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

European Association of Cardio-Thoracic Surgery (EACTS) expert consensus statement on perioperative myocardial infarction after cardiac surgery

Cardiac surgery may lead to myocardial damage and release of cardiac biomarkers through various mechanisms such as cardiac manipulation, systemic inflammation, myocardial hypoxia, cardioplegic arrest and ischaemia caused by coronary or graft occlusion. Defining perioperative myocardial infarction (PMI) after cardiac surgery presents challenges, and the association between the current PMI definitions and postoperative outcomes remains uncertain. To address these challenges, the European Association of Cardio-Thoracic Surgery (EACTS) facilitated collaboration among a multidisciplinary group to evaluate the existing evidence on the mechanisms, diagnosis and prognostic implications of PMI after cardiac surgery. The review found that the postoperative troponin value thresholds associated with an increased risk of mortality are markedly higher than those proposed by all the current definitions of PMI. Additionally, it was found that large postoperative increases in cardiac biomarkers are prognostically relevant even in absence of additional supportive signs of ischaemia. A new algorithm for PMI detection after cardiac surgery was also proposed, and a consensus was reached within the group that establishing a prognostically relevant definition of PMI is critically needed in the cardiovascular field and that PMI should be included in the primary composite outcome of coronary intervention trials.

Hypothermia-induced accelerated idioventricular rhythm after cardiac surgery; a case report

BACKGROUND

Accelerated idioventricular rhythm (AIVR) is a slow ventricular arrhythmia, commonly due to myocardial ischemia in coronary artery disease. It is a transitory rhythm that rarely causes hemodynamic instability or necessitates any specific therapy. Besides, the common predisposing factors for ventricular arrhythmias after open-heart surgery are hemodynamic instability, electrolyte imbalances, hypoxia, hypovolemia, myocardial ischemia and infarction, acute graft closure, reperfusion injury, and administration of inotropes and antiarrhythmic drugs. Here we report a case of AIVR after cardiac surgery, mostly due to hypothermia that to our knowledge, it is the first report.

CASE PRESENTATION

We describe a 76-year-old man presenting with typical chest pain. Following routine investigations, the patient underwent coronary artery bypass grafting. Postoperatively, he was transferred to the intensive care unit with good hemodynamic status. However, about 3 h later, he developed rhythm disturbances, leading to hemodynamic instability without response to volume replacement or inotropic support. His rhythm was AIVR, although, at first glance, it resembled the left bundle branch block. Given his unstable hemodynamic status, he was emergently transferred to the operating room. Cardiopulmonary bypass (CPB) was resumed for hemodynamic support. After the patient was rewarmed to about 35 ºC, AIVR returned to normal. He was weaned from CPB successfully and with an uneventful hospital course.

CONCLUSIONS

Hypothermia is a potential cause of rhythm disturbance. Preventing the causes of arrhythmias, including hypothermia, is the best strategy.

Diagnostic dilemma of perioperative myocardial infarction after coronary artery bypass grafting: A review

Coronary artery bypass grafting (CABG) is one of the most commonly performed cardiac procedures in the United States (US) and Europe. In the US, perioperative morbidity and mortality related to CABG are below 5%. One of the most significant complications following CABG, however, is perioperative myocardial infarction (PMI). Cardiac biomarkers, intra- and post-operative echocardiography, and electrocardiography are routinely used to monitor for evidence of PMI. In this review, we seek to summarize how each of these modalities is used in the clinical setting to differentiate PMI from expected procedure-related changes, and how these findings impact patients' outcomes. We conclude that while no perfect diagnostic test for the detection of clinically meaningful PMI exists, using a combination of existing modalities with knowledge of expected post-procedure changes allows for early and reliable detection. Future development is needed to create more sensitive and specific modalities for the detection of PMI in patients undergoing CABG.

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

Introduction

Disturbances of the cardiac conduction system are frequent in the postoperative period of coronary artery bypass surgery. They are mostly reversible and associated with some injury of the conduction tissue, caused by the ischemic heart disease itself or by perioperative factors.

Objective

Primary: investigate the association between perioperative factors and the emergence of atrioventricular block in the postoperative period of coronary artery bypass surgery. Secondary: determine the need for temporary pacing and of a permanent pacemaker in the postoperative period of coronary artery bypass surgery and the impact on hospital stay and hospital mortality.

Methods

Analysis of a retrospective cohort of patients submitted to coronary artery bypass surgery from the database of the Postoperative Heart Surgery Unit of the Sao Lucas Hospital of the Pontifical Catholic University of Rio Grande do Sul, using the logistic regression method.

Results

In the period from January 1996 to December 2012, 3532 coronary artery bypass surgery were carried out. Two hundred and eighty-eight (8.15% of the total sample) patients had atrioventricular block during the postoperative period of coronary artery bypass surgery, requiring temporary pacing. Eight of those who had atrioventricular block progressed to implantation of a permanent pacemaker (0.23% of the total sample). Multivariate analysis revealed a significant association of atrioventricular block with age above 60 years (OR=2.34; CI 95% 1.75-3.12; P<0.0001), female gender (OR=1.37; CI 95% 1.06-1.77; P=0.015), chronic kidney disease (OR=2.05; CI 95% 1.49-2.81; P<0.0001), atrial fibrillation (OR=2.06; CI 95% 1.16-3.66; P=0.014), functional class III and IV of the New York Heart Association (OR=1.43; CI 95% 1.03-1.98; P=0.031), perioperative acute myocardial infarction (OR=1.70; CI 95% 1.26-2.29; P<0.0001) and with the use of the intra-aortic balloon in the postoperative period of coronary artery bypass surgery (OR=1.92; CI 95% 1.21-3.05; P=0.006). The presence of atrioventricular block resulted in a significant increase in mortality (17.9% vs. 7.3% in those who did not develop atrioventricular block) (OR=2.09; CI 95% 1.46-2.99; P<0.0001) and a longer hospital stay (12.75 days x 10.53 days for those who didn't develop atrioventricular block) (OR=1.01; CI 95% 1.00-1.02; P=0.01).

Conclusions

In most cases, atrioventricular block in the postoperative period of coronary artery bypass surgery is transient and associated with several perioperative factors: age above 60 years, female sex, chronic kidney disease, atrial fibrillation, New York Heart Association functional class III or IV, perioperative acute myocardial infarction and use of an intra-aortic balloon. Its occurrence prolongs hospitalization and, above all, doubles the risk of mortality.

Synthesis of AApeptides

The creation and development of nonnatural peptidomimetics has become an area of increasing significance in bioorganic and chemical biology. A wide range of new peptide mimics with novel structures and functions are urgently needed to be explored in order to identify potential drug candidates and targeted probes, and to study protein functions. AApeptides are a new class of peptide mimics based on chiral PNA backbone. They are resistant to proteolytic degradation and have limitless potential for diversification. They have been found to have a wide variety of biological applications including cellular translocation, disruption of protein-protein interactions, formation of nanostructures, antimicrobial activity, etc. The synthesis of AApeptides is modular and straightforward. In this chapter, methods for the synthesis of AApeptides (including different subclasses) are described.

Design and synthesis of AApeptides: a new class of peptide mimics

A new family of peptide mimics termed 'AApeptides', which are oligomers of N-acylated-N-aminoethyl amino acids, was proposed. The design and efficient synthesis of AApeptides are described. As proof-of-the-concept, we show that AApeptides can inhibit p53/MDM2 protein-protein interaction with significant activity (IC(50)=38 μM) and specificity. Preliminary data also demonstrates that AApeptides are resistant to enzymatic hydrolysis. With the ease of synthesis and diversification, potent bioactivity, and resistance to proteolysis, the development of sequence-specific AApeptides may expand the potential biomedical applications of peptidomimetics.

QRS duration and early hemodynamic instability after coronary revascularization surgery

INTRODUCTION AND OBJECTIVES

The duration of the QRS interval measured by ECG is a marker of ventricular dysfunction and indicates a poor prognosis. Its value in patients undergoing coronary revascularization surgery has not been established.

METHODS

The study involved 203 consecutive patients (age 64+/-9 years, 74% male) scheduled for elective coronary surgery. The maximum QRS duration measured on a preoperative 12-lead ECG was recorded. Hemodynamic instability was defined as the occurrence of cardiac death, heart failure, or a need for intravenous inotropic drugs or intra-aortic balloon counterpulsation during the postoperative period.

RESULTS

The occurrence of hemodynamic instability (n=94, 46%) was associated with a longer preoperative QRS duration (97.5+/-21.14 ms vs 88.5+/-16.9 ms; P=.001). The QRS duration was also longer in patients who developed heart failure (n=23; 104.3+/-22.9 ms vs. 91.1+/-18.5 ms; P=.002), needed inotropic drugs (n=77; 96.5+/-20.5 ms vs. 90.1+/-18.2 ms; P=.007) or developed postoperative atrial fibrillation (n=58; 98.2+/-23.8 ms vs. 90.4+/-17.0 ms; P=.018). Bundle branch block was associated with a greater need for intra-aortic balloon counterpulsation (29% vs 12%; P=.012) or inotropic drugs (58% vs 35%; P=.014) and a higher incidence of hemodynamic instability (69% vs 42%; P=.006). Multivariate analysis identified the following independent predictors of hemodynamic instability: QRS duration (adjusted odds ratio [OR] per 10 ms=1.49; 95% confidence interval [CI], 1.11-2; P=.007), the lack of an arterial graft (OR=3.6; 95% CI, 1.14-11.6; P=.029) and extracorporeal circulation time (OR per min=1.013; 95% CI, 1.003-1.023; P=.013).

CONCLUSIONS

The intraventricular conduction delay, or QRS duration, was associated with a higher risk of postoperative hemodynamic instability following coronary surgery.