2. Signs of constriction: In the patient with constrictivepericarditis, early diastolic filling of the ventricle occursnormally, but the filling is suddenly stopped by the nonelasticthickened pericardium. This cessation of fillingcan be observed on the pressure-time curve of the ventricleand is probably responsible for the diastolic knock( Figure 10–29 ). In addition, the rapid emptying of theatrium leads to a prominent y descent that makes thev wave more noticeable on the atrial pressure tracing( Figure 10–30 ). Systemic venous pressure is elevated,because flow entering the heart is limited. Usually withinspiration, the decrease in intrathoracic pressure is transmittedto the heart, and filling of the right side of the heartincreases with an accompanying fall in systemic venouspressure. In patients with constrictive pericarditis, this
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