Multiple Episodes Of Ventricular Tachycardia Research Articles

Canine Model of Ischemia-Induced Ventricular Tachycardia

IntroductionDespite advances in antiarrhythmia therapies, ventricular tachycardia (VT) is a leading cause of sudden cardiac death. Investigation into the characteristics and new treatments for this arrhythmia is required to improve outcomes and a reproducible model of VT would be useful in these endeavors. We therefore created a canine model of ischemia-induced VT. Materials and methodsA pacing lead was implanted in the right ventricle in canines (n = 13) and the left anterior descending artery was occluded in two locations for 2 h and subsequently released to create an ischemia-reperfusion injury. In the 10 dogs that survived the first 48 h following the initial study, a terminal study was conducted 4-7 d later and VT was induced using premature stimulation or burst pacing through the right ventricle lead. The arrhythmia was terminated using either antitachycardia pacing or a defibrillatory shock. Multiple inductions into sustained VT were attempted. ResultsSustained VT was induced in eight of 10 dogs with an average cycle length of 335 ± 70 bpm. Multiple episodes of VT were induced. Episodes of VT exhibited different electrocardiogram morphologies and cycle lengths in individual animals. ConclusionsThis canine model provides a consistent technique for inducing multiple episodes of sustained VT. It may be useful for investigating VT mechanisms and testing novel therapeutics and treatments for patients with VT.

Repetitive multiform narrow complex tachycardia

A 73-year-old man presented to the emergency department with palpitations. After experiencing transient exertional palpitations and dyspnea a few months earlier, investigation revealed moderate left ventricular dysfunction and extensive coronary artery disease with evidence of prior inferior infarction. He underwent bypass grafting and remained symptom free with normalization of his ejection fraction until the current presentation. Figure 1 demonstrates his presenting rhythm that did not respond to adenosine but terminated with intravenous diltiazem. What is the most likely mechanism of the tachycardia? Figure 1 shows a regular narrow complex tachycardia with 3 distinct alternating QRS morphologies: (1) right bundle branch block (RBBB), V1 R 120 ms, V4 precordial transition, left superior axis; (2) RBBB, V1 rsRʹ 100 ms, positive precordial concordance, left superior axis; and (3) RBBB, V1 R 100 ms, positive precordial concordance, left superior axis. The RBBB and left superior axis of all 3 morphologies suggest that the ventricles are activated via the left posterior fascicle, or at the very least, there is early engagement of this fascicle. While supraventricular tachycardia with aberrant conduction is theoretically possible, varying ventricular morphologies in this fashion, lack of termination with adenosine, and the relatively narrow QRS duration (<130 ms) would make this less likely. Together with the response to diltiazem, the overall evidence suggests ventricular tachycardia involving the left posterior fascicle. The classic form of idiopathic fascicular ventricular tachycardia involves the left posterior fascicle, in which there is slow antegrade conduction along abnormal Purkinje fibers in the mid-septum (resulting in P1 potentials) and conduction over the left posterior fascicle (resulting in P2 potentials).1Nogami A. Naito S. Tada H. et al.Demonstration of diastolic and presystolic Purkinje potentials as critical potentials in a macroreentry circuit of verapamil-sensitive idiopathic left ventricular tachycardia.J Am Coll Cardiol. 2000; 36: 811-823Crossref PubMed Scopus (218) Google Scholar In any individual patient, variable relationships of the abnormal Purkinje fiber to the left posterior fascicle can result in a more basal or apical site of breakout to the left ventricle; these differences can often be suggested on the surface electrocardiogram by the width of the QRS complex and the precordial transition.2Liu Q. Shehata M. Jiang R. et al.Macroreentrant loop in ventricular tachycardia from the left posterior fascicle: new implications for mapping and ablation.Circ Arrhythm Electrophysiol. 2016; 9e004272Crossref Scopus (7) Google Scholar,3Ma W. Lu F. Shehata M. et al.Catheter ablation of idiopathic left posterior fascicular ventricular tachycardia: predicting the site of origin via mapping and electrocardiography.Circ Arrhythm Electrophysiol. 2017; 10e005240Crossref PubMed Scopus (1) Google Scholar Sung et al4Sung R.K. Kim A.M. Tseng Z.H. et al.Diagnosis and ablation of multiform fascicular tachycardia.J Cardiovasc Electrophysiol. 2013; 24: 297-304Crossref PubMed Scopus (29) Google Scholar described multiform fascicular QRS complexes due to alternate conduction over the left anterior fascicle and the left posterior fascicle from the septal fascicle, but the QRS forms described in the present report are different. Idiopathic fascicular ventricular tachycardia typically occurs in patients with structurally normal hearts, which was not the case in the present report. However, abnormal Purkinje fibers have also been implicated in a minority of patients with ischemic ventricular tachycardia and extension of inferoposterior scar to the left posterior fascicle.5Bogun F. Good E. Reich S. et al.Role of Purkinje fibers in post-infarction ventricular tachycardia.J Am Coll Cardiol. 2006; 48: 2500-2507Crossref PubMed Scopus (121) Google Scholar In this case, it was hypothesized that different QRS morphologies were due to varying sites of left ventricular breakout (Figure 2). The patient underwent electrophysiology study, where multiple episodes of ventricular tachycardia were able to be induced with ventricular extrastimuli similar to those seen on presentation. Ablation of the left posterior fascicle was undertaken, with subsequent noninducibility and no further episodes after 12 months of follow-up.

484 PAPILLARY FIBROELASTOMA OF THE AORTIC VALVE ASSOCIATED WITH MYOCARDIAL INFARCTION, COMPLICATED BY ELECTRICAL STORM AND ENDOVENTRICULAR THROMBOSIS

Abstract Introduction Papillary fibroelastomas (PFE) are reported to be the most common tumors of the heart valves and are a possible source of systemic embolism, including myocardial infarction. Case Report We report the case of a 67-year-old female with no background of cardiovascular disease, admitted to our hospital with worsening dyspnea and chest tightness over the prior 10 days. The ECG showed a sustained hemodynamically tolerated monomorphic ventricular tachycardia, successfully treated with antiarrhythmic therapy, and ECG in sinus rhythm revealed signs of previous anterior myocardial infarction. Transthoracic echocardiogram showed a severely depressed systolic function (LVEF 19%), akinesia and thinning of the anterior wall and of all middle-apical segments, complicated by left ventricular aneurysm and endoventricular thrombosis. In the ventricular side of right aortic coronary cusp a mobile, pedunculated mass of 12×8 mm was visualized. A subsequent TEE corroborated the suspicion of PFE. She underwent cardiac MRI which showed areas of transmural late enhancement in all akinetic segments. A coronary angiography revealed sub-occlusion of the mid-anterior descending artery with no angiographic evidence of coronary atherosclerosis elsewhere. In view of her reduced LVEF and history of VT, an ICD was implanted. She started oral anticoagulant therapy and complete resolution of the endoventricular thrombosis was evidenced. After several days of electrical instability, characterized by multiple episodes of ventricular tachycardia, the clinical course was characterized by progressive clinical and electrical improvement and she was discharged in good clinical conditions after four weeks. Due to the severe impairment of the systolic function, not susceptible to surgical remodeling and the high operative risk, no indication for surgical removal of the mass was made. Conclusion Aortic PFE carry a not negligible risk of acute coronary syndrome, electrical storm and sudden death. It should be considered as the cause of myocardial infarction, and not an incidental finding, especially in patients with no angiographic evidence of coronary atherosclerosis.

Abstract 10988: The Dynamic Duo of Electrical and Thyroid Storm Caused by Amiodarone

Case description: A 61 year-old male with a hx of CAD s/p CABG and HFrEF s/p AICD presents with a 4-day history of dizziness and shortness of breath; he was found to be in ventricular tachycardia (VT) storm. ICD interrogation was found to have 13 shocks in 24 hours. His thyroid function tests (TFT) were abnormal: TSH undetectable, elevated FT4 7.7 (0.93-1.7) and T3 246.6 (84-202) ng/dL, respectively. He was diagnosed with severe thyrotoxicosis, likely due to amiodarone-induced thyrotoxicosis (AIT) type 2 and a Burch-Wartofsky score of 50, highly suggestive of thyroid storm (TS). He was started on hydrocortisone, prednisone, propylthiouracil, and metoprolol for the TS. Procainamide drip had been initiated for VT and titrated until VT was controlled. Repeat TFTs in 48 hours showed no changes in TSH or FT4, but T3 had normalized. Procainamide and hydrocortisone were discontinued after VT frequency had decreased. Discussion: An electrical storm (ES) is a state of electrical instability characterized by multiple episodes of VT in 24 hours. In patients with ICD, it is defined as &gt;3 anti-tachycardic pacing therapies or shock. Most patient with ES have severe underlying structural heart disease with various inciting events such as thyrotoxicosis. Amiodarone is the drug of choice in VT; however, complications such as AIT should be recognized. Thyroid hormone has a direct arrhythmogenic effect on the heart through various cellular mechanisms. In our patient, amiodarone was discontinued after the diagnosis of AIT. Procainamide and antithyroid therapy were started, which subsequently controlled the VT. Resistance to therapy can occur, and more elaborate interventions such as plasmapheresis are an option to remove amiodarone, its metabolites, and free thyroid hormones. Conclusion: Amiodarone is the most efficacious medication for VT. However, it is important to recognize possible life-threatening complications of this medication, such as AIT, which itself can exacerbate VT.

409 Not all ST elevation are myocardial infarction: a lesson learned from ‘spiked helmet sign’

Abstract Aims ST segment elevation is an electrocardiogram (ECG) finding first of all suggestive of acute coronary syndrome (ACS). However, there are other causes of ST segment elevation that seem to not have any relationship with coronary artery disease (CAD). One of these is the so-called ‘Spiked Helmet Sign’ (SHS), an ECG pattern characterized by upslope of ST segment before R wave onset that is reported to be found in critical illness and is associated with negative outcomes. Methods and results A 14-years-old boy came comatose (Glasgow Coma Scale = 4) to the Emergency Room after being run over by a car. He was immediately intubated and mechanically ventilated. Baseline ECG was reported to be normal, showing an incomplete right bundle branch block and a slightly prolonged QTc interval. CT-scan showed subarachnoid haemorrhage and multiple skull fractures requiring decompressive craniectomy. During hospitalization the patient developed marked hypotension complicated by rise of inflammation indexes and 12 lead ECG revealed new-onset of diffuse ST-segment elevation with spike-and-dome appearance mainly in lateral precordial leads, while lead II and V2 didn’t show any ST-segment alteration. Transthoracic echocardiogram was reported to be normal. Due to critical conditions and low likelihood of CAD, angiography wasn’t performed. The clinical course was worsened by occurrence of hyperkalaemia, acute kidney injury, and multiple episodes of ventricular tachycardia evolving in pulselessness electrical activity which required advanced life support. The patient subsequently died due to multi-organ failure, without the possibility of escalation therapy due to his status. SHS is an emerging ECG sign that is reported to be associated with critical conditions (mechanical ventilation, sepsis, bowel perforation) and in the majority of cases it is not related to CAD. It usually occurs in inferior leads (especially in case of abdominal disease) and in precordial leads (pneumothorax, aortic dissection, mechanical ventilation). Our patient had features consistent with previous cases reported in literature and, even if he experienced several episodes of cardiac arrest and blood exams revealed elevated values of cardiac troponin, the typical ECG pattern and the normal echocardiogram suggest SHS instead of ACS, avoiding unnecessary percutaneous coronary intervention. As reported in literature, even if in our case the appearance of this sign was associated with poor prognosis. Conclusions SHS mainly occurs in critically ill patients and is associated with death and poor outcomes. The potential pathophysiological mechanisms are still unclear. It is important to promptly recognize this pattern and differentiate between other causes of ST-segment elevation to select the appropriate therapy according to the setting. This is the first case-report among Italian hospitals of SHS.

Evaluating physiology of a human heart during ventricular tachycardia: new insights of mechanical alterations via beat to beat strain analysis-case report.

BackgroundVentricular tachycardia can be triggered by myocardial ischaemia. These often fatal events are nearly always accompanied by a significant circulatory depression. However, the exact mechanical alterations and mechanisms of adaption during such arrhythmia episodes are still unknown.Case summaryWe report on a 71-year-old male patient with a distinct cardiovascular risk profile, recurrent incidences of dizziness and palpitations. A Holter electrocardiogram was performed showing multiple episodes of ventricular tachycardia. He was immediately transferred to our hospital for further monitoring and diagnostics. During echocardiography, one of these episodes could be recorded with a four-dimensional (4D) probe in triplane acquisition mode and strain analysis was done. Afterwards, a heart catheter examination was performed. A one-vessel coronary heart disease was diagnosed and treated with three drug-eluting stents. The burden of non-sustained ventricular tachycardia (nsVT) significantly reduced post-procedure. During the follow-up, new episodes of nsVT occurred after 6 weeks, which were treated by electrophysiological examinations.DiscussionModern 4D echocardiography machines offer the possibility to visualize the entire heart simultaneously. Thus ventricular arrhythmias can be evaluated using off-line strain analysis. This technology allows new real-time insights into the human heart showing compensatory mechanisms to overcome stressful episodes, such as ventricular tachycardia.

Prolonged Extracorporeal Membrane Oxygenation Support In a Patient with Drug Reaction with Eosinophilia and Systemic Symptoms Syndrome-associated Fulminant Myocarditis - A Case Report and Literature Review.

Introduction: Myocarditis is a rare presentation of drug reaction with eosinophilia and systemic symptoms (DRESS) syndrome, traditionally associated with poor clinical outcomes. Prompt recognition and treatment are crucial. Case presentation: A 16-year-old patient presented with acute chest pain, hypotension, and pulmonary oedema 2 months after being diagnosed with trimethoprim/sulfamethoxazole-induced DRESS syndrome. Typical DRESS features were absent at onset of these symptoms. Echocardiography demonstrated biventricular systolic dysfunction, and electrocardiography (ECG) showed complete right bundle branch block and diffuse ST-segment elevation. The patient was admitted for high-dose inotropic support; however, his condition deteriorated. Veno-arterial extracorporeal membrane oxygenation (VA-ECMO) and intra-aortic balloon pump were initiated on the third day of admission. Endomyocardial biopsy suggested the diagnosis of DRESS-associated myocarditis and a high-dose corticosteroid was commenced. While he was ECMO-dependent, the patient suffered multiple episodes of ventricular tachycardia on a background of cardioversion-resistant accelerated idioventricular rhythm. After 24 days of ECMO support, the ventricular function improved, and ECG reverted to sinus rhythm. His recovery allowed corticosteroid discontinuation 15 months after hospital discharge. Conclusion: Typical DRESS syndrome features may not accompany the onset of DRESS-associated myocarditis. Mechanical circulatory support and adequate immunosuppression could save patients with malignant arrhythmias and delayed myocardial recovery.

INCESSANT VENTRICULAR TACHYCARDIA IN THE SETTING OF SEPTIC SHOCK TREATED WITH BILATERAL STELLATE GANGLION BLOCK

Incessant ventricular tachycardia (VT) is defined as multiple episodes of VT within a 24 hour period, despite attempts to terminate the arrhythmia. In a patient with an ICD, this can mean three or more therapies (anti-tachycardia pacing (ATP) or defibrillations). Management of these patients include

Acute Myocardial Infarction Complicated By Storming Dysrhythmia: Vt Storm

Electrical storm refers to a state of cardiac electrical instability characterized by multiple episodes of ventricular tachycardia (vt storm) or ventricular fibrillation (vf storm) over a short period of time, typically 24 hrs. Patients with acute myocardial infarction are particularly at a higher risk. The disease has a very high mortality and hence an early recognition with prompt treatment is warranted. We report a case of a 47 year old male who had a vt storm following extensive anterolateral wall myocardial infarction. He initially had an unstable vt and was cardioverted by dc shock. However, he continued to have multiple episodes of monomorphic vt within the next 24 hours. He was initially treated with dc shock (under sedation) and amiodarone. He continued to have stable monomorphic vt for which intravenous amiodarone and metoprolol was administered. He still continued to have a dysrhythmia and intravenous lidocaine was tried which finally controlled his arrhythmia. Later, he was later put on icd for secondary prevention and had no further episodes. Key words: Electrical storm, Vt storm, Implantable cardioverter-defibrillator, Iignocaine, Amiodarone, MI.

0172 : Refractory electrical storm rescued by venoarterial extracorporeal membrane oxygenation

Electrical storm refers to a state of cardiac electrical instability characterized by multiple episodes of ventricular tachycardia or ventricular fibrillation within 24 hours despite antiarrhythmic drugs or devicerelated therapies and for which overall mortality was 22-82% in previous series. Since Venoarterial extracorporeal membrane oxygenation (VA-ECMO) can be used as a rescue therapy in this setting, we reviewed our experience and assessed the outcomes of patients who received VA-ECMO for refractory electrical storm in our center. We retrospectively collected demographic, pre and post ECMO data and in-ICU mortality of patients who received VA-ECMO for refractory electrical storm in our intensive care unit from March 2007 to March 2015. 38 patients had ECMO for refractory electrical storm. Median age, SAPS II and SOFA scores at admission were 58 (49-62) years, 80 (55-87) and 13 (11-15), respectively. Electrical storm was secondary to myocardial infarction in 26 (68%) patients. Cannulation was performed during and after cardiac arrest in 5 (13%) and 17 (45%) patients, respectively. Overall ICU survival was 47%. Survivors spent 5 (4-10) days on ECMO, 14 (9-25) days in ICU and 52 (34-59) days in hospital. Patients discharged alive from the ICU had lower body mass index, lower SOFA score before ECMO and at day 1 and received less inotropes in the 24h following cannulation (p=0.02). No difference was identified between alive and deceased patients regarding pre-ECMO antiarrhythmic treatments and number of electrical shocks. Refractory electrical storm is a very severe condition that might be rescued by VA-ECMO support. The 47% ICU survival rate we observed in this series parallels that of other cardiogenic shock populations rescued by VA-ECMO. Earlier ECMO support in the course of the disease might allow a rapid decrease in inotrope doses and less organ failures, which were both associated with more favorable outcomes. The author hereby declares no conflict of interest

Carcinoid Syndrome-Induced Ventricular Tachycardia.

Introduction. Carcinoid tumors are rare neuroendocrine malignancies that secrete multiple bioactive substances. These bioactive substances are responsible for the carcinoid syndrome characterized by diarrhea, flushing, syncope, and right-sided valvular heart disease. Previous case reports have described carcinoid syndrome associated with coronary vasospasm and the well-characterized carcinoid heart disease. Case. Our patient is a 73-year-old female with complex past medical history most notable for metastatic carcinoid tumors diagnosed in 2013-05. She initially presented in 2014-09 with syncope and dizziness associated with sinus pause on an event monitor. She received a pacemaker given normal left ventricular function and was discharged. However, she was readmitted with similar symptoms corresponding to multiple episodes of ventricular tachycardia. She was started on high-dose beta blockade and has had no recurrence of arrhythmia over a follow-up period of 12 months. Conclusion. We hypothesize that the patient's ventricular tachycardia was mediated by the multiple bioactive substances secreted by her carcinoid tumors. Her carcinoid tumor biomarkers were elevated and other explanations for arrhythmia were investigated and ruled out. To our knowledge, this is the first case of ventricular tachycardia mediated by carcinoid syndrome and suppressed by beta-blocker. Further investigation into this relationship is needed.

The SCN5A Mutation A1180V is Associated With Electrocardiographic Features of LQT3

Mutations of the SCN5A gene are associated with several arrhythmic syndromes including the Brugada syndrome, conduction disease, long QT syndrome type 3 (LQT3), atrial fibrillation, and dilated cardiomyopathy. We report LQT3 associated with an A1180V cardiac sodium channel mutation, previously associated with cardiac conduction block, and dilated cardiomyopathy in three generations of a Chinese family. Clinical, electrocardiographic (ECG), and echocardiographic examination was followed by direct sequencing of SCN5A and HERG to screen genomic DNA from blood samples. The proband presented with multiple syncopes from the age of 7years and was found to share a mutation with two other members of his family. Continuous ECG monitoring after presentation showed prolonged QTc and biphasic T waves, multiple episodes of ventricular tachycardia and torsades de pointes. The other two mutation carriers showed ECG features of LQT3 without clinical symptoms. Transthoracic echocardiography showed normal cardiac structure in all three mutation carriers. This study shows LQT3 features associated with an A1180V cardiac sodium channel mutation, expanding the spectrum of phenotypes resulting from this mutation in which biophysical study has shown a persistent late Na(+) current.

Percutaneous Stellate Ganglion Block Suppressing VT and VF in a Patient Refractory to VT Ablation

Electrical storm is a condition characterized by multiple episodes of ventricular tachycardia (VT) or ventricular fibrillation (VF) in a short period of time. An 80-year-old male with a history of ischemic cardiomyopathy presented with multiple ICD shocks. As a last resort, he underwent percutaneous left, followed by right, stellate ganglion block under fluoroscopic guidance. Since his discharge, he has been managed with alternating, biweekly left and right stellate ganglion blocks, and he has received no ICD shocks. This case illustrates the potential of ongoing, temporary percutaneous stellate ganglion blockade in suppressing ventricular arrhythmogenesis.

Successful Ablation of an Epicardial Ventricular Tachycardia Using a Surgical Ablation Tool

A 62-year-old woman with ischemic cardiomyopathy (left ventricular ejection fraction, 15%) underwent HeartMate II (Thoratec, Inc, Pleasanton, CA) left ventricular assist device (LVAD) placement in January 2011 for cardiogenic shock. After implantation, the patient's hemodynamic status improved, but she had multiple episodes of ventricular tachycardia (VT) leading to implantable cardioverter-defibrillator therapies. The episodes led to marked reduction in LVAD flows and presyncope. Amiodarone, mexilitine, and quinidine therapy did not change the VT burden. The patient underwent endocardial catheter ablation in March 2011 at an outside institution. During this procedure, the basal lateral LV was noted to have low voltage consistent with scar, yet pace maps obtained in this region did not match the clinical VT. Despite extensive ablation of late potentials and scar border zones, the clinical VT remained inducible. In April 2011, the patient underwent epicardial mapping and ablation of VT at our institution. Because the patient had previous cardiac surgery and the 12-lead ECG of the clinical VT suggested a basal anterolateral exit, epicardial access was obtained by limited anterior thoracotomy in the cardiac catheterization laboratory, as described previously.1 Based on the clinical VT morphology and preprocedure CT, the fourth intercostal space was chosen for the incision (Figure 1A). Figure 1. CT scan, voltage map, and ECG. A , Preprocedure CT imaging demonstrating the left ventricular assist device inflow cannula site as well as …

Fabry disease mimicking hypertrophic cardiomyopathy: genetic screening needed for establishing the diagnosis in women

Fabry disease, an X-linked storage disorder caused by defective lysosomal enzyme alpha-galactosidase A activity, may resemble sarcomere-gene-associated hypertrophic cardiomyopathy (HCM). The 'cardiac variant' of Fabry disease which only affects the heart may be missed unless specifically tested for. We evaluated 90 consecutively recruited HCM probands and their relatives. Probands without sarcomere-gene mutations were tested for alpha-galactosidase A gene (GLA) mutations. Of the 90 families, 31 (34%) had sarcomere gene mutations and were therefore excluded. In the remaining 59 probands, 3 (5%) had GLA mutations as follows. The first proband, a female with asymmetric septal hypertrophy (ASH), a significant left ventricular outflow tract gradient, and chronic obstructive pulmonary disease, was heterozygous for a novel missense mutation (p.N139S). The second proband, a male with ASH and multiple episodes of ventricular tachycardia, was hemizygous for a missense mutation (p.A156T). His daughter was heterozygous, but had normal enzyme activity. The third proband was a female with ASH, and no other indices of Fabry disease. She was heterozygous for a GLA missense mutation (p.G271S). She had one affected daughter but her two other children were unaffected. The affected daughter had three children, of whom two were also affected--a boy aged 8 and a daughter aged 10 years. This is the first report of systematic mutation screening of GLA in HCM patients without sarcomere gene mutations. GLA mutations were found in 3/90 (3%) of HCM families and in 2/20 (10%) of females without sarcomere-gene mutations. None of the probands presented other indices of Fabry disease. This, in combination with putative reversibility of cardiac changes by enzyme replacement therapy, supports systematic testing for Fabry disease. Enzyme measurements are sufficient in men, but genetic testing is needed in women.

The cardiac sodium channel mutation delQKP 1507-1509 is associated with the expanding phenotypic spectrum of LQT3, conduction disorder, dilated cardiomyopathy, and high incidence of youth sudden death

AimWe report diverse phenotypic consequences of the delQKP-1507–1509 cardiac sodium channel mutation in three generations of a Chinese family.Methods and resultsClinical and electrocardiographic (ECG), echocardiographic examination was followed by direct sequencing of SCN5A, KCNQ1, HERG, and LAMIN A/C to screen genomic DNA from blood samples. Of two mutation carriers, the proband was born with conduction disorders including second-degree atrioventricular (AV) block with prolonged QTc interval, additionally showing left anterior fascicular block (LAFB), incomplete right bundle-branch block (IRBBB), and intermittent third-degree AV block at 2 years, and clinical presentations of multiple syncope despite normal electroencephalograms at 8 years. Continuous ECG monitoring following presentation at 13 years revealed prolonged QTc and biphasic T-waves, multiple episodes of ventricular tachycardia, ventricular fibrillation, and torsades de pointes. Transthoracal echocardiography then revealed left ventricular dilatation and reduced systolic function. Another mutation carrier showed features of long QT syndrome type 3 (LQT3), LAFB, and dilated cardiomyopathy (DCM). Two additional subjects died suddenly at 13 and 33 years.ConclusionThis data compliments and expands the spectrum of phenotypes resulting from this known gain-of-function mutation, including not only LQT3, cardiac conduction defects, and sudden death but also DCM, hitherto associated with loss-of-function mutations, for the first time.

Multiple episodes of ventricular tachycardia induced by silent coronary vasospasm

We present a 46-year-old patient who suffered from cardiac arrest and subsequently underwent placement of an implantable cardioverter defibrillator (ICD). The patient underwent a cardiac catheterization which revealed no significant coronary artery disease. About 1 year later he experienced appropriated and frequent ICD discharges due to monomorphic ventricular tachycardia (VT) with left bundle branch block morphology. His prodromal symptoms were mild dizziness and lightheadedness with no chest pain. Amiodarone, mexiletine, sotalol and dofetilide as well as ablation of two inducible ventricular tachycardias in the electrophysiology studies were unsuccessful in controlling the arrhythmias and ICD discharges. During the last episode, he experienced a mild burning sensation in his chest and was given nitroglycerin 0.4 mg sublingually, which relived his symptoms and aborted the VT. This led to a second cardiac catheterization to investigate whether the VT was being induced by myocardial ischemia. This second coronary angiogram spontaneously revealed significant coronary vasospasm and simultaneously, the patient's cardiac rhythm showed short runs of VT with left bundle branch block morphology. Intracoronary nitroglycerine relieved the coronary vasospasm and terminated the arrhythmia. The patient was treated with isosorbide mononitrate and diltiazem. He remained symptom free with no ICD discharges and no VT in ICD interrogations for more than 2 years. Coronary vasospasm may be silent and with no chest pain which creates a difficult clinical situation particularly if it is associated with ventricular tachycardia and sudden cardiac death. The mechanisms of VT in the setting of coronary vasospasm are not known and increased automaticity, focal discharges, functional unidirectional block with reentry, or a combination of these mechanisms may contribute to inducing the VT during the transient ischemia or rarely in the reperfusion phase. It is important to perform provocative tests to diagnose silent coronary vasospasm in unexplained sudden cardiac arrests.

Minimally Invasive Aortic Valve Surgery

Minimally Invasive Aortic Valve Surgery

A new intraoperative approach for endocardial mapping of ventricular tachycardia

Results of operation for control of ventricular tachycardia have improved since endocardial mapping techniques have been developed that allow a directed approach to the problem. In some patients, a limitation of established techniques has been difficulty in initiating the arrhythmia after a ventriculotomy has been made to allow introduction of endocardial recording electrodes. This paper describes a transatrial approach for endocardial mapping with a balloon array of 112 electrodes, which has been used intraoperatively in 15 patients. Surgical success in this group has been compared to that obtained in a similar group of patients in whom standard techniques of intraoperative mapping were used. With our new balloon technique we have been able to easily induce and map multiple episodes of ventricular tachycardia in all cases. On the basis of detailed endocardial maps, the locations of earliest activation and possible reentry loops have been identified and ablated with either endocardial excision or application of the cryoprobe. When indicated, concomitant procedures including aneurysm resection (9/15) and bypass grafting (14/15) have been performed. Hospital mortality in this group was 20%. None of the deaths have been related to recurrent ventricular tachycardia or complications of the mapping technique. Postoperative electrophysiologic studies performed at 2 weeks have been normal in 11 of 12 or 92% of patients. To date (mean follow-up 12 +/- 6 months) there has been no clinical recurrence or evidence of ventricular tachycardia by Holter monitoring in these patients. We conclude that the transatrial balloon approach to endocardial mapping facilitates intraoperative induction of ventricular tachycardia, allows complete mapping during multiple runs of the arrhythmia without prolonging cardiopulmonary bypass time, and improves results of operation using standard ablation techniques.

Efficacy of coronary bypass grafting in exercise-induced ventricular tachycardia

The effects of coronary bypass grafting on ventricular tachycardia induced by treadmill stress testing (TST) were analyzed in nine patients by repeating the test an average of 5 months after operation. Preoperatively, eight patients experienced pain and all had ischemic ST-segment depression during exercise. Six patients had a single episode and two patients had multiple episodes of ventricular tachycardia; in one patient ventricular tachycardia degenerated into ventricular flutter necessitating direct-current cardioversion. Postoperatively, time of exercise and double product were significantly higher during TST. Electrocardiographic ischemic changes were present in only two patients and ventricular tachycardia was not observed. All patients are alive and average of 24 months after the operation, and eight of them are asymptomatic. In conclusion, among patients with coronary artery disease who have exercise-induced ventricular arrhythmias, myocardial revascularization is associated with improvement of exercise capacity and suppression of arrhythmias.