Even when presenting the results as favorably as possible, we found no benefit with PVS-guided drug therapy in patients with clinical unsustained VT who had inducible sustained VT. These findings are unaltered by using different end points for PVS or considering the response to individual drugs.

The ICM provides an objective measure of AF ablation success and may be useful in making clinical decisions. This device may be used in future ablation studies to develop a more rigorous definition of procedural success.

Patients undergoing ICD implantation for NICM and NS-VT receive appropriate ICD therapy at a greater rate than those implanted for ICM, NS-VT, and a positive EPS. Although these data do not prove survival benefit in NICM, they suggest a beneficial effect.

This study was designed to determine if a combination of extreme thermal and exercise stress result in an inability to increase cardiac output (CO) in aerobically fit males. Six males served as subjects (average V ˙ O 2max of 4.10 l/min). Subjects cycled in an upright position at 40, 60 and 80% V Ȯ 2max for 24 minutes at 36 o C with zero air flow. V ˙ O 2 , cardiac output (CO), heart rate (HR), and mean arterial blood pressure (MAP) were monitored during each bout. CO was determined at four minute intervals utilizing CO 2 rebreathing. Time dependent changes (drift) were assessed by linear regression on each subject's response and testing group mean slopes for significance differences from zero using a one way t-test (P<.05). V ˙ O 2 , CO, and MAP were constant over time for all work intensities indicating steady state was achieved. Subsequently, mean values for each subject, as well as a group mean for V ˙ O 2 , CO, and MAP, were tested for significant work rate effects by utilizing repeated measures ANOVA and Scheffe' post hoc tests (P<.05). Group mean steady state MAP was significantly higher at each increased work intensity (118 + 1.48, 127 + 2.74, and 133 + 1.66 mmHg, respectively), while CO was higher at 60 than at 40 but similar at the 60 and 80% work rates (14.1 + 0.89, 17.3 + 0.35, and 18.4 + 0.56 L/min for the 40, 60 and 80% V ˙ O 2max , respectively). HR increased significantly during each exercise bout while stroke volume decreased significantly during the 60 and 80% work rates. In conclusion, the lack of an increase in CO at the 80% work rate is hypothesized to be due to insufficient venous return from the peripheral circulation. However, the increase in MAP at the 80% work rate suggests a blood volume shift from the venous to the arterial circulation may have preceeded the insufficient venous return. Thus, venous return may have been compromised by an inability to decrease venous compliance in response to decreased venous volume rather than by a thermoregulatory induced increase in venous compliance commonly referred to as peripheral blood pooling.

No abstract