56 year-old morbidly obese female with no PMH presented to the hospital with acute onset of SOB, DOE, orthopnea, and lower extremity swelling with progressive worsening in the past 2 weeks. She denied fevers, chills, chest pain or recent travel. On vital signs, patient was hypertensive with an O2 sat of 94% on 2 Liters nasal cannula. Physical examination revealed elevated JVP, bibasilar crackles, and audible heart sounds without murmur. Lab work revealed normal troponins, BNP of 13 and mild transaminitis. Chest xray showed bilateral pleural effusions and pulmonary edema. An EKG showed low voltage. Patient was admitted for new onset CHF and Lasix was initiated for diuresis. A bedside ultrasound was performed which showed right heart strain and a large pericardial effusion with tamponade physiology. Patient was initiated on fluids and an urgent pericardiocentesis was performed with removal of 900cc of bloody fluid with resultant symptomatic relief. Patient was subsequently diagnosed with adenocarcinoma of the lung and is currently undergoing chemotherapy treatment.
Discussion:
Cardiac tamponades has an incidence of 2 cases per 10,000 in the US. It generally progresses rapidly and is fatal if left untreated. There are four types of cardiac tamponade: acute, subacute, low pressure and regional. Subacute occurs gradually which is demonstrated by this patient’s presentation. This patient was confounding in her presentation as her symptoms were more consistent with CHF than cardiac tamponade. She did not have the typical Beck’s triad of cardiac tamponade which includes hypotension, dilated neck veins, and muffled heart sounds; nor did her EKG reveal electrical alternans. Her low BNP was a red herring. Because obese patients with HF are known to have a lower BNP than those with normal BMI, this finding did not sway the clinician to consider a diagnosis other than HF. According to the Breathing Not Properly study, which observed the correlation between BNP, HF and BMI, a lower cut off (BNP > 54 pg/ml) should be used for morbidly obese patients in diagnosing HF. Since this patient’s BNP was well under this cut off, recognition of this knowledge could have led to the correct diagnosis earlier.
Conclusions:
Patients who present with cardiac tamponade may not have the typical findings of Beck’s triad. Instead, as in this case, they may present with symptoms suggestive of heart failure. As Hospitalists, it is important to recognize the atypical presentations of this life- threatening condition and understand the use of biomarkers such as BNP in relation to BMI in order to arrive at the correct diagnosis. A delay in distinguishing these two conditions can lead to fatal consequences.