Adriamycin cardiotoxicity: endomyocardial biopsy evidence of enhancement by irradiation

Endomyocardial biopsies were examined in 12 patients receiving total doses of Adriamycin from 90 to 445 mg/M2. These patients had also received previous mediastinal irradiation (from less than 600 to 5700 rad) over periods varying from 6 months to 14 years prior to the endomyocardial biopsy. Severity of pathological change in these 12 patients was compared with that of dose-matched control patients who had not received mediastinal radiation. The severity of the histopathologic changes was scored on a scale from 0 (normal) to 3 (marked abnormality). The mean score of the group receiving irradiation (2.0 +/- 0.89) was significantly higher than the score in those not irradiated (1.18 +/- 0.23) (p less than 0.001). Morphological demonstration of a "recall phenomenon" of latent radiation changes by Adriamycin was demonstrated in small intramyocardial vessels. This study indicates that radiation, even if remote, enhances Adriamycin-induced cardiomyopathy. Therefore, Adriamycin must be given cautiously in patients who have received previous mediastinal radiotherapy.

The electrophysiologic effects of quinidine in the transplanted human heart

Using His bundle recording techniques, we examined direct and autonomically mediated conduction system effects of quinidine in five cardiac transplant recipients who have anatomically denervated hearts. We made control conduction interval and refractory period measurements, and then infused 10 mg/kg quinidine gluconate over a 20-min period. At 30 min, we determined the electrophysiologic changes induced by quinidine. Quinidine significantly increased the atrial-His (AH) interval (from 97+/-9 [SEM] to 108+/-7 ms, P less than 0.001), the His-ventricular (HV) inteval (from 43.9 +/- 1 to 52.8 +/- 3 ms, P less than 0.01), the donor heart sinus cycle length (from 599 +/- 38 to 630 +/- 56 ms, P less than 0.08), and the atrial effective refractory period (from 214 +/- 14 to 241 +/- 11 ms, P less than 0.01). Quinidine significantly decreased the innervated, remnant atrial sinus cycle length (from 847 +/- 104 to 660 +/- 96 ms, P less than 0.01) and the blood pressure. The mean plasma concentration of quinidine at the time that electrophysiologic measurements were repeated was 4.37 +/- 0.449 micrograms/ml. We conclude that quinidine's predominant sinus nodal and atrioventricular nodal effects in man are autonomically mediated and opposite to its direct actions upon these structures. On the other hand, quinidine's prevailing effect on atrial refractoriness and His-Purkinje conduction in man is direct.

Plasma growth hormone and cortisol changes following limbic stimulation in conscious monkeys

Electrical stimulation of the amygdaloid nuclei in conscious monkeys sufficient to produce after-discharge was found also to produce a prompt and usually large increase in plasma growth hormone (GH) levels if prestimulation values were low and stable. Plasma GH responses were observed to parallel and slightly precede changes in serum cortisol. Stimulation of the temporal tip of the hippocampus, just posterior to the amygdala, did not produce elevations of GH or cortisol despite the spread of after-discharge activity to the amygdala.

Bacterial endocarditis after cardiac catheterization

Bacterial endocarditis is a rare complication of cardiac catheterization. We present the history of a patient who developed fatal, acute bacterial endocarditis following diagnostic cardiac catheterization. The implications regarding antibiotic prophylaxis and catheterization technique are discussed.

Infections after cardiac transplantation: relation to rejection therapy

We have analyzed the relation of the treatment of 76 acute graft rejection episodes in 45 late postoperative cardiac transplant patients to the 56 infections occurring in these patients. Intensification of immunosuppressive therapy for acute rejection greatly increased the occurrence of infection from a control incidence of 1.3 infections per 1000 patient-days to a posttreatment incidence of 3.6. Two modes of treatment, increased oral prednisone and high-dose methylprednisolone plus antithymocyte globulin, were further analyzed. Actuarial analysis of infections after these two treatment modes showed that the treatment-related increase in infection was nearly exclusively due to the latter form of therapy. Invasive cardiac procedures did not appear to be causally related to infections in these immunocompromised patients.

Autonomic nervous system and arrhythmias: studies in the transplanted denervated human heart

The function of the cardiac autonomic nervous system (ANS) was evaluated by comparison of normal subjects with cardiac transplant recipients. By use of standard intracardiac His bundle recording techniques, the following conclusions regarding basic cardiac electrophysiology were drawn: (1) the sinus node functions normally at rest despite autonomic denervation; (2) the AV node does not show the expected decrease in functional refractory period with increased heart rate in the denervated state, and (3) the adrenergic receptor of the cardiac conduction system does not depend upon autonomic innervation to function normally. Electrophysiologic studies of digitalis demonstrated: (1) in therapeutic doses, the AV nodal blocking effect of digitalis is autonomically mediated; (2) sinus node slowing by digitalis also requires an intact autonomic innervation. Arrhythmia analysis in 47 transplant patients revealed an increased incidence of ventricular arrhythmias in autonomic cardiac denervation. In addition, sudden death in the ischemic denervated heart does occur, weakening the concept of a primary role of the cardiac ANS in this phenomenon.

A historical view of the stress field

An analysis is presented of selected aspects of stress theory and research in biology and medicine, both before and after the introduction of Selye's stress formulations, which have been of major importance in the development and popularity of this research area. An attempt is made to explore some possible sources of present confusion and controversy in the stress field, with a view to the development of new research strategies that may enable us to clarify, update, and revise stress concepts and to facilitate future progress. In particular, it is suggested that an experimental reevaluation of the concept of the non-specificity of pituitary-adrenal cortical response is a matter of particular strategic importance, if we are to move out of the present prolonged period of stalemate and confusion over stress theory and terminology. Recent experimental studies which suggest that the nonspecificity concept may have been applied erroneously to lower level physiological mechanisms, rather than to higher level psychological processes, are reviewed. The possible implications of this development are discussed in terms of clarifying current concepts and providing guidelines for future lines of approach in stress research.

Renin, noradrenaline and adrenaline responses to simulated altitude

1. Plasma renin activity, plasma adrenaline and noradrenaline concentrations, and urinary adrenaline and noradrenaline excretion rates were measured in ten subjects during 3 days of exposure to a simulated altitude of 12 000 ft.

2. In both the supine and standing positions, renin activities were suppressed during all 3 days at altitude.

3. Plasma noradrenaline and adrenaline concentrations were significantly increased by the third day at altitude.

4. Urinary adrenaline excretion tended to be increased during the entire 3 days at altitude, with no significant change between the first and third day. Noradrenaline excretion was significantly increased on the third day.

5. The finding of decreased renin levels suggests that the enhanced activity of the sympathetic nervous system at high altitude does not stimulate renin release.