Abnormal Jugular Contours The Giant A Wave

1. How high is abnormally high for an A wave?

ANS: Over 4.5 cm above the sternal angle with the chest at 45°.

2. What is an A wave called if it is higher than normal due to too strong an atrial contraction?

ANS: A giant A wave.

Note: a. A stronger-than-normal right atrial contraction may not produce a giant A wave but only a jugular "flicker" in the right supraclavicular area.

b. A loud "knocking" sound accentuated by inspiration may be heard in the neck in the presence of a giant A wave.

3. What can cause an exaggerated atrial contraction?

ANS: a. Obstruction at the tricuspid valve due to either tricuspid stenosis or right atrial tumor, such as a right atrial myxoma. b. A noncompliant or stiff RV due to either pulmonary outflow obstruction, as with pulmonary stenosis, or pulmonary hypertension.

Note: The right atrium contracts strongly when the tricuspid valve is obstructed because the atrium is stretched by the increased residual volume produced by its inability to empty adequately through the obstructed orifice.

4. Why does an RV systolic pressure overload as in pulmonary stenosis or pulmonary hypertension cause a stronger than normal atrial contraction?

ANS: When the RV has a pressure load to overcome, it becomes thicker and less compliant than normal. Because in diastole the atrium and ventricle are in continuity, the pressure in this atrioventricle rises very rapidly as it fills with blood. The stretch of the atrium produces a Starling effect and a powerful atrial contraction which, in turn, stretches the ventricle before it contracts. The Starling effect on the ventricle strengthens its contraction.

Pulmonary Artery Wave Tracing

Tricuspid stenosis—This jugular pulse tracing from a patient with tricuspid stenosis shows a very slow Y descent due to difficulty in emptying the right atrium in diastole. The X' descent (descent of the base) is also slow, probably because of a poor right ventricular contraction caused by an underfilled right ventricle. Clinically, you could see that this patient had a giant A wave because the top level of the jugular pulsation was high. It was 6 cm from the sternal angle with the chest at 45° elevation (upper normal is 4.5 cm).

Tricuspid stenosis—This jugular pulse tracing from a patient with tricuspid stenosis shows a very slow Y descent due to difficulty in emptying the right atrium in diastole. The X' descent (descent of the base) is also slow, probably because of a poor right ventricular contraction caused by an underfilled right ventricle. Clinically, you could see that this patient had a giant A wave because the top level of the jugular pulsation was high. It was 6 cm from the sternal angle with the chest at 45° elevation (upper normal is 4.5 cm).

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