p.11 抽出テキスト

.................................. pulmonary arteries, combined with zones of overflow in the capillary bed served by non-obstructed pulmonary vessels, result in ventilation/perfusion mismatch, which contributes to hypoxaemia. In about one-third of patients, right-to-left shunting through a patent foramen ovale can be detected by echocardiography; this is caused by an inverted pressure gradient between the right atrium (RA) and left atrium, and may lead to severe hypoxaemia, and an increased risk of paradoxical embolization and stroke.67 Finally, even if they do not affect haemodynamics, small distal emboli may create areas of alveolar haemorrhage resulting in haemoptysis, pleuritis, and pleural effusion, which is usually mild. This clinical presentation is known as ‘pulmonary infarction’. Its effect on gas exchange is normally mild, except in patients with pre-existing cardiorespiratory disease.

In view of the above pathophysiological considerations, acute RV failure, defined as a rapidly progressive syndrome with systemic congestion resulting from impaired RV filling and/or reduced RV flow output,68 is a critical determinant of clinical severity and outcome in acute PE. Accordingly, clinical symptoms, and signs of overt RV failure and haemodynamic instability, indicate a high risk of early (in-hospital or 30 day) mortality. High-risk PE is defined by haemodynamic instability and encompasses the forms of clinical presentation shown in Table 4.

©ESC 2019

Increased RV afterload

RV O2 delivery

Coronary perfusion of RV

Systemic BP

CO

LV preload

RV output

RV contractility RV ischaemia, hypoxic injury

Intrapulmonary A-V shunting

RV O2 demand

Myocardial inflammation

Neurohormonal activation

RV wall tension

TV insufficiency

RV dilatation

Obstructive

shock

Death a

Figure 2 Key factors contributing to haemodynamic collapse and death in acute pulmonary embolism (modified from Konstantinides et al.65 with permission). A-V= arterio-venous; BP= blood pressure; CO= cardiac output; LV - left ventricular; O2= oxygen; RV= right ventricular; TV= tricuspid valve. aThe exact sequence of events following the increase in RV afterload is not fully understood.

Table 4 Definition of haemodynamic instability, which delineates acute high-risk pulmonary embolism (one of the following clinical manifestations at presentation)

(1) Cardiac arrest (2) Obstructive shock6870 (3) Persistent hypotension Need for cardiopulmonary resuscitation Systolic BP < 90 mmHg or vasopressors required

to achieve a BP >_90 mmHg despite adequate filling status Systolic BP < 90 mmHg or systolic BP drop >_40

mmHg, lasting longer than 15 min and not caused by new-onset arrhythmia, hypovolaemia, or sepsis

And End-organ hypoperfusion (altered mental status; cold, clammy skin; oliguria/anuria; increased serum lactate)

BP = blood pressure. Downloaded from academic.oup.com/eurheartj/article/41/4/543/5556136 by guest on 07 October 2026