[Volume loading experiment in dogs with large area infarction of right and left ventricles]

In order to study volume loading effect on large area myocardial infarction (MI) in right and left ventricles, large area MI in both ventricles and cardiogenic shock in 12 dogs were induced by occluding coronary arteries. Left ventricular systolic pressure (LVSP) and +/- dp/dt max. dropped markedly by 54%, 51% and 47% respectively, whereas right ventricular systolic pressure (RVSP) and +/- dp/dt max. fell by 9%, 25% and 27% respectively. The condition was obviously worse by rapid volume loading (dextran, 30 ml/kg, i.v. in 20 min.) in group I (n = 6), leading to increased retrograde beat of right ventricle, further decrease of +/- dp/dt max. in both ventricles, significant increase of right atrial pressure (RAP) and left ventricular and diastolic pressure (LEVDP) (2.9 +/- 0.2 kPa, P < 0.01 and 5.0 +/- 0.3 kPa, P < 0.001, respectively), and even ventricular fibrillation. Shock was reversed by combined treatment of dopamine (10 micrograms/kg.min) and glyceryl trinitrate (1 microgram/kg.min) in group II (n = 6) in 30 min, showing evident increase of arterial pressure, cardiac output, LVSP and +/- dp/dt max. without rise in RAP and LVEDP.