Treatment of Cardiac Shock by Metaraminol
Authors: E. M. M. Besterman
Journal: BMJ (1959)

An 80% mortality has been reported in shock following acute cardiac infarction (Hellerstein et ai, 1952 ; Griffith et al., 1954). However, this figure is probably an underestimate, as it is based on hospital experience alone. The early use of pr?ssors has been advocated by Griffith et al. (1954): in a series of cases treated for shock within three hours of its onset only 13% died. Noradrenaline infusions have reduced the overall mortality to between 40% and 50% (Mover et al., 1953 ; Sampson and Zipser, 1954 ; Garai and Smith, 1958). However satisfactory noradrenaline may be in hospital practice, the use of a drip in a patient's home presents many difficulties, and this drug is rarely used in domiciliary treatment of shock. This complication may therefore persist for several hours, with a consequently poorer prognosis, before the patient reaches hospital. Moreover, in some cases the shock is too severe to allow removal to hospital. The immediate requirement for such patients is a drug similar to noradrenaline, yet possible to administer by intravenous, intramuscular, or subcutaneous injections. Such a substance might be used either for continued therapy at home or to counter shock temporarily to allow transfer to a hospital. Noradrenaline has been shown to increase the contractile force of the heart, increase coronary flow, and raise the peripheral vascular resistance without inducing arrhythmias or tachycardia (Burn and Hutcheon, 1949 ; Gazes et al., 1953 ; Denison et ai, 1956). Other pressors such as phenylephrine work by a purely peripheral action on the systemic resistance and have been found less effective in the treatment of cardiac shock. This difference is attributed to the direct myocardiai action of noradrenaline (Gazes et al., 1953). Mephentermine sulphate has been used successfully in the treatment of cardiac shock by Brofman et al. (1952), Hellerstein et al. (1952), and Garai and Smith (1958). This drug may be given by injection or by drip, and causes a rise in systemic pressure and an increased coronary blood flow. Recent experimental studies in dogs have shown that the pressor effects of mephentermine are due to its central action rather than to peripheral vasoconstriction (Welch et al, 1958). Clinically the only drawback to this drug is the occasional development of tachyphylaxis : an increasing refractoriness to repeated injections necessitating larger doses of mephentermine in order to achieve a satisfactory pressor response. Metaraminol bitartrate ( aramine  ; laevo-1 (hydroxyphenyl) 2 amino 1 propanol hydrogen d tartrate) seems to possess the properties of direct action on the heart as well as on the peripheral resistance. It may be administered by repeated injections without the development of tachyphylaxis. In experimental cardiac ischaemia Sarnoff et al. (1954) produced a fall of arterial pressure, of cardiac output, and of ventricular stroke work, with a rise of left atrial pressure. Subsequent intravenous metaraminol returned these values to near normal levels and increased coronary flow. This and other experiments indicated that metaraminol produced a sustained increase of myocardial contractility without requiring increased coronary flow per unit of ventricular work. This central action, together with the peripheral effects, achieve the most desirable results?namely, increased arterial pressure and cardiac output at a low atrial pressure. No arrhythmias or tachycardia were observed.