A 47-year-old woman with a history of metastatic breast cancer and paroxysmal atrial fibrillation presented with four days of shortness of breath associated with orthopnea. The patient was initially normotensive with a sinus tachycardia of 115bpm, and examined with a raised JVP and muffled heart sounds. An ECG demonstrated sinus rhythm with low voltage QRS complexes and electrical alternans (Figure 1). Echocardiography confirmed a large pericardial effusion with swinging of the heart and collapse of the right atrium in end diastole, and diastolic collapse of the right ventricle (Video 1).

Figure 1:

Video 1:

In large pericardial effusion, electrical alternans results from swinging of the heart. This changes the position of the heart within the enlarged, fluid-filled pericardium and is responsible for the beat-to-beat shift in amplitude of the QRS. Although classically associated with large pericardial effusion, QRS alternans has a broad differential diagnosis that includes ischaemia, cardiomyopathy, re-entrant tachycardia, hyperkalemia, pregnancy and digoxin toxicity.1,2Ventricular interdependence also occurs as a result of impaired ventricular filling due to increased pericardial pressure; the expansion of the right ventricular free wall that normally occurs as the right ventricle fills during inspiration is impaired, and as a consequence there is displacement of the interventricular septum to the left causing reduced left ventricular filling. The reverse is seen during expiration. This can be identified on echocardiography as a >25% reduction in mitral inflow E velocity during inspiration or a >40% reduction in tricuspid inflow E velocity during expiration.3 A dilated inferior vena cava which fails to collapse with inspiration can also be seen.3 These, alongside the diastolic collapse of right heart chambers and swinging of the heart demonstrated in this case, are echocardiographic features of cardiac tamponade.3 Recognition of a large pericardial effusion via ECG or echocardiography findings described above can facilitate emergent pericardiocentesis. In this case, pericardiocentesis drained 1,125mL of blood-stained fluid containing malignant epithelial cells consistent with breast cancer. The patient subsequently commenced chemotherapy and proceeded to pericardial window formation.

A 47-year-old woman with a history of metastatic breast cancer and paroxysmal atrial fibrillation presented with four days of shortness of breath associated with orthopnea. The patient was initially normotensive with a sinus tachycardia of 115bpm, and examined with a raised JVP and muffled heart sounds. An ECG demonstrated sinus rhythm with low voltage QRS complexes and electrical alternans (Figure 1). Echocardiography confirmed a large pericardial effusion with swinging of the heart and collapse of the right atrium in end diastole, and diastolic collapse of the right ventricle (Video 1).

Figure 1:

Video 1:

In large pericardial effusion, electrical alternans results from swinging of the heart. This changes the position of the heart within the enlarged, fluid-filled pericardium and is responsible for the beat-to-beat shift in amplitude of the QRS. Although classically associated with large pericardial effusion, QRS alternans has a broad differential diagnosis that includes ischaemia, cardiomyopathy, re-entrant tachycardia, hyperkalemia, pregnancy and digoxin toxicity.1,2Ventricular interdependence also occurs as a result of impaired ventricular filling due to increased pericardial pressure; the expansion of the right ventricular free wall that normally occurs as the right ventricle fills during inspiration is impaired, and as a consequence there is displacement of the interventricular septum to the left causing reduced left ventricular filling. The reverse is seen during expiration. This can be identified on echocardiography as a >25% reduction in mitral inflow E velocity during inspiration or a >40% reduction in tricuspid inflow E velocity during expiration.3 A dilated inferior vena cava which fails to collapse with inspiration can also be seen.3 These, alongside the diastolic collapse of right heart chambers and swinging of the heart demonstrated in this case, are echocardiographic features of cardiac tamponade.3 Recognition of a large pericardial effusion via ECG or echocardiography findings described above can facilitate emergent pericardiocentesis. In this case, pericardiocentesis drained 1,125mL of blood-stained fluid containing malignant epithelial cells consistent with breast cancer. The patient subsequently commenced chemotherapy and proceeded to pericardial window formation.