Vascular Medicine. Thomas Zeller

not invasive and allows differential diagnoses to be excluded.

      Magnetic resonance imaging (MRI)

      Imaging of the central vessels, with sensitivity and specificity comparable to those with spiral CT.

      Advantages: noninvasive, exclusion of differential diagnoses, contrast administration not necessary.

      Disadvantages: long examination time (with breathing pauses).

      Pulmonary artery catheter

      

Complete data on pressure conditions and hemodynamics

      

Increased PAP_mean > 25 mmHg: obstruction of pulmonary bloodstream in only 50%

      

Increased PAP_mean > 40 mmHg: only with a previously preloaded right ventricle

      Caution: bleeding complications in planned lysis. Pulmonary angiography is the gold standard for massive and submassive pulmonary embolism and planned treatment (lysis). Definite signs include vascular abruption and filling defects. Catheter fragmentation of thrombi can be carried out in the same session if appropriate.

      

      2.2.1.4 Treatment

      Conservative treatment

       General measures

      

Bed rest

      

Oxygen administration: nasal probe, oxygen glasses or mask up to 10 L O₂/min. When there is hypoxemia despite O₂ administration (SaO₂ < 80%): intubation and ventilation

      

Analgesia and sedation: morphine 5 mg i.v./s.c., diazepam (e.g., Valium®) 5–10 mg i.v.

      

Heparin 5000–10,000 IU i.v. as a bolus, followed by therapeutic heparinization (20 IU/kg/h) aiming for 1.5–2.5 times partial thromboplastin time (PTT)

       Initial care

      

Volume administration:

      – Caution when there is severe right ventricular dysfunction; 500 mL “fluid challenge” (e.g., HAES-steril® 10%) with cardiac output ↓ and normal blood pressure (BP)

      

Catecholamines:

      – Mild hypertension: dobutamine (Dobutrex®) 2.5–12.0 μg/kg/min. Effect: cardiac output ↑, oxygen transport ↑, peripheral vasodilation (β₂ receptors), peripheral vascular resistance ↓, possible deterioration of ventilation-perfusion mismatch with Po₂ ↓

      – Severe shock: norepinephrine (Arterenol®) 0.05–0.30 μg/kg/min. Effect: mean arterial pressure ↑ (α₁ receptors), right ventricular coronary perfusion ↑, right ventricular ischemia ↓, cardiac output ↑ (β₁ receptors)

       Systemic fibrinolytic therapy

      Indications. Massive pulmonary embolism (it is currently being debated whether this type of treatment can also be used in submassive pulmonary embolism—i.e., when there is right ventricular dysfunction without shock and with no contraindications for lysis). The pulmonary embolism should be confirmed by CT in submassive pulmonary embolism before lysis treatment is started, or there should be a high clinical likelihood of acute cor pulmonale (TTE, TEE) without prior cardiorespiratory disease.

      Contraindications. The same contraindications as those for systemic lysis apply:

      

Absolute:

      – Active internal bleeding

      – Spontaneous intracranial bleeding

      

Relative:

      – Larger operation

      – Pregnancy, labor

      – Organ biopsy

      – Puncture of noncompressible vessels < 10 days

      – Cerebral ischemia < 2 months

      – Gastrointestinal bleeding < 10 days, severe trauma < 15 days

      – Neural or ophthalmic surgery < 1 month

      – Severe hypertension, BP_syst > 180 mmHg, BP_diast > 110 mmHg

      – Bacterial endocarditis

      – Diabetic hemorrhagic retinopathy, thrombocytes < 100,000/μL

      – Status post resuscitation

      Procedure:

      

rt-PA (Actilyse®): short-term lysis: 10 mg bolus i.v., 90 mg over 2 h, bolus lysis: 50 mg bolus i.v., second bolus after 30 min, always with simultaneous full heparinization

      

Urokinase (Actosolv®, Corase®): short-term lysis: 1 million IU as bolus i.v., 2 million IU over 2 h, bolus lysis: 3 million IU as a bolus i.v., always with simultaneous full heparinization

      

Streptokinase (Streptase®): short-term lysis: 1.5 million over 30 min, 1.5 million/h over 3–4 h, repetition after 24 h possible

      Limitations of systemic fibrinolytic therapy. The Management Strategies and Prognosis in Patients with Pulmonary Embolism (MAP-PET) registry has shown that 40% of patients with acute pulmonary embolism have at least one contraindication against fibrinolytic therapy. In the International Cooperative Pulmonary Embolism Registry (ICOPER), it was clearly shown that 17.4% of the patients included died within 90 days; 21.7% of patients who received fibrinolytic therapy had severe bleeding complications, and 3% developed intracerebral hemorrhage. It must therefore be assumed that fibrinolysis treatment actually has a higher complication rate than has been postulated in controlled and therefore fairly selective and artificial individual studies. Some 15–25% of patients who receive lysis have only partial dissolution of the emboli in the pulmonary vascular circulation. However, persistent pulmonary hypertension after pulmonary embolism is associated with increased mortality. Meneveau et al. (2003) showed that the “residual embolism burden” after incomplete fibrinolytic reopening of the pulmonary vascular bed is an independent prognostic factor for the long-term results in these patients. When there was a residual obstruction of more than 30% of the pulmonary vascular bed, the multivariate analysis showed a relative risk of 2.2, with a 95% confidence interval of 1.7 to 2.7, for long-term mortality. While it was previously assumed that chronic thromboembolic pulmonary hypertension only develops in very few patients after acute pulmonary embolism, Meneveau et al. suggest that the numbers of patients affected may have been underestimated and propose more careful follow-up for patients with residual obstruction so that they can then undergo pulmonary thromboendarterectomy if appropriate. A flow model (Fig. 2.2-2) may provide a flow-physiological explanation for the incomplete thrombolysis. Proximal to the occlusion, there is turbulence with diversion of the blood flow into nonoc-cluded vascular segments, so that the contact between the thrombolytic agent and