His-ventricular Interval Research Articles

Wide QRS Tachycardia with Two P Wave Morphologies: What Is the Mechanism?

A 38 years old male complained of occasional palpitation and came to our hospital for help. Twelve-lead electrocardiogram during the palpitation revealed a wide QRS tachycardia with two different P wave morphologies. Two different atrial activation sequences were found in the intracardiac recordings and they were comparable to the two different P wave morphologies from the surface ECG recordings. The first type of atrial activation pattern was retrograde concentric VA conduction with the earliest atrial activation at the proximal coronary sinus which created a negative polarity of P wave in the lead II of ECG. The second type of atrial activation pattern was conducted from the right atrium to the coronary sinus which was considered to be a normal sinus impulse and created a positive polarity of P wave in the lead II of ECG. The idiopathic left ventricular tachycardia was diagnosed by atrioventricular dissociation and the short His-ventricular interval. The catheter ablation was performed during tachycardia. The site of catheter ablation was located at the distal septum of the left ventricle where the characteristic double diastolic potentials as previous studies demonstrated was recorded. The tachycardia was terminated after one pulse of ablation. No further tachycardia could be induced after the ablation even under isoproterenol infusion.

Wenckebach During Supraventricular Tachycardia

In case 1, a 71-year-old man with a history of coronary artery disease presented with recurrent paroxysmal supraventricular tachycardia (SVT) despite treatment with β-blockers. During electrophysiology study, the baseline sinus cycle length was 895 ms, atrial-His (AH) interval was 120 ms, and His-ventricular interval was 60 ms. A narrow complex SVT with tachycardia cycle length of 480 ms was initiated with atrial overdrive pacing at 400 ms, as well as with single atrial extrastimuli. The tachycardia showed a long RP interval with regular concentric atrial activation pattern and atrioventricular Wenckebach conduction (Figure 1). Ventricular overdrive pacing during tachycardia repeatedly terminated the tachycardia without activation of the atrium (Figure 2). Figure 1. Inducible SVT with Wenckebach block above the His (arrows) in patient 1 (ECG leads I, III, V1, and V6). His d indicates distal His; His p, proximal His; CS 1,2, distal coronary sinus; CS 7,8, proximal coronary sinus; and RVa, right ventricular apex. Figure 2. Ventricular overdrive pacing terminates tachycardia with ventriculoatrial block (arrow) (ECG leads I, III, V1, and V6 …

Entrainment versus resetting of a long RP tachycardia: What is the diagnosis?

t c s a p b c d t t d i t P s Case presentation A 71-year-old man with a history of chronic obstructive pulmonary disease presented for electrophysiological study because of recurrent hospitalizations due to a long-RPinterval narrow complex tachycardia refractory to verapamil therapy. His 12-lead electrocardiogram and echocardiogram were normal. Baseline atrio-His and His-ventricular intervals measured 56 ms and 41 ms, respectively. During programmed atrial extrastimulation, dual atrioventricular (AV) node physiology was not observed. Retrograde conduction was midline (earliest at the anteroseptum) and confirmed to be over the fast pathway (FP) of the AV node by paraHisian pacing at multiple cycle lengths. Tachycardia was easily and reproducibly induced from both the ventricle and the atrium (Figure 1). The response of tachycardia to entrainment from the ventricle and diastolic ventricular premature depolarizations (VPDs) are shown in Figures 2 and 3, espectively. Based on these observations, what is the mechnism of tachycardia?

Effects of Remifentanil Anesthesia on Cardiac Electrophysiologic Properties in Children Undergoing Catheter Ablation of Supraventricular Tachycardia

Remifentanil is commonly used during anesthesia in pediatric electrophysiologic studies (EPS). The purpose of this study is to determine the effects of remifentanil on the cardiac electrophysiologic properties of children undergoing ablation of supraventricular tachycardia (SVT). A prospective study was performed in patients undergoing EPS before ablation of SVT. Each patient received two different anesthetic protocols: protocol 1 = propofol (200 mcg/kg/min) and protocol 2 = propofol (120 mcg/kg/min) plus remifentanil (0.3 mcg/kg/min). EPS data were measured during the steady state of each protocol. Paired Student t test was performed for analysis of continuous data. All p values <0.05 were considered statistically significant. Fifteen patients were enrolled between April 2005 and January 2006. The mean age was 13.3 ± 2.9 years (range 6.7 to 17.7). Seven patients had atrioventricular (AV) nodal re-entry tachycardia; 5 patients had Wolff-Parkinson-White syndrome; 2 patients had a concealed accessory pathway; and 1 patient was not inducible. Of the 14 patients who underwent ablation, 13 (93%) achieved successful. The baseline sinus cycle length extended from 884 ± 141 ms during protocol 1 to 980 ± 165 ms during protocol 2 (p = 0.01), and the Wenckebach cycle length lengthened from 377 ± 96 ms to 406 ± 109 ms (p = 0.01). No other variables measured (atrial-His (AH) and His-ventricular (HV) interval, atrioventricular node (AVN), and atrial, ventricular, and accessory pathway effective refractory periods) changed significantly between the two different protocols. In pediatric patients undergoing EPS before ablation of SVT, remifentanil appears to slow both sinus and AV nodal function. These effects should be taken into consideration when performing EPS.

Supraventricular tachycardia with alternating cycle lengths: What is the mechanism?

c Case presentation A 68-year-old woman with hypertension and emphysema presented with daily palpitations since childhood. At electrophysiological (EP) study, multipolar catheters were placed in the right atrium, His bundle region, right ventricle (RV), and coronary sinus (CS). At baseline, the patient was in normal sinus rhythm with normal atrial-His (AH) and His-ventricular (HV) intervals. Multiple episodes of a long RP supraventricular tachycardia (SVT) occurred spontaneously. Ventricular pacing predominantly exhibited concentric atrial activation but intermittently (and inconsistently) revealed an eccentric atrial activation, with earliest activation near the

Response to a single atrial extrastimulus during a long-RP supraventricular tachycardia

A 30-year-old man with a 3-year history of paroxysmal supraventricular tachycardia was referred for catheter ablation. Due to mechanical trauma by a catheter at the beginning of the study, a right bundle branch block developed and was present throughout the entire procedure. The baseline sinus cycle length and atrial-His (AH) and His-ventricular intervals were 730, 85, and 52 ms, respectively. Dual atrioventricular (AV) node physiology and a single AV nodal echo beat were demonstrated. Ventricular pacing during sinus rhythm showed ventriculoatrial (VA) conduction that was concentric and decremental.

A single atrial extrastimulus during a short RP tachycardia

A 26-year-old female underwent electrophysiological study for recurrent palpitations. She was in sinus rhythm at baseline with cycle length (CL), atrial-His (AH), and His-ventricular (HV) intervals of 802, 87, and 48 ms, respectively. Ventricular pacing showed decremental ventriculoatrial (VA) conduction with concentric atrial activation. Parahisian pacing showed VA prolongation with loss of His capture consistent with nodal conduction. Rapid atrial pacing induced a short RP tachycardia with a CL of 580 ms that corresponded to the tachycardia documented clinically (Figure 1). The VA interval was 30 ms during the tachycardia with the earliest atrial activation at the proximal coronary sinus. The short VA interval is not consistent with atrioventricular reentrant tachycardia, but atrial tachycardia (AT), atrioventricular nodal reentrant tachycardia (AVNRT), and junctional tachycardia (JT) are possible differential diagnoses. During tachycardia, a single premature atrial complex (PAC) was introduced from the proximal coronary sinus (Figure 2). Based on the response to the extra stimulus, what is the most likely mechanism of the tachycardia? Commentary The short RP tachycardia with a very short VA interval can represent AT with a long atrioventricular (AV) delay, typical slow-fast AVNRT, or JT. Although JT is an uncommon tachycardia mechanism in this setting, it becomes a distinct possibility due to the long CL of the tachycardia.

Predictors of Atrial Tachyarrhythmias in Subjects with Type 1 ECG Pattern of Brugada Syndrome

Previous studies have demonstrated a high incidence of atrial tachyarrhythmias (ATs) in patients with Brugada syndrome (BS). The present study aimed to investigate whether various 12-lead electrocardiogram (ECG) and electrophysiological parameters may help to differentiate subjects with a high probability to develop ATs. The clinical records of 38 individuals (31 males, age 44.4 +/- 13.9) with spontaneous (n = 15) or ajmaline-induced (n = 23) type 1 ECG pattern of BS were analyzed. During a mean follow-up period of 4.6 +/- 2.2 years, nine subjects suffered ATs (24%). Six subjects displayed paroxysmal atrial fibrillation and three typical atrial flutter. Among the studied 12-lead ECG parameters, subjects with ATs exhibited increased values of P-wave duration in lead II, P-wave dispersion, PR interval in leads II, QRS duration in leads II and V(2), Tpeak-end interval in lead II, and Tpeak-end dispersion of the 12 leads in relation to those without ATs (P < 0.05). Among the assessed electrophysiological parameters, atrial-His (AH) and His-ventricular (HV) intervals were significantly prolonged in subjects with ATs (P < 0.05). Multiple Cox proportional hazards analysis revealed that P-wave duration in lead II, P-wave dispersion, Tpeak-end in lead II, Tpeak-end dispersion of the 12 leads, as well as AH and HV intervals are independent predictors of ATs in subjects with BS (P < 0.05). Cut-off point analysis showed that an HV interval>or=56 ms displayed the highest predictive ability (P < 0.01). Our findings demonstrate that simple 12-lead ECG and electrophysiological parameters may easily be applied to identify high-risk subjects with BS ECG phenotype to develop ATs.

Abnormal Atrioventricular Node Conduction and Atrioventricular Nodal Reentrant Tachycardia in Patients Older Versus Younger Than 65 Years of Age

We examined the possible role of atrioventricular node (AVN) conduction abnormalities as a cause of AVN reentrant tachycardia (RT) in patients >65 years of age. Slow pathway radiofrequency catheter ablation (RFCA) was performed in 104 patients. Patients in group 1 (n = 14) were >65 years of age and had AV conduction abnormalities associated with structural heart disease. Patients in group 2 (n = 90) were <65 years of age and had lone AVNRT. Patients in group 1 versus group 2 (66% vs. 46% men) had a first episode of tachycardia at an older age than in group 2 (68 +/- 16.8 vs 32.5 +/- 18.8 years, P = 0.007). The history of arrhythmia was shorter in group 1 (5.4 +/- 3.8 vs 17.5 +/- 14, P = 0.05) and was associated with a higher proportion of patients with underlying heart disease than in group 2 (79% vs 3%, P < 0.001). The electrophysiological measurements were significantly shorter in group 2: atrial-His interval (74 +/- 17 vs 144 +/- 44 ms, P = 0.005), His-ventricular (HV) interval (41 +/- 5 vs 57 +/- 7 ms, P = 0.001), Wenckebach cycle length (329 +/- 38 vs 436 +/- 90 ms, P = 0.001), slow pathway effective refractory period (268 +/- 7 vs 344 +/- 94 ms, P = 0.005), and tachycardia cycle length (332 +/- 53 vs 426 +/- 56 ms, P = 0.001). The ventriculoatrial block cycle length was similar in both groups. The immediate procedural success rate was 100% in both groups, and no complication was observed in either group. One patient in group 2 had recurrence of AVNRT. One patient with a 98-ms HV interval underwent permanent VVI pacemaker implantation before RFCA procedure. In patients undergoing RFCA for AVNRT at >65 years of age had a shorter history of tachycardia-related symptoms than patients with lone AVNRT. The longer AVN conduction intervals and refractory period might explain the late development of AVNRT in group 1.

Malignant Ventricular Arrhythmia in a Case of Adult Onset of Spinal Muscular Atrophy (Kugelberg–Welander Disease)

We present a case of a 43-year-old male patient with adult onset of spinal muscular atrophy (SMA). The patient first came to our attention with atrioventricular (AV) block. A dual-chamber pacemaker (DDD-PM) was implanted. Four years later, the PM data log showed occurrence of frequent episodes of nonsustained ventricular tachycardia (NSVT). The episodes progressed in duration and frequency. An electrophysiological study revealed prolonged His-ventricular (HV) interval duration and induction of sustained ventricular tachycardia. The patient was successfully upgraded to a prophylactic dual-chamber cardioverter defibrillator. Our case is the first description of a patient with adult-onset SMA (Kugelberg-Welander disease [KWD]) and malignant ventricular arrhythmias.

Significance of Early Onset and Progressive Increase of Activation Delay During Premature Stimulation in Brugada Syndrome

The relationship between the activation delay during programmed stimulation and the inducibility of ventricular fibrillation (VF) and filtered QRS duration on signal-averaged ECG (SAECG) were assessed in patients with Brugada syndrome (BS). The activation delay was assessed using the interval between the stimulus and the QRS complex during programmed stimulation in 25 patients with BS and 10 with idiopathic ventricular tachycardia (controls). The mean increase of delay (MID) was used to characterize the conduction curves. The filtered QRS duration (fQRSd) in leads V(2) (RfQRSd) and V(5) (LfQRSd) were also evaluated using SAECG. Both MIDs at the right ventricular outflow tract (RVOT) were significantly greater in symptomatic and asymptomatic BS patients than in the control group (symptomatic, 7.1 +/-2.7 ms vs control, 2.5 +/-1.2 ms, P<0.001, asymptomatic, 7.3 +/-3.3 ms vs control, P<0.001, respectively). The MID correlated with the His-ventricular interval; however, there were no significant correlations between the MID and RfQRSd or RfQRSd - LfQRSd. The MID, which indicates an increase of the St-QRS during premature stimulation, was much greater in patients with BS (regardless of clinical symptoms) than in the control group, especially in the RVOT, which might be related to the easy inducibility of VF from the RVOT.

Short PR Interval in the Absence of Preexcitation: A Characteristic Finding in a Patient with Fabry Disease

Fabry disease (FD) is a rare lysosomal storage disease characterized by intracellular deposition of glycosphingolipids that can involve various organs including the heart. Here, we report the finding of a short PR interval in a patient with FD and recurrent syncope associated with short atrial-His (A-H) and His-ventricular (H-V) intervals in the absence of preexcitation. While electrocardiographic abnormalities are not uncommon among FD patients, there have been few reports on electrophysiological studies performed on these patients. The exact mechanism for the short A-H and H-V intervals remains unclear, but they may result from accelerated conduction in the AV node-His-Purkinje system.

Swallow Syncope Associated with Complete Atrioventricular Block in an Adolescent

We describe a 16-year-old female with a history of swallowing-induced syncope. The physical examination, ECG, echocardiography, barium swallow test, and thyroid function tests were within normal limits. The ambulatory ECG revealed intermittent complete atrioventricular block only associated with swallowing. There was also intermittent first-degree atrioventricular block not related to eating. An electrophysiologic study was performed during the implantation of a single-chamber transvenous ventricular pacemaker. There was mild atrioventricular nodal conduction disturbance with a His-ventricular interval of 70 msec and Wenckebach cycle length of 420 msec. During 1 year follow-up, the patient remained asymptomatic.

Supraventricular tachycardia with simultaneous atrial and ventricular activation: What is the mechanism?

A 50-year-old man underwent an electrophysiologic study for very frequent episodes of supraventricular tachycardia. He had a left bundle branch block with a baseline sinus cycle length, atrial-His (AH) interval, and His-ventricular (HV) interval of 670, 100, and 65 ms, respectively. Atrial pacing induced a regular supraventricular tachycardia with a cycle length of 540 ms. Ventricular pacing at a cycle length of 500 ms was performed during the tachycardia (Figure 1). A premature atrial stimulus was introduced in the high right atrium during tachycardia (Figure 2).

Response to overdrive pacing during regular paroxysmal supraventricular tachycardia: What is the tachycardia mechanism?

A 42-year-old woman with a 2-year history of paroxysmal supraventricular tachycardia was referred for electrophysiologic study. The patient had a normal baseline ECG and no structural heart disease. Baseline sinus cycle length, atrial-His (AH), and His-ventricular (HV) intervals were 778, 77, and 45 ms, respectively. A narrow QRS complex tachycardia with inverted P waves in the inferior leads was reproducibly induced by programmed stimulation with a single atrial extrastimulus (Figure 1). During tachycardia (cycle length 350 ms), the shortest HA and AH intervals were 140 and 210 ms, respectively.

Validation of Criteria for Selective His Bundle and Para‐Hisian Permanent Pacing

His Bundle (HB) pacing is a valid alternative to right ventricular pacing for patients with preserved His-ventricle conduction who are candidates for permanent stimulation. Permanent pacing in the HB area enables Selective HB pacing (SHBP) or para-Hisian pacing (PHP) to be achieved. The aim of our study was to draw up a set of easy criteria to differentiate and validate the two kinds of stimulations according to the pacing output and the ECG/EKG signals. From February to July 2005, 17 patients eligible for a pacemaker (PM) procedure underwent implantation with the Medtronic SelectSecure lead (Medtronic, Minneapolis, MN, USA) screwed into the HB area.SHBP was defined when the intrinsic QRS was equal, in both duration and morphology, to the paced QRS, the His-Ventricular (H-V) interval was equal to Pace-Ventricular interval (Vp-V) and, at low output, only the HB was captured, while increasing the output resulted in both the HB and right ventricular (RV) being captured (widening of QRS at high output). Conversely, PHP was defined when the intrinsic QRS differed from the paced one, either in morphology or in duration and, at high output, both the RV and HB were captured (non-SHBP), while decreasing the output resulted in losing HB capture (widening of QRS at low output). According to these criteria, SHBP was achieved in 11 patients, while in the remaining 6, PHP was obtained. No adverse events were reported. The above criteria enabled SHBP and PHP to be validated easily and clearly. A longer follow-up will be needed in order to ascertain whether the clinical outcome of these two approaches differs.

Randomized Study of Propofol Effect On Electrophysiological Properties of the Atrioventricular Node in Patients with Nodal Reentrant Tachycardia

Atrioventricular nodal reentrant tachycardia (AVNRT) is probably the most common form of paroxysmal supraventricular tachycardia. Percutaneous catheter ablation is a technique to interrupt cardiac conduction pathways selectively. The anesthetist is challenged to provide a safe anesthetic which takes into account the electrophysiologist's requirements for minimal cardiac conduction interference. Propofol is an ideal drug. However, previous studies have shown that the infusion of propofol has sometimes been associated with bradyarrhythmias or conversion of arrhythmias to sinusal rhythm. The purpose of this report is to verify the interferences of propofol in the electrophysiological properties of the atrioventricular (AV) node conduction system in patients with AVNRT. Patients were randomly assigned to receive either a placebo or propofol at sedative doses. An electrophysiological study was performed consisting of measuring the anterograde (AERPFP) and retrograde effective refractory period of the fast (RERPFP) and the anterograde effective refractory period of the slow (AERPSP) AV nodal pathway. Reciprocating tachycardia was induced and the cycle length (CL) and atrial-His (AH), His-ventricular (HV), and ventriculoatrial (VA) intervals were measured. Propofol did not cause alteration (P > 0.05) in the AERPFP or RERPFP and the AERPSP AV nodal pathway. The AH, HV, and VA intervals were not affected. Sustained reciprocating tachycardia could be induced in the all patients. All slow pathways were successfully identified and ablated. Propofol has no effect on the electrophysiological properties of the AV node conduction system. It is thus a suitable anesthetic agent for use in patients undergoing ablative procedures.

Short Communication

A 35-year-old man with a 6-year history of paroxysmal supraventricular tachycardia (PSVT) was referred for radiofrequency catheter ablation. Baseline sinus cycle length and atrial-His and His-ventricular intervals were 820, 65, and 40 ms, respectively. PSVT was reproducibly induced by programmed stimulation with a single atrial extrastimulus. Atrioventricular (AV) block was present during one of the PSVT episodes, and the atrial cycle length varied between 280 and 310 ms (Figure 1). What is the mechanism of the tachycardia? Why did the AV block resolve?

Supraventricular tachycardia with atrioventricular block: What is the mechanism?

A 35-year-old man with a 6-year history of paroxysmal supraventricular tachycardia (PSVT) was referred for radiofrequency catheter ablation. Baseline sinus cycle length and atrial-His and His-ventricular intervals were 820, 65, and 40 ms, respectively. PSVT was reproducibly induced by programmed stimulation with a single atrial extrastimulus. Atrioventricular (AV) block was present during one of the PSVT episodes, and the atrial cycle length varied between 280 and 310 ms (Figure 1). What is the mechanism of the tachycardia? Why did the AV block resolve?

Atrioventricular block: What is the mechanism?

An 88-year-old woman was referred for diagnostic electrophysiologic study because of multiple episodes of presyncope. Twelve-lead ECG showed first -degree atrioventricular (AV) block with left bundle branch block. At electrophysiologic study, baseline sinus cycle, atrio-His (AH), and His-ventricular (HV) intervals measured 1,245, 159, and 161 ms, respectively. Multiple episodes of AV block were observed (Figure 1). During the study, she developed complete AV block that required ventricular pacing (Figure 2).