Astronaut psychiatric selection procedures: a Japanese experience.

This paper presents the results of the first application of a structured NASA psychiatric interview for Japanese astronaut selection. We undertook a semi-structured, diagnostic, clinical psychiatric interview with 45 Japanese astronaut applicants for the position of mission specialist-astronaut, and performed "select-out" psychiatric evaluations according to DSM-III-R psychiatric diagnostic criteria. Two applicants (4.4%) who met Axis I or Axis II disorder criteria in DSM-III-R were evaluated as "Disqualified." There were 13 applicants "Qualified with Reservation"; the majority of their diagnoses were "hypomania." Those applicants "Qualified with Reservation" and "Disqualified" were not finally selected to be astronauts. This structured interview was not only useful for "select-out" psychiatric screening of Japanese astronauts, but also made clear the Japanese characteristics of this selection procedure.

Individual differences of cerebrovascular responses to gravitational stress--prediction of orthostatic intolerance.

This experiment was designed to investigate the individual differences in the cerebrovascular responses to orthostatic stress. Seven male volunteers were exposed to head-up tilt (HUT) at 60 degrees for 15 min and to lower body negative pressure (LBNP) at 30 mmHg for 25 min. We measured the flow velocity of the middle cerebral artery and the quantity of the oxygenated and deoxygenated hemoglobin (oxy-Hb and deoxy-Hb) in the brain. Based upon oxy-Hb change during exposure to HUT, we classified the subjects into two groups: 1) the "good responder" group in which the oxy-Hb gradually increased from the 5th to 10th minute of HUT; 2) the "bad responder" group in which the oxy-Hb stabilized at lower levels after the initial decrease. The oxy-Hb changes between the two groups were significantly different during exposure to LBNP. During exposure to HUT and LBNP, no significant difference was observed in blood pressure and heart rate between the two groups. Our results suggest that there might be an individual difference in the cerebrovascular responses to orthostatic stress.

Effect of head up tilt on cerebral circulation.

This study was performed to study the effect of the head up tilt (HUT) on cerebral circulation across the time course (60 degrees HUT for 15 minutes) and across the different angles of HUT (15, 30, 45, 60 degrees HUT for 15 minutes). Cerebral circulation was continuously monitored during 15 minutes of HUT by the carotid Doppler flow meter, the transcranial Doppler flow meter, and the near infra-red spectrophotometer. The results show that the cerebral blood flow decreased during HUT and that the cerebral blood volume decreased initially and then gradually increased. And the magnitude of the effect may have the relationship with the angles of the HUT.

Difference in the cardiovascular response to prolonged sitting in men and women.

Orthostatic stress, sitting, results in adjustments of cardiovascular variables to maintain blood pressure and is prominent in a variety of occupations. Sitting serves as the control position for head-out water immersion studies. This study addressed gender differences in the cardiovascular response to prolonged sitting. Ten men and 10 women had cardiovascular measurements in the supine position compared with measurements during 2 hours in the seated position (Sit). Supine cardiovascular measurements were similar for both sexes. Heart rate changed similarly for both sexes with Sit. With Sit, men had elevated mean arterial pressure (9 +/- 3%), total peripheral resistance (54 +/- 9%), and decreased cardiac index (-27 +/- 5%), while women had no change in mean arterial pressure, lesser elevations in total peripheral resistance (17 +/- 7%), and lesser decreases in cardiac index (-12 +/- 5%) than men. Thus men, compared to women, had an elevated mean arterial pressure response to prolonged orthostatic stress.

[Detection of viability by percent thallium uptake with conventional thallium scintigraphy].

Thallium myocardial scintigraphy (TMS) is used for diagnosis of viability in infarcted myocardium before coronary revascularization. Underestimation of viability by TMS has been reported by many investigators. To evaluate viability precisely, thallium re-injection method or 24 hour delayed imaging is performed. However these techniques are not convenient and are difficult to perform in clinical practice. Percent Tl-uptake method was developed for predicting myocardial viability. To evaluate usefulness of this method, TMS was performed before and after PTCA in 23 patients with myocardial infarction. Left ventricle was divided into 3 layers, then each layer was divided into 4 segments (12 segments in total). Forth three segments showed recovery of perfusion on TMS after PTCA. Viability in infarcted myocardium is predicted by 1) redistribution (RD), 2) %Tl-uptake > or = 45% on the image immediately after exercise (TE), and 3) %Tl-uptake > or = 45% on delayed image (TD). Sensitivity was RD: 60%, TE: 90% and TD: 95% (p < 0.001 vs. RD). Specificity was RD: 74%, TE: 68%, and TD: 60% (NS). Predictive accuracy (PA) was RD: 69%, TE: 77%, TD: 73% (NS). Compared with RD, %Tl-uptake, either TE or TD, increased sensitivity with slightly improved PA, but decreased specificity slightly. Therefore %Tl-uptake would be a sensitive and useful predictor to find patients who are most likely to benefit from re-vascularization.

Hemodynamic and hormonal correlates with exposure to lower body negative pressure after 12 hours head-down tilt.

Hemodynamic and hormonal responses to lower body negative pressure (LBNP) after 12-h head-down tilt (HDT) were examined to investigate the mechanism of orthostatic intolerance following spaceflight. Ten young healthy male volunteers participated in the experiment. After 6 degrees HDT for 12 h, the tolerance to 1 h continuous -30 mm Hg LBNP was tested. Variables were measured before and after HDT, during LBNP, and 1 and 10 min after LBNP. Significant reduction in leg volume and plasma volume were observed at the end of 12-h HDT (500 ml and 5.5%, respectively). In the tolerant group, stroke volume index (SI) was decreased by 35% after 15 min LBNP, and carotid arterial blood flow (CBF), by 27% at the end of LBNP compared to the pre-LBNP value. Of the 10 subjects, 5 developed presyncope during LBNP; they exhibited remarkable reduction in SI, CBF, and heart rate, and increased secretion of ADH and adrenaline during or just prior to presyncope. This non-tolerant group tended to be hemo-concentrated from the start of the experiment. However, it will require a prospective study to determine if this variable is a reliable predictor of the outcome of the post-HDT LBNP test from data collected at the end of HDT.

Effect of the prelaunch position on the cardiovascular response to standing.

Astronauts spend a minimum of 2 h in the reclined seated position (prelaunch position) prior to the launch of the Space Shuttle. This position favors a cephalad shift of blood volume and subsequent loss of body fluid volume, a physiologic situation associated with cardiovascular deconditioning and orthostatic intolerance following spaceflight. It is not known if the prelaunch position results in cardiovascular deconditioning and, therefore, impaired cardiovascular performance during standing. If so, this might hinder the ability of the crewmember to make an emergency egress from the shuttle during the launch. The purpose of this study was to evaluate the cardiovascular responses of men and women to the stand test before and after 2 h in the prelaunch position. Nine men and nine women performed the stand test before and after 2 h in the seated position (SIT), the prelaunch position (PL), or seated immersed to the neck in water (WI). Heart rate, blood pressure, and cardiac output were measured. Men had higher blood pressures than women and demonstrated increases in blood pressure with standing. There were no other gender differences. SIT did not alter the cardiovascular response to standing, while PL and WI resulted in greater increases in heart rate after 2 h in the position. This increase was only 4 to 7 beats/min greater than after SIT, and was the same for PL and WI. Thus, a small, but significant, degree of cardiovascular deconditioning occurred during the minimum time astronauts spend in the prelaunch position.

[Silent myocardial ischemia evaluated by ambulatory left ventricular function monitoring].

To determine whether left ventricular function is less disturbed in asymptomatic ischemia than in symptomatic ischemia, exercise-induced left ventricular function was measured in beat-to-beat using an ambulatory left ventricular function monitoring system. The study subjects were 22 patients with coronary artery disease. Supine and sitting ergometer exercise tests were performed. Of 44 exercise tests, 33 showed significant ST depression on electrocardiograms. Among these 33, 17 were asymptomatic: 16, symptomatic. The left ventricular functions during exercise of these 33 were analyzed and compared with those of five normal controls. The changes in end-diastolic volume were not so significant either in controls or in the asymptomatic and symptomatic groups, but the changes in end-systolic volume were reversed in the diseased groups, particularly in the symptomatic group. The changes in ejection fraction (EF), therefore, were significantly negative in the diseased group, particularly in the symptomatic group. The correlation between exercise-induced left ventricular dysfunction and symptoms was evaluated among the 33 patients. Symptoms were present in 35% (6/17) in less than 10% decrease in EF, 44% (4/9) in 10-15% decrease, and 85% (6/7) in greater than or equal to 15% decrease, respectively. Thus, asymptomatic ischemia represents a lesser degree of myocardial ischemia as indicated by mild left ventricular dysfunction, compared with symptomatic ischemia. However, some cases of severe myocardial ischemia did not develop symptoms. We concluded that silent myocardial ischemia is responsible for a lesser degree of myocardial ischemia and decreased pain perception.

Sequence of mechanical and electrical changes during myocardial ischemia: assessment by an ambulatory left ventricular function monitor.

To investigate the relationship between left ventricular function and electrical changes during myocardial ischemia, ambulatory left ventricular function monitoring and ECG recording were made during the ergometer exercise test in 14 patients with coronary artery disease. An ambulatory ventricular function monitor consists of a small cadmium telluride (CdTe) radionuclide probe (250 g) affixed to the patient's chest wall, a preamplifer (10 g), and a portable data acquisition unit (600 g). Left ventricular time-activity curves were recorded continuously using this monitor, and the end-systolic count (volume), end-diastolic count (volume) and ejection fraction were calculated after background subtraction. Twenty-eight exercise tests were performed in the supine and upright positions. In 15 tests, left ventricular dysfunction, i.e., an increase in the end-systolic count (greater than or equal to 10%) and a decrease in ejection fraction (greater than or equal to 5%), and ST depression (greater than or equal to 0.1 mV) were observed. In these 15 tests, exercise duration was 362 +/- 27 sec. Left ventricular dysfunction occurred earlier than ST depression and the time difference was 97 +/- 19 sec. Left ventricular function recovered 33 +/- 8.5 sec after discontinuation of exercise, while ST depression continued for the additional 85 +/- 18.5 sec after recovery of left ventricular function. In conclusion, 1) left ventricular dysfunction occurs earlier than electrical changes during exercise-induced ischemia; 2) left ventricular dysfunction improves earlier than electrical changes after exercise; and 3) the same temporal sequence exists in the restoration from myocardial ischemia.

Exact mechanisms contributing to instability and refractoriness to therapy in patients with unstable angina: coronary arteriographic evaluation.

Ninety one patients with unstable angina were evaluated by clinical and angiographic study. Of 91 patients, 42 (46%) responded poorly to the intensive medical treatment. Emergency coronary arteriography was then performed on these patients. The important pathoanatomical mechanisms contributing to instability of angina pectoris and/or refractoriness to the intensive medical treatment were observed in 19 of 42 patients (45%). These include: 1) More severe disease with left main lesion; 2) Refractory coronary spasm; 3) Coronary dissection; 4) Rapid progression of atherosclerosis; 5) Ulcerating plaque and 6) Coronary thrombus. Our results presented here suggest that an appropriate knowledge regarding pathophysiology might improve the approach to treatment.

[Long-term vasodilator therapy of chronic refractory heart failure in patients with dilated cardiomyopathy].

The effect of long-term vasodilator therapy (hydralazine, ecarazine or budralazine + isosorbide dinitrate) were evaluated for 20 patients with chronic congestive heart failure due to dilated cardiomyopathy (DCM) resistant to conventional therapy. There were 16 men and four women whose ages ranged from 30 to 74 years (mean 52 years). Fifteen patients were in NYHA class III, and five in class IV. All patients continued their previous therapeutic regimens during this study. Hemodynamic measurements were performed with a triple lumen flow-directed balloon-tipped catheter for 15 patients to evaluate the effects of vasodilator therapy. In the other five patients, heart rate, blood pressure, chest radiography for heart size (CTR) and M-mode echocardiography were monitored. The hemodynamic responses to the combined vasodilator therapy for 15 patients showed significant decreases in afterload and preload concomitant with an increase in cardiac output. The noninvasive evaluations of combined vasodilator therapy in five patients resulted in significant improvement in heart size and ejection fraction. In all 20 patients, symptoms were significantly improved. Side effects and drug toxicity were uncommon during vasodilator therapy. It is concluded that combined vasodilator treatment is the most ajunctive therapy for the management of severe refractory heart failure due to DCM. In addition, long-term nonparenteral vasodilators can be administered even in an outpatient clinic without hemodynamic monitoring.

Ambulatory long-term vasodilator therapy for chronic refractory heart failure: hemodynamic evaluation and clinical response.

We evaluated long-term combined vasodilator therapy (hydralazine or ecarazine + isosorbide dinitrate) in 29 patients with chronic congestive heart failure resistant to the optimal conventional therapy. There were 24 men and 5 women, aged 28 to 76 years (mean 52 y/o). The etiology of heart failure was congestive cardiomyopathy in 24 patients, ischemic cardiomyopathy in 4 patients and advanced mitral regurgitation due to calcified mitral annulus in 1 patient. There were 21 patients in NYHA class III and 8 patients in NYHA class IV. All patients continued their previous therapeutic regimen during the period of this study. Hemodynamic measurements were performed with a triple lumen flow-directed balloon-tipped catheter in 20 patients to evaluate the effects of vasodilator therapy. In the rest of 9 patients, heart rate, blood pressure, chest X-ray examination for heart size (CTR) and M-mode echocardiograms for ejection fraction (EF) were monitored. The hemodynamic responses to the combined vasodilator therapy in 20 patients showed significant decreases in afterload and preload concomitant with an increase in cardiac output. The noninvasive evaluation of combined vasodilator therapy in 9 patients resulted in significant improvement in CTR and EF. We also noted a significant improvement in their symptoms of 29 patients. Side effects and drug toxicity were uncommon during vasodilator therapy. It is concluded that the combined vasodilator therapy is most useful adjunctive therapy in the management of severe refractory heart failure. Moreover, long-term nonparenteral vasodilators can be administered even at outpatient clinic without hemodynamic monitoring.