Master the board step 3

Cardiology
Pericardial Tamponade
Tamponade presents with shortness of breath, hypotension, and jugular
venous distention. On CCS, also examine the lungs, because they will be clear.
Following are the unique features of tamponade:
··
Pulsus paradoxus: This is a decrease of blood pressure > 10 mm Hg on
inhalation.
··
Electrical alternans: This is alterations of the axis of the QRS complex on
EKG, manifested as the height of the QRS complex.
Basic Science Correlate
Mechanism of Pulsus Paradoxus
Inhalation increases venous return. Increased venous return expands the right
ventricle (RV). Expanded RV compresses the left ventricle (LV). Compressed
LV decreases blood pressure. Tamponade compresses the whole heart.
Inhale = Big RV = Smaller LV = BP drop > 10 mm Hg
Diagnostic Testing
Echocardiography is the most accurate diagnostic test. The earliest finding
of tamponade is diastolic collapse of the right atrium and right ventricle.
Remember that it is normal to have 50 mL or less of pericardial fluid, but there
should be no collapse of the cardiac structures.
EKG will show low voltage and electrical alternans. Electrical alternans is
variation of the height of the QRS complex from the heart moving backward
and forward in the chest.
Right heart catheterization will show “equalization” of all the pressures in
the heart during diastole. The wedge pressure will be the same as the right
atrial and pulmonary artery diastolic pressure.
Treatment
··
Best initial therapy: Pericardiocentesis
··
Most effective long-term therapy: Pericardial window placement
··
Most dangerous therapy: Diuretics
Constrictive Pericarditis
Constrictive pericarditis presents with shortness of breath and the following
signs of chronic right heart failure:
··
Edema
··
Jugular venous distention
79