Search Results (4)

Background: In patients requiring dual-chamber pacemaker (DDD) implantation, optimal atrial lead position remains a matter of debate. While most centers prefer implantation in the right atrial appendage position (Non-BB-P), due to a speculated favorable impact on atrial conduction characteristics, often, a Bachman bundle pacing (BB-P) is recommended. However, data investigating clinical outcomes in these patients are still rare. Methods: To evaluate this issue, in this retrospective single-center study, one-year clinical follow-up, pacemaker interrogations and available echocardiography findings in 301 consecutive patients (BB-P: age 76 ± 10 years, 46.7% female, n = 169; Non-BB-P: 77.6 ± 9 years, 50% female, n = 132, p = n.s.) scheduled for dual-chamber implantation were analyzed. Results: During follow-up, the incidence of atrial fibrillation (AF) remained similar in both groups (BB-P: 38.3%, n = 154 vs. Non-BB-P: 34.2%, n = 117 p = n.s.). However, we detected significantly more mode switch episodes in the BB-P group (BB-P: 51.9%, n = 154 vs. Non-BB-P: 38.8%, n = 116, p = 0.032). Furthermore, left ventricular functional parameters, including left ventricular ejection fraction (BB-P: 57.1 ± 8.4%, n = 60 vs. Non-BB-P: 56.0 ± 9.6, n = 45 p = n.s.) and incidence of diastolic dysfunction (BB-P: 55.2%, n = 67 vs. Non-BB-P: 38.3%, n = 47, p = n.s.), as well as the rate of left (BB-P: 58.8%, n = 68 vs. Non-BB-P: 42.0%, n = 50, p = n.s.) and right atrial dilatation (BB-P: 27.9%, n = 68 vs. Non-BB-P: 28.0%, n = 50 p = n.s.), were not significantly affected by the atrial lead position. However, stimulated p-waves were significantly shorter in BB-P vs. Non-BB-P (BB-P: 132.9 ± 23.7 ms, n = 127 vs. Non-BB-P: 139.6 ± 23.4 ms, n = 93, p = 0.031). Conclusions: In patients requiring dual-chamber implantation, the position of the atrial lead significantly altered atrial conduction, but this did not seem to affect left ventricular function parameters or the occurrence of atrial fibrillation within our follow-up period. Interestingly, we even detected more mode switch episodes in the BB-P group, hinting at an even proarrhythmic potential of BB-P. On the other hand, we found a decreased ventricular stimulation percentage in BB-P vs. Non-BB-P. Further studies should investigate the impact of Bachmann bundle pacing on clinical outcomes. Full article

Over the years, pacemakers have evolved from a life-saving tool to prevent asystole to a device to treat heart rhythm disorders and heart failure, aiming at improving both cardiac function and clinical outcomes. Cardiac stimulation nowadays aims to correct the electrophysiologic roots of mechanical inefficiency in different structural heart diseases. This has led to awareness of the concealed risks of customary cardiac pacing that can inadvertently cause atrioventricular and inter-/intra-ventricular dyssynchrony, and has promoted the development of new pacing modalities and the use of stimulation sites different from the right atrial appendage and the right ventricular apex. The perspective of truly physiologic pacing is the leading concept of the continued research in the past 30 years, which has made cardiac stimulation procedure more sophisticated and challenging. In this article, we analyze the emerging evidence in favor of the available strategies to achieve an individualized physiologic setting in bradycardia pacing. Full article

Aldehyde dehydrogenase 2 (ALDH2) is an enzyme that detoxifies reactive oxygen species (ROS)-generated aldehyde adducts such as 4-hydroxy-trans-2-nonenal (4-HNE). Previous meta-analyses have shown an increase in the risk of atrial fibrillation (AF) in patients with chronic alcohol consumption. ALDH2*2, a common dysfunctional polymorphism in the ALDH2 gene, has been linked to an increased risk of cancer and heart disease. We tested the effect of ALDH2 deficiency on alcohol-induced AF in a murine model of chronic-binge ethanol feeding, with ALDH2*2 knock-in (KI) mice generated by a CRISPR/CAS9 system. In addition, right atrial appendages were obtained from eight patients with AF undergoing open heart surgery. The results showed that burst atrial pacing induced a greater susceptibility to AF in ALDH2*2 KI mice exposed to chronic ethanol intoxication than in wild-type mice, resulting from a higher degree of 4-HNE accumulation and collagen deposition in their atria. Alda-1 attenuated transforming growth factor beta 1 (TGF-β1) expression and collagen deposition in the atria and reduced AF inducibility. Patients with AF and the ALDH2*2 allele exhibited greater oxidative stress and substrate remodeling in their atria than non-carriers. In conclusion, ALDH2 deficiency may increase the risk of chronic alcohol and tachypacing-induced AF through the accumulation of 4-HNE and increased ROS production. Full article

Matrix metalloproteinase (MMP) plays an important role in the pathogenesis of atrial fibrillation (AF). The MMP9 promoter has a functional polymorphism rs3918242 that can regulate the level of gene transcription. This study recruited 200 AF patients and 240 controls. The MMP9 rs3918242 was examined by polymerase chain reactions. HL-1 atrial myocytes were cultured and electrically stimulated. Right atrial appendages were obtained from six patients with AF and three controls with sinus rhythm undergoing open heart surgery. The MMP9 expression and activity were determined using immunohistochemical analysis and gelatin zymography, respectively. Rapid pacing induces MMP9 secretion from HL-1 myocytes in a time- and dose-dependent manner. The responsiveness of MMP9 transcriptional activity to tachypacing was significantly enhanced by rs3918242. The expression of MMP9 was increased in fibrillating atrial tissue than in sinus rhythm. However, the distribution of rs3918242 genotypes and allele frequencies did not significantly differ between the control and AF groups. HL-1 myocyte may secrete MMP9 in response to rapid pacing, and the secretion could be modulated by rs3918242. Although the MMP9 expression of human atrial myocyte is associated with AF, our study did not support the association of susceptibility to AF among Taiwanese subjects with the MMP9 rs3918242 polymorphism. Full article