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Background Mechanical heart valves require long-term anticoagulation strategies to prevent valve thrombosis. Pregnant women with mechanical heart valves are especially susceptible to valve thrombosis given their procoagulant state and complexity of anticoagulation strategies during pregnancy. We describe a case of prosthetic valve thrombosis in a pregnant woman treated successfully with low dose slow infusion of thrombolytic therapy. Case Summary A 23-year-old pregnant woman with a mechanical aortic valve on subcutaneous enoxaparin presented to the maternal cardiac clinic for a follow up visit. Her physical exam was notable for a loud grade 3 crescendo decrescendo murmur and follow up transthoracic echocardiography revealed peak and mean gradients of 87 and 58 mmHg, respectively. The Doppler Velocity Index was 0.24 with an acceleration time of 130 ms. Fluoroscopy confirmed a stuck leaflet disk. Thrombolysis was performed using a low dose ultra-slow infusion of thrombolytic therapy (1 mg/hour of tissue-type plasminogen activator) with restoration of normal valve function after 8 days. A repeat transthoracic echocardiography showed a decrease in the peak and mean gradients to 37 and 21 mmHg, respectively with an improvement in the Doppler Velocity Index to 0.53. Repeat fluoroscopy confirmed opening of both leaflet disks. Discussion Treatment options for mechanical aortic valve thrombosis are either slow-infusion, low dose thrombolytic therapy or emergency surgery. The hypercoagulable state of pregnancy makes adequate anticoagulation, proper monitoring, and medication adherence even more critical to prevent valve thrombosis. Physicians should educate pregnant patients on anticoagulation strategies and participate in shared decision making.

Cardiac allograft vasculopathy (CAV) remains a common long‐term complication of cardiac transplantation. While invasive coronary angiography is considered the gold standard, it is also invasive and lacks sensitivity to detect early, distal CAV. Although vasodilator stress myocardial contrast echocardiography perfusion imaging (MCE) is used in the detection of microvascular disease in non‐transplant patients, there is little data guiding its use in transplant recipients. Herein is a case series of four heart transplant recipients that had vasodilator stress MCE performed in addition to invasive coronary angiography for CAV surveillance. MCE at rest and after regadenason was performed using a continuous infusion of lipid‐shelled microbubbles. We describe a case of normal microvascular function, diffuse microvascular dysfunction, patchy sub‐endocardial perfusion defects and a focal sub‐endocardial perfusion defect. Cardiac allograft vasculopathy can be heralded by several different perfusion patterns on MCE in patients after orthotopic heart transplant. The varying prognoses and potential interventions for these different patterns require further investigation.