Grzegorz Suwalski

The effect of off-pump coronary artery bypass grafting on platelet activation in patients on aspirin therapy until surgery day §

OBJECTIVE Antiplatelet therapy is a class I indication in perioperative care after coronary artery bypass grafting to prevent graft occlusion. We sought to determine whether continuation of aspirin until surgery day suppresses platelet activity in the early period after off-pump coronary artery bypass grafting (OPCAB). MATERIAL AND METHODS Forty-two patients at mean age of 62.5 (+/-7.9) years were included. Average risk rate (EuroScore logistic) was 2.2 (+/-1.7) %. In all patients collagen/epinephrine stimulated platelet plug formation (closure time, CT) (CEPI-CT, s) using a platelet function analyzer (PFA-100), troponin I (TnI), creatine kinase-MB (CK-MB), ST segment elevation were evaluated a day before surgery, 4h after chest closure, 24 and 120 h after surgery. RESULTS Preoperative mean CEPI-CT was 224.8 (+/-79.7)s. In 13 (30%) patients aspirin resistance (CEPI-CT<163 s.) was observed. In 4, 24 and 120 h time points CEPI-CT was significantly reduced: 164.4 (+/-79), 168.5 (+/-83.3) and 167.5 (+/-80.4), respectively (p<0,001). TnI and CK-MB (ng/ml) levels raised in respective time points: 4 h (0.26 range 4; 1.9 range 6), 24 h (0.2 range 6; 2.6 range 8), 120 h (0.04 range 2; 0.6 range 5). ST segment elevation (mV) changed in time: 4h (0.7 range 3.5), 48 h (0.7 range 2.8) and 120 h after surgery (0.2 range 1.5). There were no significant correlations between CEPI-CT and TnI, CK-MB, ST segment elevation found. CONCLUSION Aspirin therapy continued until surgery day does not protect against acute platelet activation in patients after OPCAB.

Assessment of Nonlinear Heart Rate Dynamics after Beating-Heart Revascularization

BACKGROUND Advanced nonlinear methods of measuring heart rate variability (HRV) derived from the mathematics of complex dynamics and fractal geometry have provided new insights into the abnormalities of heart rate behavior in various pathologic conditions. These methods have provided additional prognostic information compared with traditional HRV measures and clearly have complemented the conventional linear methods. Knowledge about the behavior of complex cardiac dynamics indices after different cardiac procedures is very limited, however. We aimed to clarify how nonlinear heart rate dynamics are affected by beating-heart revascularization (off-pump coronary artery bypass graft [CABG] surgery) within the first week after the procedure. METHODS Included in the study were 66 patients who had isolated stable multivessel coronary artery disease and were in normal sinus rhythm. The patients were on chronic beta-blocker therapy and were scheduled for off-pump CABG. We performed 15-minute high-resolution electrocardiographic recordings preoperatively and on the third and seventh postoperative days to assess linear and nonlinear heart rate dynamics. Frequency-domain measurements, detrended fluctuation analysis (DFA) with short-term (<or=11 beats, alpha1) and long-term (>11 beats, alpha2) correlation properties of RR-intervals, and fractal dimension (FD) measurements (average, high, and low) were made. Arrhythmia was monitored preoperatively with 24-hour Holter recordings, postoperatively by continuous monitoring for the first 4 days after the procedure, and subsequently by clinical monitoring; 24-hour Holter recordings were obtained again on the seventh postoperative day. We used the paired-samples Student t test, the Mann-Whitney U test, and the Fisher exact test for statistical analyses. Differences in arrhythmia occurrence before and after the procedure were tested with the Wilcoxon signed rank test and the McNemar test. A P level < .05 was considered statistically significant. RESULTS Values for all frequency-domain parameters decreased significantly after off-pump CABG (P< .001). Values for the alpha1 and high FD parameters decreased significantly after the procedure (P= .028 and .001, respectively), whereas alpha2 increased significantly (P= .023). DFA alpha1 was significantly lower in patients with postoperative atrial fibrillation than in patients remaining in sinus rhythm (mean +/- SD, 0.79+/-0.32 versus 1.13+/-0.45 [P= .003] on the third postoperative day; 0.89+/-0.31 versus 1.22+/-0.34 [P< .001] on the seventh postoperative day), whereas low and average FDs were significantly higher (1.84+/-0.16 versus 1.68+/-0.19 [P= .003] on the third postoperative day and 1.77+/-0.18 versus 1.66+/-0.17 [P= .01] on the seventh postoperative day for the low FD; 1.83+/-0.09 versus 1.76+/-0.10 [P= .011] on the third postoperative day and 1.80+/-0.11 versus 1.73+/-0.10 [P= .014] on the seventh postoperative day for the average FD). The low FD was significantly higher on the third postoperative day in patients with postoperative deterioration of ventricular ectopy than in patients with improved ventricular ectopy (1.74+/-0.17 versus 1.48+/-0.08, [P= .03]). CONCLUSION The decreases in alpha1, average FD, and high FD indicate that a profound decay of cardiac complexity and fractal correlation can be observed after off-pump CABG. Furthermore, a more extensive impairment of nonlinear indices was observed in patients who developed postoperative arrhythmias than in those who remained in stable sinus rhythm. Our findings suggest that the postoperative hyperadrenergic setting acts as a preliminary condition in which both reduced and enhanced vagal activity may predispose patients to arrhythmia, indicating that postoperative rhythm disturbances are an end point associated with divergent autonomic substrates.

Ventricular arrhythmic disturbances and autonomic modulation after beating-heart revascularization in patients with pulmonary normotension.

SummaryBACKGROUND: De-novo ventricular arrhythmias are potentially life-threatening complications after beating-heart revascularization (off-pump CABG). Whether pulmonary hypertension can influence initiation of ventricular arrhythmias through increased sympathetic activity is controversial. In order to determine the influence of pulmonary hypertension on its relative contribution to ventricular arrhythmia, we first had to define the role of cardiac autonomic modulation in patients with pulmonary normotension. We aimed to observe how parameters of linear and nonlinear heart rate variability are changed pre- and postoperatively in patients with pulmonary normotension undergoing off-pump CABG. METHODS: Fifteen-minute ECG recordings were collected before and after off-pump CABG in 54 patients with multivessel coronary artery disease and pulmonary normotension to determine linear (TP, HF, LF, LF:HF ratio) and nonlinear detrended fluctuation analysis (α1, α2) and fractal dimension (average, high and low) parameters of heart rate variability. Arrhythmia was monitored preoperatively in 24-hour Holter recordings and postoperatively by continuous monitoring and clinical assessment. RESULTS: Deterioration from simple (Lown I–II) to complex (Lown III–V) ventricular arrhythmia was observed in 19 patients, and improvement from complex to simple arrhythmia in five patients (P = 0.022). Patients with postoperative deterioration of ventricular arrhythmia had preoperatively significantly lower values of TP, HF and LF (P = 0.024–0.043) and postoperatively significantly higher values on the low fractal dimension index (P = 0.031) than patients with postoperative improvement of arrhythmia. CONCLUSION: Patients experiencing postoperative deterioration of ventricular arrhythmia already have impaired autonomic regulation before surgery. Higher postoperative values on the low fractal dimension index indicate that sympathetic predominance with or without concomitant vagal withdrawal is the underlying neurogenic mechanism contributing to ventricular arrhythmia.

Short- versus long-term ECG recordings for the assessment of non-linear heart rate variability parameters after beating heart myocardial revascularization

Non-linear analyses of heart rate dynamics reveal subtle changes not evident from conventional heart rate variability measures. Traditionally, the information was inferred from 24-hour ECG recordings, making it less suitable for clinical application. Moreover, only few studies have attempted to evaluate the reliability of non-linear analyses in relation to varying proportion of artifacts in tracings. In 67 patients revascularized with beating-heart technique, fractal dimension and detrended fluctuation analyses were obtained from 24-hour Holter and 15-minute high-resolution ECG recordings pre and postoperatively. We found strong correlations of non-linear indices between 24-hour and 15-minute recordings (0.54-0.77, p<0.001), unaffected by proportion of artifacts.

Delayed Pulmonary Artery Perforation With Left Atrial Appendage Occluder Hooks

We describe a case of delayed pulmonary artery perforation with the anchoring hooks of the Amplazer Cardiac Plug (ACP) (St Jude Medical, MN), which occurred 17 days after its proper and uncomplicated implantation. The patient was successfully treated with a surgical procedure. Technologic improvement of the ACP anchoring system seems to be most rational solution necessary to eliminate the risk of the adverse event described here.

Early operative comparison of two epicardial left atrial appendage occluding systems applied during off-pump coronary revascularisation in patients with persistent atrial fibrillation

Introduction Atrial fibrillation (AF) increases long-term mortality and stroke rate in patients having coronary artery bypass grafting (CABG). Because oral anticoagulation (OAC) is associated with both a significant incidence of discontinuation and well known complication rates, left atrial appendage occlusion might be beneficial for stroke prevention. This study presents the first clinical and practical comparison of two epicardial left appendage occluders (LAAO) accruing experience in application during off-pump coronary revascularisation in patients with persistent AF. Material and methods Fifteen consecutive patients with persistent AF were assigned to intraoperative LAA occlusion with either TigerPaw System II (n = 8) or AtriClip (n = 7) device during off-pump CABG and concomitant left atrial epicardial ablation. Both systems were analysed in terms of ease and safety of application along with intraoperative LAA occlusion success. Results Surgical risk was increased in the study population (mean EuroScore II: 3.2 ± 0.3%). In all patients in the AtriClip group successful off-pump LAA occlusion confirmed by intraoperative transoesophageal echocardiography was achieved. The TigerPaw application was quicker and easier, but in 2 patients it was unsuccessful. During the hospital stay there were no bleeding or thromboembolic events recorded. Conclusions In a pilot cohort epicardial LAAO during off-pump CABG in patients with persistent AF was performed safely and successfully with an AtriClip device. The TigerPaw System requires technological improvement. It might be useful to adapt the use of the type of occluding device to the LAA morphologic type and target revascularisation vessels to avoid the additional use of a heart positioner or obviate coronary compression.

Left Atrial Ganglionated Plexi Detection is Related to Heart Rate and Early Recurrence of Atrial Fibrillation after Surgical Ablation

Introduction Left atrial ganglionated plexi ablation is an adjuvant technique used to increase the success rate of surgical ablation of atrial fibrillation. Ganglionated plexi ablation requires previous detection. We aimed to assess determinants of successful ganglionated plexi detection and to correlate range of ganglionated plexi ablation with risk of early atrial fibrillation recurrence. Methods The study involved 34 consecutive patients referred for surgical coronary revascularization with concomitant atrial fibrillation ablation. Ganglionated plexi detection was done by inducing vagal reflexes in the area of the pulmonary veins and left atrial fat pads. Results Detection of GP was successful in 85% of the patients. There was no difference in preoperative characteristics nor in atrial fibrillation type between patients in whom ganglionated plexi detection was successful and others. The number of detected ganglionated plexi correlated significantly only with preoperative resting heart rate. Significant negative correlation was found in patients with preoperative heart rate>75 beat/min in terms of total number of detected ganglionated plexi (P=0.04). Average number of detected ganglionated plexi was significantly higher in patients with in-hospital atrial fibrillation recurrence requiring electrical cardioversion (3.8±3) in comparison to rest of the study population (2±1.3; P=0.02). In patients in whom 4 or more ganglionated plexi were detected, significantly increased risk of in-hospital atrial fibrillation recurrence was observed (OR 15; 95% CI 1.5-164; P=0.003). Conclusion Left atrial ganglionated plexi detection was unsuccessful in a considerable percentage of patients. Preoperative heart rate significantly influenced positive ganglionated plexi detection and number of ablated ganglia. Higher number of detected ganglionated plexi was related with early recurrence of atrial fibrillation.

Successful surgical ablation of atrial fibrillation does not disturb long-term sinus rhythm variability

OBJECTIVES Surgical ablation of atrial fibrillation (AF) aims to restore normal sinus rhythm while protecting the sinus node from surgical damage. Surgical lesions may affect autonomic neural structures and influence physiological heart rate variability (HRV). The primary aim of this study was to describe long-term dynamics of HRV after successful surgical ablation of AF. The secondary aim was to compare sinus node function after successful ablation of AF with either left atrial modified Maze procedure or epicardial pulmonary vein isolation after long-term follow-up. METHODS This retrospective study included 75 patients who underwent successful ablation of paroxysmal or persistent AF (53 patients, 71%) and long-standing persistent AF (22 patients, 29%). Standard variables were selected to describe HRV and the minimal and mean heart rates. In all patients, a 24-h Holter ECG study was performed preoperatively, at hospital discharge and after 3, 6, 12 and 24 months. RESULTS A significant reduction in the main HRV parameters and an increase in heart rate were observed at discharge when compared with the preoperative period. During follow-up, all HRV parameters returned to preoperative levels. No significant differences were observed in HRV parameters and HR between the modified Maze and pulmonary vein isolation procedure groups at any time. CONCLUSIONS Successful surgical ablation of paroxysmal, persistent and long-standing persistent AF using either pulmonary vein isolation or modified left atrial Maze procedure does not disrupt long-term HRV. A significant early postoperative reduction in HRV with a gradual increase in the following months is typical in patients after surgical restoration of sinus rhythm.

Freedom from pulmonary vein stenosis after multiple applications of epicardial ablation energy

OBJECTIVES In patients undergoing cardiac surgical procedures, pulmonary vein isolation may be easily accomplished, and it is important to achieve bidirectional conduction block across created lesions. The primary aim of this study was to assess the risk of pulmonary vein stenosis (PVS) after multiple applications of epicardial bipolar radiofrequency energy. METHODS Thirty-five consecutive patients who were referred for off-pump coronary revascularization with concomitant pulmonary vein isolation and left atrial appendage occlusion were prospectively included in the study. The ablation protocol provided 8 standard epicardial applications of bipolar energy with additional applications until the acute bidirectional conduction block was achieved. Three to 6 months after surgery, patients underwent computed tomography to assess PVS. RESULTS In all patients, bidirectional conduction block was achieved across the created lesions. In 31 (89%) patients, conduction block was accomplished after the standard 8 energy applications on each side. In 4 (11%) patients, additional applications of energy were needed. All patients had computed tomography (128 total pulmonary veins) scans, which showed no evidence of PVS. CONCLUSIONS Multiple applications of bipolar radiofrequency energy during off-pump epicardial pulmonary vein isolation did not lead to PVS. Creating bidirectional conduction block using multiple energy applications through created lesions is feasible in all patients using the ablation protocol described.

Intraoperative epicardial focal pulmonary venous electrocardiography in patients with atrial fibrillation

OBJECTIVES In patients referred to off-pump coronary artery bypass grafting, pulmonary vein isolation (PVI) may be used for those with persistent atrial fibrillation (AF), an alternative to the Maze procedure. However, the success rate of PVI in persistent AF is limited. The study assesses the prognostic value of focal epicardial electrocardiography of the pulmonary veins (PVs) for surgical ablation results. METHODS We mapped 140 PV in 35 cases undergoing off-pump coronary artery bypass grafting. Data obtained using a sensing-pacing probe before ablation were analysed. The composite study end-point consisted of the need for electrical cardioversion for in-hospital recurrence of AF and the presence of AF at hospital discharge and after 6 months follow-up confirmed by 24-h Holter electrocardiographic monitoring. RESULTS In patients with epicardial far-field (FF) signals recorded over at least 1 PV, the composite end-point occurred in 61% (14) vs 25% (3) of patients with no FF signal recorded over any PV (P = 0.04). The presence of FF signals in at least 1 PV significantly increased the risk of composite end-point occurrence (odds ratio 3; P = 0.04). The composite end-point occurred in 86% (6) of patients with FF signals recorded over all PVs and in 39% (11) in the remainder of the study population (P = 0.03). CONCLUSIONS Intraoperative epicardial focal electrocardiography of PVs revealed more than 40% of PVs had only FF atrial signals. The presence of FF signals in PVs is related to a lower early effectiveness of PVI on ablating AF. Epicardial focal electrocardiography of PVs may be a clinically effective intraoperative tool in the decision-making process between less invasive PVI and the standard Maze procedure.