant a wave

* Pulmonary stenosis

* Pulmonary hypertension

* Tricuspid stenosis

Cannon a wave

* Complete heart block

* Paroxysmal nodal tachycardia

Ventricular tachycardia

* Dominant v wave

* Tricuspid regurgitation

 * Absent x descent

* Atrial fibrillation

* Exaggerated x descent

* Cardiac tamponade

* Constrictive pericarditis

* Sharp y descent

* Constrictive pericarditis

* Tricuspid regurgitation

* Slow y descent

* Right atrial myxoma

Explanation:

Ans. is A

The first elevation (a wave) corresponds to the slight rise in atrial pressure resulting from atrial contraction.

The first descent (x descent) reflects a fall in atrial pressure that starts with atrial relaxation.

The second elevation (v wave) corresponds to ventricular systole when blood is entering the right atrium from the vena cavae while the tricuspid valve is closed.

Finally, the second descent (y descent) reflects falling right atrial pressure as the tricuspid valve opens and blood drains from the atrium into the ventricle.

Explanation:

Ans. is ‘c’ i.e.. Closure of aortic valve

Aortic pressure curve

• With the onset of the rapid ejection phase of the ventricular systole, the aortic pressure rises steeply to reach a maximum of about 120 mm Hg. The ejection of blood into the aorta causes a stretch on the aortic walls and makes the blood in the entire arterial system to move at a faster rate. This sets up a pressure wave that travels along the arteries. The pressure wave expands the arterial wall as it travels, and expansion is palpable as the pulse. In the later part of the ventricular systole, the aortic pressure declines and continues to decline through­out the diastole, to reach a minimum of about 80 mm Hg during the isometric contraction of the next cardiac cycle. The elastic recoil of the aorta and the resistance of arterioles help to maintain relatively high aortic pressure during diastole.
• A notch (incisura or dicrotic notch) is recorded in the early part of the downstroke of the aortic pressure curve. It corresponds to the closure of the aortic valve. It is produced by the sudden backward flow of aortic blood followed by the immediate cessation of backflow due to closure of the aortic valves.