Urine cortisol/creatinine ratio in controlled insulin-induced hypoglycemia.

An elevated urine cortisol/creatinine ratio has been presented as a simple laboratory method to detect nocturnal hypoglycemia. The present study examines the time course of the rise and fall of the urine cortisol/creatinine ratio in 11 patients following insulin-induced hypoglycemia. The mean urine cortisol/creatinine ratios at 1 and 3 h after the onset of symptomatic hypoglycemia were 170 +/- 103 and 62 +/- 23, respectively. These were significantly greater (P less than 0.01) than the basal ratio of 13 +/- 7. By 5 h, the ratio had fallen to 19 +/- 11, which was similar to basal values. The study documents the sensitivity of the urine cortisol/creatinine ratio in detecting hypoglycemia but indicates that after 3 h, the ratio may return to normal despite a previous hypoglycemic episode.

Effect of dihydroergotamine on +Gz acceleration tolerance.

Dihydroergotamine is a potent vasoconstrictor of the venous capacitance vessels and has been shown to decrease blood pooling in patients with orthostatic hypotension. Acceleration acting on the long axis of the body (+Gz) pools blood into the lower body of the subject. Nine healthy men received an injection of 1 mg dihydroergotamine and 1 ml of saline intramuscularly in a randomised, double blind fashion, and had their Gz acceleration tolerances measured. Dihydroergotamine significantly increased Gz tolerance by 0.24 G and narrowed the difference between the maximum heart rate during the acceleration epoch and resting baseline by 10%. The drug had no effect on blood pressure and heart rate when the subjects changed from the supine to standing position. The increase in Gz tolerance was not sufficient for operational use.

Ischemia-associated intraventricular conduction disturbances during exercise testing as a predictor of proximal left anterior descending coronary artery disease.

To determine the incidence and significance of transient intraventricular conduction abnormalities occurring in association with myocardial ischemia during exercise testing, the recordings of 2,200 consecutive exercise tests were reviewed. Ten patients (0.45%) were identified as having both ischemia and intraventricular conduction abnormalities that developed transiently during the exercise test. In all 10 patients both typical angina and electrocardiographic evidence of ischemia developed during exercise. Among the 10 patients, left anterior hemiblock developed in 4, left posterior hemiblock in 2, right bundle branch block (RBBB) in 2, RBBB with left axis deviation in 1, and left anterior hemiblock progressing to complete left bundle branch block (LBBB) in 1. All 10 patients had cardiac catheterization showing significant obstruction of the left anterior descending (LAD) coronary artery at or before the origin of the first septal branch. Eight patients were treated surgically and 2 medically, all with relief of ischemic symptoms. Nine of the 10 had repeat exercise stress testing without angina or electrocardiographic evidence of ischemia and without recurrence of the transient intraventricular conduction disturbance. It is concluded that the development of transient intraventricular conduction abnormalities associated with myocardial ischemia during exercise testing is an uncommon occurrence (0.45%). When such conduction disturbances do develop, the existence of significant disease in the proximal portion of the LAD coronary artery is strongly suggested. With control of myocardial ischemia, the transient conduction disturbances during exercise are ameliorated.

Anatomic and prognostic implications of an early positive treadmill exercise test.

Eighty men (group A) with clinical coronary artery disease underwent coronary angiography regardless of symptoms and previous therapy because they had a positive treadmill exercise test in stage I or II of the Bruce protocol. Thirty-four other men (group B) who also had an early positive treadmill test underwent coronary angiography because they had disabling angina pectoris despite medical therapy. We found left main coronary artery stenosis of 50% or greater of the vessel diameter in 28% of group A and 35% of group B (p greater than 0.3). In contrast, only 10% of 93 other catheterized patients who had treadmill tests that were not early positive had left main coronary disease (p less than 0.001). Fifty-four patients from group A who did not have left main stenosis of 50% or greater were treated medically. In this subgroup, 85% had 2 or 3 major coronary vessels with 75% or greater stenosis. These patients had a 36 month survival rate of 89.2%. We conclude that an early positive treadmill test identifies patients who have an increased likelihood of having left main coronary stenosis, even if they are minimally symptomatic. To identify left main coronary stenosis, catheterization may be justified in patients whose angina pectoris has been mild or not intensively treated when they have an early positive treadmill response. After left main coronary stenosis has been excluded, these patients may be treated medically with a low mortality.

Hemodynamic effects of anti-G suit inflation in a 1-G environment.

This study evaluated effects of various anti-G inflation pressures on cardiac volumes and the relationship of these volume changes to mean arterial pressure changes. Ventricular volumes were calculated using two-dimensional echocardiography. An anti-G suit was inflated to 2, 4, and 6 psi in the standing and supine positions for 10 male subjects. In the supine position, mean arterial pressure increased from base line for all three inflation pressures (P = 0.05). The end-diastolic volume increased after 2-psi inflation (P = 0.03). Cardiac output or stroke volume did not change. After standing, mean arterial pressure (P = 0.002), end-diastolic volume (P = 0.002), and stroke volume (P = 0.05) fell after suit deflation. Peripheral vascular resistance fell in the 2- and 4-psi inflation profiles. In the standing protocol, mean arterial pressure, end-diastolic volume, stroke volume, and cardiac output rose with all three inflation pressures (P less than 0.05). After reclining, heart rate increased (P = 0.02) and mean arterial pressure fell (P less than 0.05) in the 4- and 6-psi inflation profiles after suit deflation. Increases in mean arterial pressure are caused by increases in cardiac preload and cardiac output after inflation of the anti-G suit while subjects were standing. Increased cardiac preload was not consistently seen after inflation while subjects were supine. Changes in end-diastolic volume and mean arterial pressure were dependent on the pressure used to inflate the anti-G suit.

Long-duration +Gz acceleration on cardiac volumes determined by two-dimensional echocardiography.

To enhance protection of humans exposed to long-duration low-gravity environments such as the Space Shuttle and National Aerospace Plane during re-entry or in the short-duration high(-)+Gz environment of fighter aircraft, the effects of +Gz acceleration on cardiovascular hemodynamics must be understood. This study reports the use of two-dimensional echocardiography in normal men during +Gz acceleration. The heart's position in relation to the chest did not change during acceleration up to +7 Gz. The success in maintaining high-quality images during exposures to G-forces of this magnitude may be attributed to the relatively low rate of G onset. End-diastolic volumes (EDV) and stroke volumes (SV) decreased during a +Gz acceleration ramp that increased until the subject experienced peripheral light loss (PLL) (P < .05). An inflated G-suit partially counteracted this effect. By 30 seconds of a +3 Gz acceleration plateau, the protective effects of the inflated G-suit to maintain EDV is lost and the EDV of the inflated G-suit was lower than the EDV of the uninflated G-suit (P < .05).

Aggressive diagnostic approach indicated in testicular sarcoidosis.

A twenty-nine-year-old black male presented with a testicular mass and hilar adenopathy. Histologic sections of the testis showed the 3 by 2 by 2-cm mass was an inflammatory granuloma due to sarcoidosis. The epididymides were involved bilaterally. The initial differential diagnosis included: sarcoidosis, testicular neoplasm, an infectious process, or a combination of the three. Biopsy of the testicle is recommended to confirm the diagnosis of sarcoidosis. We believe there are only 6 reported cases of clinically detected testicular sarcoidosis.

Response to upright exercise after cardiac transplantation.

There is little information on the hemodynamic response to upright exercise in patients who have undergone cardiac transplantation. We compared the hemodynamic and metabolic response to upright bicycle exercise in 11 patients with heart transplants and 12 controls. Patients performed two tests--a steady-state test with a right heart catheter and a maximal incremental test. During steady-state exercise at 20% of their predicted maximum workload, patients with heart transplants had a higher (mean +/- SD, p < 0.05) heart rate (108 +/- 11 vs. 96 +/- 15 beats/min), mean systemic blood pressure (116 +/- 17 vs. 101 +/- 11 mmHg), mean pulmonary artery pressure (29 +/- 9 vs. 22 +/- 3 mmHg), mean pulmonary wedge pressure (14 +/- 6 vs. 9 +/- 2), pulmonary (302 +/- 101 vs. 220 +/- 50 d-sec-cm-5-m2) and systemic (2049 +/- 531 vs. 1459 +/- 520) resistance indices, and lactate concentration (3.4 +/- 1.7 vs. 1.7 +/- 0.4 mmol/l), and a lower stroke index (39 +/- 8 vs. 50 +/- 8 ml/m2) compared with controls. Cardiac index, right atrial pressure, and mixed venous oxygen saturation were similar. During the maximal exercise test, patients with heart transplants achieved a significantly lower percentage of predicted maximum heart rate (77 +/- 13 vs. 91 +/- 8%), workload (70 +/- 25 vs. 102 +/- 23%), oxygen consumption (63 +/- 11 vs. 108 +/- 19%), and ventilation (67 +/- 18 vs. 89 +/- 15%) compared with controls. Heart transplant patients also had a lower blood pressure and anaerobic threshold. We conclude that heart transplant patients have an altered hemodynamic and metabolic response to upright bicycle exercise.

Comparison of exercise electrocardiography and dobutamine echocardiography.

It is uncertain whether dobutamine echocardiography is a better test than exercise electrocardiography for the detection of coronary disease in patients who can exercise. We compared the hemodynamics, sensitivity, and specificity of these tests in 24 patients, 16 with coronary disease and 8 controls. The tests were performed within six weeks of one another and were interpreted without knowledge of other clinical data. The exercise electrocardiogram was considered abnormal if the patient developed one mm of ST-segment depression, while the dobutamine test (up to 40 micrograms/kg/min) was considered abnormal if the patient developed ST-segment depression or a left ventricular wall motion abnormality. Exercise testing resulted in a higher heart rate (145 +/- 29 vs. 110 +/- 24, p less than 0.001) and blood pressure (176 +/- 31 vs. 148 +/- 24, p less than 0.001). Dobutamine testing was 25% more sensitive than exercise testing (94 vs. 69%, 95% confidence interval for difference is 0 to 50%, p = 0.09), while exercise testing was 38% more specific (88 vs. 50%, 95% confidence interval for difference is -3 to 79%, p = 0.14). We conclude that exercise results in a higher heart rate and blood pressure than dobutamine infusion. Differences in sensitivity and specificity are inconclusive, but indicate that the sensitivity of exercise testing is, at best, equivalent to dobutamine testing, while any increase in specificity with dobutamine testing, compared with exercise testing, would not be clinically significant.

The effects of inflation of antishock trousers on hemodynamics in normovolemic subjects.

Antishock trousers may maintain mean arterial pressure in trauma patients by increasing central blood volume and cardiac output. Hemodynamics, end-diastolic volume, stroke volume, cardiac output, and blood pressure were recorded in eight supine, healthy men in antishock trousers using two-dimensional echocardiography. Two inflation protocols were used. The antishock trousers were inflated to 50 and 100 mm Hg in a random fashion and inflation was maintained for 30 minutes before deflation. End-diastolic volume and blood pressure rose significantly (p less than 0.05) after antishock trouser inflation of 50 and 100 mm Hg. With the 50 mm Hg inflation, the stroke volume and end-diastolic volume fell below baseline over time. This did not occur with the 100 mm Hg inflation. After suit deflation, the stroke volume, end-diastolic volume, and cardiac output increased with 50 mm Hg inflation. The study shows that the antishock trousers alter several hemodynamic parameters. With lower inflation pressures, antishock trousers cause an increase in arterial pressure by increasing peripheral resistance. At higher inflation pressures, the antishock trousers increase cardiac output and as the cardiovascular system adjusts, maintain the pressure by increasing peripheral resistance.

The effects of various antishock trouser inflation sequences on hemodynamics in normovolemic subjects.

In an attempt to maximize the hemodynamic effects of antishock trousers, a pair of such trousers was modified to a five-bladder trouser (one abdominal, two thigh, and two calf bladders) and inflated using three different inflation sequences. These three sequences were simultaneous inflation of all five bladders; concurrent inflation of the calf and thigh bladders and then inflation of the abdominal bladder (standard inflation); and sequential inflation of the calf, thigh, and abdominal bladders. Simultaneous inflation resulted in the greatest increase in blood pressure and the smallest increase in end-diastolic volume, stroke volume, and cardiac output. The standard inflation sequence resulted in slightly higher increases in end-diastolic volume, stroke volume, and cardiac output than the sequential inflation sequence, and a significantly larger increase in cardiac output than the simultaneous inflation sequence. Our study indicates that of the three sequences used, the standard inflation sequence produces the greatest blood return to the heart.

Comparison of adenosine, dipyridamole, and dobutamine in stress echocardiography.

OBJECTIVE: To compare adenosine, dipyridamole, and dobutamine in stress echocardiography with regard to sensitivity, specificity, accuracy, and side effects. DESIGN: Crossover, blinded comparison, with coronary angiography serving as the criterion standard. SETTING: U.S. Army tertiary care hospital. PARTICIPANTS: Forty participants, 25 with coronary disease and 15 without coronary disease. Patients were eligible if they had coronary angiography within 6 weeks of stress testing or if they had a risk for coronary disease of less than 5%. MEASUREMENTS: Left ventricular wall motion was recorded after dobutamine (0.38 mg/kg body weight), adenosine (0.84 mg/kg body weight), and dipyridamole (0.84 mg/kg body weight) stress testing. Stress echocardiographic evaluation was considered to be abnormal if the patient developed new or progressive wall motion abnormalities. The rate of side effects for the types of echocardiography and the patient preference were recorded. MAIN RESULTS: The sensitivity of dobutamine stress echocardiography (76%; 95% CI, 59% to 93%) was significantly higher than that of adenosine echocardiography (40%; CI, 21% to 59%; P less than 0.001) and that of dipyridamole echocardiography (56%; CI, 37% to 75%; P = 0.019). The specificity of adenosine testing (93%; CI, 80% to 100%) was significantly higher than that of dobutamine echocardiography (60%; CI, 35% to 85%; P = 0.008) and that of dipyridamole echocardiography (67%; CI, 43% to 91%; P = 0.028). Symptoms were more frequent with adenosine echocardiography (100%) than with dipyridamole (88%; P less than 0.001) or dobutamine (80%; P less than 0.001) echocardiography. Treatment for persistent symptoms was required in more patients after dipyridamole echocardiography (40%) than after dobutamine (12%; P less than 0.001) or adenosine (0%; P less than 0.001) echocardiography. More patients preferred dobutamine (48%) or dipyridamole (40%) echocardiography to adenosine echocardiography (12%; P less than 0.001). CONCLUSIONS: Dobutamine stress echocardiography is more sensitive and is better tolerated than adenosine or dipyridamole stress echocardiography. Adenosine echocardiography is more specific than dobutamine or dipyridamole echocardiography and is less likely to cause persistent symptoms.