Such tuberculin preparations as are currently used for skin testing in human beings are not specific for tuberculous infection. There is, in particular, reason to believe that the kind of low-grade tuberculin sensitivity that is highly prevalent in many tropical areas is "non-specific". A new kind of tuberculin, obtained as supernatant after acid precipitation followed by alcohol precipitation of the unheated concentrate from ultrafiltration of a culture of tubercle bacilli of human type, has been compared with ordinary tuberculin by skin tests in man in East Africa (Malawi) and South India. The results, reported in this paper, indicate that the new preparation gives rise to much smaller non-specific reactions than does the ordinary tuberculin.

Chemical Precipitation↗

PubMedDate not supplied

Effect of blood pressure cuffs on neonatal circulation: their potential application to newborns with persistent pulmonary hypertension.

The contribution of vasoactive pharmacologic agents to the care of the infant with primary pulmonary hypertension of the newborn (PPHN) is hampered by their limited ability to act selectively on different vascular beds. In contrast, blood pressure (BP) cuffs decrease flow and increase resistance only in the extremities around which they are applied. They therefore offer a means of increasing systemic vascular resistance without affecting pulmonary vascular resistance, a hemodynamic effect that may be particularly desirable among PPHN patients receiving vasodilators. We studied the effect of BP cuffs on the circulation of nine healthy neonates and three infants with severe PPHN. Among the healthy neonates, inflation of the cuffs to 20 mmHg had no discernible hemodynamic effect. Inflation to systolic pressures, however, caused the left ventricular preejection period to increase from 36 +/- 9 ms to 45 +/- 10 ms, the end-diastolic dimension to increase from 1.80 +/- 0.16 cm to 1.92 +/- 0.16 cm, and the cardiac output to fall to 87 +/- 12% of baseline (all p < 0.05)--changes indicative of an increase in systemic vascular resistance. Application of BP cuffs to the patients with PPHN was associated with 10-25 mmHg increases in transcutaneous arterial oxygen tensions. Administration of tolazoline to these patients while the cuffs were inflated resulted in additional 10-20 mmHg increases and did not precipitate hypotension. These observations suggest that BP cuffs can play a useful role in the management of patients with PPHN.

Blood Circulation↗

PubMedDate not supplied

Aerobic exercise function of patients with persistent coronary artery aneurysms secondary to Kawasaki disease.

Nine patients with persistent coronary artery aneurysms 1.7-14.0 years after an episode of Kawasaki disease underwent progressive bicycle ergometry with expiratory gas analysis. Two of the patients had aneurysms complicated by angiographically documented coronary artery stenosis. Results of the exercise tests were compared to those obtained from a group of age- and gender-matched normal control subjects. The Kawasaki disease patients did not differ significantly from the control subjects with regard to peak oxygen consumption (81 +/- 7% versus 79 +/- 12% predicted), peak workload (75 +/- 13% versus 77 +/- 9% predicted), anaerobic threshold (21.9 +/- 6.5 versus 18.9 +/- 4.0 ml/kg per minute) or oxygen pulse (96 +/- 7% versus 90 +/- 14% predicted). None of the patients developed significant ST segment changes or rhythm disturbances during exercise. The exercise function of the patients with coronary artery stenosis did not differ from that of patients without stenosis. It was concluded that the aerobic exercise function of patients with persistent coronary artery aneurysms after an episode of Kawasaki disease appears to be well preserved. Kawasaki disease patients with significant coronary artery pathology are not accurately identified by a single assessment of aerobic exercise function.

Adolescent↗

PubMedDate not supplied

Factors affecting the exercise capacity of pediatric patients with aortic regurgitation.

Although exercise testing is commonly employed to identify adult aortic regurgitation (AR) patients with early left ventricular (LV) dysfunction, the role and value of exercise testing in the management of pediatric AR patients have not been established. The purposes of this study were to evaluate the cardiorespiratory response to exercise of pediatric patients with chronic AR, examine the relation between exercise function and baseline echocardiographic measurements, and identify factors related to diminished exercise capacity (EC). The study group consisted of 26 patients aged 8 to 21 years (mean 14.4 +/- 3.7) with moderate or severe AR referred for exercise physiology testing. All patients underwent a baseline echocardiographic study and a symptom-limited, progressive cycle ergometer exercise test. LV diastolic dimension averaged 120 +/- 12% predicted, systolic dimension 112 +/- 20% predicted, shortening fraction 0.41 +/- 0.07, end-systolic wall stress 65 +/- 23 g/cm(2), and regurgitant fraction 38 +/- 16%. The average EC was 88 +/- 28% (56-143) predicted. No statistically significant correlation was found between EC and any of the echocardiographic parameters studied. Nine patients had EC < 75% predicted. These individuals did not differ from patients with higher EC with regard to any of the echocardiographic parameters or with regard to peak heart rate, blood pressure, respiratory exchange ratio, and incidence of ectopy or ST depression. However, the oxygen pulse at peak exercise (an index proportional to forward stroke volume at peak exercise) was significantly depressed among patients with EC < 75% predicted (77 +/- 6 vs. 106 +/- 16% predicted, p <. 0001). In conclusion, most pediatric patients with moderate or severe AR compensate well for their valve disease, maintain normal forward stroke volume during exercise, and have normal EC. However, a subset of AR patients have diminished EC secondary to an inability to augment forward stroke volume appropriately. These patients cannot be identified on the basis of resting echocardiographic studies. Timely identification of these patients, through formal exercise physiology testing, may have important clinical implications.

Adolescent↗

PubMedDate not supplied

Measurement of atrial septal defect size: a comparative study between three-dimensional transesophageal echocardiography and the standard balloon sizing methods.

Atrial septal defect (ASD) size measurement is of paramount importance for the successful deployment of a transcatheter septal occluder. The stretched balloon diameter (SBD) has long been regarded as the gold standard for selection of the size of any device. Three-dimensional (3-D) transesophageal echocardiography (TEE) can visualize the overall structure of the atrial septum, therefore rendering an accurate size of the ASD. In this study we aimed to validate the accuracy of ASD size measurement by 3-D TEE and to elucidate the reason for the difference between balloon sizing and 3-D measurement. Forty-one consecutive patients were enrolled in this protocol for ASD device closure using the Amplatzer septal occluder. Thirty-nine patients were diagnosed by 2-D transthoracic echocardiography as secundum ASD and 2 patients were diagnosed as patent foramen ovale. Two measurements of the balloon size were sequentially obtained by 2-D TEE after the balloon was fully inflated in the left atrium. First, no residual shunt across the septum could be seen while the balloon was pulled back against the septum. This measurement was called the balloon occlusive diameter (BOD). Second, with balloon deflation, a slight deformity of the balloon was seen just prior to its popping through the septum. This measurement was called the stretched balloon diameter (SBD). Three-dimensional TEE was performed in all patients at the beginning of the procedure before device deployment and within 15 minutes after device release. Three-dimensional TEE provided superior views of the ASDs, showing the spatial relationship between the ASD and the neighboring structures. For maximal ASD size measurement, balloon sizing was larger than 3-D TEE examination, whereas 2-D was smaller than the other two methods. The best correlation was found between 3-D TEE measurements and the BOD (r = 0.98, p < 0.0001). Three-dimensional TEE provides en face view of ASD; thus, it can accurately measure the size of ASD. Three-dimensional TEE measurement of ASD can be used instead of balloon sizing for the selection of transcatheter ASD occluder size.

Adolescent↗