Embolism I74.9

Graham first described thrombotic occlusion of the infrarenal abdominal aorta in 1814, also known as "Leriche syndrome" after the French surgeon René Leriche (1879 - 1955) (Bürger 2013),

The first description of central retinal artery occlusion (CAD) was in 1859 by Albrecht von Graefe. In 1982, Arrugua and Sanders described emboli as consisting of cholesterol and fibrin, which can sometimes be calcified (Laubach 2002).

Trendelenburg first presented pulmonary thrombectomy for pulmonary embolism (SPE) at an annual congress of the German Surgical Society in 1908 (Licha 2020) (Martin 2013). He operated on 3 patients, successfully removing the thrombi. However, none of the patients survived. It was not until 1924 that Martin Kirschner achieved the first successful SPE using a modified surgical method (Licha 2020).

Heparin has been used since 1936 for the treatment and prophylaxis of venous thromboembolism. The first heart-lung bypass device was used in 1961 for venous embolism (Licha 2020).

An embolism is defined as endogenous or exogenous material (such as air, etc.) carried along the arterial or venous blood pathway that becomes lodged at a site where the diameter of the clot is greater than the diameter of the vessel (Frömke 2006). The entrained material is called an "embolus" (Herold 2022).

A distinction is made between venous and arterial emboli.

- Venous embolisms :

- usually occur in the small circulatory system and lead to pulmonary embolism (this is semantically correctly called "pulmonary artery embolism", which, however, does not play a role in Anglo-Saxon countries [Dürschmied 2015]).

- Arterial Embolism:

- Always play out in the large circulation (Herold 2022).

- Paradoxical or also crossed (Höfler 2019) thromboembolism:

- in the exceptional case of an open foramen ovale, venous plugs can enter the great circulation (Herold 2022).

One differentiates between the following embolus- material:

- Thromboembolism

- Cholesterol embolism (consisting of atheromatous plaques)

- Fat embolism (occurring after trauma)

- air embolism

- septic embolism in e.g. bacterial endocarditis

- Tumor embolism (represents an important mechanism of metastasis)

- amniotic fluid embolism during birth

- Foreign body embolism (e.g., due to torn catheters or talcum etc. in i.v. drug abuse)

Venous embolism

Thromboembolism is the most common form of embolism (Herold 2022). Between 3%-10% pulmonary emboli are found in forensic sections. The source of emboli is found in the veins of the lower extremity or pelvis in approximately 95%. (Madea 2013). The upper extremities are affected by emboli 10 x less frequently (Kasper 2015).

Pulmonary embolism (LE) represents a relatively common condition, but is often elusive as a diagnosis (Howard 2019). Annually, an estimated 370,000 deaths are associated with LE in Europe (Hach- Wunderle 2015).

In the Western world, LE is considered the third leading cause of death after myocardial infarction and apoplexy (Licha 2020).

Venous Embolism:

- Venous thrombosis

Risk factors for venous embolism are:

- Virchow triad criteria such as

- blood stasis

- hypercoagulability

- injury of the endothelial vessel wall (Licha 2020)

- genetic disposition (such as Factor V Leiden)

- Tumor disease (present in approximately 15% of patients with thromboembolism [Hach- Wunderle 2015]).

If a co-factor such as obesity, immobilization, oral contraception, gravidity (Madea 2013), advanced age, smoking, post apoplexy, decompensated heart failure, sepsis, hormone replacement therapy, etc. is added, venous embolism may become manifest (Licha 2020).

Arterial emboli:

s. Arterial embolisms

- Venous emboli can travel to the lungs and cause pulmonary embolism (Höfler 2019).

- Arterial embolisms are clustered at vascular branches and physiological stenoses (Herold 2022).

Venous embolism:

Pulmonary embolism is found in about 50% of patients with deep vein thrombosis. The majority of pulmonary embolisms are asymptomatic, symptoms develop in about 20%, and about 2% are fulminant (Endres 2008).

In thromboembolism of the leg, there is often a:

- pronounced swelling

- redness

- Pressure sensitivity of the affected vein section (Kasper 2015).

If pulmonary embolism occurs, the characteristic symptoms are:

- acute dyspnea (Howard 2019): Found in 81% of patients (Licha 2020).

- Tachycardia in 70 %

- Hypoxia in 50

- syncope

- hypotension

- Hypocapnia (Licha 2020)

- Sudden onset of severe thoracic pain (Kasper 2015)

- Hemoptysis (Hach- Wunderle 2015)

- Hemoptysis (especially in peripheral LE with pulmonary infarction)

- cyanosis

- Neck vein congestion (found in central LE)

- subfebrile temperature (Endres 2008).

However, pulmonary embolism may also present with nonspecific symptoms such as:

- Dyspnea slowly increasing over days to weeks (Howard 2019).

The majority of emboli, however, are clinically silent and diagnosed only as incidental findings (Dürschmied 2015).

Arterial embolism: see d.

Venous embolism

The presence of pulmonary embolism is correctly diagnosed clinically or at necropsy in less than 50% (Madea 2013).

If the clinical probability of pulmonary embolism is low, a normal D- dimer has a high negative predictive value. If the D- dimer is elevated or the clinical likelihood of pulmonary embolism is increased, further instrumental testing is always recommended (Howard 2019).

If the patient is hemodynamically stable, i.e., ECG demonstrates right heart strain but systolic blood pressure is still > 90 mmHg (Licha 2020), the clinical probability of thromboembolism should be determined using scores-such as the Wells score. In clinically unstable patients, further diagnostics should be avoided and therapeutic measures should be initiated immediately (Hach- Wunderle 2015).

- Validated clinical score according to Wells:

- 1, 5 points for previous deep vein thrombosis (DVT) or pulmonary embolism (LE).

- 1, 5 points in case of recent surgery or immobilization

- 1 point for tumor disease

- 1 point for hemoptysis

- 1, 5 points if heart rate ≥ 100 beats / min

- 3 points if clinical signs of DVT

- 3 points if an alternative diagnosis is less likely than LE (Hach- Wunderle 2015).

- The clinical probability of LE is:

- low at 0 -1 points

- intermediate at 2 - 6 points

- high if ≥ 7 points (Hach- Wunderle 2015).

- Dichotomized score:

- LE unlikely at 0 - 4 points

- LE likely at ≥ 5 points (Hach- Wunderle 2015).

Venous embolism:

- ECG

If LE is already present, there may be:

- new onset atrial fibrillation or atrial flutter

- incomplete or complete right bundle branch block

- sinus tachycardia

- Q in III

- S in I

- negative T in III

- T- negation in V1 - V 4

- QRS- axis > 90 degrees (Endres 2008)

Sonography

Sonography of the lower extremities should always be performed (Licha 2020). This can be used to visualize thrombi of the deep vessels (Di Nisio 2016).

Transesophageal echocardiography (TEE).

The sensitivity of TEE is 90-95%, and the specificity is 100% (Licha 2020).

- right ventricular systolic dysfunction

- systolic dysfunction

- Dilatation of the right ventricle (RV)

- RV: LV diameter ratio on four-chamber view > 0.9 (Licha 2020).

Computed tomography

The sensitivity of contrast-enhanced CT is 90-95%, and the specificity is 100% (Licha 2020).

Contrast-enhanced CT should be performed if pulmonary embolism is present (Di Nisio 2016).

CT pulmonary angiography.

This examination represents the gold standard in the diagnosis of venous embolism. Nevertheless, contrast-enhanced CT is the most commonly performed test in pulmonary embolism (Licha 2020).

- common vital signs

- Blood gas analysis. Here, typically:

- SaO2 decreased

- pO2 decreased

- pCO2 decreased (Endres 2008)

- D- dimer testing (di Niseo 2016).

D- dimer- testing should always be done in case of clinically low or intermediate probability. If the D- dimers are negative, no further diagnostics are subsequently required. However, if there is a clinically high likelihood of embolism, the D- dimer test is not required; rather, further diagnostics should be performed immediately (Hach- Wunderle 2015).

- BNP > 90 pg / ml

- N- terminal Pro- BNP > 500 pg / ml

- Troponin:

- Troponin I > 0.4 ng / ml

- Troponin T > 0.1 ng / ml (Licha 2020).

In venous embolus:

- Pulmonary embolism (Herold 2022)

In the case of an arterial embolus depending on the location:

- cerebral infarction

- acute occlusion of the extremity arteries

- renal infarction

- splenic infarction

- mesenteric infarction (Herold 2022)

Patients who show right heart strain on ECG but whose systolic blood pressure is still > 90 mmHg are considered hemodynamically stable (Licha 2020). In them, cardiopulmonary support, supplemental oxygen, and reperfusion of the affected vessel should be provided after appropriate diagnostic testing (Licha 2020).

Hemodynamically unstable patients require immediate intensive care monitoring and, in particular, rapid therapy, as further diagnosis depends on this (Hach- Wunderle 2015).

In the case of venous embolism, therapy consists of:

• immediate systemic lysis

Lysis can be performed with streptokinase, urokinase or a recombinant tissue plasminogen activator (rt-PA).

- Recommended dosage of streptokinase: 250,000 I. U. over 30 min, then 100,000 I. U. / h over 12 - 24 h.

- Recommended dosage urokinase: 4,400 I. U. / kg bw over 10 min., then 4,400 I. U. / kg bw / h over 12 - 24 h

- Dosage recommendation rt- PA: bolus injection of 10 mg over 1 - 2 min, followed by 90 mg over 2 h (Hach- Wunderle 2015).

• mechanical procedures

These include surgical thrombectomy and catheter-based procedures (Hach- Wunderle 2015).

Revascularization can be performed for arterial embolism by:

- Embolectomy

- local lysis

- Aspiration embolectomy (Herold 2022).

(For more details see Arterial Embolism).

Venous Embolism:

The validated clinical Pulmonary Embolism Severity Index (PESI) is used for risk stratification of pulmonary embolism:

- Age (age in years)

- plus 10 if male sex

- plus 30 if tumor disease

- plus 10 if chronic heart failure

- plus 10 if chronic lung disease

- plus 20 if pulse rate ≥ 100 beats / min

- plus 30 if systolic blood pressure < 100 mmHg

- plus 20 if respiratory rate exceeds 30 breaths / min

- plus 20 if temperature < 36 degrees Celsius

- plus 60 if consciousness is disturbed

- plus 20 if arterial hemoglobin saturation < 90 % (Hach- Wunderle 2015).

Evaluation:

- Category I: ≤ 65 points = very low 30 day risk of death (0 - 1.6%).

- Category II: 66 - 85 points = low 30-day risk of death (1.7 - 3.5 %)

- Category III: 86 - 105 points = moderate 30-day risk of death (3.2 - 7.1 %)

- Category IV: 106 - 125 points = high risk of death (4.0 - 11.4 %)

- Category V: > 125 points = very high risk of death (10.0 - 24.5 %) (Hach- Wunderle 2015).

Approximately 70 - 75 % of all patients with pulmonary embolism show a mild course. In this case, the prognosis is good (Kasper 2015).

A massive form of progression is found in 4.5 - 10 % of those affected. The lethality in this case is > 50 %. In lethal cases, death occurs in > 70 % within the first hour. The 90-day mortality is about 15 % (Licha 2020).

Venous emboli are usually survived if only < 15% of the vessel cross-section of the terminal stromal pathway in the lung is occluded by the embolus. If >50% of the vessel cross-section is acutely affected, death occurs due to right heart failure (Madea 2013).

In addition to the elimination of risk factors, should be made:

- Venous emboli:

- Anticoagulants (Herold 2022): Anticoagulant therapy should be continued for at least 3 months to prevent recurrence (di Nisio 2016).

- Vena cava filter: Implantation should be reserved for exceptional cases, as the data on this is not uniform and is based on only a few studies (Hach- Wunderle 2015).

- Arterial embolism:

- Usually platelet aggregation inhibitors.

- Exception: anticoagulants for cardiac embolism (Herold 2022).

If patients complain of persistent dyspnea after LE, a "chronic thromboembolic pulmonary hytertension" = CTEPH diagnosis should be performed. CTEPH is a rare complication of LE (5 cases per 1 million persons per year) (Hach-W Wunderle 2015).

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