Preface

An embolism is defined as the intravascular lodging of an *embolus* or a *vascular blockage-causing fragment*. Emboli are a diverse group of pathological objects that travel within blood vessels, including blood clots or thromboemboli, air bubbles or *aeroembolism*, fat globules, infected particles or *septic emboli*, amniotic fluid or *amniotic emboli*, iatrogenically introduced foreign material like a catheter or wire fragments, and even bullet fragments and shrapnel. The most dreaded complication of an embolus is either partial or total blockage of blood flow distal to the site of embolization. This risk is inherent to the process of intravascular embolus migration, and can be controlled or limited only in cases where proper risk assessment based on known predisposing factors—has been completed and appropriate therapeutic steps (e.g., anticoagulation, treatment of endocarditis) implemented.

Distal embolization can lead to limb, organ, and life-threatening sequelae of end-organ dysfunction, tissue ischemia, and potential necrosis. In cases of fat or amniotic fluid embolism, associated neurological sequelae may be devastating and severe. In fact, as a marker of the severity and complexity of the clinical problem, even in the absence of obvious neurologic findings, patients who present with a source of embolism, such as an intracardiac mass, often benefit from neurological imaging since many patients may have subclinical or *silent* strokes—a key clinical finding, critical in medical decision making, treatment, and risk stratification.

Although heterogeneous in their genesis, emboli often constitute a manifestation of other, concurrent pathological processes. For example, fat emboli are associated with long-bone fractures and surgical fixation. In another typical example, venous emboli may begin in the setting of trauma, malignancy, or various other hypercoagulable states. Arterial emboli, secondary to untreated atrial fibrillation, constitute a common emergency, leading to cerebrovascular infarcts and bowel and acute limb ischemia. Less common, but not less concerning, are left ventricular clots, often resulting from apical wall-motion abnormalities related to a previous myocardial infarction, which may present in a similar fashion.

Septic emboli originate from a variety of infectious foci, including endocarditis, prosthetic implants, soft tissue infections, and abscesses. If not recognized promptly, affected patients can suffer devastating systemic and neurological sequelae. Air emboli are most often iatrogenically induced. Due to their rarity, providers who are more likely to encounter air emboli in their practices must remain vigilant whenever in a situation prone to these uncommon phenomena. Foreign body emboli, whether iatrogenic or traumatic, constitute an acquired group of conditions. A phenomenon that is becoming better understood is the concept of a *paradoxical* embolism in which a venous source, such as a deep vein thrombosis, migrates across an intracardiac shunt or arteriovenous malformation and enters into the systemic, arterial, circulation. As such, whenever cases of paradoxical embolism are encountered, a search for venous-to-arterial shunting should be pursued and factored into the next steps. Finally, amniotic fluid embolism—one of the most devastating and poorly understood embolic phenomena—continues to be

associated with prohibitively high morbidity and mortality. Consequences of such occurrences can be truly catastrophic, with both short-term and long-term impacts on the patient and her family.

Many of the salient points emphasized throughout this book reflect the ongoing challenges and frustrations experienced by frontline clinicians. When embolic complications emerge, management is focused on treating the complication. The editors would like to emphasize how critical it is to identify and address the causative factors. Once a source of the embolus (or emboli) is identified, options for treatment are caged in discussions regarding the risks and benefits of various therapeutic options. When potential sources of embolisms are identified in the course of imaging for other reasons, discussions regarding clinical management are much more complicated—the decision to intervene, often with potentially high-risk treatments, on an asymptomatic patient cannot be taken lightly in the setting of the significant, and often life-long, implications of therapy in the context of the unknown risks for watchful waiting and hoping that a devastating embolic complication does not evolve or recur.

While our knowledge and scientific data on some causative pathologies is well established, many cases are nuanced and complicated not only by clinical manifestations of embolism but also by the inability to safely obtain a "tissue diagnosis" or ascertain greater diagnostic certainty. Consequently, in most instances both evaluation and treatment must be highly individualized. It is crucial to understand that therapies for *very similar problems can often be very different based upon patient risk factors and comorbidities*. For example, the management of a pulmonary embolism from a deep vein thrombosis after an orthopedic procedure is substantially different than a similar embolism in a patient with a known or newly diagnosed hypercoagulable state—such as lupus or an antiphospholipid antibody syndrome. A treatment plan for a young patient with a fat embolism following orthopedic surgery without any neurologic sequelae will be very different than the management of a young woman with an amniotic embolism who suffered from massive bilateral hemispheric strokes. Both patients will require highly individualized approaches, although their care will likely involve longer-than-expected hospital stays with a requirement for intensive care unit admission.

The primary goal of this book is to provide an overview of the most common types of embolic phenomena encountered in clinical practice, including certain key diagnostic and therapeutic considerations. Among the topics featured in the current collection are highly pertinent, up-to-date contributions in the areas of pulmonary embolism, fat embolism, embolic complications of non-malignant cardiac tumors, acute arterial embolism in the lower extremity, thrombophilia in pregnancy, bullet and shrapnel embolization, coronary artery embolization, as well as a comprehensive review of certain interventions utilized in the management of thromboembolic disorders.

When measured in terms of both human and financial costs, broadly defined *embolic phenomena* have a tremendous impact on individual patients, healthcare systems, and society around the globe. The introductory chapter provides a powerful overview of both economic and non-economic impacts of various types of embolism. Through our collaborative academic effort, of both the editorial team and the individual chapter authors, we hope to provide the reader with a valuable resource and a meaningful new insight into the gravity of the collective problem. Among other salient takeaway points is the ongoing dilemma of diagnostic relativity

**V**

and frequent uncertainty when managing embolic complications. Consequently, much more progress is required before any sort of "clinical victory" is declared in

> **Stanislaw P. Stawicki, MD, MBA, FAIM** St. Luke's University Health Network, Bethlehem, Pennsylvania, USA

**Michael S. Firstenberg, MD, FACC, FAIM**

**Mamta Swaroop, MD, FACS, FICS, FAIM**

The Medical Center of Aurora,

Aurora, Colorado, USA

Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA

this important area of medicine and surgery.

and frequent uncertainty when managing embolic complications. Consequently, much more progress is required before any sort of "clinical victory" is declared in this important area of medicine and surgery.

> **Stanislaw P. Stawicki, MD, MBA, FAIM** St. Luke's University Health Network, Bethlehem, Pennsylvania, USA

**Michael S. Firstenberg, MD, FACC, FAIM** The Medical Center of Aurora, Aurora, Colorado, USA

**Mamta Swaroop, MD, FACS, FICS, FAIM**

Northwestern University, Feinberg School of Medicine, Chicago, Illinois, USA

**IV**

disorders.

associated with prohibitively high morbidity and mortality. Consequences of such occurrences can be truly catastrophic, with both short-term and long-term impacts

Many of the salient points emphasized throughout this book reflect the ongoing challenges and frustrations experienced by frontline clinicians. When embolic complications emerge, management is focused on treating the complication. The editors would like to emphasize how critical it is to identify and address the causative factors. Once a source of the embolus (or emboli) is identified, options for treatment are caged in discussions regarding the risks and benefits of various therapeutic options. When potential sources of embolisms are identified in the course of imaging for other reasons, discussions regarding clinical management are much more complicated—the decision to intervene, often with potentially high-risk treatments, on an asymptomatic patient cannot be taken lightly in the setting of the significant, and often life-long, implications of therapy in the context of the unknown risks for watchful waiting and hoping that a devastating embolic complication does not

While our knowledge and scientific data on some causative pathologies is well established, many cases are nuanced and complicated not only by clinical manifestations of embolism but also by the inability to safely obtain a "tissue diagnosis" or ascertain greater diagnostic certainty. Consequently, in most instances both evaluation and treatment must be highly individualized. It is crucial to understand that therapies for *very similar problems can often be very different based upon patient risk factors and comorbidities*. For example, the management of a pulmonary embolism from a deep vein thrombosis after an orthopedic procedure is substantially different than a similar embolism in a patient with a known or newly diagnosed hypercoagulable state—such as lupus or an antiphospholipid antibody syndrome. A treatment plan for a young patient with a fat embolism following orthopedic surgery without any neurologic sequelae will be very different than the management of a young woman with an amniotic embolism who suffered from massive bilateral hemispheric strokes. Both patients will require highly individualized approaches, although their care will likely involve longer-than-expected hospital stays with a

The primary goal of this book is to provide an overview of the most common types of embolic phenomena encountered in clinical practice, including certain key diagnostic and therapeutic considerations. Among the topics featured in the current collection are highly pertinent, up-to-date contributions in the areas of pulmonary embolism, fat embolism, embolic complications of non-malignant cardiac tumors, acute arterial embolism in the lower extremity, thrombophilia in pregnancy, bullet and shrapnel embolization, coronary artery embolization, as well as a comprehensive review of certain interventions utilized in the management of thromboembolic

When measured in terms of both human and financial costs, broadly defined *embolic phenomena* have a tremendous impact on individual patients, healthcare systems, and society around the globe. The introductory chapter provides a powerful overview of both economic and non-economic impacts of various types of embolism. Through our collaborative academic effort, of both the editorial team and the individual chapter authors, we hope to provide the reader with a valuable resource and a meaningful new insight into the gravity of the collective problem. Among other salient takeaway points is the ongoing dilemma of diagnostic relativity

requirement for intensive care unit admission.

on the patient and her family.

evolve or recur.

**1**

**Chapter 1**

Phenomena

**1. Introduction**

Introductory Chapter: Defining

*Samantha Wolfe, Stanislaw P. Stawicki, Mamta Swaroop,* 

*Jennifer C.B. Irick and Michael S. Firstenberg*

the management of thromboembolic disorders.

gravity of the collective problem.

**2. Embolism types: a synopsis**

ity, and the pre−/posttest probabilities.

the True Global Impact of Embolic

In the realm of medical practice, the word "embolism" has many implications to many people [1, 2], with most providers instinctively placing this word within a negative context [3–5]. Derived from the Greek word, ἐμβολισμός, this term most literally means "interposition" [6]. Yet regardless of how benign the etymology may be, the clinical context is quite the opposite—synonymous with much dreaded morbidity and mortality [1, 2, 7–10]. Whether the embolus consists of a blood clot [8], a fat globule [11], a bubble of gas [12], amniotic fluid [9, 10], or even an iatrogenic or traumatic foreign body [13, 14], the unfavorable connotations persist even if the patient has few or no associated symptoms and requires no intervention. The primary goal of this book is to provide the reader with an overview of the most common types of embolic phenomena encountered in clinical practice, including some of the key related diagnostic and therapeutic areas. The current collection of chapters includes important contributions in the areas of pulmonary embolism (PE), fat embolism (FE), embolic complications of nonmalignant cardiac tumors, acute arterial embolism (AAE) of the lower extremity, thrombophilia in pregnancy, bullet and shrapnel embolization (BSE), and coronary artery embolization (CAE), as well as a comprehensive chapter on venous interventions utilized in

Perhaps the best way to paint the picture of the tremendous impact of "embolism" globally is to present the human costs and the resources required to treat various types, manifestations, and complications of embolic diseases. Although challenging to gather, such information was compiled by our team for the purposes of this introductory chapter and summarized in **Table 1** [12, 14–37]. Although far from comprehensive, we hope to provide the reader with valuable insight into the

No discussion of "embolism" can be complete without the discussion of risk factors, diagnostics including laboratory and imaging tests, and therapeutic

considerations. Here, one must emphasize the importance of looking at the "totality of evidence," considering things like clinical suspicion, presence/absence of specific risk factors, positive/negative predictive values, diagnostic test sensitivity/specific-

### **Chapter 1**
