Idiopathic fascicular ventricular tachycardia

Idiopathic fascicular ventricular tachycardia is an important cardiac arrhythmia with specific electrocardiographic features and therapeutic options. It is characterized by relatively narrow QRS complex and right bundle branch block pattern. The QRS axis depends on which fascicle is involved in the re-entry. Left axis deviation is noted with left posterior fascicular tachycardia and right axis deviation with left anterior fascicular tachycardia. A left septal fascicular tachycardia with normal axis has also been described. Fascicular tachycardia is usually seen in individuals without structural heart disease. Response to verapamil is an important feature of fascicular tachycardia. Rare instances of termination with intravenous adenosine have also been noted. A presystolic or diastolic potential preceding the QRS, presumed to originate from the Purkinje fibers can be recorded during sinus rhythm and ventricular tachycardia in many patients with fascicular tachycardia. This potential (P potential) has been used as a guide to catheter ablation. Prompt recognition of fascicular tachycardia especially in the emergency department is very important. It is one of the eminently ablatable ventricular tachycardias. Primary ablation has been reported to have a higher success, lesser procedure time and fluoroscopy time.     

Emergency epicardial dissection of the accessory pathway in a patient with atrioventricular nodal reentrant tachycardia]

Diagnostic and therapeutic problems in 14 year old patient with concealed WPW syndrome were presented. Paroxysms of atrio-ventricular reentrant tachycardia 180-220/min were frequently recurring, usually with normal QRS pattern. Tachycardias often had to be terminated by intravenous administration of antiarrhythmic drugs. Long term treatment with various antiarrhythmic agents did not prevent recurrence of tachycardias but they became sustained and were recurring more often. Their other side effects manifested with sinus node disfunction and depression of the heart muscle. The electrophysiologic study revealed right anterior septal accessory pathway. Epicardial dissection of the accessory pathway was urgently performed. The control electrophysiologic study revealed no evidence of conduction through the accessory pathway. The patient did not require antiarrhythmic treatment. During the 12 months follow up no tachycardia occurred.     

Ventricular tachycardia based on cardiac sarcoidosis with a narrow QRS complex,ablated on the left ventricle free-wall

A septuagenarian female with cardiac sarcoidosis suffered from drug refractory ventricular tachycardia (VT) requiring multiple implantable cardioverter-defibrillator shocks. The QRS complex during the VT was very similar to that during sinus rhythm although the QRS width during the VT (142 ms) was relatively wider than that during sinus rhythm (107 ms). The VT exit was located on the ventricular septum close to the His-bundle recording region. However, the critical pathway of this VT was detected on the anterior free wall of the left ventricle (LV), and a radiofrequency application at that site could terminate the VT. No Purkinje potentials were recorded there during the VT or sinus rhythm. According to the electrophysiological study, 3-D mapping, and the response to the ablation, the critical circuit of the VT was surrounded by a protected area of scar associated with cardiac sarcoidosis. As a result, the VT circuit was connected to the basal septal area close to the His-Purkinje system as an outer loop of the VT circuit. This unique trajectory of the VT might have caused a similar QRS morphology to that of sinus rhythm, and the relatively narrow QRS complex despite the critical isthmus was located on the anterior free wall of the LV.     

Clinical and electrophysiologic variants of false ventricular tachycardia (supraventricular tachycardia with wide QRS complex)

Electrophysiological abnormalities of the heart conduction system and their role in development of different forms of supraventricular tachycardias, are discussed. Electrophysiological mechanisms and diagnostic criteria of the supraventricular tachycardias with wide QRS complex, are described.     

Bundle branch reentrant ventricular tachycardia

Bundle branch reentrant (BBR) tachycardia is an uncommon form of ventricular tachycardia (VT) incorporating both bundle branches into the reentry circuit. The arrhythmia is usually seen in patients with an acquired heart disease and significant conduction system impairment, although patients with structurally normal heart have been described. Surface ECG in sinus rhythm (SR) characteristically shows intraventricular conduction defects. Patients typically present with presyncope, syncope or sudden death because of VT with fast rates frequently above 200 beats per minute. The QRS morphology during VT is a typical bundle branch block pattern, usually left bundle branch block, and may be identical to that in SR. Prolonged His-ventricular (H-V) interval in SR is found in the majority of patients with BBR VT, although some patients may have the H-V interval within normal limits. The diagnosis of BBR VT is based on electrophysiological findings and pacing maneuvers that prove participation of the His- Purkinje system in the tachycardia mechanism. Radiofrequency catheter ablation of a bundle branch can cure BBR VT and is currently regarded as the first line therapy. The technique of choice is ablation of the right bundle. The reported incidence of clinically significant conduction system impairment requiring implantation of a permanent pacemaker varies from 0% to 30%. Long-term outcome depends on the underlying cardiac disease. Patients with poor systolic left ventricular function are at risk of sudden death or death from progressive heart failure despite successful BBR VT ablation and should be considered for an implantable cardiovertor-defibrillator.     

Treatment of Cardiac Arrhythmias with Synchronized Electrical Counter-shock

Synchronized electrical countershock is an intriguing new method for the treatment of ectopic tachycardias. The authors applied this treatment to 20 patients with chronic atrial fibrillation and, in 17 patients, sinus rhythm was restored immediately. An additional four patients with atrial flutter were successfully converted to sinus rhythm. One patient developed a hemiplegia two weeks after cardioversion. No other untoward side effects were observed. In two patients with ventricular fibrillation electrical countershock terminated the arrhythmia. After successful cardioversion of atrial fibrillation, a maintenance dose of quinidine is given to help maintain sinus rhythm. In spite of this precaution, one-half of the patients reverted to atrial fibrillation within a month. The quinidine was administered for two to three days in advance of cardioversion; on this regimen, 10 of 34 patients reverted to sinus rhythm on quinidine alone and did not require countershock. The exact place of this treatment of cardiac arrhythmias has not yet been clearly defined.     

Sinus versus nonsinus tachycardia in the emergency department: Importance of age and heart rate

Background

The emergency department diagnosis of sinus versus nonsinus tachycardia is an important clinical challenge. The objective of this study was to identify subjects with a high prevalence of nonsinus tachycardia.

Methods

Heart rate and cardiac rhythm were prospective reviewed in 500 consecutive patients with heart rate ≥ 100 beats/min in a busy emergency department. A predictive model based on age and heart rate was then developed to identify the probability of nonsinus tachycardia.

Results

As age and heart rate increased, nonsinus tachycardias became more frequent. The probability of nonsinus tachycardia in a subject ≥ 71 years with heart rate ≥ 141 beats/minute was 93%, compared to only three percent in a subject ≤ 50 years with heart rate 100–120 beats/minute. A simple point score system based on age and heart rate helps predict the probability of sinus tachycardia versus nonsinus tachycardia.

Conclusion

Nonsinus tachycardia is significantly more common than sinus tachycardia in elderly patients in the emergency department. The diagnosis of sinus tachycardia becomes much less likely as age and heart rate increase.     

Self-conversion of drug-resistant paroxysmal atrial tachycardia.

A 56-year-old woman had paroxysmal atrial tachycardia (PAT) that was recurrent, drug-resistant and required frequent electroversion. The mode of onset and termination of initiated episodes of PAT suggested an AV junctional reentrant mechanism. The problem was successfully managed by a permanent electrode implanted transvenously in the coronary sinus and connected to a subcutaneous radio frequency receiver. For the past 24 months the patient has successfully terminated all episodes of PAT (at least 60) by activating an external radio frequency transmitter that transmits impulses to the implanted receiver and electrode catheter. Conversion to sinus rhythm requires 5 seconds or less of pacing.     

Sudden unexpected improvement in the atrioventricular conduction. What is the mechanism?

The 12-lead electrocardiogram (ECG) of a 79-year-old male patient with recurrent pre-syncope showed irregular sinus rhythm with constant PR interval and left bundle branch block (LBBB) with intermittently blocked P waves. The beat following the blocked P wave had a narrower QRS with a shorter PR interval. The phenomenon of bilateral bundle branch block explains the sudden improvement in the atrioventricular conduction.     

Coronary sinus norepinephrine concentrations during ventricular tachycardia induced by left stellate ganglion stimulation in dogs

Coronary sinus catecholamine overflow was measured in open-chest dogs, anesthetized with sodium thiopental and alpha-chloralose, during left sympathetic stimulation. Uniform ventricular tachycardias were induced in 9 out of 16 dogs during either left stellate ganglion or left ventrolateral cardiac nerve stimulations. Significant increases in norepinephrine (8.1 ng/mL, plasma) and epinephrine (0.19 ng/mL, plasma) overflows were obtained after 30 and 90 s of stimulation, respectively. Maximum norepinephrine overflow was significantly higher in dogs with ventricular tachycardia than in those without it (16.0 vs. 7.4 ng/mL, p less than 0.05). This suggests that the induction of ventricular tachycardia in the normal myocardium is related to the amount of local secretion of norepinephrine during nerve stimulation.     

Defining the substrate for ventricular tachycardia ablation: The impact of rhythm at the time of mapping

BackgroundVoltage mapping is critical to define substrate during ablation. In ventricular tachycardia, abnormal potentials may be targets. However, wavefront of activation could impact local signal characteristics. This may be particularly true when comparing sinus rhythm versus paced rhythms. We sought to determine how activation wavefront impacts electrogram characteristics.MethodsPatients with ischemic cardiomyopathy, ventricular tachycardia, and without fascicular or bundle branch block were included. Point by point mapping was done and at each point, one was obtained during an atrial paced rhythm and one during a right ventricular paced rhythm. Signals were adjudicated after ablation to define late potentials, fractionated potentials, and quantify local voltage. Areas of abnormal voltage (defined as <1.5 mV) were also determined.Results9 patients were included (age 61.3 ± 9.2 years, 56% male, mean LVEF 34.9 ± 8.6%). LV endocardium was mapped with an average 375 ± 53 points/rhythm. Late potentials were more frequent during right ventricular pacing (51 ± 21 versus 32 ± 15, p < 0.01) while overall scar area was higher during atrial pacing (22 ± 11% vs 13 ± 7%, p < 0.05). In 1/9 patients, abnormal potentials were seen during a right ventricular paced rhythm that were not apparent in an atrial paced rhythm, ablation of which resulted in non-inducibility.ConclusionRhythm in which mapping is performed has an impact on electrogram characteristics. Whether one rhythm is preferable to map in remains to be determined. However, it is possible defining local signals during normal conduction as well as variable paced rhythms may impart a greater likelihood of elucidating arrhythmogenic substrate.     

Incessant tachycardia in a patient with advanced heart failure and left ventricular assist device: What is the mechanism?

We present a case of incessant wide-complex tachycardia in a patient with left-ventricular assist device, and discuss the differential diagnosis with an in-depth analysis of the intracardiac tracings during the invasive electrophysiologic study, including interpretation of the relative timing of the fascicular signals during tachycardia and in sinus rhythm, and interpretation of pacing and entrainment maneuvers.     

Robotic-assisted cryosurgical treatment of atrioventricular node reentrant tachycardia

Atrioventricular nodal reentrant tachycardias typically arise from the existence of variable refractoriness in fast and slow conduction pathways within the triangle of Koch, which provide input to the atrioventricular node. Standard therapy includes medical management and catheter-based ablation procedures. Robotic-assisted, minimally invasive cryosurgical modification of the atrioventricular node can provide definitive therapy for patients who fail traditional therapy. A 65-year-old man presented with a several-year history of recurrent atrioventricular nodal reentrant tachycardia. Despite medical management and attempted percutaneous ablation, the patient remained symptomatic with weekly episodes. Access was via a 4-cm right anterolateral thoracotomy and peripheral perfusion. The da Vinci S robotic system was used to manipulate the cryoprobe (CryoMaze Probe; ATS Medical, Plymouth, MN USA). A series of spot freezes (tip 60°C) were made along the boundaries of the triangle of Koch until transient complete heart block was achieved and nodal rhythm was recovered. At follow-up 3 weeks postoperatively, the patient was asymptomatic in first-degree heart block. Robotic-assisted cryosurgical atrioventricular node ablation is an effective, minimally invasive treatment for patients with atrioventricular nodal reentrant tachycardia.     

Programmed electrical stimulation and Amiodarone therapy for the control of persistent junctional tachycardia

The use of radiofrequency as a means of synchronization and stimulation does not necessitate an external lead, and thus has allowed the construction of an implantable device for long-term treatment of reentry tachycardias. The device is used along with Amiodarone therapy and can be triggered by the patient himself.     

Interesting electrophysiological findings in a patient with coincidental right ventricular outflow tract and atrioventricular nodal reentrant tachycardia

Tachycardia induced tachycardias are not common in clinical practice, and it is believed that most cases of double tachycardia are coincidental. The existence of two different tachycardias in the same patient almost always poses problems in the electrophysiology laboratory. However, in rare instances, the emergence of a second tachycardia can actually provide invaluable information about the first one. In this report, we describe a 30-year-old woman who presented with palpitations. Electrophysiological study revealed that atrial programmed stimulation at baseline induced right ventricular outflow tract (RVOT) tachycardia and supraventricular tachycardia. The study also showed that each of the tachycardias was able to induce the other. A short run of RVOT tachycardia during supraventricular tachycardia was able to entrain the latter. This finding provided important information about the nature of the supraventricular tachycardia, which proved to be atrioventricular nodal reentrant tachycardia. Both of these tachycardias were successfully ablated, and the patient's palpitations disappeared.     

Outflow-tract ventricular tachycardia: Can 12 lead ECG during sinus rhythm identify underlying cardiac sarcoidosis?

BackgroundPatients with outflow tract ventricular tachycardia (OTVT) with normal echocardiogram are labeled as idiopathic VT (IVT). However, a subset of these patients is subsequently diagnosed with underlying cardiac sarcoidosis (CS). Objective:Whether electrocardiogram (ECG) abnormalities in sinus rhythm (SR) can differentiate underlying CS from IVT.MethodsWe retrospectively analyzed the SR-ECGs of 42 patients with OTVT/premature ventricular complexes (PVC) and normal echocardiography. All underwent advanced imaging with cardiac magnetic resonance (CMR)/¹⁸FDG PET-CT for screening of CS. Twenty-two patients had significant abnormalities in cardiac imaging and subsequently had biopsy-proven CS (Cases). Twenty patients had normal imaging and were categorized as IVT (Controls). SR-ECGs of all patients were analyzed by 2 independent, blinded observers.ResultsBaseline characteristics were comparable. Among the ECG features analyzed – fascicular (FB) or bundle branch block (BBB) was seen in 9/22 Cases vs. 1/20 controls (p = 0.01). Among patients without FB or BBB, fragmented QRS (fQRS) was present in 9/13 cases but in none of the controls (p < 0.001). Low voltage QRS was more often seen among cases as compared to controls (10/22 vs. 3/20 p = 0.03). A stepwise algorithm based on these 3 sets of ECG findings helped to diagnose CS among patients presenting with OTVT/PVC with sensitivity of 91%, specificity of 75%, a PPV of 80%, and a NPV of 88%.ConclusionsIn patients presenting with OTVT/PVC: FB/BBB, fQRS, and low QRS voltage on the baseline ECG were more often observed among patients with underlying CS as compared to true IVT. These findings may help to distinguish underlying CS among Cases presenting with OTVT/PVC.     

Hemodynamic effects of pacing-induced tachycardia in valvular aortic stenosis.

The hemodynamic effects of tachycardia were studied in 13 patients with valvular aortic stenosis. Observations were made during sinus rhythm (average heart rate 80 beats/min) and two periods (P1 and P2) when atrial pacing increased the heart rate to 109 and 131 beats/min respectively. The cardiac index did not change, but the left ventricular stroke work index fell from 61.8 to 39.5 g X m/m2 (p less than 0.001) as the heart rate increased. The left ventricular end-diastolic pressure averaged 18 mm Hg during sinus rhythm and fell to about 11.5 mm Hg at P1 and P2 (p less than 0.001). The brachial arterial systolic pressure did not change during pacing, but the left ventricular systolic pressure fell from 208 mm Hg to 201 mm Hg during P1 (p less than 0.05) and 193 mm Hg during P2 (p less than 0.001). The mean systolic aortic valve gradient averaged 64 mm Hg during sinus rhythm and fell to 51 mm Hg during P2 (p less than 0.001), and the peak aortic valve gradient fell from 82 to 69 mm Hg during P2 (p less than 0.001). The left ventricular ejection time fraction increased from 26.9% during sinus rhythm to 31.9% during P1 (p less than 0.05) and 34.7% during P2 (p less than 0.005). Because of the prolonged left ventricular ejection time fraction and smaller stroke volume, a smaller pressure gradient developed across the stenosed valve at higher heart rates. The pacing test was of little value in assessing left ventricular function and thus is not useful during invasive investigations of valvular aortic stenosis.     

Down syndrome associated with hypothyroidism and chronic pericardial effusion: echocardiographic follow-up

We present a 39-year-old male patient with Down syndrome who was evaluated for fatigue, palpitations and bouts of cyanosis. Physical examination showed features of trisomy-21(Down syndrome), with a slow pulse rate, distant cardiac sounds and absent apex beat. He had normal jugular venous pressure without pulsus paradoxus. The ECG showed QRS microvoltage and flattened P and T segments. The 48-hour ambulatory ECG depicted normal sinus rhythm with intermittent short PR interval without tachyarrhythmias. The chest Xray revealed cardiomegaly without pulmonary venous congestion. Although serial transthoracic echocardiographic examination demonstrated pericardial effusion with features of tamponade, there were no overt signs of clinical cardiac tamponade. Biochemically, the serum thyroxine of 3 pmol/l (normal 10 to 25) and thyroid-stimulating hormone of 160 mU/l (normal 0.20 to 4.20)) were compatible with hypothyroidism. The patient was treated with L-thyroxine sodium daily, which was gradually increased to 0.125 mg daily. Within a few months he lost weight and became more alert; furthermore, the symptoms of hypothyroidism and the pericardial effusion resolved. It can be concluded that Down syndrome may be associated with hypothyroidism and pericardial effusion. These were alleviated following hormone replacement. Regular evaluation of thyroid function tests is important in Down syndrome. (Neth Heart J 2007;15:67-70.)     

Confounding factors leading to misdiagnosing ventricular tachycardia as supraventricular in the emergency room

Studies conducted during the last 50 years have proposed electrocardiographic criteria and algorithms to determine if a wide QRS tachycardia is ventricular or supraventricular in origin. Sustained ventricular tachycardia is an uncommon reason for consultation in the emergency room. The latter and the complexity of available electrocardiographic diagnostic criteria and algorithms result in frequent misdiagnoses. Good hemodynamic tolerance of tachycardia in the supine position does not exclude its ventricular origin. Although rare, ventricular tachycardia in patients with and without structural heart disease may show a QRS duration <120 ms. Interruption of tachycardia by coughing, carotid sinus massage, Valsalva maneuver, or following the infusion of adenosine or verapamil should not discard the ventricular origin of the arrhythmia. In patients with regular, uniform, sustained broad QRS tachycardia, the presence of structural heart disease or A-V dissociation strongly suggest its ventricular origin. Occasionally, ventricular tachycardia can present with AV dissociation without this being evident on the 12-lead ECG. Cardiac auscultation, examination of the jugular venous pulse, and arterial pulse palpation provide additional clues for identifying A-V dissociation during tachycardia. This paper does not review the electrocardiographic criteria for categorizing tachycardia as ventricular but rather why emergency physicians misdiagnose these patients.