<prompt> Sudden death, right sided heart failure cor pulmonate or cardiovascular collapse occur whenSmall pulmonary embolismMassive pulmonary embolism60 or more of pulmonary artery is obstructed with emboliEnd artery obliteration  <response>: CONSEQUENCES OF PULMONARY EMBOLISMi Sudden death. Massive pulmonary embolism60 or moreof pulmonary artery results in instantaneous death, without occurrence of chest pain ordyspnoea. However, if the death is somewhat delayed, the clinical features resemble myocardial infarction i.e. severechest pain, dyspnoea and shock.ii Acute cor pulmonale. Numerous small emboli may obstruct most of the pulmonary circulation resulting in acuteright heart failure. Another mechanism is by release of vasoconstrictor substances from platelets or by reflexvasoconstriction of pulmonary vessels.iii Pulmonary infarction. Obstruction of relatively smallsized pulmonary arterial branches may result in pulmonaryinfarction . The clinical features include chest pain due to fibrinous pleuritis, haemoptysis and dyspnoea dueto reduced functioning pulmonary parenchyma.iv Pulmonary haemorrhage. Obstruction of terminal branches endarteries leads to central pulmonaryhaemorrhage. The clinical features are haemoptysis, dyspnoea, and less commonly, chest pain due to centrallocation of pulmonary haemorrhage. Sometimes, there may be concomitant pulmonary infarction.v Resolution. Vast majority of small pulmonary emboli 60-80 are resolved by fibrinolytic activity. These patientsare clinically silent owing to bronchial circulation so that lung parenchyma is adequately perfused.vi Pulmonary hypertension, chronic cor pulmonale and pulmonary arteriosclerosis. These are the sequelae ofmultiple small thromboemboli undergoing healing ratherthan resolution. 