In the latest Case Record of the Massachusetts General Hospital, a 60-year-old woman was seen in the emergency department after a syncopal episode. Oxygen saturation was 71% while she was breathing ambient air. A focused cardiac ultrasound revealed right-sided heart strain and McConnell’s sign. Additional diagnostic procedures were performed.
A FOCUS examination, also referred to as clinician-performed ultrasonography or point-of-care ultrasonography, provides time-sensitive information that may narrow the differential diagnosis, inform resuscitation strategies, and guide treatment of patients with cardiovascular disease. The purpose of a FOCUS examination is to look for any evidence of pericardial effusion, assess global cardiac function and relative chamber size, and guide emergency procedures. A FOCUS examination is intended to serve as a complement to comprehensive echocardiography and is now considered an essential part of training in emergency medicine.
• What is “clot in transit”?
Clot in transit is a dangerous manifestation of pulmonary embolism that is seen in approximately 4% of cases, although this may be an underestimate. The mortality associated with pulmonary embolism with clot in transit is high (27 to 45%), with nearly all deaths occurring in the first 24 hours, so rapid and aggressive treatment is essential. With clot in transit, anticoagulation alone is unlikely to be sufficient because it is associated with a higher mortality (38%) than thrombolysis or surgery.
• What is the role of systemic thrombolysis versus catheter-directed thrombolysis in massive pulmonary embolism?
In cases of massive, hemodynamically unstable pulmonary embolism and in the presence of clot in transit, systemic thrombolysis is associated with improved survival, as compared with anticoagulation alone. Thrombolytic therapy can be delivered locally through a catheter inserted into a pulmonary artery. The main advantage of a catheter-directed approach is that a low dose of the thrombolytic agent is typically used in someone with a higher risk of bleeding. However, in a patient with suspected clot in transit, passing a catheter through the right atrium is risky and could disrupt the clot.
Morning Report Questions
Q: What is the role of aspiration versus surgical thrombectomy in the treatment of pulmonary embolism?
A: Aspiration thrombectomy is a relatively new technique that allows clinicians to remove a large volume of thrombus from the right side of the heart or the proximal pulmonary artery. This procedure requires a venotomy and a perfusion team, but it is less invasive than an open surgical thrombectomy. Although there is a paucity of data describing its use in patients with a pulmonary embolism and clot in transit, the procedure is typically well tolerated. A major risk of this approach is that aspiration can fragment a fragile clot and lead to further embolization. In a patient with a patent foramen ovale, a fragmented clot could release emboli into the systemic circulation. Open surgical thrombectomy allows for rapid removal of clots from both the pulmonary arteries and the right side of the heart. The procedure requires a median sternotomy and cardiopulmonary bypass, but improvements in technique and patient selection have greatly increased survival over the past two decades.
Q: What is the duration of anticoagulation and evaluation recommended in a patient with an unprovoked pulmonary embolus?
A: Current guidelines suggest lifelong treatment in patients who have had unprovoked thrombosis. Routine screening according to the patient’s age, symptoms, and sex is usually advocated, but a more extensive evaluation is generally not warranted. For patients who have had an unprovoked event and who are reluctant to take anticoagulants on a lifelong basis, the risk of recurrence can be predicted by measuring the D-dimer level while the anticoagulant is withheld. Deep venous thrombosis and pulmonary embolism tend to recur in the same form as the initial clinical manifestation; which should also be considered before discontinuing anticoagulation.