Little is known about how isosorbide dinitrate (ISDN) contribute to bathing effects on patients with myocardial infarction. A study using an invasive method was made on 29 patients with myocardial infarction to clarify the hemodynamic changes occurring during bathing with and without sublingual ISDN, and to evaluate the overall effects of the ISDN. In bathing after discontinuing dosing of vasodilators (PRE-ISDN), patients were divided into the following two groups depending on the difference between the peak pulmonary capillary wedge pressure (PCWP) during bathing and PCWP before bathing: Increased PCWP group [(Group A): Δ PCWP≥10mmHg] and Unincreased PCWP group [(Group B): Δ PCWP <10mmHg].
Bathing was taken for 5 minutes at 42°C in a Hubbard tank, hemodynamics were observed during bathing and for 10 minutes after bathing, and after 30 minutes of sublingual administration of 5mg ISDN, bathing was taken in a similar manner. Group A patients showed a greater increase in heart rate, blood pressure, pulmonary arterial pressure (PAP), and right artial pressure than of Group B patients during bathing before being dosed with ISDN, and it seemed to be a considerable load on the heart. Although the remarkable increase of PAP and PCWP observed during the early stage of bathing before dosing with ISDN significantly decreased after sublingual dosing of ISDN (POST-ISDN) among Group A patients, these effects were not found in Group B patients. Group A showed more frequent reinfarction from a clinical viewpoint and triple vessel disease upon coronary arteriography, a lower ejection fraction upon left ventriculography, a higher left ventricular end-diastolic pressure, and lower left ventricular performance in most cases as compared to Group B. Although ISDN was found to be effective for severe cases in which the marked pre-load was observed by bathing, no beneficial effect on mild cases with well-maintained left ventricular performance was obtained.