To assess the effectiveness of bipolar epicardial atrial pacing using an active fixation bipolar endocardial lead implanted on the atrial surface in an experimental model.
A total of ten Large White ...adult pigs underwent pacemaker implantation under general anesthesia. Atrial pacing and sensing parameters were obtained at the procedure, immediate postoperative period and on the 7th and the 30th postoperative in unipolar and bipolar configurations.
All procedures were successfully performed. There were no perioperative complications and no early deaths. Atrial pacing and sensing parameters for both unipolar and bipolar modes remained stable throughout the study. We observed a progressive increase in atrial thresholds, ranging from 0.49 ± 0.35 (at implantation) to 1.86 ± 1.31 volts (30th postoperative day), in unipolar mode. Atrial impedance measurements decreased slightly over time, ranging from 486.80 ± 126.35 Ohms (at implantation) to 385.0 ± 80.52 Ohms (30th postoperative day). Atrial sensing measures remained stable from the immediate postoperative period until the end of the study.
The bipolar active fixation endocardial lead implanted epicardially can provide stable conditions of pacing and sensing parameters throughout the postoperative follow-up.
Background: The incidence of venous lesions following transvenous cardiac device implantation is high. Previous implantation of temporary leads ipsilateral to the permanent devices, and a depressed ...left ventricular ejection fraction have been associated with an increased risk of venous lesions, though the effects of preventive strategies remain controversial. This randomized trial examined the effects of warfarin in the prevention of these complications in high‐risk patients.
Method: Between February 2004 and September 2007, we studied 101 adults who underwent a first cardiac device implantation, and who had a left ventricular ejection fraction ≤0.40, or a temporary pacing system ipsilateral to the permanent implant, or both. After device implantation, the patients were randomly assigned to warfarin to a target international normalized ratio of 2.0–3.5, or to placebo. Clinical and laboratory evaluations were performed regularly up to 6 months postimplant. Venous lesions were detected at 6 months by digital subtraction venography.
Results: Venous obstructions of various degrees were observed in 46 of the 92 patients (50.0%) who underwent venography. The frequency of venous obstructions was 60.4% in the placebo, versus 38.6% in the warfarin group (P = 0.018), corresponding to an absolute risk reduction of 22% (relative risk = 0.63; 95% confidence interval = 0.013–0.42).
Conclusions: Warfarin prophylaxis lowered the frequency of venous lesions after transvenous devices implantation in high‐risk patients.
Cardiac resynchronization therapy consists of a promising treatment for patients with severe heart failure, but about 30% of patients do not exhibit clinical improvement with this procedure. However, ...approximately 10% of patients undergoing this therapy may have hyperresponsiveness, and three-dimensional echocardiography can provide an interesting option for the selection and evaluation of such patients.
Note: These guidelines are for information purposes and should not replace the clinical judgment of a physician, who must ultimately determine the appropriate treatment for each patient.
We aimed to identify, among Chronic Chagas Cardiomyopathy (CCC) patients with left ventricular dysfunction (LVD) and non-left bundle branch block (non-LBBB), subgroups with different functional and ...mechanical patterns of global longitudinal strain (GLS) and intraventricular dyssynchrony (IVD) at rest and after exercise stress test, and reclassify them using a new echocardiographic approach.
In this single-center cross-sectional study, 40 patients with CCC, left ventricular ejection fraction (LVEF) ≤ 35% and non-LBBB underwent rest echocardiography and then treadmill exercise stress echocardiography with GLS and IVD analysis. The sample was divided into four groups, based on GLS and IVD significant variation between rest and exercise: GLS + IVD+ (9 patients); GLS + IVD- (9 patients); GLS-IVD+ (10 patients); GLS-IVD- (10 patients).
At rest, median LVEF was 28% (21.3%–33%) and GLS (−7% (−5%/−9.3%), were not different among groups. The average response of GLS was an increase of 0.74% over rest values, and the average response of IVD was a decrease of 6.9 ms. Group GLS-IVD+ presented more dyssynchrony at rest (p = 0.01). Left atrial (LA) volume (higher in GLS-IVD-) (p = 0.022) and TAPSE (higher in GLS + IVD+) (p = 0.015) were also different among groups at baseline. Of the 40 patients evaluated, 27 (67.5%) had very severe LVD (GLS < −8%). In addition, among these patients, 11 patients had contractile reserve after undergoing stress echocardiography.
In patients with CCC, severe LVD and non-LBBB, the evaluation of GLS and IVD between rest and exercise was able to reclassify myocardial function and to identify subgroups with contractile reserve and significant dyssynchronopathy.
•Myocardial mechanics behavior at exercise differentiate four groups of Chagas cardiomyopathy patients•Evaluation of IVD on exercise refines findings of baseline ventricular dyssynchrony•Evaluation of GLS (rest and exercise) can reclassify myocardial function identifying subgroups with contractile reserve•Even among patients with severe left ventricular dysfunction, there was a subgroup with contractile reserve
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