Ongoing Tachycardia Research Articles

Simultaneous, But Dissociated Left Atrial Fibrillation and Pulmonary Vein Tachycardia

A 74-year-old man with symptomatic drug-refractory persistent atrial fibrillation (AF) was referred for a catheter ablation procedure. The patient was in AF at the beginning of the procedure. As shown in Figure 1A, a decapolar catheter in the coronary sinus and a spiral mapping catheter within the ostium of the left common pulmonary vein (LCPV) demonstrated the presence of AF within both the left atrium (LA) and the LCPV, respectively. During circumferential ablation of the LCPV, the electrograms (EGMs) in the LCPV changed to an organized rhythm (mean cycle length, 178 ms) consistent with an ongoing PV tachycardia (Figure 1B). Suspecting that the LCPV was in fact isolated, the patient underwent electrical cardioversion, which terminated both the LA AF and the LCPV tachycardia (Figure 2A). PV entrance and exit block was confirmed by (1) spontaneous isolated PV potentials (Figure 2A, arrows), (2) catheter-induced AF confined solely to the LA (Figure 2B), and (3) pacing within the PV (Figure 2C). Following a second cardioversion, …

Atrial Tachycardia Confined Within the Left Atrial Appendage

Left atrial tachycardias are often seen following catheter ablation of persistent atrial fibrillation (AF). We report here an unusual case where AF was converted to sinus rhythm following catheter ablation, but ongoing atrial tachycardia confined within the left atrial appendage (LAA) was observed. Although the LAA tachycardia was dissociated from the atrium in sinus rhythm, bidirectional conduction between the left atrium and the LAA was, however, demonstrated after tachycardia termination.

Double intra-atrial connections in a patient late after orthotopic heart transplantation

Atrial tachycardias occurring late after orthotopic heart transplantation are frequently caused by an ongoing atrial tachycardia in the recipient remnant atrium that is associated with intra-atrial muscle band connections between the 2 atrial compartments. The standard approach for most centers that treat these patients is to identify and disconnect these intra-atrial connections. We present a patient where double intra-atrial connections were capable of different degrees of stimulus propagation from the recipient remnant atrium to the donor atrial compartment. After the ablation of both intra-atrial connections, we also ablated the index arrhythmia in the recipient remnant atrium. This case presentation draws attention to the possibility of the presence of multiple intra-atrial connections.

Acute progression of congestive heart failure during paroxysmal supraventricular tachycardia in a patient without structural heart disease

This report presents the case of a 48-year-old male with acute congestive heart failure caused by paroxysmal supraventricular tachycardia. The patient showed no structural heart disease with normal echocardiography parameters of the left ventricle. The pulmonary capillary wedge pressure (PCWP) was continuously monitored during the electrophysiological study. The PCWP and the plasma B-type natriuretic peptide increased from the normal range during ongoing tachycardia. The tachycardia was diagnosed as orthodromic atrioventricular reciprocating tachycardia and it was successfully eliminated by radiofrequency catheter ablation.

Electrophysiologic Characteristics of Wide QRS Complexes during Pharmacologic Termination of Sustained Supraventricular Tachycardias with Verapamil and Adenosine: Observations from Electrophysiologic Study

In this study we evaluate wide QRS complexes observed during pharmacologic termination of supraventricular tachycardias. Patients with supraventricular tachycardia, undergoing electrophysiologic study were enrolled. 12 mg of adenosine or 10 mg of verapamil were administered during tachycardia, under continuous monitoring of intaracardiac and surface electrocardiograms. Electrocardiographic features of ventricular ectopy were noted. Seventy-four patients were enrolled. 48 patients were randomized to adenosine and 26 to verapamil. Five different appearance patterns of ventricular ectopy were observed during termination of tachycardias. All wide QRS complexes were of ventricular origin and all of them were observed during the termination of tachycardia. Adenosine more frequently resulted in appearance of ventricular beats (15.4% vs 41.7%, P = 0.003), and this was more frequently observed in patients with atrioventricular nodal reentrant tachycardia. Patients with ventricular beats were younger than those without, in both, verapamil (47.5 +/- 15.6 vs 65.0 +/- 8.8 years, P = 0.04) and adenosine (40.9 +/- 13.8 vs 49.7 +/- 16.8, P = 0.03) groups. Left bundle branch block (LBBB)/superior axis morphology was most frequent morphology in adenosine group (55%). Two of 4 patients in verapamil group displayed LBBB/inferior axis QRS morphology and another 2 patients displayed LBBB/superior axis morphology. Noncatheter induced, five different appearance patterns and four distinct morphologies of ventricular origin were observed. Most of them do not directly terminate tachycardia, but are associated with its termination and are not observed in ongoing tachycardia.

Maintenance of Atrial Fibrillation by Pulmonary Vein Tachycardia with Ostial Conduction Block: Evidence of an Interpulmonary Vein Electrical Connection

We report a case of a 56-year-old man with paroxysmal atrial fibrillation who underwent segmental, ostial pulmonary vein (PV) isolation while in arrhythmia. During isolation of the left superior PV (LSPV), organized electrical activity was seen within the vein, suggestive of a PV tachycardia with a cycle length of 90 ms. Simultaneously, organized electrical activity with a cycle length of 180 ms was seen in the left inferior PV (LIPV), suggestive of 2:1 conduction between the LSPV and the LIPV. Isolation of the LIPV resulted in conversion to sinus rhythm, while confirming isolation of the LSPV by the presence of ongoing PV tachycardia in this vein. This case demonstrates a direct electrical connection between the ipsilateral left PVs, leading to maintenance of atrial fibrillation.

Pre-Existing Cardiac Disease, Troponin I Elevation and Mortality in Patients with Severe Sepsis and Septic Shock

A prospective, observational study was undertaken to determine the frequency of troponin I elevation and the incidence of pre-existing cardiac disease in patients with severe sepsis and septic shock, and to determine their relationship to mortality. The setting was the surgical intensive care unit of a tertiary care medical centre. Sixty-six consecutive patients admitted with severe sepsis or septic shock requiring pulmonary artery catheterisation for haemodynamic monitoring were studied. Measurement of troponin I was done at the time of pulmonary artery catheterisation and every six to eight hours if there was ongoing tachycardia, hypotension or arrhythmias requiring treatment. Preexisting cardiac disease was determined from the patient and/or family members as well as from the medical record. Significant cardiac history was defined as prior myocardial infarction; abnormal treadmill report, nuclear medicine study or coronary angiogram; history of congestive heart failure or arrhythmia requiring treatment. Forty-two patients (64%) had elevated troponin I at study entrance and 23 patients (35%) had pre-existing cardiac disease. History of cardiac disease was associated with reduced cardiac index and oxygen delivery, and a nearly three-fold increase in mortality (44% vs. 16%, P = 0.03), irrespective of elevated troponin I levels. Troponin I elevation alone was not associated with increased mortality. We conclude that pre-existing cardiac disease and elevated troponin I are commonly found in surgical patients with severe sepsis and septic shock. In our study, pre-existing cardiac disease, and not troponin I elevation, was associated with increased mortality.

Sinus rhythm and ventricular tachycardia coexisting simultaneously in the same heart

4 A 26-year-old man presented with near-syncope and venricular tachycardia (VT) at 270 bpm. The VT morphology was eft bundle branch block with inferior axis pattern. Cardiac agnetic resonance imaging revealed right ventricular (RV) ysplasia as a probable source of the VT. During electrophysilogic testing, two different morphologies of VT were induced y programmed cardiac stimulation. Both VT morphologies xhibited a left bundle branch block, superior axis pattern, onsistent with an RV site of origin. Radiofrequency ablation f two inferior basal right ventricular sites did not ameliorate nducible VT. The patient underwent an RV disarticulation operation. he RV was dissected free along the left anterior descending oronary artery, extending superiorly to just under the pulmoary valve and posteriorly back to the crux of the posterior escending coronary artery. Cryoablation was performed in egions under the tricuspid valve and the moderator band. uring the postoperative period, the patient developed signs of V failure. Normal sinus rhythm apparently was maintained, nd there were no further recurrences of VT (Figure 1). The atient was taken to the electrophysiology laboratory on postperative day 42 to establish the cardiac rhythm in the RV. ultiple RV locations were mapped. Figure 1 shows a repreentative recording of RV electrical activity in one of the ocations. ECG leads I, II, aVF, and V1 demonstrate sinus achycardia with inferior Q waves. The next channel (labeled RV”) demonstrates recordings from a bipolar catheter placed n the right ventricular apex. Open arrows show electrograms ssociated with sinus rhythm recorded from left ventricular yocardium, which was not disconnected during the operation long the RV septum. Closed arrows identify RV electrograms ecorded from the disarticulated RV free wall. The RV elecrograms revealed ongoing RV tachycardia (cycle length 400 s), which persisted even though the remainder of the heart as in sinus rhythm. Moreover, the surface ECG revealed inus rhythm but not VT.

P6-60: Differentiation of atrio-ventricular nodal reentrant tachycardia from orthodromic atrio-ventricular reentrant tachycardia by ΔHA intervals during entrainment from the ventricle

Differentiating atrio-ventricular nodal reentrant tachycardia (AVNRT) from orthodromic atrio-ventricular reentrant tachycardia (AVRT) can be problematic. Differences in His bundle-atrial (HA) intervals during supraventricular tachycardia (SVT) and ventricular pacing in sinus rhythm facilitate diagnosis, but would be better analyzed during ongoing tachycardia when retrogradely conducting structures are operative. The ΔHA interval (HA Entrain - HA SVT) during entrainment of SVT from the ventricle has not been studied.

Severe cardiac failure associated with presumed jellyfish sting. Irukandji syndrome?

We present a retrospective review of twelve cases of Irukandji syndrome associated with pulmonary oedema. This is a life-threatening envenoming due to a presumed jellyfish sting throughout Northern Australia, although only one case occurred outside North Queensland. Patients presented with significant and ongoing pain, tachycardia and hypertension. Half the patients became hypotensive requiring inotropic support. Cardiac echocardiography revealed significant cardiac dysfunction. Six patients required ventilatory support. There was no death reported due to pulmonary oedema, but one patient died of intracerebral haemorrhage. We believe patients may develop a toxin associated cardiomyopathy, and jellyfish other than Carukia barnesi may be responsible. As there is confusion with nomenclature, Carukia barnesi should be known as the Barnes jellyfish, and the diagnosis of cardiotoxic marine envenoming is suggested for any patient who has been stung by a jellyfish, develops no or minimal skin markings, and develops cardiogenic pulmonary oedema associated with Irukandji syndrome.

Prevention of reentrant tachycardia by single beat or repetitive stimulation.

Eleven patients with an atrioventricular accessory pathway were studied by programmed electrical stimulation to determine if reentrant tachycardia could be prevented by delivery of either a single atrial extrastimulus, applied at a critical time after the tachycardia-initiating stimulus (or stimuli), or a train of stimuli. In all 11 patients, reentrant tachycardia was reproducibly induced from the high right atrium with a single premature beat, and in all patients initiation of tachycardia was prevented from the same site by a second premature beat. This second extrastimulus was effective if delivered within a zone which began 10 ms outside the effective refractory period of the tachycardia-initiating stimulus and averaged 61 ms in width. This was termed the 'preventive zone'. In 7 patients the effect of train stimulation to the high right atrium was studied. In all 7, the results were concordant with those obtained by single-beat stimulation. Any train which achieved single atrial capture within the preventive zone was effective in preventing tachycardia. Prevention was always possible with a single atrial extrastimulus or with single-capture train stimulation, whereas termination of an ongoing tachycardia required at least 2 atrial extrastimuli, or stimulation from the right ventricle.

Tachycardia prevention by programmed stimulation

Ten patients with an atrioventricular accessory pathway were studied by standard electrophysiologic techniques to determine if reentrant tachycardia can be prevented in these patients by delivery of a single extrastimulus, applied at a critical time after the tachycardia-initiating stimulus (or stimuli). In all 10 patients, reentrant tachycardia was reproducibly induced from the high right atrium with a single premature beat, and initiation of tachycardia could be prevented from the same site by a second premature beat. This second extrastimulus was effective if delivered within a zone that began 10 ms outside of the effective refractory period of the tachycardia-initiating stimulus and averaged 50 ms in width. This zone was termed the “preventive zone.” The width of the preventive zone was independent of the initial tachycardia interval and the tachycardia cycle length. Prevention of reentrant tachycardia was always possible with a single atrial extrastimulus, whereas termination of the ongoing tachycardia required at least 2 atrial extrastimuli or stimulation from the right ventricle.