REDUCTION OF PLASMA TRIIODOTHYRONINE (T3) INDUCED BY PROPRANOLOL

The effect of propranolol on plasma triiodothyronine (T3), thyroxine (T4) and triiodothyronine uptake by Sephadex G-25 (RT3U%) was studied in fourteen thyrotoxic patients and eight normal volunteers. 40 mg of propranolol as a single oral dose caused significant reduction in total serum T3 which began 60 min after administration. No significant changes were observed in T4 and RT3U% values. Plasma T3 levels remained suppressed during a 5 day course of treatment with propranolol. These results suggest that propranolol has a direct effect on peripheral metabolism of T3 rather than on thyroid hormone secretion.     

Supernormal Conduction in the Left Bundle Branch

Supernormal Conduction. This report describes a patient with tachycardia-dependent left bundle branch block (LBBB) and atrial extrasystoles, some of which were followed by an unexpectedly narrow QRS complex. His-bundle recordings and premature atrial stimulation were performed to analyze the mechanism underlying the normalized intraventricular conduction of some of the early atrial impulses. The results suggested the presence of supernormal conduction in the left bundle branch (LBB), because(1) the HV interval was identical in LBBB complexes and in early narrow QRS complexes; (2) during single lest stimulation using different paced atrial cycle lengths, there was a well-defined range of H₁, H₂, intervals resulting in normalization of intraventricular conduction; and (3) atrial pacing with a cycle length of 500 msec resulted in alternation between wide and narrow QRS complexes. These findings rule out alternative mechanisms that could explain the unexpectedly normal intraventricular conduction of early impulses.     

Comparison of ThermoCool® Surround Flow Catheter Versus ThermoCool® Catheter in Achieving Persistent Electrical Isolation of Pulmonary Veins: A Pilot Study

Persistent Electrical Isolation of Pulmonary Veins . Introduction: Aim of this study was to compare efficacy and safety of the new ThermoCool Surround Flow® catheter (SFc) versus the ThermoCool® (TCc) in achieving persistent circumferential electrical isolation of the pulmonary veins (PVs) in patients with paroxysmal atrial fibrillation (AF). Methods and Results: This multicenter, randomized, controlled study enrolled patients suffering from paroxysmal AF. Randomization was run in a one‐to‐one fashion between radiofrequency ablation by TCc or SFc. Aim of PVs ablation was documentation of electrical isolation with exit/entrance block recorded on a circular catheter. Among the 106 enrolled patients, 52 (49.0%) were randomized to TCc and 54 (51.0%) to SFc. Total volume of infused saline solution during the procedure was lower in the SFc than in TCc group (752.7 ± 268.6 mL vs 1,165.9 ± 436.2 mL, P < 0.0001). Number of identified and isolated PVs was similar in the 2 groups. Number of PVs remaining isolated 30 minutes after ablation was higher in the SFc than in TCc group (95.2% vs 90.5%, P < 0.03), mainly driven by acute ablation result in the left PVs (96.1% vs 89.7%, P < 0.04). Complications were seldom and observed only in the TCc group (0% vs 3.84%, P < 0.03). At 6‐month follow‐up SFc patients reported a trend toward less AF recurrences compared to those in the TCc group (22.9% vs 27.0%, P = 0.69). Conclusion: PV isolation by SFc lowered the rate of left PV early reconnections and reduced the volume of infused saline solution while maintaining the safety profile of AF ablation. (J Cardiovasc Electrophysiol, Vol. 24, pp. 269‐273, March 2013)     

Periprocedural Management and In-Hospital Outcome of Patients with Indication for Oral Anticoagulation Undergoing Coronary Artery Stenting

Purpose: In patients on oral anticoagulation (OAC) undergoing coronary stenting (PCI-S), procedural management and in-hospital outcome have never been specifically and prospectively investigated. Also, the contribution of early bleeding to the relevant hemorrhagic rate reported at follow-up with triple therapy of OAC, aspirin, and clopidogrel is largely unknown.
Methods: Consecutive patients with indication for OAC undergoing PCI-S at 5 centers were enrolled and prospectively evaluated.
Results: Out of 3410 patients undergoing PCI-S in the study period, indication for OAC was present in 4.8%. Femoral approach and bare metal stents were the most frequently used. During PCI-S, OAC was continued in about 30% of patients, whereas in about 20% heparin bridging was carried out. Glycoprotein IIb/IIIa inhibitors were rarely used (11%), whereas a standard bolus of unfractionated heparin was given in 93% of cases. Major adverse cardiovascular events (MACE) occurred in 4.8% of patients and major bleeding in 4.3%. No predictors of MACE or bleeding were identified, although the femoral approach was of borderline significance for major bleeding (OR 4.6, 95% CI 1.0–20.8; P = 0.05). A history of previous hemorrhage (OR 5.3, 95% CI 1.6–18.1; P = 0.007) predicted Carbofilm™-coated stent implantation.
Conclusions: A limited, albeit clinically relevant, proportion of patients undergoing PCI-S has indication for OAC. Procedural management appears not substantially different from that of common patients. In-hospital major bleeding is relevant and should be taken into account when evaluating the overall hemorrhagic rate at a medium- to long-term follow-up.     

Sleep and time course of consolidation of visual discrimination skills in patients with narcolepsy–cataplexy

The level of procedural skills improves in normal individuals when the acquisition is followed by a period of sleep rather than wake. If sleep plays an important role in the consolidation process the advantage it provides should be reduced or delayed when its organization is altered, as in patients with chronic sleep disorders. To test this prediction in patients with narcolepsy–cataplexy (NC), who usually have a more fragmented organization of sleep than normals, we compared the initial, intermediate and delayed level of consolidation of visual skills . Twenty-two drug-naive NC patients and 22 individually-matched controls underwent training at a texture discrimination task (TDT) and were re-tested on the next morning (after a night spent in laboratory with polysomnography) and after another six nights (spent at home). TDT performance was worse in patients than controls at training and at both retrieval sessions and the time course of consolidation was different in NC patients (who improved mainly from next-day to 7th-day retrieval session) compared with controls. Moreover, the less-improving patients at next-day retrieval had a wider disorganization of sleep, probably because of an episode of rapid eye movement (REM) sleep at sleep onset REM, on post-training night more frequently than more-improving patients. These findings suggest that the time course of the consolidation process of procedural skills may be widely influenced by the characteristics of sleep organization (varying night-by-night much more in NC patients than controls) during post-training night.     

Automatic Management of Left Ventricular Stimulation: Hints for Technologic Improvement

Background: We used a cardiac resynchronization therapy defibrillator device with an algorithm for automatic verification of left ventricular (LV) stimulation to understand LV threshold variability, such as to provide hints to program the algorithm features. We also evaluated the algorithm performance over long term, and tested a stimulation setting to achieve 99% effective stimulation while maximizing device longevity. Methods: The LV output was programmed as threshold + 0.5 V; the upper limit of LV output adjustment was 6 V at programmed pulse width. The algorithm is insensitive to the strength of the pacing pulse, thus pulse width was conveniently programmed to minimize the use of voltage multipliers in all the patients. Follow‐ups occurred at 1 month, then every 3 months, for clinical assessment and manual threshold verification. The efficacy of this programming at long term was also evaluated by Holter validation of LV stimulation. Results: Twenty patients were followed for 14 ± 5 months (6–21). LV threshold showed no changes in 97% of consecutive days, whereas a 0.5‐V and 1‐V increase occurred, respectively, in 2.3% and 0.6%. Maximum variability of LV threshold was ≤0.5 V during 90% of the follow‐up period. Our programming of LV output provided 99–100% effective stimulation in 18 of 20 patients, and 90% efficacy in two patients because of missed threshold measurements. A 25% increase of device longevity can be expected by this programming. Conclusions: LV threshold variability is truly modest. Daily update of LV threshold should be improved to ensure 100% LV stimulation by a threshold + 0.5 V safety margin. Device longevity is maximized when LV stimulation occurs below battery voltage.     

Near‐infrared spectroscopy correlates with continuous superior vena cava oxygen saturation in pediatric cardiac surgery patients

Background: Cerebral regional oxygen saturation (rSO₂) measured with near‐infrared spectroscopy (NIRS) has a well‐proven clinical utility. A goal‐oriented treatment based on the rSO₂ resulted in a significant reduction in major morbidity and in a shortening of postoperative hospital stay in patients undergoing coronary revascularization. In this study, we have compared the values of superior vena cava saturation (ScvO₂) continuously measured with a Pediasat catheter and the corresponding NIRS rSO₂ values obtained during cardiac operations in pediatric patients. Methods: This was a prospective observational study enrolling fifteen pediatric patients (age: 6 days–7 years) undergoing cardiac operations. ScvO₂ data obtained with the Pediasat during the operation were compared with simultaneously recorded NIRS rSO₂ values. Results: One hundred and seventeen matched sets of data were obtained during the operation. ScvO₂ continuously measured with the Pediasat was significantly correlated with the corresponding NIRS rSO₂ values. However, there was a constant positive bias (ScvO₂ values were higher than NIRS rSO₂ values) of 5.6%, with a precision of 10.4%. Time‐related percentage changes of NIRS rSO₂ were significantly correlated with the corresponding ScvO₂ percentage changes. A decrease in ScvO₂ is predictive for a decrease in rSO₂ with a sensitivity of 73.7% and a specificity of 85.7%. Conclusions: The continuous measurement of ScvO₂ values obtained by the Pediasat may provide useful information about the metabolic conditions of the brain during cardiac operations in pediatric patients if considered as percentage changes. Absolute values of ScvO₂ tend to overestimate the correspondent rSO₂ values.