Sinus Rhythm ECG Research Articles

Utility of transesophageal atrial pacing in the diagnostic evaluation of patients with unexplained syncope associated or not with palpitations

Background: Noninvasive studies are often negative in patients with syncope, normal surface ECG and without heart disease. The purpose of the study was to determine the diagnostic impact of an esophageal electrophysiological study performed during a consultation. Methods: A total of 154 patients aged from 16 to 87 years were consecutively recruited for unexplained syncope; they had a normal ECG in sinus rhythm, no documented arrhythmia and no patent heart disease. Half of them complained of palpitations. Electrophysiologic study was performed during a consultation by transesophageal route: rate of 2nd d AV block occurrence during atrial pacing and sinus node recovery time were determined; programmed atrial stimulation using one and two atrial extrastimuli were delivered in control state and then after infusion of 0.02–1 μg/min of isoproterenol; arterial blood pressure was monitored. Results: (1) Electrophysiologic study was positive in 107 patients (69%); (2) sinus node dysfunction was noted in 9 patients (6%); (3) atrioventricular conduction disturbances were noted in 2 patients (1%); (4) vasovagal reaction which associated a junctional bradycardia and a fall of arterial blood pressure and which reproduced spontaneous symptoms was provoked by isoproterenol infusion in 21 patients (14%); (5) sustained atrial fibrillation was induced in 23 patients (15%); and (6) paroxysmal junctional tachycardia was induced in 52 patients (34%). Patients with negative study were younger (44±21.5 years) than those with sinus node dysfunction or atrial fibrillation (71±9 and 63±14 years, respectively). The treatment was guided by these data: patients with inducible atrial fibrillation were treated by antiarrhythmic drugs and those with inducible paroxysmal junctional tachycardia by the radiofrequency ablation of reentrant circuit. Syncope disappeared in all patients but 2. Conclusion: Esophageal electrophysiologic study performed during a consultation was a safe, rapid and economic means to detect an arrhythmia (sinus node dysfunction or supraventricular tachycardia) in patients with dizziness/syncope and palpitations in half cases. Supraventricular tachycardia was clearly an underestimated cause of syncope in this population.

Paroxysmal tachycardia in children and teenagers with normal sinus rhythm and without heart disease.

The purpose of this study was to evaluate the value of esophageal programmed stimulation in children and teenagers with normal sinus rhythm ECG and normal noninvasive studies, having palpitations and syncope, and no documented tachycardias. Paroxysmal tachycardias are frequent in children and are often related to accessory connection. These tachycardias are sometimes difficult to prove. Transesophageal atrial pacing was performed at rest and during infusion of isoproterenol in 31 children or adolescents aged 9-19 years (16 +/- 3 years) with normal sinus rhythm ECG and suspected or documented episodes of paroxysmal tachycardia. Sustained tachycardia was induced in 27 patients, at rest in 13 patients, and after isoproterenol in 14 remaining patients. Atrioventricular nodal reentrant tachycardia was found as the main cause of paroxysmal tachycardia (22 cases). Six patients were followed by a vagal reaction and dizziness. These patients had spontaneous tachycardia with syncope. In three other patients, atrial fibrillation was also induced. Concealed accessory pathway reentrant tachycardia was identified in three patients. In two patients, a regular wide tachycardia with right bundle branch block morphology was induced; the diagnosis of verapamil-sensitive ventricular tachycardia was made in a second study by intracardiac study. In conclusion, atrioventricular nodal reentrant tachycardia was found as the main cause of symptoms in children with normal sinus rhythm ECG. Syncope is frequently associated and provoked by a vagal reaction. This diagnosis could be underestimated in adolescents frequently considered as hysterical because noninvasive studies are negative.

Relation between spatial distribution of late potentials and location of origin of premature ventricular complexes on body surface map in patients with postinfarction ventricular tachycardia

We studied the relationship between the spatial distribution of late potentials (LPs) and the origin of premature ventricular complexes (PVCs) using body surface maps in 55 patients with postinfarction sustained ventricular tachycardia (VT). Body surface maps were recorded from 87 leads to construct departure maps during sinus rhythm and signal-averaged ECGs were recorded from 32 unipolar leads to construct a LP map. The root-mean-square values during 40 ms intervals behind the QRS end were computed as LPs. The PVC map was recorded simultaneously in 14 patients presenting PVC with similar morphology to VT during LP detection. The origin of PVC was localized at the site of isopotential minimum when the potential exceeded −0.5 mV during the early QRS period. The LP area and the departure area showed a similar distribution. However, the PVC origin was closer to the site of LP maximum than the departure minimum in 11 (79%) patients, and the spatial correlation between the LP maximum and the PVC origin was good in 12 (86%) patients. LP and PVC mapping from the body surface is feasible and of worth to predict noninvasively the site of origin of ventricular arrhythmias in patients with remote myocardial infarction and sustained VT.

Correlation Method for Detection of Transient T‐Wave Alternans in Digital Holter ECG Recordings

Background:Spectral and complex demodulation methods for detection of microvolt T‐wave alternans (TWA) have limited ability to identify transient (nonstationary) TWA episodes. We aimed to develop and test new time‐domain technique allowing TWA detection and quantification in as few as 7 consecutive beats from sinus rhythm ECGs. Methods and results:Quantification of TWA during sinus rhythm required preprocessing consisting of: low‐pass filtering, RR stability testing, baseline and respiratory modulation removal, and T‐wave windowing and synchronization. Our time‐domain correlation method (CM) detects TWA by computing, for each consecutive T wave, an alternans correlation index based on a crosscorrelation technique. CM allows quantitative analysis of the amplitude, duration, and overall magnitude of the TWA episode. The technical performance of CM was confirmed in testing with simulated TWA of varying amplitude, duration, and noisy conditions. The clinical performance of CM was demonstrated by analyzing digital Holter recordings of 39 long QT syndrome patients compared to 36 healthy subjects. CM identified TWA in 17 (44%) patients with nonstationary TWA detected in 8. Conclusion:Our computer algorithms consisting of ECG preprocessing and TWA quantification by the correlation method provides the opportunity to detect nonstationary and stationary TWA in sinus rhythm of digital Holter ECG recordings. A.N.E. 1999;4(4):416–424

Wide Complex Tachycardia

An 84-year-old woman was seen in the emergency department complaining of weakness and palpitation that had begun suddenly one hour earlier while she was resting at home. She did not complain of chest pain, dyspnea, nausea, or vomiting. However, she had had a similar episode three years earlier, and at that time a diagnosis of ventricular tachycardia had been made. Her ECG in sinus rhythm had shown right bundle branch block. No special cardiologic studies had been done, and she had been discharged from the hospital taking amiodarone, 400 mg daily.She appeared anxious and in some distress from palpitation. Her pulse was 154 and regular, blood pressure was 120/80 mm Hg, respirations were 16 per minute, and temperature was 36.9°C. The lungs were clear to percussion and auscultation. The jugular venous pressure appeared to be slightly elevated. The arterial pulse was small in volume. The heart sounds were soft, with no murmur, rub, or gallop. The remainder of the examination findings were normal.The ECG is shown. Adenosine, administered as an intravenous bolus of 6 mg followed by a 12-mg bolus, and lidocaine, administered as an intravenous bolus of 50 mg followed by an infusion at 2 mg per minute and a second intravenous bolus of 50 mg, had no effect on the ECG.

Differentiating SVT from VT--a personal viewpoint.

There are two situations in which it may be difficult to differentiate supraventricular tachycardia from ventricular tachycardia via the surface 12 lead electrocardiogram: (1) when supraventricular tachycardia is conducted to the ventricles with aberration, and (2) when ventricular preexcitation is present. In both cases, the physician in faced with a tachycardia with wide (> = 0.12 s) QRS complexes. In order to avoid improper or delayed therapy the physician should keep in mind simple facts. Ventricular tachycardia is far more common than supraventricular with aberrant conduction, as it accounts for more than 80% of tachycardia with wide QRS complexes. The first step is to determine the tolerance of the tachycardia and therefore whether prompt termination is required. If the tachycardia is associated with syncope, cardiac arrest, severe hypotension or angina, DC cardioversion is necessary. Diagnosis should be delayed until after termination of the tachycardia. If tachycardia is well tolerated, the bedside diagnosis should take into account the clinical context: age of the patient, history or presence of heart disease and patient medications. In an adult patient with a history of myocardial infarction, the most likely diagnosis is ventricular tachycardia. The second step is to exclude or ascertain the presence of preexcitation. If this is suspected in young adults or children an ECG in sinus rhythm should indicate overt preexcitation. The physician should be aware of the various mechanisms of tachycardia with preexcited QRS complexes, all of which have a common denominator: anterograde conduction through the accessory pathway.(ABSTRACT TRUNCATED AT 250 WORDS)

Ventricular tachycardias of right ventricular origin: Markers of subclinical right ventricular disease

The diagnosis of subclinical myocardial disease in patients with ventricular tachycardias of right ventricular (RV) origin and no overt cardiac abnormalities is important, inasmuch as the presence of RV cardiomyopathy or arrhythmogenic dysplasia can be associated with a poor prognosis. To this end the relative value of symptoms, ECG features of ventricular tachycardia, signal-averaged ECGs, and RV echocardiograms as compared with endomyocardial biopsy findings was prospectively evaluated. Twenty-seven patients with chronic ventricular tachycardias with a left bundle branch block-like morphology, presumed to be of RV origin, were studied. Clinical examination findings, 12-lead ECGs in sinus rhythm, radiographs of the chest, coronary angiograms, and left ventricular cineangiograms were normal in all patients. RV biopsies were abnormal in 11 patients (41%) with findings suggestive of RV dysplasia or cardiomyopathy. A multivariate analysis showed a significant correlation between an abnormal biopsy and sustained ventricular tachycardia (p < 0.05), tachycardia with a superior frontal plane axis (p < 0.001), an abnormal signal-averaged ECG (p < 0.05), and an abnormal RV echocardiogram (p < 0.001). An abnormal RV echocardiogram was both a sensitive (73%) and a specific (94%) indicator of an abnormal RV biopsy. Sustained tachycardia although sensitive (90%) had a low specificity (56%). In comparison, a superior frontal plane axis of ventricular tachycardia and an abnormal signal-averaged ECG were indicative of high specificity and low sensitivity for abnormal myocardial histologic findings. We conclude that in a patient with RV tachycardia and no overt cardiac abnormalities, sustained tachycardia, a superior frontal plane axis of ventricular tachycardia, an abnormal signal-averaged ECG, and an abnormal RV echocardiogram suggest the presence of subclinical RV disease. An abnormal RV echocardiogram is both a specific and a sensitive indicator of myocardial abnormalities and precludes the need for endomyocardial biopsy.

Radiofrequency Catheter Ablation of WPW Syndrome in National Institute of Cardiovascular Diseases, Dhaka: Initial and Four Years Follow-up Results

Background: Radiofrequency (RF) catheter ablation is an effective method of treatment of patients with WPW syndrome. The purpose of this study was to analyze the initial and follow-up results of RF ablation of such cases in our hospital. Methods: 255 cases with WPW syndrome that had delta wave in sinus rhythm ECG underwent electrophysiological studies in this hospital. All the cases underwent radiofrequency ablation. These cases are selected for analysis. Results: Ablations were performed in these 255 patients between December 2005 and December 2008. One accessory pathway (AP) was found in 250 patients, two accessory pathways-in 05 patients. The mean duration of the procedure was 130 ± 32 min. The initial and overall success rate was 92.15% and 95.68% respectively. Major complications encountered are none. Conclusions: RF ablation of WPW syndrome has good initial (92.15%) and overall (95.68%) success rate and low recurrence rate (5.00%) at long term follow-up. Keywords: Catheter ablation; Radiofrequency ablation; WPW syndrome. DOI: 10.3329/cardio.v2i2.6638Cardiovasc. j. 2010; 2(2) : 188-194