Heart Sounds Research Lab
Pericardial Knock (PK)
The Heart Sounds and Murmurs Laboratory | 6560 Fannin St, Suite 1836| Houston, Texas 77030 | 832-355-2937
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A pericardial knock is best heard along the lower left sternal border. When S1 and S2 are reduced in intensity, the loud
pericardial knock may be misconstrued as a first heart sound and result in erroneous timing of cardiac events.
The jugular venous column in constrictive pericarditis is often unique and of diagnostic value. When the heart is
constricted venous pressure is markedly elevated, and the height of both the V-wave and A-wave may be strikingly
above normal. After the tricuspid valve opens, early diastolic filling proceeds unimpaired and is accompanied by a
rapid, flicking VY collapse of the venous pulse. However, filling is quickly impeded by the constricting pericardium and
the jugular venous pressure rapidly rebounds upward. The striking observation then in the venous pulse is the
sudden downward VY collapse and sudden rebound of the pulse. This corresponds with a simultaneous pericardial
knock (PK) audible over the precordium.