Study of shock with normal pulmonary capillary pressure caused by right ventricular failure in acute myocardial infarction

Of 698 cases of acute myocardial infarction (AMI), 65 cases of cardiogenic shock underwent haemodynamic study. 25 cases had pulmonary capillary pressures (PCP) less than 14 mmHg, 15 of which responded favourably to vascular filling. None of these cases died in a state of shock. In comparison with cardiogenic shock with PCP equal to or greater than 14 mmHg, these 25 patients showed the following features: 1) electrocardiography usually showed posterior or inferior infarction; 2) a higher incidence of right ventricular (RV) involvement; 3) left ventricular (LV) function was relatively unaffected; 4) haemodynamic criteria of RV infarction were demonstrated in most cases. In the absence of causes of hypovolaemia, AMI involving mainly the RV may lead to circulatory failure with normal LV filling pressures and responds favourably to vascular filling. When diagnosed and treated correctly this form of cardiogenic shock has a much lower mortality than usually associated with cardiogenic shock caused by AMI (28 p. 100 compared to 87.5 p. 100 in our series).