Implanted atrial pacemakers for paroxysmal atrial flutter. Long-term efficacy

Five patients with drug-resistant paroxysmal atrial flutter received permanent burst atrial pacemakers for the treatment of tachycardia. All patients had extensive electrophysiologic evaluations to determine the safety and efficacy of atrial pacing. The absence of prolonged spontaneous or electrically induced atrial fibrillation was also documented in all patients. Three pulse generators were patient activated (nonautomatic) and two were multiprogrammable and automatic. The atrial pacemakers terminated many attacks of paroxysmal atrial flutter safely and reliably in a follow-up period ranging from 24 to 60 months (average, 42). No major complications developed. In four patients, concomitant drug therapy was necessary, although to a lesser degree, to reduce the frequency of attacks and the ventricular rate. Our study documents the long-term efficacy and low risk associated with permanent-burst atrial pacing in the treatment of drug-refractory paroxysmal atrial flutter in selected patients.     

Significance of QRS complex duration in patients with heart failure.

Prolongation of QRS (> or =120 ms) occurs in 14% to 47% of heart failure (HF) patients. Left bundle branch block is far more common than right bundle branch block. Left-sided intraventricular conduction delay is associated with more advanced myocardial disease, worse left ventricular (LV) function, poorer prognosis, and a higher all-cause mortality rate compared with narrow QRS complex. It also predisposes heart failure patients to an increased risk of ventricular tachyarrhythmias, but the incidence of cardiac or sudden death remains unclear because of limited observations. A progressive increase in QRS duration worsens the prognosis. No electrocardiographic measure is specific enough to provide subgroup risk categorization for excluding or selecting HF patients for prophylactic implantable cardioverter-defibrillator (ICD) therapy. In ICD patients with HF, a wide underlying QRS complex more than doubles the cardiac mortality compared with a narrow QRS complex. There is a high incidence of an elevated defibrillation threshold at the time of ICD implantation in patients with QRS > or =200 ms. Mechanical LV dyssynchrony potentially treatable by ventricular resynchronization occurs in about 70% of HF patients with left-sided intraventricular conduction delay, a fact that would explain the lack of therapeutic response in about 30% of patients subjected to ventricular resynchronization according to standard criteria relying on QRS duration. The duration of the basal QRS complex does not reliably predict the clinical response to ventricular resynchronization, and QRS narrowing after cardiac resynchronization therapy does not correlate with hemodynamic and clinical improvement. Mechanical LV dyssynchrony is best shown by evolving echocardiographic techniques (predominantly tissue Doppler imaging) currently in the process of standardization.     

VDD pacemaker replacement is safe and reliable independently of the previously implanted lead: A prospective and controlled study

Theoretically, replacement of a VDD device requires using a similar pacemaker to provide the best match between the filtering characteristics of the pacemaker and the atrial dipole of the lead. This study evaluated the performance of newly implanted Vitatron VDD pacemakers connected to dedicated leads and compared the results with those of the same Vitatron pacemakers used as replacement but connected to a variety of nondedicated leads. Methods: 23 consecutive patients (15 M, 8 F, 78 ± 6 years) in Group 1 underwent pacemaker replacement with a VDD(R) Saphir 3 (Vitatron BV, Arnhem, The Netherlands) device designed for an 8.6 mm atrial dipole. Atrial dipoles of the previously implanted leads ranged from 5 to 30 mm. Another 22 consecutive patients (14 M, 8 F, 80 ± 7 years) in Group 2 received a Saphir 3 pacemaker with the related dedicated lead. Results: P-wave amplitude measured by the same Pacing Sensing Analyzer (PSA) at the first implantation was 1.7 ± 0.8 vs. 1.7 ± 0.5 mV (P = NS) in groups 1 and 2 respectively. P-wave amplitudes measured at 1 month follow-up after replacement in Group 1 and at 1 month follow-up after implantation in Group 2 were 0.69 ± 0.5 vs. 0.85 ± 0.3 mV (P = NS) respectively. The percentage of atrial sensing at the same follow-up was 97 ± 3 vs. 95 ± 5% (P = NS) in groups 1 and 2 respectively. Conclusions: Replacement of VDD pacemakers with the Saphir 3 model designed for a short dipole is safe and reliable when used in combination with previously implanted nondedicated leads.     

Intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block

A patient is described who had intermittent tachycardia-dependent combined right bundle branch and left anterior conduction block (left axis deviation) with simultaneous onset and disappearance during observations extending over 15 months. Although the site of conduction block could not be definitely determined the pathologic and electrophysiologic data suggest that there was a lesion in the distal part of the His bundle, presumably in fibers already arranged and predestined to supply the right bundle branch and left anterior areas. A single lesion at the so-called pseudobifurcation or two separate lesions with similar electrophysiologic consequences could also account for the observations.     

High-intensity focused ultrasound extracorporeal ablation of liver tissues in rabbits

ＨｉｇｈｉｎｔｅｎｓｉｔｙｆｏｃｕｓｅｄｕｌｔｒａｓｏｕｎｄｅｘｔｒａｃｏｒｐｏｒｅａｌａｂｌａｔｉｏｎｏｆｌｉｖｅｒｔｉｓｓｕｅｓｉｎｒａｂｂｉｔｓＣＨＥＮＧＳｈｕＱｕｎ１，ＺＨＯＵＸｉｎＤａ１，ＴＡＮＧＺｈａｏＹｏｕ１，ＹＵＹａｏ１，Ｂ...     

B cell growth factor-induced proliferation of hairy cell lymphocytes and inhibition by type I interferon in vitro

Malignant B cells from hairy cell leukemia (HCL) patients are unable to proliferate when stimulated with standard B cell mitogens. Using chromatographically purified B cell growth factor (BCGF), HCL can be stimulated to proliferate as assessed by incorporation of tritiated thymidine [3HTdR] into DNA. Proliferation was found to be time dependent, with no detectable 3H-TdR incorporation in up to three days of culture, and significant stimulation evident at days 6 and 10. The presence of 10% BCGF in culture was an absolute requirement for HCL proliferation; however, this BCGF-induced DNA synthesis could be further augmented by the addition of anti-immunoglobulin heavy chain antibodies. BCGF-induced proliferation was abrogated in six of six patients by addition of 1,000 U/mL of recombinant alpha 2-interferon (IFN) at day 0, although 1,000 U/mL of recombinant gamma-IFN had no inhibitory effect in five of six patients studied. Specific cellular receptors for type I IFN were demonstrated in HCL by inhibition of binding of 125I-alpha 2-IFN by a 40-fold excess of unlabeled alpha 2 or beta IFN with no inhibition by unlabeled gamma-IFN. These data demonstrate that malignant HCL lymphoblasts express specific type I IFN receptors and that type I, but not type II IFN, can inhibit growth factor-induced DNA synthesis by hairy cells in vitro. They further suggest a direct antiproliferative mechanism of action for IFN in HCL and predict equivalent clinical activity by either alpha or beta, but not gamma IFN in this malignancy.     

热休克蛋白70、90基因在糖皮质激素抵抗型哮喘患者血单个核细胞中的表达

】