Tachycardia-dependent augmentation of "notched J waves" in a general patient population without ventricular fibrillation or cardiac arrest: not a repolarization but a depolarization abnormality?

Is ischemic stimulus involved for J wave augmentation during coronary angiography and intracoronary administration of normal saline?

BACKGROUND

J waves may be augmented by coronary angiography (CAG) or intracoronary drug administration but the underlying mechanism is unknown.

PURPOSE

The effect of intracoronary normal saline (NS) on J waves were investigated.

PATIENTS AND METHODS

After the standard CAG using iopamidol (IopamiroR Inj), NS was injected into the right coronary artery in 10 patients with and eight patients without J waves at the baseline. The 12-lead ECG was monitored, stored on a computer and retrieved later for measurement of the J wave amplitude before or during the coronary interventions.

RESULTS

J waves in leads II, III and aVF at baseline increased significantly in each lead during the right CAG and NS injection into the right coronary artery. The J wave changes were similar between the two interventions and distinct similar alterations were observed in the QRS complex. We postulated that the ischemic myocardium that was induced during CAG or intracoronary NS administration slowed the conduction velocity of depolarization in the perfusion territory and delayed the timing of J waves to appear. Then, the delayed appearance of J waves would be less opposed by electromotive force from other areas resulting in augmentation.

CONCLUSION

J wave augmentation was observed during CAG and intracoronary NS administration. As a mechanism of augmentation, we postulated that contrast media and NS induce myocardial ischemia and delay the timing of J waves to a point of less opposition by electromotive force from other areas.

HIGHLIGHTS

J wave augmentation has been reported during intracoronary injection of contrast media or drugs. The present study confirmed that normal saline alone was able to augment J waves. Mechanistically, coronary interventions using anoxic solutions can cause regional myocardial ischemia and reduce the conduction velocity of depolarization. Then, delayed J waves are less opposed by the electromotive force from remote areas which leads to augmentation. When a drug is diluted in normal saline and given intracoronarily, changes in J waves can be due to normal saline. The pathophysiological and clinical significance of J waves augmented during coronary interventions need to be established.

J wave dynamicity during coronary angiography and intracoronary acetylcholine administration

BACKGROUND

J-waves may be observed during coronary angiography (CAG) or intracoronary acetylcholine (ACh) administration, but their significance is unknown.

METHODS

Forty-nine patients, 59.1 ± 11.5 years old and 59% male, were studied on suspicion of vasospastic angina, and J wave dynamicity was compared between CAG and Ach administration.

RESULTS

Diagnostic (≥0.1 mV) or nondiagnostic (<0.1 mV) J waves in 9 and 3 patients, respectively, were augmented, and J waves were newly observed in 2 patients during CAG and Ach administration. Similar changes in the J-wave amplitude were observed: from 0.10 ± 0.09 mV to 0.20 ± 0.15 mV (p < .002) and from 0.10 ± 0.10 mV to 0.20 ± 0.16 mV (p < .001) during CAG and Ach administration, respectively. J waves were located in the inferior leads and changed only during the right coronary interventions. In the remaining 35 patients, J waves were absent before and during the coronary interventions. Augmentation of J waves was found when the RR interval was shortened in some patients. Injection of anoxic media into the coronary artery might induce a conduction delay from myocardial ischemia that manifests as augmentation or new occurrence of J waves.

CONCLUSIONS

Both CAG and intracoronary Ach administration affected J waves similarly in the same individuals. A myocardial ischemia-induced conduction delay may be responsible for the changes in J waves, but further studies are needed.

Novel SCN5A frame‑shift mutation underlying in patient with idiopathic ventricular fibrillation manifested with J wave in inferior lead and prolonged S‑wave in precordial lead

Mutations in the SCN5A gene has been recognized as resulting in a series of life-threatening arrhythmias. However, it also causes idiopathic ventricular fibrillation (IVF) with J wave in inferior leads and prolonged S-wave upstroke in precordial leads, which has not been previously reported. The present study aimed to study the mechanisms of a patient with IVF manifested with J wave in inferior leads and prolonged S-wave upstroke in precordial leads. The electrocardiograms (ECG) of the proband were recorded and genetic testing was conducted. Patch-clamp and immunocytochemical studies were performed in heterologously transfected 293 cells. The VF attacks was documented in a 55-year-old male proband with syncope episodes. 12-lead ECG shown the transient J wave in the inferior leads and prolonged S-wave upstroke in precordial V1-V3 leads in the same timeframe. Genetic analysis revealed a novel 1 base deletion (G) at position 839 in exon 2 in SCN5A gene (C280S*fs61), which causes a severe truncation of the sodium channel. The functional study revealed that in 293 cells transfected with mutant channel, no sodium current could be recorded even though the immunocytochemical experiment confirmed the truncated sodium channel existed in cytosol. The kinetics of the wild-type (WT) channel were not altered when co-transfected with C280S*fs61 mutant which suggested a haploinsufficiency effect of sodium channel in the cells. The present study identified a novel C280Sfs*61 mutation that caused the 'loss of function' of the sodium channel by haploinsufficiency mechanism. The reduced sodium channel function in the heart may cause conduction delay that may underlie the manifestation of J wave and prolonged S-wave upstroke associated with IVF.

Atrial Fibrillation-triggered Ventricular Fibrillation in a Patient with Early Repolarization Syndrome

A 54-year-old man with early repolarization syndrome (ERS) implanted with an implantable cardioverter-defibrillator (ICD) developed persistent atrial fibrillation (AF) three years after the implantation. Similarly, the remote monitoring system begun frequently detecting ventricular fibrillation (VF) and polymorphic ventricular tachycardia (PVT). Longer RR intervals were repeatedly observed just before the initiation of PVT/VF. Catheter ablation for AF successfully diminished both the PVT and VF events.

Incidence and Implications of J waves Observed During Coronary Angiography

J waves may be observed during coronary angiography (CAG), but they have not been fully studied. We investigated the characteristics of J waves in 100 consecutive patients during CAG. The patients and their family members had no history of cardiac arrest. Approximately 60% of patients had ischemic heart disease, previous myocardial infarction, or angina pectoris, but at the time of this study, the right coronary artery was shown to be normal or patent after stenting. Electrocardiogram was serially recorded to monitor J waves and alteration of the QRS complex during CAG. In 12 patients (12%), J waves (0.249 ± 0.074 mV) newly appeared during right CAG, and in another 13 patients (13%), preexisting J waves increased from 0.155 ± 0.060 mV to 0.233 ± 0.133 mV during CAG. Left CAG induced no J waves or augmentation of J waves. Distinct alterations were observed in the QRS complex during CAG of both coronary arteries. Mechanistically, myocardial ischemia induced by contrast medium was considered to result in a local conduction delay, and when it occurred in the inferior wall, the site of the late activation of the ventricle, the conduction delay was manifested as J waves. In conclusion, J waves were confirmed to emerge or increase during angiography of the right but not the left coronary artery. Myocardial ischemia induced by contrast medium caused a local conduction delay that was manifested as J waves in the inferior wall, the site of the late activation of the ventricle.

Electrocardiographic features of the presence of occult myocardial disease in patients with VPD-induced cardiomyopathy

Background

Frequent ventricular premature depolarizations (VPDs) can cause reversible cardiomyopathy (CMP). However, many patients maintain a normal left ventricular (LV) function with a high VPD burden. The electrocardiographic characteristics of VPD‐induced CMP have not been elucidated.

Methods

One hundred and eighty (91 men, age; 51 ± 15 years) patients with frequent idiopathic VPDs (>10% VPDs/day or >10 000 VPDs/day) were studied. All patients underwent successful ablation and were then divided into two groups according to the echocardiographic findings before and after the ablation procedure.

Results

Group A (n = 139) had a normal LV function with VPD frequencies, and Group B (n = 41) had reversible LV dysfunction after ablation. The VPD QRS duration (QRSd) was wider in patients with CMP (Group A vs Group B; 137.2 ± 12.0 milliseconds vs 159.7 ± 5.3 milliseconds, P < .001). VPDs with a terminal QRS delay marked by a notch followed by a discrete lower amplitude signal after the peak R wave in any precordial lead were identified. The incidence of terminal signals was higher in the CMP group (Group A vs Group B; 2.1% vs 53.6%, P < .001).

Conclusions

The wider VPD QRSd and terminal QRS delay in patients with VPD‐induced CMP suggest subclinical cell‐to‐cell conduction abnormalities as a potential factor predisposing VPD‐induced CMP.

Conduction Delay-Induced J-Wave Augmentation in Patients With Coronary Heart Disease

Electrocardiogram records were surveyed for the presence of an atrial premature beat (APB) and J waves in patients with coronary heart disease and patients with noncardiac diseases. The prevalence and response of J waves to sudden shortening of the RR interval on the conducted APB were determined and compared between the 2 patients groups. The change in the QRS complexes on the APB was also determined. Among 17,013 patients, 243 patients who underwent percutaneous coronary intervention for acute myocardial infarction or angina pectoris had an APB, and J waves were observed in 16 patients (6.6%). In an additional 729 patients with noncardiac diseases and APB, 19 patients showed J waves (2.6%; p = 0.010). The clinical features were almost similar between the ischemic and nonischemic groups. J waves were located more often in inferior and high lateral leads in the ischemic group. When the RR interval shortened from 942 ± 228 to 621 ± 175 ms and 869 ± 158 to 570 ± 118 ms at baseline and in the conducted APB (p<0.001 for both), the J-wave amplitude increased from 0.16 ± 0.04 to 0.19 ± 0.06 mV (p<0.001) and 0.21 ± 0.07 to 0.24 ± 0.08 mV (p = 0.010) in the ischemic and nonischemic groups, respectively. J waves in patients with chronic coronary heart disease and in patients with noncardiac diseases were augmented at short RR intervals together with distinct changes in the QRS complexes, and an augmentation of J waves at short RR interval may represent a conduction delay.

"J waves" induced after short coupling intervals: a manifestations of latent depolarization abnormality?

Aims

To confirm the presence of tachycardia-induced slur or notch in the terminal portion of the QRS complexes in a general patient population.

Methods and results

A tachycardia-induced J wave was defined as a slur or notch in the terminal portion of the QRS complexes newly induced at short RR intervals during atrial premature contractions (APCs) or atrial electrical stimulation in the electrophysiological study (EPS). Twenty-three out of 2000 patients with general diseases were involved. All patients with aborted sudden cardiac death, ventricular fibrillation or a family history of sudden cardiac death were excluded. The mean age was 72 ± 9 years, and 11 patients were male (47.8%). When the RR interval was shortened from 821 ± 142 ms to 464 ± 52 ms in the conducted APCs (P < 0.0001), J waves became diagnostic (0.02 ± 0.03 mV to 0.20 ± 0.07 mV, P < 0.0001). J waves were confined to the inferior leads in 22 (95.7%) patients and were notched in 11 (47.8%) and slurred in 12 (52.2%) patients. The induction of J waves was accompanied by visible changes of the QRS morphology. When the post-APC RR interval was prolonged to 992 ± 305 ms (P = 0.0154 vs. baseline), the J waves were similar to baseline levels. During the EPS, J wave induction was confirmed during atrial stimulation. There were no characteristic clinical or ECG features in the patients with tachycardia-induced J waves.

Conclusions

J waves can be newly induced by short RR intervals in a general patient population, and a conduction delay is the likely mechanism causing such J waves.

Dynamicity of hypothermia-induced J waves and the mechanism involved

BACKGROUND

J waves develop during hypothermia, but the dynamicity of hypothermia-induced J waves is poorly understood.

OBJECTIVE

The purpose of this study was to investigate the mechanism of the rate-dependent change in the amplitude of hypothermia-induced J waves.

METHODS

Nineteen patients with severe hypothermia were included (mean age 70 ± 12 years; 16 men [84.2%]). The rectal temperature at the time of admission was 27.8° ± 2.5°C. In addition to prolonged PR, QRS complex, and corrected QT intervals, the distribution of prominent J waves was widespread in all 19 patients.

RESULTS

Nine patients showed changes in RR intervals. When the RR interval shortened from 1353 ± 472 to 740 ± 391 ms (P = .0002), the J-wave amplitude increased from 0.50 ± 0.29 to 0.61 ±0.27 mV (P = .0075). The J-wave amplitude increased in 7 patients (77.8%) and decreased in 2 patients (22.2%) after short RR intervals. The augmentation of J waves at short RR intervals was associated with a significant prolongation of ventricular activation time (35 ± 5 ms vs 46 ± 5 ms; P = .0020), suggesting accentuated conduction delay. Increased conduction delay at short RR intervals was suggested to accentuate the phase 1 notch of the action potential and J waves in hypothermia. None developed ventricular fibrillation, and in 2 of 9 patients with atrial fibrillation, atrial fibrillation persisted after rewarming to normothermia.

CONCLUSION

J waves in severe hypothermia were augmented after short RR intervals in 7 patients as expected for depolarization abnormality, whereas 2 patients showed a bradycardia-dependent augmentation as expected for transient outward current-mediated J waves. Increased conduction delay at short RR intervals can be responsible for the accentuation of the transient outward current and J waves during severe hypothermia.

Intracoronary acetylcholine application as a possible probe inducing J waves in patients with early repolarization syndrome

Acetylcholine is widely used for a diagnostic provocation test of coronary spasm in patients with vasospastic angina. Acetylcholine usually induces coronary vasodilatation mediated by muscarinic receptor activation, but sometimes it evokes vasoconstriction of coronary arteries where the endothelium is damaged. Early repolarization syndrome is characterized by a J wave observed at the end of the QRS complex in a surface electrocardiogram. The J wave is attributed to the transmural voltage gradient at the early repolarization phase across the ventricular wall, which stems mainly from prominent transient outward current in the epicardium, but not in the endocardium. Transient high-dose application of acetylcholine into the epicardial coronary arteries provides a unique opportunity to augment net outward current, selectively, in the ventricular epicardium and unmask the J wave, irrespective of the cardiac ischemia based on coronary spasm. Acetylcholine augments cardiac membrane potassium conductance by enhancing acetylcholine-activated potassium current directly and by activating adenosine triphosphate-sensitive potassium current, in addition to the reduced sodium and calcium currents in the setting of severe ischemia due to vasospasm. However, the role of acetylcholine as an arrhythmogenic probe of the J wave induction in patients with suspected early repolarization syndrome warrants future prospective study.

High Prevalence and Clinical Implication of Myocardial Bridging in Patients with Early Repolarization

PURPOSE

Recent evidence suggests that early repolarization (ER) is related with myocardial ischemia. Compression of coronary artery by a myocardial bridging (MB) can be associated with clinical manifestations of myocardial ischemia. This study aimed to evaluate the associations of MB in patients with ER.

MATERIALS AND METHODS

In consecutive patients (n=1303, age, 61±12 years) who had undergone coronary angiography, we assessed the prevalence and prognostic implication of MB in those with ER (n=142) and those without ER (n=1161).

RESULTS

MB was observed in 54 (38%) and 196 (17%) patients in ER and no-ER groups (p<0.001). In multivariate analysis, MB was independently associated with ER (odd ratio: 2.9, 95% confidence interval: 1.98-4.24, p<0.001). Notched type ER was more frequently observed in MB involving the mid portion of left anterior descending coronary artery (LAD) (69.8% vs. 30.2%, p=0.03). Cardiac event was observed in nine (6.3%) and 22 (1.9%) subjects with and without ER, respectively. MB was more frequently observed in sudden death patients with ER (2 out of 9, 22%) than in those without ER (0 out of 22).

CONCLUSION

MB was independently associated with ER in patients without out structural heart disease who underwent coronary angiography. Notched type ER was closely related with MB involving the mid portion of the LAD. Among patients who had experienced cardiac events, a higher prevalence of MB was observed in patients with ER than those without ER. Further prospective studies on the prognosis of MB in ER patients are required.

J Wave Syndromes: History and Current Controversies

The concept of J wave syndromes was first proposed in 2004 by Yan et al for a spectrum of electrocardiographic (ECG) manifestations of prominent J waves that are associated with a potential to predispose affected individuals to ventricular fibrillation (VF). Although the concept of J wave syndromes is widely used and accepted, there has been tremendous debate over the definition of J wave, its ionic and cellular basis and arrhythmogenic mechanism. In this review article, we attempted to discuss the history from which the concept of J wave syndromes (JWS) is evolved and current controversies in JWS.

12-lead electrocardiogram features of arrhythmic risk: A focus on early repolarization

The 12-lead electrocardiogram (ECG) is still the most used tool in cardiology clinical practice. Considering its easy accessibility, low cost and the information that it provides, it remains the starting point for diagnosis and prognosis. More specifically, its ability to detect prognostic markers for sudden cardiac death due to arrhythmias by identifying specific patterns that express electrical disturbances of the heart muscle, which may predispose to malignant arrhythmias, is universally recognized. Alterations in the ventricular repolarization process, identifiable on a 12-lead ECG, play a role in the genesis of ventricular arrhythmias in different cardiac diseases. The aim of this paper is to focus the attention on a new marker of arrhythmic risk, the early repolarization pattern in order to highlight the prognostic role of the 12-lead ECG.

J-wave syndromes: Brugada and early repolarization syndromes

A prominent J wave is encountered in a number of life-threatening cardiac arrhythmia syndromes, including the Brugada syndrome and early repolarization syndromes. Brugada syndrome and early repolarization syndromes differ with respect to the magnitude and lead location of abnormal J waves and are thought to represent a continuous spectrum of phenotypic expression termed J-wave syndromes. Despite two decades of intensive research, risk stratification and the approach to therapy of these 2 inherited cardiac arrhythmia syndromes are still undergoing rapid evolution. Our objective in this review is to provide an integrated synopsis of the clinical characteristics, risk stratifiers, and molecular, ionic, cellular, and genetic mechanisms underlying these 2 fascinating syndromes that have captured the interest and attention of the cardiology community in recent years.