Analysis of low-speed rotational atherectomy for the reduction of platelet aggregation.

Platelet activation is an important determinant of acute outcomes of percutaneous intervention. The objective of this study was to assess the effect of rotational atherectomy on platelet activation in an in vitro model. Freshly collected heparinized porcine blood was exposed to a 2.0-mm Rotablator burr rotating at one of three speeds: 180,000, 140,000, or 0 rpm. The specimens were analyzed immediately for concentration and size of platelet aggregates and plasma-free hemoglobin. There were significantly more platelet aggregates of >20-microm diameter at higher speeds (7,434+/-2,193 at 180,000, vs. 2,269+/-627 at 140,000, vs. 633+/-258 aggregates/ml at 0 rpm; P < 0.001). Plasma-free hemoglobin, a simple measure of cell damage, decreased with decreasing rotational speed (429+/-168 mg/dl at 180,000, vs. 88+/-44 mg/dl at 140,000, vs. 9+/-9 mg/dl at 0 rpm; P < 0.0001). In vitro, platelet activation decreases with decreasing burr speed, suggesting that the use of the Rotablator system at its minimum approved speed (140,000 rpm) could prove clinically beneficial.

Analysis of heat generation during rotational atherectomy using different operational techniques.

Rotational atherectomy can generate heat from the friction of the burr as it ablates atherosclerotic plaque. The objective of this study is to correlate Rotablator technique and heat generation using two experimental models. First, 2.0 mm burrs were advanced through a lesion model derived from bovine bone implanted with thermal probes. Intermittent ablation with minimal decelerations resulted in a smaller temperature increase than continuous ablation with maximal decelerations (2.6 +/- 1.3 vs. 13.9 +/- 1.0 degrees C, respectively, P < 0.01). The second model used porcine femoral arteries cradled in constricting polyethylene grafts with thermal probes in contact with the adventitia. As the burr advanced through the segment, RPM decreases of 5-7 k resulted in a temperature rise of 4.1 +/- 1.2 degrees C, whereas decelerations of 10-20 k resulted in a 11.3 +/- 6.2 degrees C temperature increase. We conclude that excessive drops in speed and aggressive advancement of the burr are related to significant increases in temperature and potential thermal injury.

Preventive intervention during the perinatal and infancy periods: overview and guidelines for evaluation.

This paper reviews recent changes in perspectives of development in the prenatal, neonatal, and infancy periods and describes exemplary preventive interventions and their evaluation. Particular emphasis is placed on expanding criteria for successful early interventions to include measures of socioemotional and physical health as well as the more traditional measures of intellectual development. A theme which emerges is the need for peer and professional support for early parenting.

A model for teaching early child development.

A model of teaching psychological aspects of infant growth and development to medical students in a pediatric clinical rotation is described. Small groups of 8 to 10 medical students observe an infant developmental-assessment-parent-interview conducted by a child development specialist. Emphasis is placed upon demonstrating infant temperament, age-appropriate competencies, and the dynamic interplay between parent and child. Evaluation of this training program suggests its effectiveness as a method of instruction and its usefulness as an approach to the evaluation of the young child.