Vasodilator drugs in patients with chronic ischaemic heart failure

The effects of intravenous nitroglycerin (NTG), trimetaphan (TMP), and phentolamine (PTL) on pulmonary artery diastolic pressure (PADP), systemic arterial pressure (SAP), cardiac index (CI) and systemic vascular resistance (SVR) in patients (12 in each treated group) with chronic ischaemic heart failure are analyzed. Each group was divided into two subgroups according to the initial PADP taking into account the mean value in the whole group. A significant decrease in PADP (by 40%; p less than 0.001) was observed in the NTG-treated group, with no significant changes in CI and SVR except for patients with moderately elevated initial PADP, in whom SVR increased slightly in the early period of treatment, and CI decreased (by 25%; p less than 0.05). TMP and PTL reduced SVR (by 25 and 30% respectively; p less than 0.01) and increased CI irrespective of the initial PADP. TMP significantly decreased PADP in patients in whom its level was initially high. The results suggest that NTG is mainly a venodilating agent which should be used in patients with high PADP and normal or slightly decreased CI. PTL acts mainly by reducing SVR and increasing CI. TMP influences both PADP and SVR and is a drug of choice in patients with high or elevated PADP and low cardiac output.