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Clinical Case: Pulmonary Embolism - want to learn more about it?

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Clinical Case: Pulmonary Embolism

Some diseases, like most of the chronic ones, give the clinicans enough time for thorough diagnostic procedures. But, in some cases, doctors are presented with patients with very intense signs and symptoms, and just a moments ago those patients were completely fine. 

In these situations, you must think fast and be sure in your knowledge, because sometimes even minutes can determine if the outcome for the patient would be fatal. That is the case with pulmonary embolism, which is presented in this clinical case. You will see how this condition is presented, why its development is 'silent' and not noticable unless you look for it, and eventually, how to treat it and save someone's life.

Key Facts
Diabetes mellitus definition & causes

Diabetes mellitus - prolonged high blood glucose levels

Type I causes - unknown (most likely autoimmune)

Type II causes - obesity, lack of excercise

Methicilin-resistant Staphylococcus aureus (MRSA) Usually causes intrahospital infections hard to treat due to MRSA's resistance to most antibiotics
D-dimer & S1Q3T3 sign

D-dimer - fibrin degradation product elevated in blood during activation of coagulation system; non-specific for PE, but suggests further test to confirm the PE

S1Q3T3 - electrocardiographic finding in severe PE patinets; presented with:

- large S wave in lead I

- Q wave and inverted T wave in lead III

Surgery as the method of choice for PE Clots that obstruct pulmonary arteries block the blood flow to parts of the lung and can quickly cause stroke or death -> surgery is urgent
Doppler ultrasound exam Provides early diagnosis of clots in circulatory system for the sake of preventing the development of pulmonary embolus

After reviewing this case you should be able to describe the following:

  • Why it is likely that this patient had Type 2 diabetes.
  • What is MRSA and why it represents potential morbidity?
  • What is the significance of the elevated D-Dimer and the S1 T3 Q3 electrocardiogram pattern?
  • Why the patient was rushed into surgery when it was discovered that he had a pulmonary embolism.
  • Why in this patient a Doppler lower limb ultrasound at the time of the first admission might have reduced the likelihood of the development of a pulmonary embolus.

This article is based on a case report published in the Journal "Case Reports in Cardiology" in 2017, by Shepard F, White-Stern A, Rahaman O, Kurian D, Simon K.

Case Description

Past Medical History

An obese 25-year-old man, recently diagnosed with diabetes, presented to the emergency department with acute onset of shortness of breath for several hours. Importantly, he had been seen at the ED two weeks earlier for left foot pain and was diagnosed at the time as having an abscess on the sole of his foot. He denied foot trauma, insect, or animal bites.

Figure 1. Photo of cadaver heart showing the section of CT indicated (blue-dashed line) (figure 1).

The abscess was incised and drained, and he received intravenous antibiotics. During that admission, he was given subcutaneous heparin for DVT (deep venous thrombosis) prophylaxis. Cultures taken at the time grew methicillin-resistant Staphylococcus aureus (MRSA); he was discharged five days later on oral antibiotics. Since the time of the foot abscess, he had been mostly sedentary; this was not however significantly different from his normal behavior.

Present Illnes Chief Complaints & Examination

Sometime afterward, the patient returned to the ED. While playing video games at home he became aware of acute onset shortness of breath with associated palpitations and sharp left-sided chest pain. Upon admission had no fever, leg swelling, or calf pain. The patient denied smoking or illicit drug use. 

When examined at the hospital, the patient was slightly tachypnoeic at 20 breaths per minute, but spoke in full sentences. He was tachycardiac at 135 beats per minute and afebrile at 97.1 degrees Fahrenheit. His blood pressure was 144/96 mmHg. A cardiac exam revealed normal heart sounds with regular rhythm and no murmurs, rubs, or gallops. Breath sounds were normal. Limbs were not edematous and the left foot wound was well-healed.

Laboratory results revealed significantly elevated D-dimer, and an electrocardiogram showed sinus tachycardia with S1 Q3 T3 pattern. Considering the suspicion for pulmonary embolism, the patient was presumptively started on heparin and a CT pulmonary angiogram was ordered (Figure 2). The consulting radiologist upon reviewing the CT images urgently called the following day to report that the patient had an extensive saddle pulmonary embolism.

Figure 2. CT showing large thrombus in pulmonary arteries.

Management

The intensive care team then accepted the patient to the IC unit, and then arranged for transfer to a tertiary care cardiothoracic center for possible surgical intervention. An echocardiogram done there revealed a separate whirling echogenic mass in the right atrium (Figure 3 and Figure 4).

Figure 3. Photo of cadaver heart with right atrium opened.

Now let's see on Figure 4 what was found in the right atrium of this patient.

Figure 4. Image from echocardiogram showing thrombus in right atrium.

The patient was urgently taken to the operating room for a cardiopulmonary bypass through a median sternotomy. Following the clamping of the aorta, when the incision was made for cannulation of the inferior vena cava, the surgeons observed a large amount of clot material extruding through the incision site. The patient then had right atriotomy and pulmonary endarterectomy with a removal of a large amount of thrombotic material from superior vena cava, right atrium and pulmonary arteries (Figure 5).

Figure 5. Clot removed from pulmonary trunk and arteries.

He had what is known as a saddle pulmonary embolus because the clot that straddles the pulmonary trunk at its bifurcation into the right and left pulmonary arteries. During the procedure, the surgeons noted that the patient also had a patent foramen ovale and that the atrial thrombus had actually straddled the foramen.

The surgeons removed the clot material from the atrium and sutured the patent foramen ovale closed. The surgical procedures were performed smoothly and the patient tolerated the procedure well.

Surgical and Anatomical Considerations

The patient, in this case, had a relatively sedentary lifestyle, with recent hospitalization and increased immobilization after incision and drainage of the left foot abscess from MRSA. This factor likely increased his risk of thrombogenesis because lower limb muscle activity normally assists in venous return from the limbs, and reduced venous flow increases the likelihood of clot formation.

The visualization of a right atrial thrombus is referred to as a thrombus in transit and is a very rare echocardiographic finding, especially one in which the embolus is straddling the patent foramen ovale. This patient had a patent foramen ovale (PFO).

Figure 6. The valve of foramen ovale (closed in adults).

Foramen ovale in fetuses

In the fetal heart, the atria are initially closed-off from one another by the septum primum except for a small opening in the septum, the ostium primum. As the septum primum develops further, the ostium primum narrows and finally closes. However, prior to this closing, the ostium secundum develops in the septum primum. This opening allows communication between the atria after the ostium primum closes.

Subsequently, a second wall of tissue, the septum secundum, develops over the ostium secundum in the right atrium. Blood then only flows from the right to left atria via a small passageway in the septum secundum and then through the ostium secundum. This canal is the foramen ovale.

Foramen ovale in adults

When the lungs become aerated at birth, the pulmonary pressure decreases and the left atrial pressure becomes higher than that of the right. This acts to force the septum primum against the septum secundum, functionally closing the foramen ovale. Later the septae fuse, but a remnant of the foramen ovale remains, the fossa ovalis. And, in about 25% of adults the foramen ovale is not closed completely, but remains as a small PFO.

This defect is usually asymptomatic because left atrial pressure is higher than right atrial pressure. Complications of PFO are rare and incidental discovery of PFO generally does not require any surgical or pharmacological intervention. PFO is associated with cryptogenic stroke, potentially due to paradoxical embolism. Patients undergoing coronary bypass surgery have a higher risk of postoperative atrial fibrillation and hypoxemia, if they also have PFO. Decompression sickness, air embolism and migraine with aura are also associated with PFO.
 

Explanation to Objectives

Objectives

After reviewing this case you should be able to describe the following:

  • Why it is likely that this patient had Type 2 diabetes.
  • What is MRSA and why it represents potential morbidity?
  • What is the significance of the elevated D-Dimer and the S1 T3 Q3 electrocardiogram pattern?
  • Why the patient was rushed into surgery when it was discovered that he had a pulmonary embolism.
  • Why in this patient a Doppler lower limb ultrasound at the time of the first admission might have reduced the likelihood of the development of a pulmonary embolus.

Diabetes Mellitus definition & causes

Diabetes (mellitus) is a condition characterized by prolonged high blood glucose levels. Diabetes is caused by either the pancreas not producing sufficient insulin (Type I) or the cells of the body not responding to the insulin that is produced (Type 2).

Whereas the cause of Type I diabetes is not known the cause of type 2 (adult-onset) is associated with obesity and lack of exercise. In type 2 eventually, there may be decreased insulin production. Diabetes is associated with risk for heart disease, stroke, kidney failure, foot ulcers and eye damage.

MRSA

Methicillin-resistant Staphylococcus aureus (MRSA) infection results from a type of bacteria that has developed resistance to most antibiotics used to treat staph infections. Typically, MRSA occurs in hospital settings and is often associated with invasive surgical procedures. However, as in the case of this patient, MRSA is also found in the community-associated and often begins as a painful skin infection. It's typically spread by skin-to-skin contact.

D-dimer & S1Q3T3 sign

D-dimer is a blood test that can indirectly measure ongoing activation of coagulation system. What is measured is a fibrin degradation product, which is cleaved by plasmin. In low to moderate risk patients, normal D-dimer level is enough to rule out diagnosis of PE.

If the D-dimer levels are high, further tests (CT, ventilation-perfusion lung scan, or venous compression ultrasound) are done to confirm the diagnosis. Positive D-dimer test is not specific for PE and positive D-dimer test alone cannot provide diagnosis of PE. ECG is not very sensitive for diagnosing PE. There is a unique S1Q3T3 pattern observed in PE patients, which is a large S wave in lead I, a Q wave and an inverted T wave in lead III. However, the S1Q3T3 sign is seen most commonly in severe PE patients.

Surgery as the method of choice for PE

Pulmonary embolism (PE) occurs when a thrombus dislodges from a vein, flows through the veins and typically lodges in the lung. Most thrombi form in one of the deep veins of the lower limb or those of the pelvis; this condition is referred to as deep vein thrombosis (DVT). The thrombi lodge in the lungs because veins get larger as they flow to the heart but then blood flows in the pulmonary arteries to the lungs, which become progressively smaller as they enter the lungs.

The clot or clots in the pulmonary arteries block the blood flow to parts of the lung, preventing oxygenated blood from then passing to the rest of the body. If the emboli block a significant portion of the pulmonary trunk or arteries, the patient is subject to stroke or death. This is why the surgeons acted so quickly in the case of this patient. And this risk was amplified because of the additional clot in the right atrium. Treating a PE quickly can reduce the risk of serious complications and death.

Doppler ultrasound

This patient had a lifestyle that was conducive to the development of DVT. Furthermore, the MRSA infection increased his lack of movement in the affected limb. DVT’s are diagnosed using Doppler ultrasound in the veins of the lower limb to check for venous blood stasis and clots.

Had the patient undergone a Doppler ultrasound exam at the time of his first admission it is possible that the lower limb venous stasis or actual clots might have been seen and prevented the development of the pulmonary embolus. It is worthwhile noting that the patient was given subcutaneous heparin for DVT prophylaxis at that admission so either the treatment was ineffective or the clots were already present.

Clinical Case: Pulmonary Embolism - want to learn more about it?

Our engaging videos, interactive quizzes, in-depth articles and HD atlas are here to get you top results faster.

Sign up for your free Kenhub account today and join over 1,052,809 successful anatomy students.

“I would honestly say that Kenhub cut my study time in half.” – Read more. Kim Bengochea Kim Bengochea, Regis University, Denver

Show references

References:

  • Shepard F, White-Stern A, Rahaman O, Kurian D, Simon K. Saddle Pulmonary Embolism with Thrombus in Transit across a Patent Foramen Ovale. Case Reports in Cardiology, Volume 2017, Article ID 6752709, https://doi.org/10.1155/2017/6752709
  • Modified by Joel A. Vilensky PhD, Carlos A. Suárez-Quian PhD, Aykut Üren, MD.

Authors:

  • Joel A. Vilensky 
  • Carlos A. Suárez-Quian
  • Aykut Üren

Layout:

  • Dimitros Mytilinaios
  • Abdulmalek Albakkar
  • Jana Vaskovic
© Unless stated otherwise, all content, including illustrations are exclusive property of Kenhub GmbH, and are protected by German and international copyright laws. All rights reserved.

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