This book contains five chapters, each focusing on an aspect of understanding and treating acute pulmonary embolism. Chapter One is an overview of the state of the science regarding the treatment of acute pulmonary embolism, and provides modern insights into recent developments. The second chapter reviews a novel technology for the detection and diagnosis of pulmonary embolism which may provide benefits over currently used technologies. The third chapter is a wide ranging review of the state of clinical practice in diagnosing pulmonary embolism prior to the COVID-19 pandemic in Southern Spain. Chapter Four provides a systematic review of the use of ultrasound-assisted catheter-directed thrombolysis in treating acute pulmonary embolism. The final chapter discusses the issue of subsegmental pulmonary embolism, and whether it should be treated directly.