Fascicular Conduction Disturbances After Coronary Artery Bypass Surgery: A Review With a Meta-Analysis of Their Long-term Significance

Abstract

Fascicular conduction abnormalities are frequently reported following adult cardiac surgery, but their pathogenesis and long-term outcomes remain unclear. In this article, we review the epidemiological features, pathogenesis, diagnosis, and management, and the short-term and long-term significance of fascicular conduction abnormalities following coronary artery bypass graft (CABG) surgery, based on data from 30 studies. Conduction disturbances have an incidence of 3.4% to 55.8% after CABG surgery, the most common being right bundle branch block (RBBB). RBBB is usually transient and benign. Although a slew of factors have been implicated in the pathogenesis of fascicular conduction disturbances, the two most important factors are myocardial ischemia and type of cardioplegia. While a 12-lead electrocardiogram is the gold standard for diagnosis, additional tests such as myocardial enzymes or echocardiography may have additional diagnostic and prognostic value. Short-term prognosis after RBBB is good, but its impact on long-term survival is unclear. We conducted a meta-analysis, the first of its kind in this area, using long-term survival data from five studies. There was no difference in long-term survival between patients who developed conduction disturbances after CABG surgery, and those who did not, indicating a benign influence of conduction disturbances on long-term survival, and the lack of the necessity for monitoring or pacing. While the older literature reported an adverse impact of fascicular conduction disturbances on long-term survival, the more recent studies report a substantially reduced mortality after CABG surgery, despite a higher incidence of conduction disturbances, pointing to the effect of improved surgical techniques.

Atrioventricular block in coronary artery bypass surgery: perioperative predictors and impact on mortality

“…Previous studies have reported an incidence of conduction disturbances (CD) after CABG that varies from 18 to 55% of cases [ 1 - 6 ] , with the right bundle branch block being the most common [ 4 ] . Atrioventricular block (AVB) is one of these conduction disturbances and its incidence ranges from 0.5 to 16% [ 3 , 5 - 9 ] .…”

“…The etiology of AVB seems to be multifactorial. The patient's age (>60 years), hypertension, number of revascularized vessels, aortic clamping time, total time of CPB, use of digitalis and beta-blockers, type of cardioplegia and previously existing left bundle branch block may be related to its appearance [ 1 - 4 , 8 , 9 , 13 , 14 ] .…”

“…Myocardial ischemia seems to be the factor that is most implicated in the emergence of AVB, since there is a correlation with coronary artery disease (CAD) and preoperative AMI [ 4 ] . Studies [ 3 , 10 ] have demonstrated that perioperative AMI also increases the incidence of AVB in the PO of CABG.…”

“…As such, the perfusion injury determined by the myocardial ischemia and the hypothermic injury caused by the cardioplegic solution are the mechanisms that are most involved in the genesis of AVB, acting on the proximal portions of the bundle of His, which are more sensitive to this type of aggression than the more distal conduction tissue, determining the emergence of bundle branch blocks and increasing the risk of AVB [ 4 ] .…”

AApeptides as a New Class of Peptidomimetics to Regulate Protein-Protein Interactions

“…Compared to traditional peptides, peptidomimetics have great proteolytic and metabolic stability and are believed to be less immunogenic, also with an enhanced bioavailability (Patch et al 2002;Goodman et al 2007;Wu et al 2008). The development of peptidomimetics to disrupt MDM2/p53 has led to a diverse set of oligomers such as -peptides (Seebach et al 1996;Cheng et al 2001;Kritzer et al 2005), -and -peptides (Arndt et al 2004;Trabocchi et al 2005;Kumbhani et al 2006), / -peptides (Horne et al 2008;Horne et al 2009), azapeptides (Graybill et al 1992;Lee et al 2002), -aminoxy-peptides (Li et al 2008), sugar-based peptides (Risseeuw et al 2007;Tuwalska et al 2008), peptoids (Simon et al 1992), oligoureas (Boeijen et al 2001;Violette et al 2005), polyamides (Dervan 1986), and phenylene ethynylenes (Nelson et al 1997), etc. Nonetheless, the development of peptidomimetics is far less straightforward, with the major limit lying in the availability of framework (Goodman et al 2007).…”