摘要:

No Abstract

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

No Abstract

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

No Abstract

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTRecent studies showed that taurine, a sulphonic amino acid, could decrease blood pressure and increase sympathoadrenal tone in DoCA-salt-treated hypertensive rats. To determine whether taurine exerts its antihypertensive action in man in a similar fashion, we studied the effect of oral administration of taurine (6 g for 7 days) on blood pressure and plasma catecholamines in 19 young patients with borderline hypertension in a double-blind, placebo-controlled fashion. Systolic blood pressure in the 10 patients who were treated with taurine decreased by 9.0 ± 2.9 mm Hg (mean ± SE; p > .05 by paired t test), compared with a 2.7 + 2.3 mm Hg decrease (NS) in the nine patients treated with placebo and diastolic blood pressure in the taurine-treated patients decreased by 4.1 + 1.7 mm Hg (p > .05) compared with 1.2 ± 3.0 mm Hg (NS) in the placebo-treated subjects. In the patients receiving taurine plasma epinephrine (E) decreased significantly, with a negligible decrease in plasma norepinephrine (NE). The effect of taurine on plasma catecholamines and the response of plasma E after the stimulation with glucagon was also studied in 12 borderline hypertensive and nine agematched normotensive subjects. Basal plasma E was significantly higher in borderline hypertensive than in normal subjects, but basal plasma NE did not differ in the two groups. The intravenous bolus injection of glucagon (1 mg) caused a rapid and transient increase in plasma E in each subject studied; plasma E reached a peak concentration 2 to 5 min after the injection of glucagon and thereafter declined rapidly to the baseline level. The overall response of plasma E to glucagon stimulation was significantly (p > .01) greater in the borderline hypertensive than in the normotensive subjects. Taurine not only reduced mean blood pressure and basal plasma E, but also attenuated the increased response to glucagon in the borderline hypertensive subjects. In the normotensive subjects, however, the administration of taurine did not significantly change blood pressure, basal plasma catecholamines, or the response of plasma E to glucagon. Overall, there was a direct correlation (r = .670, p > .01) between the decrements in mean blood pressure and those in plasma E after taurine in the 22 borderline hypertensive subjects. Evidence presented suggests, therefore, that sympathoadrenal tone is increased in young borderline hypertensive individuals, and that oral administration of taurine attenuates increased tone, leading to the reduction of blood pressure.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTTo investigate disturbances in the coronary circulation and myocardial metabolism during septic shock, we examined coronary sinus blood flow and myocardial substrate extraction in 40 patients with septic shock and 13 control patients. Patients with coronary artery disease were excluded from this study. The global hemodynamic pattern of the septic patients was characterized by a lower stroke volume, despite an elevated cardiac index. Coronary sinus blood flow was high (187 + 47 vs 130 ± 21 ml/min in the control group, p > .001) due to marked coronary vasodilation, especially in the subgroup of nonsurvivors. In contrast to the control group, myocardial lactate uptake was elevated, while that of free fatty acids, glucose, and ketone bodies was diminished in patients with septic shock. These findings were especially prominent in the nonsurvivors. Expressed as oxygen equivalents, the contribution of free fatty acids as an energy source of the myocardium was markedly diminished in septic patients (12% vs 54% in the control group, p > .005), while that of lactate was increased (36% vs 12%, p > .01). The observed shift in myocardial substrate extraction was associated with a discrepancy between measured myocardial oxygen consumption and that calculated chemically from commonly available exogenous substrates: 41% of myocardial oxygen consumption was not explained by the utilization of commonly available substrates extracted from coronary circulation in all patients with septic shock. These data indicate that myocardial utilization of endogenous substrates may probably account for this discrepancy, suggesting that a “mandatory” utilization of endogenous energy sources might underlie progressive cardiac involvement in septic shock.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTWe report results of follow-up transesophageal electrophysiologic studies in 35 infants seven to 27 months old (mean, 12 months) in whom paroxysmal atrial tachycardia (PAT) using an accessory atrioventricular (AV) connection had been previously evaluated by transesophageal study in the first 2 months (mean, 14 days) of life. No infants were receiving antiarrhythmic drug therapy at the time of follow-up study. To evaluate AV conduction and initiate PAT, a standard transesophageal pacing protocol was used: single extrastimuli in sinus rhythm, incremental pacing to second-degree AV block, and burst pacing at cycle lengths near those resulting in second-degree AV block. If PAT was not initiated during the baseline period, the protocol was repeated during the infusion of isoproterenol and after administration of atropine. At follow-up study, PAT was reinitiated in 24 of 35 (68%) infants, six of whom had exhibited recent spontaneous recurrence of PAT. AV nodal function did not differ in those with and those without inducible PAT. However, when initial and follow-up studies were compared, changes in antegrade conduction of the accessory AV connection were observed, since only five of 10 infants with preexcitation at initial study continued to exhibit preexcitation at follow-up study (1/5 infants only after isoproterenol). Additionally, changes in retrograde conduction of the accessory AV connection were observed; the ventriculoatrial interval in PAT induced at follow-up study increased by 20 to 40 msec in eight of 24 infants and by 50 to 80 msec in five of 24 infants compared with the interval at initial study. Thus, in 24 of 35 infants with PAT in the first 2 months of life, susceptibility to inducible PAT persisted whether or not spontaneous PAT was observed. Since AV nodal function was similar in infants with and those without inducible PAT, the loss of susceptibility to both inducible and/or spontaneous PAT may in part be due to observed developmental changes in electrophysiologic properties of accessory AV connections.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTOscillations in ventricular myocardial refractoriness after a change in rate have not been described in man. During 25 baseline paced cycle lengths (SB_SB) of 400 to 800 msec in 14 patients, a shorter cycle length (S′-S′) was introduced that was 10 to 20 msec (mean 15 ± 5) greater in duration than the ventricular effective refractory period (VERP) determined after 12 beats of the respective baseline cycle length (group 1 trials). In addition, during 14 of the 25 baseline cycle lengths, a second shorter cycle length was introduced that was 50 to 80 msec (mean 65 ± 10) greater than the VERP of the respective baseline cycle length (group 2 trials). In all 39 group 1 and group 2 trials the VERP was determined after each of at least 3 beats (S′, SJ2, S′3) of the shorter cycle length and in six of the 25 group I trials the VERP was determined after each of at least 12 beats of the shorter cycle length. In all group 1 trials oscillations of the VERP were observed, with a mean S′, VERP of 202 + 28 msec, an S′2 VERP of 228 ± 25 msec (p > .001 vs S′, VERP), and an S′3 VERP of 210 ± 26 msec (p > .001 vs S′, VERP). Oscillations dampened within 4 beats, but persisted at a lower amplitude in four of the six group I trials during which the shorter cycle length was maintained for at least 12 beats. In group 2 trials, oscillations in VERP were never seen with an S′, VERP of 238 ± 27 msec, an S′2 VERP of 233 25 msec (p > .01 vs S′, VERP) and an S′3 VERP of 232 + 27 msec (p = NS vs S′2 VERP). In six of the patients a series of shorter cycle lengths ranging from 10 to 100 msec greater than the VERP of the baseline length were introduced and in all cases the amplitude of the initial oscillation in VERP was noted to be inversely related to the increment by which the new cycle length exceeded the VERP of the baseline cycle length. In summary, oscillations in VERP in man (1) occur after an abrupt change to a shorter cycle length that approaches the VERP of the baseline cycle length, (2) rapidly dampen but may persist at a low amplitude when the shorter cycle length is maintained, and (3) have an initial amplitude that is inversely related to the increment by which the new cycle length exceeds the VERP of the baseline cycle length. These oscillations in VERP may contribute to arrhythmia initiation and termination.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTWith the increasing popularity of the Jatene procedure for the treatment of common or D-transposition of the great arteries (D-TGA), the preoperative definition of coronary artery anatomy in D-TGA has assumed great importance. Consequently, the reliability of two-dimensional echocardiography for determining the coronary artery anatomy was studied in 32 infants with D-TGA. Surgical observation of the coronary anatomy was used to assess the accuracy of the echocardiographic diagnosis. The coronary arteries were visualized in 29 of 32 patients (90%), predominantly with the use of parasternal and apical views. In the three remaining patients visualization of the coronary arteries was inadequate to allow determination of their anatomy. The coronary artery anatomy was correctly predicted in 25 of the 29 patients in whom the coronary arteries were visualized. The anatomic patterns included usual coronary anatomy for D-TGA (n = 16), left circumflex coronary from the right coronary artery (n = 6), single right coronary artery (n = 1), single left coronary artery (n = 1), and inverted origin of the coronary arteries (n = 1). The errors in the remaining four patients were (1) false-negative diagnosis of origin of the left circumflex coronary from the right coronary artery (n = 1); (2) false-positive diagnosis of origin of the left circumflex coronary from the right coronary artery (n = 1), and (3) diagnosis of origin of the left circumflex coronary from the right coronary artery when the correct diagnosis was single right coronary artery (n = 2). In conclusion, the coronary arteries could be visualized in 90% of patients with D-TGA and the anatomy was defined correctly in 86% of patients in whom the coronary arteries could be visualized. We anticipate that more experience will further improve the accuracy of two-dimensional echocardiography for defining coronary anatomy in patients with D-TGA.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTIn a previous study of 543 patients we developed, using echocardiographic left ventricular mass as the reference standard, two new sets of criteria that improve the electrocardiographic diagnosis of left ventricular hypertrophy (LVH). One set of criteria, which is suitable for routine clinical use, detects LVH when the sum of voltage in RaVL + SV3 (Cornell voltage) exceeds 2.8 mV in men and 2.0 mV in women. The second set of criteria, suitable for use in interpretation of the computerized electrocardiogram, uses logistic regression models based on electrocardiographic and demographic variables with independent predictive value for LVH, with separate equations for patients in sinus rhythm and atrial fibrillation. To test these criteria prospectively with use of a different reference standard, antemortem electrocardiograms were compared with left ventricular muscle mass measured at autopsy in 135 patients. Sensitivity of standard Sokolow-Lyon voltage (SLV) criteria (SV, + RV5or RV6>3.5 mV) for LVH was only 22%, but specificity was 100%. The Cornell voltage criteria improved sensitivity to 42%, while maintaining high specificity at 96%. Higher sensitivity (62%) was achieved by use of the new regression criteria, with a specificity of 92%. Overall test accuracy was 60% for SLV criteria, 68% for the Cornell voltage criteria, and 77% for the new regression criteria (p > .005 vs SLV). We conclude that the Cornell voltage criteria improve the sensitivity of the electrocardiogram for detection of LVH and are easily applicable in clinical practice. In addition, the new regression criteria, incorporating the T wave in V1, QRS duration, the magnitude of the negative P terminal force in V,, and patient sex, further improve electrocardiographic accuracy for the detection of LVH and are suitable for computer-based analysis of the electrocardiogram.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID

摘要:

ABSTRACTFetal echocardiography has yet to have an impact on the treatment of congenital heart disease. Critical aortic valve stenosis was diagnosed by echocardiography before birth in a 35 week gestation fetus. The risks to the fetus and mother associated with prolonged rupture of membranes prompted their transport to a hospital with cardiac surgical and high-risk perinatal facilities. Prenatal and postnatal echocardiographic findings agreed regarding the diagnostic criteria for critical aortic stenosis and primary forms of cardiomyopathy were excluded. Results of fetal Doppler examination were consistent with valvular aortic stenosis and excluded mitral regurgitation. Determination of the left ventricular size excluded ventricular hypoplasia. The infant was delivered by cesarean section and underwent successful emergency aortic valvotomy at 12 hr of age. Fetal echocardiography, in combination with a multidisciplinary postnatal approach, can be used in the successful treatment of a severe form of congenital heart disease.

ISSN:0009-7322    

出版商:OVID    

年代:1987

数据来源: OVID