(236) Echocardiogram Versus Swan-Ganz Catheter for Evaluation of Cardiac Tamponade

Introduction: Cardiac tamponade is classically diagnosed by Beck’s Triad and “pulsus paradoxus,” but sensitivity and specificity are poor. Diagnostic modalities include echocardiogram, pulmonary artery catheterization (PAC), and pericardiocentesis. We present a case of shock evaluated with echocardiogram, PAC and ultimately pericardiocentesis confirming cardiac tamponade. This case cautions against overreliance on ultrasound for diagnosis of tamponade.

Description: A 51yo female with a history notable for pulmonary hypertension, obesity hypoventilation and emphysematous pyelonephritis presented with dyspnea. She was placed on bilevel ventilation for hypercapnic respiratory failure, treated for suspected urinary tract infection and transferred to our hospital. She ultimately required intubation for worsening mental status then became hypotensive requiring norepinephrine infusion. CT chest demonstrated a large pericardial effusion. On echo, there was no right atrial or ventricular diastolic collapse and no significant respirophasic variation in peak mitral inflow velocity. Hypotension worsened and vasopressin was added. A repeat echo the following day again showed no evidence of tamponade. Measurements from PAC were: Central Venous Pressure (CVP) 14 mmHg, PAP 38/17 (25 MPAP) mmHg, and PCWP 13 mmHg, Cardiac Index 1.81 L/min/m2. Right atrial and ventricular pressures were not recorded. These values confirmed cardiac tamponade based on “diastolic equalization” in all chambers assuming CVP (14 mmHg) approximated mean RA pressure, and PAPd (17 mmHg) as a surrogate for RV pressure along with a PCWP of 13 mmHg. Pericardiocentesis performed 24 hours after the initial echocardiogram led to hypertension and vasopressors were discontinued.

Discussion: Classic clinical signs of tamponade are not reliable for diagnosis of cardiac tamponade and a negative echocardiogram may not exclude tamponade. In retrospect, echo findings may have been obscured by pulmonary hypertension, positive pressure ventilation or volume status. This led to a delay in pericardiocentesis of at least 24 hours. Clinicians need to maintain a high index of suspicion with patients with known pericardial effusions and signs of shock. Pulmonary artery catheterization may be helpful after equivocal echocardiogram.