Effects of right coronary artery PTCA on variables of P-wave signal averaged electrocardiogram

The influence of epidural anesthesia on the electrical activity of heart atria

Introduction

High thoracic epidural anesthesia (TEA) causes blockade of sympathetic fibers involved in innervation of the heart (segments T1-T4), which results in changes of cardiac electrophysiology. The anti-arrhythmic effects of TEA on supraventricular arrhythmias, mainly atrial fibrillation, are controversial.

The aim of the study

The aim of the study was to assess the influence of epidural anesthesia on the electrical function of heart atria, including proven markers of increased risk of perioperative atrial fibrillation, such as P wave dispersion and P wave maximum duration.

Material and methods

The study involved 50 male patients, without a history of previous heart diseases, scheduled for elective surgical procedures. Patients received thoracic epidural anesthesia (group T, n = 25) or lumbar epidural anesthesia (group L, n = 25). The measurements were obtained from a continuous recording of ECG before epidural anesthesia and after the detection of blockade (T1 or T8 segment sensory block in groups T and L, respectively).

Results

The statistical analysis of electrocardiographic parameters, including the maximum, minimum and mean P wave duration; P wave dispersion; the maximum, minimum and mean PR interval duration; and PR interval dispersion, did not show any inter- or intragroup differences at selected time points.

Conclusions

Regardless of its location, epidural anesthesia and sympathetic blockade associated with this procedure do not significantly affect the electrical functions of the cardiac atria reflected in superficial ECG, including the electrocardiographic parameters that are considered to be markers of increased risk of perioperative atrial fibrillation, such as P wave dispersion and its maximum duration.

Subocclusion of the sinus node artery during coronary angioplasty: arrhythmological considerations

We report the case of a 58-year-old man who developed atrial fibrillation as a result of iatrogenic subocclusion of a diseased sinus node artery, originating from the left circumflex artery (LCx), occurring during LCx stenting, suggestive of an ischemic etiology of sinus node dysfunction.

Post PCI atrial fibrillation

Atrial fibrillation (AF) is a major arrhythmia with a high prevalence among population. AF is not uncommon in the setting of coronary artery disease, including myocardial infarction (MI) and acute coronary syndromes (ACS). Percutaneous coronary interventions (PCI) have significantly improved outcomes of patients with acute MI and acute coronary syndromes. Nevertheless, the AF was reported to occur in patients with MI and ACS undergoing PCI. New onset AF after PCI for MI and ACS, though being infrequent, was associated with worse clinical course and prognosis. The predictive value of AF has tendency to change in parallel with improvements of reperfusion strategies and comprehensive treatment. Observational studies suggest better patency of culprit vessels achieved by PCI was accompanied by improvement in signal-averaged electrocardiography indices of atrial electrophysiological properties and higher rate of restoration of sinus rhythm during primary PCI as compared with thrombolysis. The adequate management of arrhythmia is required to reduce the risk of complications.

Angiographic localization of potential culprit coronary arteries in patients with interatrial block following a positive exercise tolerance test

Interatrial block (IAB), denoted by P waves > or =110 ms, is believed to be associated with underlying ischemia, particularly with that of its principal interatrial conduction pathway, the Bachmann bundle. We investigated if there is an angiographic association of IAB on electrocardiograms at rest in patients who underwent cardiac angiography after a positive exercise tolerance test (ETT) result. Twenty-seven patients with IAB and 42 control patients without IAB on electrocardiograms at rest who had evidence of ischemia on cardiac angiography after ETT were identified. Coronary vessels that were angiographically most significantly stenosed (> or =70% occlusion indicating stenosis) were noted for statistical comparison (a p value <0.05 was considered statistically significant). Among patients with IAB, the right coronary artery was the predominant vessel to be affected, with > or =70% narrowing compared with the left, inclusive of the left main, left circumflex, obtuse marginal, and diagonal coronary arteries (58% vs 23%, p = 0.03). Right coronary artery lesions in patients with IAB were mostly in the proximal and mid portions (54% vs 25% for the entire left coronary artery, p = 0.02). No such difference was noted in control subjects. In conclusion, in patients with IAB at rest who have coronary heart disease, the right coronary artery is predominantly more significantly affected.

Atrial fibrillation and revascularization procedures: clinical and prognostic significance. Incidence, predictors, treatment, and long-term outcome

Atrial fibrillation is the most common disorder of cardiac rhythm. In spite of simplicity of diagnosis, patients with atrial fibrillation are difficult to treat. In the recent years with the description of the phenomenon called remodelling, it has been possible to better define the principal mechanisms responsible for initiation, maintenance and, in some instances, termination of atrial fibrillation. Electrical, mechanical and anatomical remodelling indicate those alterations that, once established, may baffle any attempt to restore sinus rhythm. Atrial fibrosis is probably the most critical component of the remodelling process and appears to be mediated by several factors. Several kinds of arrhythmias, especially ventricular ones and conduction disturbances, can occur during percutaneous coronary interventions (PCI), resulting from excess catheter manipulation, intracoronary dye injection, new ischemic events, or reperfusion injury. Supraventricular arrhythmias, including atrial flutter and atrial fibrillation (AF), may also occur during or after PCI, as a complication or a sequel of the revascularisation procedure. Also post operative AF is a common complication of coronary artery bypass surgery (CABG), occurring in 5-40% of patients during the first postoperative week, depending on definitions and methods of detection. Experimental and clinical data will be discussed here.

[Atrial fibrillation]

Atrial fibrillation represents the arrhythmia that most frequently leads to hospital admission. Due to the age structure of our population and the increasing morbidity and comorbidity, one has to assume that this arrhythmia will reach an even higher prevalence. The therapeutic successes are often insufficient. First of all, it is important to diagnose and treat the underlying disease. Secondly, antiarrhythmic therapy has to be considered in symptomatic patients. In those patients and in the case of a persistent form, electrical cardioversion should be performed. Repetitive cardioversions in asymptomatic patients yield no advantage for mortality. Antiarrhythmic therapy consists of drugs of the classes Ia, Ic, and III. Concomitant anticoagulation is necessary; ASS in indicated only in patients without structural heart disease and lacking thromboembolic risk factors. If risk factors are present, effective therapy with coumarin derivatives is required. Therapy with ACE inhibitors and AT blockers leads to an advantage in patients with arterial hypertension and/or heart failure concerning the stability of sinus rhythm after cardioversion and the incidence of arrhythmia. Newer medications for anticoagulation and newer antiarrhythmic drugs raise the hope of a future therapy with higher efficacy and lower rate of side effects.

Atrial fibrillation after percutaneous coronary intervention: predictive importance of clinical, angiographic features and P-wave dispersion

Atrial fibrillation (AF) may occur during or after percutaneous coronary interventions (PCI). The purpose of the study was to determine the clinical, angiographic and electrophysiological predictors of AF after PCI. 225 patients undergoing PCI (mean age of 65 +/- 11 years) who had sinus rhythm (SR) before balloon inflation were taken to study. Of these 22 developed AF in catheterization laboratory after balloon inflation or in 24 h following PCI (AF group), 203 did not (SR group). The patients in AF group were older (67 +/- 9 vs. 63 +/- 8 years, p < 0.05) and their ventricular ejection fraction was lower than SR group (56 +/- 5 vs. 45 +/- 7%, p < 0.05). The P-wave dispersion was significantly higher in AF group than SR group (53 +/- 8 vs. 29 +/- 10 ms, p < 0.001). For the patients with ST elevation myocardial infarction, the time from the onset of symptoms to balloon inflation was 3.7 +/- 1.7 h in SR group. It was longer in AF group (4.1 +/- 1.8 h, p < 0.05). TIMI perfusion grades 2 and 3 were achieved in 23 of 27 patients in SR group, and 5 of 8 patients in AF group. Multivessel disease was documented in 93 of the patients in SR group, and 12 in AF group. Clinical reperfusion was thought to be established in 20 in SR group, and 4 in AF group. In conclusion, our results show the importance of clinical factors, angiographic results and P-wave analysis in prediction of AF following PCI.

Tachyarrhythmias in percutaneous coronary interventions

Accompanying the clear benefits, there are certain risks of tachyarrhythmias in percutaneous coronary interventions (PCI), including serious ventricular arrhythmias and atrial fibrillation (AF). Ventricular arrhythmias may result from excess catheter manipulation, intracoronary dye injection, new ischemic events, or reperfusion. In patients with heart failure such kind of arrhythmias can occur more frequently. Atrial dysfunction, sino-atrial and nodal ischemia, congestive heart failure, sympathetic stimulation, iatrogenic factors are the possible causes of AF especially in patients undergoing primary PCI. Atrial fibrillation, on the other hand, can cause clinical squeal in the setting of a rapid ventricular response or if the loss of atrial systole results in hypotension, as in a patient with mitral stenosis or diastolic ventricular dysfunction. Majority of the ventricular arrhythmias and AF tend to revert spontaneously. However, the special treatment must be given, when necessary.

Prediction of the recurrence of atrial fibrillation after successful cardioversion with P wave signal-averaged ECG

BACKGROUND

The recurrence of atrial fibrillation (AF) was often observed after cardioversion.

METHODS

In our study, a P wave triggered P wave signal-averaged ECG (P-SAECG) was performed on 118 consecutive patients 1 day after successful electrical cardioversion in order to evaluate the utility of this method to predict AF after cardioversion. We measured the filtered P wave duration (FPD) and the root mean square voltage of the last 20 ms of the P wave (RMS 20).

RESULTS

During a 1-year follow-up, a recurrence was observed in 57 patients (48%). Patients with recurrence of AF had a larger left atrial size (41.9 +/- 4.0 vs 39.3 +/- 3.1 mm, P < 0.0003), a longer FPD (139.6 +/- 16.0 vs 118.2 +/- 14.1 ms, P < 0.0001), and a lower RMS 20 (2.57 +/- 0.77 vs 3.90 +/- 0.99 microV, P < 0.0001). A cutoff point (COP) of FPD > or =126 ms and RMS 20 < or =3.1 microV could predict AF with a specificity of 77%, a sensitivity of 72%, a positive value of 75%, a negative predictive value of 75%, and an accuracy of 75%. A stepwise logistic regression analysis of variables identified COP (odds ratio 9.97; 95% CI, 4.10-24.24, P < 0.0001) as an independent predictor for recurrence.

CONCLUSIONS

We conclude that the probability of recurrence of AF after cardioversion could be predicted by P-SAECG. This method seems to be appropriate to demonstrate a delayed atrial conduction that might be a possible risk factor of reinitiation of AF.

Prediction of atrial fibrillation after coronary artery bypass grafting: The role of chemoreflexsensitivity and P wave signal averaged ECG

Atrial fibrillation (AF) after coronary artery bypass grafting (CABG) results in a prolonged hospital stay associated with higher costs. In our study P wave triggered P wave signal averaged ECG and chemoreflex-sensitivity (CHRS) was performed on 101 consecutive patients with sinus rhythm before CABG in order to evaluate the utility of these methods to predict AF. A CHRS below 3.0 ms/mm Hg was predefined as a pathological CHRS. Postoperative AF was observed in 37 (37%) of 101 patients. Patients with AF were older (68.4+/-6.9 vs. 63.8+/-9.4 years, p<0.01), had a longer filtered P-wave duration (FPD) (133.6+/-10.2 vs. 123.6+/-14.9 ms, p<0.0001), a lower root mean square voltage of the last 20 ms of the P wave (RMS 20) (2.86+/-0.88 vs. 5.10+/-2.73 microV, p<0.0001) and a significantly lower CHRS (3.32+/-1.83 vs. 4.17+/-2.19 ms/mm Hg, p<0.05). A cut-off point (COP) of FPD> or =124 ms and RMS 20< or =3.7 microV achieved a specificity of 75%, a sensitivity of 78%, a negative predictive value of 86%, a positive predictive value of 64% and an accuracy of 76% for prediction of AF. The predictive power was lower for a pathological CHRS which achieved a specificity of 63%, a sensitivity of 60%, a negative predictive value of 73%, a positive predictive value of 48% and an accuracy of 61%. A stepwise logistic regression analysis of all preoperative variables identified COP (odds ratio 8.21; 95% CI, 2.02-33.37, p<0.003) as independent predictor. Patients with postoperative AF stayed longer in the intensive care unit (2.9+/-1.7 vs. 1.3+/-0.5 days, p<0.0001) and in hospital (13.5+/-4.3 vs. 11.4+/-1.1 days, p<0.0004). The results of our study show that the risk for AF after CABG could preoperatively be predicted with P wave signal averaged ECG and an analysis of CHRS. The predictive power of the COP could be used for a preoperative risk stratification and a corresponding prophylactic therapy in order to reduce costs.

P wave signal averaged ECG and chemoreflexsensitivity in paroxysmal atrial fibrillation

Detailed analysis of the QRS-complex and autonomic dysfunction can identify patients at risk to suffer from ventricular arrhythmias. To determine whether patients at risk for paroxysmal atrial fibrillation (PAF) could be identified while in sinus rhythm, a P wave triggered signal averaged ECG and an analysis of the autonomic function by chemoreflexsensitivity (CHRS) were examined. The ratio between the difference of RR intervals in the ECG and the venous partial pressure of oxygen before and after 5-min oxygen inhalation was measured for the determination of CHRS. We examined 224 patients (group A) who suffered from PAF, 250 patients (group B) without arrhythmic history and 30 young volunteers (group C). The filtered P wave duration (FPD) was significantly longer in group A than in group B (140.9+/-21.0 vs. 118.2+/-9.4 ms, p<0.0001) or C (105.2+/-14.1 ms, p<0.0001) while the root mean square voltage of the last 20 ms of the P wave (RMS 20) was significantly lower in group A than in group B (2.68+/-1.12 vs. 4.06+/-1.57 microV, p<0.0001) or C (3.97+/-1.36 microV, p<0.0001). Atrial late potentials (ALP) were defined as a FPD>120 ms and a RMS 20< or =3.5 microV. ALP could identify patients of group A with a specificity of 78% and a sensitivity of 83%. Patients with PAF (2.32+/-1.15 ms/mm Hg) showed a significantly lower CHRS than group B (4.14+/-1.58 ms/mm Hg, p<0.0001) or group C (4.98+/-1.51 ms/mm Hg, p<0.0001). The sensitivity for the presence of atrial fibrillation was 71% for a CHRS below 3.0 ms/mm Hg with a specificity of 70%. A combination of both methods showed a specificity of 85% and a sensitivity of 65% when ALP and pathological CHRS were present. The results of our study suggest that risk of atrial fibrillation could be detected by P wave signal averaged ECG and CHRS. An analysis of CHRS seems to be an appropriate method to demonstrate a neurovegetative imbalance, which might be one possible trigger mechanism.