Role of right ventricular infarction in cardiogenic shock associated with inferior myocardial infarction

In order to assess the role of right ventricular and left ventricular dysfunction in patients with cardiogenic shock associated with combined right ventricular and inferior myocardial infarction, we reviewed the clinical records and haemodynamic data of 18 patients with inferior myocardial infarction and cardiogenic shock. Six of these patients had haemodynamic evidence of right ventricular dysfunction. There was not significant difference in left ventricular stroke work index between patients with (18 ± 3 g per m²) and without (14±2) associated right ventricular dysfunction. Though pulmonary artery wedge mean pressure was significantly lower in patients with right ventricular dysfunction (10±1 mmHg) than in those without right ventricular dysfunction (18±2), this difference is probably the consequence of the right ventricular damage, since all patients with right ventricular dysfunction had a wedge pressure 11 mmHg or less compared with only three of 12 patients without right ventricular impairment. Necropsy observations in eight patients including two with right ventricular dysfunction support this concept. All patients had 40 per cent or more infarction (old plus new) of the left ventricle. However, the two with right ventricular infarction had wedge pressures 10 mmHg or less whereas the other 6 without right ventricular infarction all had wedge pressure 14 mmHg or more. In addition, while all five patients with right ventricular dysfunction who were treated by plasma volume expansion had a rise in wedge pressure (16±1 after fluid therapy) only two survived. Mortality in the group with right ventricular dysfunction (three of six) was similar to that in the group without right ventricular dysfunction (seven of 12). We conclude that in patients with cardiogenic shock associated with combined right ventricular and inferior myocardial infarction, (1) low pulmonary artery wedge pressure is the result primarily of right ventricular dysfunction and does not necessarily imply that left ventricular damage is slight and (2) severe left ventricular damage, often with a relatively low wedge pressure, is more common than has been previously reported in these patients.