What Is the Most Appropriate Stimulation Mode in Patients with Sinus Node Dysfunction?

Sinus node disease (SND) has caused many controversies about the appropriate stimulation mode. We compared the advantages and disadvantages of VVI, AAI, DDD, and DDI mode. In an additional study, left ventricular function at rest [R] and during exercise [E] was investigated in dual chamber and ventricular stimulation mode with a stimulation rate of 70 ppm [R] and 110 ppm [E]. A total of 223 patients [pts] was investigated (67 AAI, 87 VVI, 69 DDI]. Hemodynamic disadvantages in VVI mode resulted in a 55% actuarial incidence of atrial fibrillation after five years. In AAI mode, we found another 25% complication rate due to impaired AV conduction [n = 9] or a bradyarrhythmia [n = 6] with slow ventricular response. DDD mode implies the possibility of sustaining a pacemaker mediated tachycardia. Single ventricular stimulation with a high stimulation rate (110 ppm] under E showed a worse left ventricular performance as compared to dual chamber stimulation. DDI mode shows none of the aforementioned disadvantages. To sum it up: Until a dual chamber rate responsive pacemaker becomes available, the DDI mode represents the best stimulation mode for patients with a SND.     

Effects of Aging on Reflex Autonomic Nervous Response Induced by Orthostatic Maneuvers

Background: Baroreflex sensitivity (BRS), exercise pressor reflex (EPR), and aging influence the autonomic nervous response associated with orthostatic maneuvers. Standing significantly increases heart rate (HR), with an initial increase (1.ΔHR) due to EPR and a secondary, more gradual increase (2.ΔHR) due to BRS. HR then decreases (3.ΔHR), which is also attributable to BRS. Thus far, however, few data are available regarding the interdependence of these variables.
Methods and Results: Ninety-five healthy volunteers (mean age 37 ± 11 years, range 10–70 years; 50 women) underwent continuous noninvasive measurements of beat-to-beat blood pressure, HR, and spontaneous BRS in the supine (10 minutes) and upright (10 minutes) positions. After tilt, 1.ΔHR, 2.ΔHR, and 3.ΔHR were calculated from the HR recording. From the 1^st to the 6^th decade BRS, 2.ΔHR and 3.ΔHR decreased with normal aging ([BRS 11.88 ± 7.97 ms/mmHg to 1.81 ms/mmHg, P = 0.006], 2.ΔHR [16.75 ± 3.40 beats to 5.33 ± 2.52 beats, P = 0.002], 3.ΔHR [52.25 ± 5.91 beats to 11.33 ± 4.04 beats, P < 0.001]). However, no such association was noted between 1.ΔHR and age (21.25 ± 9.35 beats to 12.00 ± 7.21 beats, ns). BRS while standing was correlated with 1.ΔHR (r = 0.432, P < 0.001).
Conclusions: EPR, in contrast to BRS, was not significantly influenced by normal aging. Furthermore, not only was BRS influenced by EPR, as is generally acknowledged, but EPR and BRS were interrelated. These observations offer new insights into the complex interactions of orthostasis-induced physiological autonomic reflexes associated with normal aging.     

The Paclitaxel‐Eluting Coroflex™ Stent Study II (PECOPS II) Acute and 6‐Month Clinical and Angiographic Follow‐Up, 1‐Year Clinical Follow‐Up

Background and Objectives: Paclitaxel‐coated stents have proven their efficacy for reducing restenosis in de novo coronary artery lesions and in‐stent restenoses with superiority compared to bare metal stents. This study was performed to evaluate the procedural and 1 year results of the Paclitaxel‐eluting Coroflex? Please stent in coronary artery lesions. Methods: One‐hundred and twenty‐nine patients (66.2 ± 8.2 years, 31.0% diabetics, 20.2% unstable angina, 41.8% multivessel disease) were enrolled per protocol for elective single stent deployment into native de novo or post‐PTCA restenotic coronary lesions.The mean reference diameter was 2.84 ± 0.43 mm, the lesion length 12.51 ± 4.6 mm, and the minimal lumen diameter 0.75 ± 0.29 mm. Follow‐up was performed clinically in 129/129 (100%) after 6 and 12 months and angiographically in 120/129 (93%) patients after 6 months. Results: The success rates of the procedure and deployment were 100% and 95.3%, respectively. The in‐stent late loss and the late‐loss index were 0.27 ± 0.59 mm and 0.17 ± 0.40 resulting in binary in‐stent restenoses in 16/120 (13.3%) subjects and in‐segment restenoses in 20/120 (16.7%) subjects. Major adverse cardiac events occurred in 23/129 (17.8%) during the first 6 months of follow‐up with 3/129 (2.3%) myocardial infarctions, 1/129 (0.8%) secondary to stent thrombosis. From 6 to 12 months, 2/129 (1.6%) nonlesion related PCI were performed. Conclusion: The data of the Paclitaxel‐eluting Coroflex? Please stent evaluated in PECOPS II are within the range of the other currently available Paclitaxel‐eluting stent. (J Interven Cardiol 2010;23:160‐166)     

A novel isotonic‐balanced electrolyte solution with 1% glucose for perioperative fluid management in children‐ an animal experimental preauthorization study

Background: The recommendations for perioperative maintenance fluid in children have been adapted from hypotonic to isotonic electrolyte solutions with lower glucose concentrations (1–2.5% instead of 5%) to avoid hyponatremia or hyperglycemia. Objective: The objective of this prospective animal study was to determine the margin of safety of a novel isotonic‐balanced electrolyte solution with 1% glucose (BS‐G1) in comparison with normal saline with 1% glucose (NS‐G1) in the case of accidental hyperhydration with a focus on acid–base electrolyte balance, glucose concentration, osmolality and intracranial pressure in piglets. Methods: Ten piglets (bodyweight 11.8 ± 1.8 kg) were randomly assigned to receive either 100 ml·kg^?1 of BS‐G1 or NS‐G1 within one hour. Before, during and after fluid administration, electrolytes, lactate, hemoglobin, hematocrit, glucose, osmolality and acid–base parameters were measured. Results: Unlike BS‐G1, administration of NS‐G1 produced mild hyperchloremic acidosis (base excess BS‐G1 vs NS‐G1, baseline 1.9 ± 1.7 vs 2.9 ± 0.9 mmol·l^?1, study end 0.2 ± 1.7 vs ?2.7 ± 0.5 mmol·l^?1, P < 0.05, chloride BS‐G1 vs NS‐G1 baseline 102.4 ± 3.4 vs 102.0 ± 0.7 mmol·l^?1, study end 103.4 ± 1.8 vs 109.0 ± 1.4 mmol·l^?1P < 0.05). The addition of 1% glucose led to moderate hyperglycemia (P < 0.05) with a concomitant increase in serum osmolality in both groups (P < 0.05). Conclusion: Both solutions showed a wide margin of safety in the case of accidental hyperhydration with less acid–base electrolyte changes when using BS‐G1. This novel solution could therefore enhance patient’s safety within the scope of perioperative volume management.     

Microfilarial clearance in loiasis involves elevation of Th1 and Th2 products and emergence of a specific pattern of T-cell populations

Diethylcarbamazine (DEC) induced clearance of microfilaraemia in loiasis is associated with severe posttreatment reactions. To define the switch from hypo- to hyper-responsiveness associated with DEC treatment, phenotypic alterations of T-lymphocytes, characterized by flow cytometry, and cytokines, determined by enzyme linked immunosorbent assay, were monitored in a microfilaraemic patient. In contrast to reports on onchocerciasis and lymphatic filariases, no elevation of interleukin (IL)-6 and tumour necrosis factor (TNF)-α was observed. The most severe side effects coincided with an elevation of interferon (IFN)-γ on day 3, followed by IL-10, transforming growth factor (TGF)-β2 and macrophage inflammatory protein-1α (MIP-1α) peaking on day 5. Phenotypieally, T-cell activation markers CD38, CD54 and CD25 were significantly expressed before treatment, with high CD38 expression still existing one year after clearance of microfilaraemia. Treatment-related increases were observed with anti-CD 122, anti-HLA-DR and anti-CD69. CD28 was expressed before treatment on almost 100% qf'CD4⁺ and CD8⁺ T cells and dropped to 20% by day 5, reaching again baseline levels on day 21. Furthermore, there emerged 20% TCRαβ^-/CD3⁺ T cells and 10%) anti-βV5(e) ⁺ T cells, altogether indicating a specific pattern of T-helper (Th)1 and Th2 cytokines as well as expansion of certain pauciclonal T-cell populations in response to microfilarial clearance.     

Investigation on the stability of the Dde protecting group used in peptide synthesis: migration to an unprotected lysine1

An investigation of the stability of the Dde protecting group for amines, used in solid-phase peptide synthesis, shows that an unprotected ε-NH₂ group of lysine can acquire the Dde protection from another ε-NH₂ group or from an α-NH₂ group. An unprotected α-NH₂, however, cannot remove Dde from an ε-NH₂ function. This migration takes place during Fmoc removal from the ε-NH₂ with piperidine and/or during the subsequent washing steps. The Dde migration is also possible in neat dimethylformamide by a direct nucleophilic attack of the free ε-NH₂ group. Addition of piperidine to the reaction medium accelerates the side reaction, probably because of the formation of an unstable piperidine-Dde adduct. Dde migration can he prevented if the 9-fluorenylmethyloxycarbonyl is cleaved with 1,8-diazabicyclo[5,4,0]undec-7-ene for a short reaction time (2%, 3 × 3 min). Finally, this rearrangement is shown to occur both as an intra- and intermolecular reaction between peptides on the same resin bead.     

Post-mortem Changes After Lead Extraction From the Ovine Coronary Sinus and Great Cardiac Vein

We investigated in sheep, non-thoracotomy extraction of leads which had been chronically implanted in the right atrium (RA), coronary sinus/great cardiac vein (CS / GCV) and right ventricle (RV) for atrial implantable defibrillation. Clinical success of extraction as well as gross and histologic findings in the heart are reported. Six of nine sheep had successful extractions. The major complication was laceration of the wall of the great coronary vein with hemorrhage into the pericardial space and cardiac tamponade. Tissue damage included several reversible changes: intra-tissue hemorrhage, thrombosis in the veins, and some necrosis of fat, vascular wall and myocardium. Myocyte necrosis was estimated as 0.03 to 0.3 grams of tissue. Osseous and cartilaginous metaplasia was more common around the RA lead than the CS/GCV lead. In cases where the lead must be removed, removal from the venous insertion site using lead extraction equipment should only be attempted with surgical back-up for emergency thora-cotomy to control hemorrhage in the event of vessel laceration. Safer explantation of these leads from the vein entry site will require the development of new extraction procedures.     

Systolic and Diastolic Function with Alternate and Combined Site Pacing in the Right Ventricle

We hypothesized that pacing at two ventricular sites simultaneously would activate the myocardium more rapidly and improve ventricular function. We studied the effect of pacing at the right ventricular outflow tract (RYOT) and the RV apex (EVA) on systolic and diastolic function. In 14 patients with a reduced systolic ejection fraction < 40% (mean EF 32%±4%)we measured RV pressures, left ventricular pressures, EF, cardiac output, peak dP/dt, peak negative dP/dt, and the time constant of relaxation, Tau, during intrinsic rhythm, atrial pacing and DVI pacing at the RVA, the RVOT, and both RV sites combined in random order. Repeated measures analysis of variance showed no significant differences in any of these parameters. The highest absolute values of dP/dt were observed during sinus rhythm and the lowest with RVA pacing. This parameter tended to improve progressively with pacing in the RVOT and at both sites. Peak negative dP/dt showed a similar nonsignificant trend. Conclusion: These data suggest that in patients with poor LV function, there may be subtle improvements in diastolic and systolic function with pacing in the RVOT and at combined sites in the RV compared to traditional RVA pacing.