Asymptomatic Ventricular Tachycardia Research Articles

Safety of cardiopulmonary exercise testing in a large contemporary cohort of adults with congenital heart disease: implications on levels of test supervision

Abstract Background Exercise intolerance is common in adults with congenital heart disease (ACHD). Cardiopulmonary exercise testing (CPET) is used routinely as an objective assessment of the exercise capacity, the severity and mechanisms of exercise intolerance, and the effect of intervention. Little is known on the safety of CPET in ACHD, resulting in the American Heart Association recommending physician supervision of all patients with intracardiac shunts. Purpose To assess the safety of CPET in ACHD. Methods We retrospectively examined 9309 CPETs performed on ACHD patients in a tertiary referral Centre over 20 years to document major or minor events. All tests were performed in-hospital, with an emergency alarm system on site, and supervised routinely by 2 clinical exercise physiologists. Major events were classified as death within 48 hours and cardiac arrest, syncope, sustained/symptomatic ventricular tachycardia (VT) and sustained/symptomatic supraventricular tachycardia (SVT) during the test. Minor events were classified as non-sustained/asymptomatic VT, non-sustained/asymptomatic SVT, bradyarrhythmia, chest pain and significant ST segment ECG changes, new onset of left or right bundle branch block). Results During the study period, 9309 CPETs were performed on 4941 ACHD patients (age 33.0±14.7 years, 52.3% male), of varying complexity by Bethesda classification (18.3% simple, 51.2% moderate, 27.4% great) Figure 1. A major event occurred in 56 (0.6%) tests and a minor event in 870 (9.3%) tests. There were no deaths within 48 hours, nor cardiac arrests during the test. There were 6 (0.1%) cases of sustained or symptomatic VT, 4 (<0.1%) syncopal episodes and 46 (0.5%) instances of sustained or symptomatic SVT. A total of 31 (0.3%) episodes of bradyarrhythmia, 377 (4%) significant ECG changes and 267 (2.8%) episodes of chest pain were recorded. Moreover, there were 107 (1.2%) cases of non-sustained or asymptomatic VT and 88 (1%) cases of non-sustained or asymptomatic SVT. Patient fatigue (3701, 40%), shortness of breath (2246, 24.1%) and leg discomfort (1286, 13.8%) were common reasons for stopping the test, whereas only 95 (1%) tests were stopped due to chest pain. Conclusions Our data on a large ACHD population undergoing CPET demonstrate a potential risk for arrhythmic complications during exercise and recovery, mostly due to sustained or symptomatic SVT, while the risk of all the other major cardiovascular events is low. Our data support the use of CPET in routine ACHD practice, with quick recognition and management of potential adverse events in a controlled environment by appropriately trained cardiac physiologists.

Ventricular Tachycardia and The Diagnosis of a Metallic Intracardiac Foreign Body

A man with a history of metallic shrapnel injury from a chisel 40 years ago presented for an elective exercise stress test due to ‘stinging’ central chest pains. After 5 minutes 48 seconds the stress test was stopped due to asymptomatic ventricular tachycardia. He was referred urgently for angiography which showed non obstructive coronaries but noted a small metal fragment lodged into the right ventricular wall. Follow up CT imaging confirmed the new finding of a 5mm intracardiac metallic foreign body. Further angiography at the site of the previous injury showed no residual metallic fragment. CT imaging also identified an incidental bronchogenic neoplasm for which he underwent lobar resection with fifteen negative nodes. No further cardiac intervention was performed. He recovered well post operatively and was followed up six months later with no arrythmi as or signs of metastatic spread.

The Efficacy of Anti-Arrhythmic Drugs in Children With Idiopathic Frequent Symptomatic or Asymptomatic Premature Ventricular Complexes With or Without Asymptomatic Ventricular Tachycardia: a Retrospective Multi-Center Study

The aim of the study is to compare the efficacy of flecainide, beta-blockers, sotalol, and verapamil in children with frequent PVCs, with or without asymptomatic VT. Frequent premature ventricular complexes (PVCs) and asymptomatic ventricular tachycardia (VT) in children with structurally normal hearts require anti-arrhythmic drug (AAD) therapy depending on the severity of symptoms or ventricular dysfunction; however, data on efficacy in children are scarce. Both symptomatic and asymptomatic children (≥ 1 year and < 18 years of age) with a PVC burden of 5% or more, with or without asymptomatic runs of VT, who had consecutive Holter recordings, were included in this retrospective multi-center study. The groups of patients receiving AAD therapy were compared to an untreated control group. A medication episode was defined as a timeframe in which the highest dosage at a fixed level of a single drug was used in a patient. A total of 35 children and 46 medication episodes were included, with an overall change in PVC burden on Holter of -4.4 percentage points, compared to -4.2 in the control group of 14 patients. The mean reduction in PVC burden was only significant in patients receiving flecainide (− 13.8 percentage points; N = 10; p = 0.032), compared to the control group and other groups receiving beta-blockers (− 1.7 percentage points; N = 18), sotalol (+ 1.0 percentage points; N = 7), or verapamil (− 3.9 percentage points; N = 11). The efficacy of anti-arrhythmic drug therapy on frequent PVCs or asymptomatic VTs in children is very limited. Only flecainide appears to be effective in lowering the PVC burden.

Left ventricular dysfunction is associated with frequent premature ventricular complexes and asymptomatic ventricular tachycardia in children.

To assess the risk factors for left ventricular (LV) dysfunction in a paediatric population with idiopathic frequent premature ventricular contractions (PVCs) and asymptomatic ventricular tachycardias (VTs). Paediatric patients with the diagnosis of idiopathic frequent PVCs and asymptomatic VTs were retrospectively evaluated. Frequent PVCs were defined as ≥5% on 24 h Holter recording. Left ventricular dysfunction was defined as a shortening fraction of ≤28%. Seventy-two children were identified. Six patients showed LV dysfunction at diagnosis [age 10 ± 7 years, 2 (33%) had symptoms such as syncope, palpitations, fatigue, and dizziness], and 66 showed normal LV function [age 8 ± 6 years, 22 (33%) with symptoms]. Patients with LV dysfunction had a higher percentage of PVCs on Holter recordings (47 ± 16 vs. 16 ± 11%, P = 0.006), higher prevalence of VT [5 (83%) vs. 27 (41%), P = 0.045] and sustained ventricular tachycardia (sVT) [3 (50%) vs. 4 (6%), P = 0.001], and a higher number of couplets [6 (100%) vs. 34 (52%), P = 0.030]. In patients with LV dysfunction, two responded to medication (Classes Ic and II) and five underwent ablation, of which one was unsuccessful. During follow-up, LV function normalized in five of six patients. In patients with a normal function, none developed LV dysfunction during the follow-up. In children with idiopathic PVCs and asymptomatic VTs, development of LV dysfunction is associated with a higher burden of PVCs, the presence of sVTs, and couplets. Left ventricular dysfunction appears to be reversible if the burden of PVCs is decreased by medication or ablation.

Boxer cardiomyopathy

Arrhythmogenic cardiomyopathy is a specific myocardial disease affecting Boxer dogs. It is an adult-onset disease that affects dogs over a wide age range, and results in a wide spectrum of clinical signs: asymptomatic ventricular tachycardia, syncope, congestive heart failure and sudden death. Veterinary nurses should be aware of this disease because it has implications for nursing of Boxer dogs with episodes of syncope. Patients with a history of fainting should be treated with caution and stress should be minimised. If a patient has an episode while in the practice, the veterinary surgeon should be informed immediately and routine airway, breathing and circulation checks commenced. Placement of an intravenous catheter would be useful in case antiarrhythmic medication is required, and an electrocardiogram (ECG) would provide important diagnostic information.

Monitoring zone-associated implantable cardioverter defibrillator shock: A case report

A 41-year-old man with Brugada syndrome, who had been implanted with an ATLAS+DR V-243 (St. Jude Medical, Inc., St. Paul, MN, USA) dual-chamber implantable cardioverter defibrillator (ICD) for secondary prevention of arrhythmia, received an inappropriate shock. The ventricular fibrillation (VF) zone was programmed to deliver maximum output shock therapy at a detection threshold of greater than 214 beats per min, and 12 consecutive instances of crossing the threshold constituted 1 VF. The monitoring zone was programmed to detect heart rates of greater than 160 beats per min with all supraventricular tachycardia (SVT) discriminators in the “ON” mode, and 12 consecutive instances of the heart rate exceeding 160 beats per min constituted 1 SVT. The ICD shock was delivered after an episode of sinus tachycardia that continued for 3min 15s. The monitoring zone is effective for detecting asymptomatic ventricular tachycardia or SVT, and therapy is not usually set up in this zone. Here, we report the possibility that in some patients implanted with certain types of ICD devices, the monitoring zone may become a factor in the delivery of an inappropriate shock.

Radiofrequency catheter ablation of ventricular tachycardia in arrhythmogenic right ventricular dysplasia/cardiomyopathy using non-contact electroanatomical mapping: single-center experience with follow-up up to median of 30 months

Objective of studyTo evaluate the efficacy of radiofrequency ablation (RFA) of ventricular tachycardia (VT) using non-contact electro-anatomic mapping in patients with arrhythmogenic right ventricular dysplasia/cardiomyopathy (ARVD/C).MethodsFifteen consecutive patients (44 ± 15 years) with ARVD/C and symptomatic VTs were studied. Eight patients had syncopal VTs. Two patients had recurrent VT while on AICD; in three patients, RFA was done prior to AICD implantation, and ten patients refused AICD. After obtaining activation maps, first, the clinical VT was targeted, and then, other VTs were sought.ResultsTwenty-five inducible VTs were mapped, and 22 of them were successfully ablated. In 13 out of 15 patients, all the clinical and inducible VTs were ablated. In two patients, non-clinical inducible VTs could not be ablated. At 25 ± 16 months (2–52 months), all patients remained asymptomatic. Antiarrhythmic medications were discontinued after 6 months. Two patients had recurrence of non-clinical VT on follow-up. There were no episodes of asymptomatic VT recorded in five patients with AICD.ConclusionA majority of induced VT in patients with ARVD/C can be successfully mapped and ablated using the non-contact Ensite Array Mapping system with good long-term VT-free outcome. Ablation can be a useful adjunct to AICD implantation in such patients.

Ventricular tachycardia in infants with structurally normal heart: a benign disorder

We evaluated the presentation, treatment, and outcome of infants who present with ventricular tachycardia in the first year of life. Seventy-six infants were admitted to our institution with a diagnosis of ventricular tachycardia between January, 1987 and May, 2006. Forty-five infants were excluded from the study because of additional confounding diagnoses including accelerated idioventricular rhythm, Wolff-Parkinson-White syndrome, supraventricular tachycardia with aberrancy, long QT syndrome, cardiac rhabdomyoma, myocarditis, congenital lesions, or incomplete data. The remaining 31 included infants who had a median age at presentation of 1 day, with a range from 1 to 255 days, and a mean ventricular tachycardia rate of 213 beats per minute, with a range from 171 to 280, at presentation. The infants were treated chronically with propranolol (38.7%), amiodarone (12.9%), mexiletine (3.2%), propranolol and mexiletine (9.7%), or propranolol and procainamide (6.5%). The median duration of treatment was 13 months, with a range from 3 to 105 months. Ventricular tachycardia resolved spontaneously in all infants. No patient died, or received catheter ablation or device therapy. Median age at last ventricular tachycardia was 59 days, with a range from 1 to 836 days. Mean follow-up was 45 months, with a range from 5 to 164 months, with a mean ventricular tachycardia-free period of 40 months. Infants with asymptomatic ventricular tachycardia, a structurally normal heart, and no additional electrophysiological diagnosis all had spontaneous resolution of tachycardia. Furthermore, log-rank analysis of the time to ventricular tachycardia resolution showed no difference between children who received chronic outpatient anti-arrhythmic treatment and those who had no such therapy. While indications for therapy cannot be determined from this study, lack of symptoms or myocardial dysfunction suggests that therapy may not be necessary.

Sunitinib in combination with gefitinib in patients (pts) with metastatic renal cell carcinoma (mRCC): Updated results from a phase I/II study

16014 Background: Sunitinib malate is an oral, multitargeted tyrosine kinase inhibitor of VEGFRs and PDGFRs that has shown substantial efficacy in pts with mRCC (JAMA 2006;295:2516; NEJM 2007;356:115). Here, we present updated safety and efficacy data from the phase II part of a study of sunitinib in combination with gefitinib, an EGFR inhibitor. Methods: Eligibility included mRCC with a clear cell component, measurable disease, and ECOG performance status (PS) of 0 or 1. In phase II, pts received sunitinib 37.5 mg (the maximum tolerated dose [MTD] determined in phase I) orally, once-daily in 6-wk cycles (4 wks on treatment, 2 wks off) plus gefitinib 250 mg/day. The primary endpoint of phase II was RECIST-defined objective response rate (ORR). Sample size was determined using a one-sided, single-stage phase II design with a 10% alpha level and 85% power. Results are reported for all pts treated at MTD (N=35) from phase II (n=31) and phase I (n=4). An exploratory analysis of VEGF pathway biomarkers was performed for phase II. Results: Median age was 62 yrs (range: 29–78); 24 pts (69%) had ECOG PS of 0; and 24 pts (69%) had prior immunotherapy. The ORR was 34% (95% CI: 19–52), and 11 pts (31%) had stable disease. Median response duration was 18 mo (95% CI: 18-NR). Median progression-free survival was 11 mo (95% CI: 6-NR), and median overall survival had not been reached; 1-year survival probability was 82% (95% CI: 71–90). The most common grade 3 treatment-related AEs included diarrhea (14%) and gastrointestinal hemorrhage (6%); 3 pts were withdrawn due to treatment- related AEs (ejection fraction decline, cardiac arrhythmia, and asymptomatic ventricular tachycardia). Increases in plasma VEGF-A levels and decreases in plasma VEGF-C and soluble VEGFR-2 and VEGFR-3 levels were observed in patterns generally consistent with those for sunitinib monotherapy. In a preliminary analysis, no statistically significant correlations between these protein levels and efficacy were noted. Conclusions: Updated results from a study of sunitinib plus gefitinib further demonstrate the feasibility of this combination, with similar efficacy and tolerability to that observed with sunitinib monotherapy, along with similar patterns of biomarker modulation. Author Disclosure Employment or Leadership Consultant or Advisory Role Stock Ownership Honoraria Research Expert Testimony Other Remuneration Pfizer Pfizer Pfizer Pfizer Pfizer

Percutaneous epicardial ablation reverses ventricular tachycardia mediated cardiomyopathy

We report on the case of an 18-year-old girl with asymptomatic incessant ventricular tachycardia. Initial attempts at endocardial ablation failed and she was monitored until her cardiac function deteriorated. A percutaneous epicardial approach with electroanatomical mapping was then used which successfully terminated the tachycardia. Left ventricular size and function subsequently returned to normal. This case demonstrates that percutaneous epicardial ablation of ventricular tachycardia is safe and feasible in young patients and highlights the importance of recognising this at an early stage.

Drug-induced linear IgA bullous dermatosis

A 73-year-old man was admitted to the University of California Davis Medical Center for treatment of a pleural effusion and congestive heart failure. His hospital course was complicated by asymptomatic sustained ventricular tachycardia requiring placement of an implantable cardiac defibrillator. The patient was treated with vancomycin and cefazolin during the procedure. After 3 days he developed tense vesicles over the dorsal aspect of the hands. Perilesional skin biopsy showed subepidermal cleavage with a neutrophilic infiltrate. Direct immunofluorescence revealed granular IgA and C3 deposition along the dermal epidermal junction. A diagnosis of drug-induced linear IgA bullous dermatosis secondary to vancomycin was established. Linear IgA bullous dermatosis is a rare autoimmune blistering disorder with clinical features that can overlap with bullous pemphigoid and dermatitis herpetiformis. Drug-induced linear IgA bullous dermatosis is a less common variant that is correspondingly less well characterized. Although a variety of medications have been implicated, vancomycin is the most common associated drug.

A phase I trial of depsipeptide in children with refractory solid tumors: A Children’s Oncology Group study

8528 Background: Depsipeptide, a histone deacetylase inhibitor, has demonstrated potent antitumor activity against human tumor cell lines (including neuroblastomas) at IC50s < 10nM and in various xenograft models. Methods: A phase I trial of depsipeptide was conducted in children with recurrent or refractory solid tumors to determine the maximum tolerated dose (MTD), dose limiting toxicity (DLT) and pharmacokinetics (PK) of depsipepetide and to assess accumulation of histone acetylation (H3) in peripheral blood mononuclear cells (PBMNC). Depsipeptide was administered as a 4-hour IV infusion weekly × 3 consecutive weeks every 28 days. Dose levels were 10, 13, 17 and 22 mg/m2. PK and histone acetylation studies were conducted in the first course. Results: Of the 24 patients enrolled on this trial, 19 were assessable for toxicity (median age at enrollment: 13, range 2–21 years, 10 male). Three patients experienced DLT: one at 13 mg/m2 had asymptomatic reversible T wave inversions in leads II, III and AVF; one at 22 mg/m2 experienced asymptomatic and reversible sick sinus syndrome and another patient 22 mg/m2 had reversible, asymptomatic T wave inversions in leads II, III and AVF as well as asymptomatic ventricular tachycardia. Six patients have been enrolled at 17 mg/m2; the 6th patient has yet to be evaluated for toxicity. No objective responses have been observed. Two patients with PNET and ependymoma had stable disease for 4 and 5+ courses, respectively. At 17 and 22 mg/m2, the median (range) depsipeptide CL and terminal t1/2 were 12.4 L/hr/m2 (3.5 - 28.9) and 2.2 hrs (1.1 - 3.8), respectively. Median (range) depsipeptide AUC0–24hr at 17 mg/m2 was 1.8 μg-hr/mL (1.1 - 4.8), which is comparable to reported adult exposure at this dosage. Immunostaining in PBMNC demonstrated an accumulation of acetylated H3 between 2–6 hours after the start of the depsipeptide infusion which lasted for up to 20 hours after the end of infusion. Conclusion: Depsipeptide is relatively well-tolerated in children when administered weekly × 3 every 28 days. DLTs include asymptomatic EKG changes, ventricular tachycardia and sick sinus syndrome. Depsipeptide PKs in children are similar to those previously reported in adults.: No significant financial relationships to disclose.

Anesthetic management of a patient with asymptomatic ventricular tachycardia

There are many causes of ventricular arrhythmias in pediatric patients, even those with structurally normal hearts. However, in young patients with 'normal' hearts, sustained ventricular arrhythmias are relatively rare. The primary concern of the physician is to identify which patients have benign ventricular arrhythmia patterns and which are at risk for sudden cardiac death. Even in asymptomatic patients, the choice of anesthetic agents may be important to minimize precipitation of episodes of tachyarrhythmias. This clinical report describes the anesthetic considerations for an asymptomatic child with a history of sustained premature ventricular contractions, ventricular tachycardia, and bigeminy. This child had chronic serous otitis media requiring repeat tympanostomy and tube replacement. This case report outlines the initial cancellation of anesthesia because of sustained arrhythmias, and subsequent conduct of the anesthesia for the case, as well as the considerations in the selection of the drugs when a child presents with significant ventricular arrhythmia.

Prediction of long-term outcomes by signal-averaged electrocardiography in patients with unsustained ventricular tachycardia, coronary artery disease, and left ventricular dysfunction.

An abnormal signal-averaged ECG (SAECG) is a noninvasive marker of the substrate of sustained ventricular tachycardia after myocardial infarction. We assessed its prognostic ability in patients with asymptomatic unsustained ventricular tachycardia, coronary artery disease, and left ventricular dysfunction. A blinded core laboratory analyzed SAECG tracings from 1925 patients in a multicenter trial. Cox proportional hazards modeling was used to examine individual and joint relations between SAECG variables and arrhythmic death or cardiac arrest (primary end point), cardiac death, and total mortality. We also assessed the prognostic utility of SAECG at different levels of ejection fraction (EF). A filtered QRS duration >114 ms (abnormal SAECG) independently predicted the primary end point and cardiac death, independent of clinical variables, cardioverter-defibrillator implantation, and antiarrhythmic drug therapy. With an abnormal SAECG, the 5-year rates of the primary end point (28% versus 17%, P=0.0001), cardiac death (37% versus 25%, P=0.0001), and total mortality (43% versus 35%, P=0.0001) were significantly higher. The combination of EF <30% and abnormal SAECG identified a particularly high-risk subset that constituted 21% of the total population. Thirty-six percent and 44% of patients with this combination succumbed to arrhythmic and cardiac death, respectively. SAECG is a powerful predictor of poor outcomes in this population. The noninvasive combination of an abnormal SAECG and reduced EF may have utility in selecting high-risk patients for intervention.

Nonsustained, asymptomatic ventricular tachycardia in patients with coronary artery disease: prognosis and incidence of sudden death of patients who are noninducible by electrophysiological testing.

The objective of this study was to determine the long-term prognosis and the sudden death risk for patients with coronary artery disease and spontaneous nonsustained ventricular tachycardia who are not inducible by electrophysiological testing. Patients with coronary artery disease (CAD) who have spontaneous or inducible sustained ventricular tachycardia (VT) by electrophysiological testing are at increased risk of dying suddenly, and noninducibility is often considered as a favorable prognostic factor in their risk assessment. We studied 120 consecutive patients with CAD and nonsustained VT during Holter monitoring and followed the patients who were noninducible (n = 93) for 3.5 +/- 1.6 years. None of these patients received antiarrhythmic therapy except beta-blockade. Overall mortality and the sudden death risk was assessed by the Kaplan-Meier estimation. Predictors for overall mortality and sudden death were determined by multivariate analysis. During follow-up, 23 of the 93 patients died, including 13 suddenly. Overall mortality was 9% after 1 year, 16% after 2 years, and 21% after 3 years, respectively. The incidence of sudden death was 1% after 1 year, 8% after 2 years, and 13% after 3 years, respectively. Patients with a LVEF < or = 0.35 had an increased overall mortality risk with 15% after 1 year, 29% after 2 years, and 34% after 3 years (P = 0.012) and a risk of dying suddenly of 4% after 1 year, 12% after 2 years, and 18% after 3 years (P = NS), respectively. LVEF was the only independent predictor for overall mortality. In conclusion, patients with coronary artery disease and nonsustained ventricular tachycardia who are not inducible by electrophysiological testing have a moderate long-term overall mortality risk. The risk of dying suddenly in this patient group is small but not negligible, especially in patients with impaired LVEF.

The Utility of Holter Monitoring Compared to Loop Recorders in the Evaluation of Syncope and Presyncope

Background:Holter monitoring is frequently used to assess patients with syncope, but rarely provides a diagnosis. Newer loop recorders provide the opportunity for prolonged electrocardiographic monitoring to enhance diagnostic yield.Methods:The results of 232 Holter monitors and 81 loop recordings performed for the investigation of syncope or presyncope were reviewed for indication, patient demographics, and presence and type of symptoms and/or arrhythmias. The results were classified as (1) symptom‐arrhythmia correlation, (2) clinically useful information (group 1 plus those excluding arrhythmic syncope, and those demonstrating asymptomatic serious arrhythmias) and (3) unhelpful (asymptomatic and no serious arrhythmias).Results:Loop recorders provided a symptom‐arrhythmia correlation in 11.1% of patients compared to only 0.4% in the Holter group (P &lt; 0.0001). Clinically useful information was obtained in 54.3% of loop patients compared to 27.6% in the Holter group (P &lt; 0.0001). Technical problems occurred in 0.4% of the Holter patients and in 3.7% of loop patients (P = 0.05). Classification was difficult in seven patients in the Holter group; two experienced symptoms during sinus rhythm but also had a serious asymptomatic arrhythmia, and five patients had 6–10 beats of asymptomatic ventricular tachycardia at a rate &lt; 160 beats/min.Conclusion:Loop recording was well tolerated and superior to Holter monitoring in providing a symptom‐arrhythmia correlation or clinically useful information in patients with syncope and presyncope. An initial approach with a loop‐recording device should be employed in these patients.

Prevención de la muerte súbita postinfarto de miocardio: ¿debe generalizarse la estrategia «MADIT»? Argumentos en contra

The Multicenter Automatic Defibrillator Implantation Trial (MADIT) suggests that survival in patients with prior myocardial infarction, asymptomatic unsustained ventricular tachycardia and reduced left ventricular function was better among the patients who received implantable cardioverter defibrillator than that in the drug-treatment group. Nevertheless the absence of data about the efficacy and security of the conventional antiarrhythmic treatment weakness its result and clinical applicability.

Syncopal Sustained Ventricular Tachycardia in a Patient with Right Ventricular Dysplasia

A 41-year-old man was hospitalized for syncopal sustained ventricular tachycardia with left bundle branch morphology. Diagnostic screening confirmed a right ventricular dysplasia: fibrofatty replacement of myocardium on endomyocardial biopsy and severe dilation of right ventricle with no left ventricular impairment was documented. His bundle recording showed an abnormally long HV interval, and programmed ventricular stimulation induced high-rate sustained ventricular tachycardia with left bundle branch block morphology associated with reduced systolic blood pressure and dizziness. Right ventricular burst pacing proved to be effective in restoring sinus rhythm. A single lead pectoral cardioverter-defibrillator was implanted and programmed for VVI and antitachycardia pacing, as first ventricular tachycardia therapeutic intervention. During 6-month follow-up, 1 asymptomatic ventricular tachycardia recurrence terminated by antitachycardia pacing was reported by the device. The possible role of the other therapeutic options such as drugs, ablation, and surgery for this specific case is also discussed. (Am J Cardiol 1996;78(suppl 5A):98–101)

Recurrent ventricular tachycardia in asymptomatic young children with an apparently normal heart

Ventricular tachycardia without underlying heart disease is rare in infancy and childhood. Four young children (median age 8 months at initial presentation) with frequently recurrent episodes of asymptomatic and self-limiting ventricular tachycardia are reported. By noninvasive investigation no apparent heart disease has been found in all patients. Initially three of the four children had been treated with an anti-arrhythmic drug. Treatment was soon stopped in two patients for lack of symptoms and for lack of efficacy of therapy; one patient remained on beta-blocker therapy. One child did not receive anti-arrhythmic therapy. After a mean follow up of 32 months all patients continued to be asymptomatic despite frequently recurrent episodes of self-limiting ventricular tachycardia. Ventricular tachycardia in asymptomatic children with an otherwise normal heart carries a good prognosis. Invasive investigation (cardiac catheterization with electrophysiological study and right ventricular biopsy) can be withhold, as long as there are no symptoms. For lack of efficiency of antiarrhythmic drugs in suppressing ventricular tachycardia in asymptomatic children with apparently normal hearts, these patients may be left without therapy but have to be followed closely.

Induction of hypomagnesemia during amsacrine treatment

Serious cardiac arrhythmias and QT interval prolongation have been reported following Amsacrine chemotherapy. The underlying mechanism is unknown. In this study, electrolyte and electrocardiographic parameters were prospectively studied in patients with acute myeloid leukemia (AML) treated with an Amsacrine containing combination chemotherapy regime. Data were collected immediately before and at 20 (+20) and 90 (+90) min after commencement of Amsacrine administration. Sixteen episodes were studied in six consecutive patients over a continuous 9 month period. One patient developed asymptomatic ventricular tachycardia during administration. Results from +20 and +90 min were compared with baseline by Wilcoxon matched pairs test. There was no significant change in potassium, albumin, or ionized calcium concentration at +20 or +90 min. The magnesium concentration at +20 min was significantly reduced (mean -0.04 mmol/liter; P < 0.05) but not so at +90 min. Sodium concentration at +20 min was significantly reduced (mean - 1.9 mmol/liter; P < 0.01). Electrocardiographic analysis showed no significant alteration in PR interval or QRS duration. Heart rate fell significantly from baseline, mean change -10 and -8 min-1 at +20 and +90 min, respectively (P < 0.01 for both). Corrected QT interval (QTc) was significantly prolonged at +20 min (+0.05) and +90 min (+0.05) (P = 0.0001 and P < 0.0001, respectively). This study confirms the high incidence of QTc prolongation with Amsacrine administration and suggests that transient hypomagnesemia may contribute to the risk of cardiac arrhythmia in this setting.