The effects of intracoronary adenosine on preconditioning during coronary angioplasty.

There is evidence that the first balloon inflation during coronary angioplasty provides a preconditioning stimulus leading to decreased ischemia during subsequent balloon inflations. Endogenous adenosine release may play a role in ischemic preconditioning. Therefore, intracoronary adenosine administration prior to the first balloon inflation during percutaneous transluminal coronary angioplasty (PTCA) might modify the preconditioning response to the first balloon inflation. Forty-one patients underwent double-blind randomization to treatment with 100 mcg of intracoronary adenosine or placebo prior to coronary angioplasty. Twenty patients (11 adenosine, 9 placebo) had complete resolution of ischemia between inflations allowing comparison between the first and second inflation. An angioplasty guidewire was used to obtain an intracoronary electrocardiogram. The mean reduction in ST elevation during the second inflation compared with the first was 4.8 mm in the placebo group and -0.8 in the adenosine group (p < 0.05 placebo vs. adenosine). Seven of 9 placebo patients had a decrease in ischemia during the second inflation compared with the first, while only 2 of 11 adenosine patients showed a reduction. It was concluded that (1) the first inflation during PTCA is a preconditioning stimulus leading to a decrease in ischemia during later inflations, and (2) intracoronary adenosine administration prior to PTCA modifies the preconditioning effect of the first inflation. These data suggest that adenosine plays a role in ischemic preconditioning in humans.

Platelet amplification of vasospasm.

Platelets may accentuate vasoconstriction in stenotic arteries capable of vasomotion. We examined the interaction of platelets, stenosis, and arterial vasoconstriction in normal and stenotic arteries with intact endothelium. Beagle carotid arteries (n = 38) were isolated, removed, and placed in an in vitro perfusion system. Platelet-rich plasma (PRP) or platelet-poor plasma (PPP) were perfused through the arteries under constant pressure (100 mmHg) and a fixed distal resistance. In intact arteries without a stenosis, angiotensin II (ANG II) decreased luminal diameter without altering flow during PRP perfusion. After creating an intraluminal stenosis, vasoconstriction produced by ANG II resulted in near total cessation of flow. During PRP perfusion, this effect was amplified, demonstrating suppression of flow at significantly (P less than 0.05) lower concentrations of ANG II (PRP, ED50 = 0.03 +/- 0.01 x 10(-8) M) compared with arteries perfused with PPP (PPP, ED50 = 2.7 +/- 0.8 x 10(-8) M). This accentuated vasoconstrictor response in the presence of platelets was not blocked by SKF 96148 (a thromboxane A2 antagonist) but was abolished by ketanserin (a 5-HT2-serotonergic blocker). This increased sensitivity to vasoconstriction was not due to significant platelet plugging inasmuch as no cyclic flow reductions were observed, aspirin (acetylsalicylic acid) did not prevent this accentuated vasoconstrictor response, and adventitial administration of nitroglycerin restored flow to baseline levels. These studies illustrate that 1) platelets amplify the effect of vasoconstrictors in stenotic arteries, 2) this amplification of vasoconstriction is primarily due to platelet release of serotonin, and 3) the amplification occurs in the absence of significant platelet plugging and endothelial damage.

[Cardiotocography in intrauterine growth retardation]. / Cardiotocografía en retardo en el crecimiento intrauterino.

Fifty seven cases of intrauterine growth retardation were analyzed at the Department of Perinatal Medicine, "Luis Castelazo Ayala" Hospital, IMSS. The main purpose of the study was to establish the usefulness of cardiotocography in the decision of pregnancy interruption. The patients were divided in three groups in relation to the last non stress test made before delivery (reactive, non reactive, non reactive, non reactive with declarations). It is concluded that cardiotocography is a useful procedure for the surveillance of these fetuses and it was found a good correlation between progressively ominous traces and fetal condition at birth.

PIP: Early diagnosis, adequate follow-up, and determination of the ideal moment for delivery are fundamental aspects of management of intrauterine growth retardation. This study evaluates the usefulness of cardiotocography in follow-up such cases and in the identification of the best moment for delivery. 57 cases of intrauterine growth retardation were studied at the Department of Perinatal Medicine of a Mexican Institute of Social Security hospital in Mexico City between July 1986-June 1987. The 57 cases were divided into 3 groups based on the results of the most recent nonstress test made 72 hours or less before delivery. Group 1 consisted of 15 cases with reactive tests, group 2 of 17 cases with nonreactive tests, and group 3 of 25 cases of nonreactive tests with decelerations. In group 1 there were no histories of previous complicated pregnancies. In group 2 there were 3 cases of low birth weight and 7 of preterm birth in previous pregnancies. In group 3 there were 3 cases of low birth weight, 2 of preterm birth in previous pregnancies. In group 3 there were 3 cases of low birth weight, 1 of preterm birth, 5 of stillbirth and 1 neonatal death. 77.1% of the 57 mothers were hypertensive, 5.2% had cardiopathies, and 1.7% each had lupus erythematosus, prolonged pregnancy, and hyperparathyroidism. There was no associated pathology in 12.2% of cases. There were 13 caesareans and 2 vaginal deliveries in group 1, with a fetal indication for cesarean in 3 cases. In group 2 there were 13 caesareans and 4 vaginal deliveries, with 9 maternal and 4 fetal indications for cesarean. 24 of 25 deliveries in group 3 were cesarean, with fetal indications in 22 cases and both fetal and maternal indications in 2 cases. The nonstress test was the basic criterion for the indication in group 3. The average birth weight and gestational age respectively were 1798 g and 37.2 weeks for group 1, 1681 g and 36.5 weeks for group 2, and 1551 g and 37 weeks for group 3. The average Apgar score at the minute of birth was 6.8 for group 1, 6.6 for group 2l, and 5.1 for group 3. There were 3 fetal deaths, 2 in group 2 including 1 case of anencephaly and 1 which occurred 48 hours after a recommendation for cesarean following a deterioration in the nonstress test. 1 death in group 3 followed a misinterpreted nonstress test. 4 neonatal deaths included 1 in group 1 from septicemia probably acquired in the nursery and 3 in group 3 attributed to cerebral hemorrhage. The results indicate that the presence of spontaneous decelerations in the fetal heart beat strongly suggest fetal compromise, and are an alarm signal in case of intrauterine growth retardation. The nonstress test is a useful tool in such cases.