Cases reported "Tachycardia"

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1/155. Right posterior atrioventricular ring: a location for different types of atrioventricular accessory connections.

    We present an unusual case of a 28-year-old female patient with recurrent episodes of tachycardias due to participation of two accessory connections located in the posterior tricuspid annulus. Both connections were of the atrioventricular type, the one with non decremental fast conducting properties at the right posteroseptal area, the other with node-like properties at the posterolateral tricuspid ring. Both pathways were successfully ablated transvenously with radiofrequency energy application at the same session. Implications about a common embryological origin of the two pathways as well as review of the literature for similar cases are presented.
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2/155. Analysis of heart rate variability during head-up tilt testing in a patient with idiopathic postural orthostatic tachycardia syndrome (POTS).

    A 16-year-old boy was diagnosed with idiopathic postural orthostatic tachycardia syndrome (POTS) during head-up tilt testing. During a passive tilt, the patient's heart rate (HR) increased by 30 beats/min within 5 min. After 25 min of tilting, his HR further increased to 133 beats/min and he began to complain of lightheadedness and weakness without hypotension. Power spectral analysis of HR variability during the tilt test revealed that the ratio of low and high frequency powers increased with the onset of orthostatic intolerance. propranolol (10mg every morning) dramatically alleviated his clinical symptoms, and he has been asymptomatic with gaining weight after discontinuing his crowded train commuting.
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3/155. The nondiagnostic ECG in the chest pain patient: normal and nonspecific initial ECG presentations of acute MI.

    The 12-lead electrocardiogram (ECG) is a powerful clinical tool used in the evaluation of chest pain patients, assisting in the selection of the proper therapy. Unfortunately, the ECG is diagnostic of acute myocardial infarction (AMI) in only one-half of such patients at initial hospital evaluation. In the remaining group of patients with the nondiagnostic 12-lead electrocardiogram, the ECG may be entirely normal, show nonspecific sinus tachycardia (ST) segment-T wave abnormalities, or obvious ischemic changes. In adult chest pain patients treated in the emergency department (ED), 1% to 4% of such patients with an absolutely normal ECG had a final hospital diagnosis of AMI; furthermore, patients with nonspecific electrocardiographic abnormalities experienced AMI in 4% of cases. These findings reinforce the teaching point that the history is the most important tool used in the evaluation of chest pain patients. Furthermore, overreliance on a normal or nonspecifically abnormal ECG in a patient with a classic description of anginal chest pain is dangerous.
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4/155. electrocardiography in the patient with the wolff-parkinson-white syndrome: diagnostic and initial therapeutic issues.

    The wolff-parkinson-white syndrome (WPW), estimated to occur in approximately 0.1% to 3% of the general population, is a form of ventricular preexcitation involving an accessory conduction pathway. The definition of WPW relies on the following electrocardiographic features: (1) a PR interval less than 0.12 seconds (2) with a slurring of the initial segment of the QRS complex, known as a delta wave, (3) a QRS complex widening with a total duration greater than 0.12 seconds, and (4) secondary repolarization changes reflected in ST segment-T wave changes that are generally directed opposite (discordant) to the major delta wave and QRS complex changes. The accessory pathway bypasses the atrioventricular (AV) node, creating a direct electrical connection between the atria and ventricles. The majority of patients with preexcitation syndromes remain asymptomatic throughout their lives. When symptoms do occur they are usually secondary to tachyarrhythmias; the importance of recognizing this syndrome is that these patients may be at risk to develop a variety of supraventricular tachyarrhythmias which cause disabling symptoms and, in the extreme, sudden cardiac death. The tachyarrhythmias encountered in the WPW patient include paroxysmal supraventricular tachycardia (both the narrow QRS and wide QRS complex varieties), atrial fibrillation, atrial flutter, and ventricular fibrillation. Diagnostic and urgent, initial therapeutic issues based on initial electrocardiographic information are presented via 5 illustrative cases.
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5/155. Electrophysiological mechanisms of conversion of typical to atypical atrioventricular nodal reentrant tachycardia occurring after radiofrequency catheter ablation of the slow pathway.

    This report presents an adult patient with conversion of typical to atypical atrioventricular nodal reentrant tachycardia (AVNRT) after slow pathway ablation. Application of radiofrequency energy (3 times) in the posteroseptal region changed the pattern of the atrioventricular (AV) node conduction curve from discontinuous to continuous, but did not change the continuous retrograde conduction curve. After ablation of the slow pathway, atrial extrastimulation induced atypical AVNRT. During tachycardia, the earliest atrial activation site changed from the His bundle region to the coronary sinus ostium. One additional radiofrequency current applied 5 mm upward from the initial ablation site made atypical AVNRT noninducible. These findings suggest that the mechanism of atypical AVNRT after slow pathway ablation is antegrade fast pathway conduction along with retrograde conduction through another slow pathway connected with the ablated antegrade slow pathway at a distal site. The loss of concealed conduction over the antegrade slow pathway may play an important role in the initiation of atypical AVNRT after slow pathway ablation.
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6/155. Pre-excitation syndrome secondary to cardiac rhabdomyomas in tuberous sclerosis.

    Rhabdomyomas are not uncommon in infants with tuberous sclerosis. We describe a neonate who presented with hydrops fetalis arising from a tachyarrhythmia during fetal life related to rhabdomyomas. After reversion of the arrhythmia, pre-excitation was noted on an interval electrocardiogram. Following regression of the tumours, the delta wave disappeared with no further arrhythmias noted.
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7/155. Monitoring equipment induced tachycardia in patients with minute ventilation rate-responsive pacemakers.

    Minute ventilation-sensing pacemakers enable the paced heart to respond to an increased workload. Two patients with such a pacemaker developed pacemaker-driven tachycardia when connected to an electrocardiogram (ECG) monitor also capable of documenting ventilatory frequency and ECG lead disconnection. This tachycardia stopped when the ECG leads were removed. These pacemakers and monitors emit a low-amplitude electrical current and measure the resultant impedence signal across the chest. When patients are connected to the monitor the pacemaker sensor summates both impedence signals and the paced heart rate is increased as a result.
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8/155. The diagnosis or ventricular tachycardia with ventriculo-atrial conduction.

    A 57 year old man developed recurrent tachycardia with QRS complexes of 0.13 second in duration at a rate of 140 beats per minute. Inverted P waves appeared to follow each QRS complex in the electrocardiographic leads II, III and aVF. The differentiation between ventricular tachycardia with1 : 1 V-A conduction and supraventricular tachycardia with aberrant ventricular conduction was difficult to make from the surface electrocardiogram. This differentiation is important for selection of appropriate therapy. The diagnosis of ventricular tachycardia with 1 : 1 V-A conduction was clearly established in this case on simultaneous recording of surface electrocardiogram, His bundle electrogram and high right atrial electrogram.
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9/155. Interatrial conduction of atrial tachycardia in heart transplant recipients: potential pathophysiology.

    Surgical suture lines formed at the site of anastamosis have been considered to be electrically inert and thus present a line of block to conduction. However, a number of reports have suggested that conduction is occasionally possible across suture lines. Most of these cases have reported conduction between donor and recipient atria following cardiac transplantation. We report an illustrative case successfully treated with radiofrequency ablation, and present pathology findings that may give insight into the pathophysiology.
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10/155. Radiofrequency ablation of focal atrial tachycardia and atrioatrial conduction from recipient to donor after orthotopic heart transplantation.

    After cardiac transplantation, atrial arrhythmias may develop in the residual recipient atrium and conduct to the donor heart. Radiofrequency (RF) ablation of the atrioatrial conduction may be effective in arrhythmia control, although the recipient atrium continues its tachycardia. We hypothesize that in patients with posttransplant atrial tachycardia, it is possible to ablate both the arrhythmogenic focus in the recipient atrium and the atrioatrial conduction. A 47-year-old patient who had orthotopic heart transplantation 9 months earlier underwent RF ablation procedure because of medically uncontrolled atrial arrhythmia. By conventional electrophysiologic mapping, we localized the focus of the atrial tachycardia in the recipient atrium and the electrical atrioatrial connection across the anastomotic suture line. Selective applications of RF energy eliminated both targets successfully. RF ablation of recipient atrial tachycardia and atrioatrial conduction from recipient to donor may lead to long-term success of arrhythmia control.
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