Inappropriate Tachycardia Research Articles

Dysautonomia and small fiber neuropathy in post-COVID condition and Chronic Fatigue Syndrome

BackgroundMyalgic Encephalomyelitis/Chronic Fatigue Syndrome (ME/CFS) and post-COVID condition can present similarities such as fatigue, brain fog, autonomic and neuropathic symptoms.MethodsThe study included 87 patients with post-COVID condition, 50 patients with ME/CFS, and 50 healthy controls (HC). The hemodynamic autonomic function was evaluated using the deep breathing technique, Valsalva maneuver, and Tilt test. The presence of autonomic and sensory small fiber neuropathy (SFN) was assessed with the Sudoscan and with heat and cold evoked potentials, respectively. Finally, a complete neuropsychological evaluation was performed. The objective of this study was to analyze and compare the autonomic and neuropathic symptoms in post-COVID condition with ME/CFS, and HC, as well as, analyze the relationship of these symptoms with cognition and fatigue.ResultsStatistically significant differences were found between groups in heart rate using the Kruskal–Wallis test (H), with ME/CFS group presenting the highest (H = 18.3; p ≤ .001). The Postural Orthostatic Tachycardia Syndrome (POTS), and pathological values in palms on the Sudoscan were found in 31% and 34% of ME/CFS, and 13.8% and 19.5% of post-COVID patients, respectively. Concerning evoked potentials, statistically significant differences were found in response latency to heat stimuli between groups (H = 23.6; p ≤ .01). Latency was highest in ME/CFS, and lowest in HC. Regarding cognition, lower parasympathetic activation was associated with worse cognitive performance.ConclusionsBoth syndromes were characterized by inappropriate tachycardia at rest, with a high percentage of patients with POTS. The prolonged latencies for heat stimuli suggested damage to unmyelinated fibers. The higher proportion of patients with pathological results for upper extremities on the Sudoscan suggested a non-length-dependent SFN.

High-power chargers for electric vehicles: are they safe for patients with pacemakers and defibrillators?

Battery electric vehicle (BEV) sales and use are rapidly expanding. Battery electric vehicles, along with their charging stations, are a potential source of electromagnetic interference (EMI) for patients with cardiac implantable electronic devices (CIEDs). The new 'high-power' charging stations have the potential to create strong electromagnetic fields and induce EMI in CIEDs, and their safety has not been evaluated. A total of 130 CIED patients performed 561 charges of four BEVs and a test vehicle (350 kW charge capacity) using high-power charging stations under continuous 6-lead electrocardiogram monitoring. The charging cable was placed directly over the CIED, and devices were programmed to maximize the chance of EMI detection. Cardiac implantable electronic devices were re-interrogated after patients charged all BEVs and the test vehicle for evidence of EMI. There were no incidences of EMI, specifically no over-sensing, pacing inhibition, inappropriate tachycardia detection, mode switching, or spontaneous reprogramming. The risk of EMI on a patient-based analysis is 0/130 [95% confidence interval (CI) 0%-2%], and the risk of EMI on a charge-based analysis is 0/561 (95% CI 0%-0.6%). The effective magnetic field along the charging cable was 38.65 µT and at the charging station was 77.9 µT. The use of electric cars with high-power chargers by patients with cardiac devices appears to be safe with no evidence of clinically relevant EMI. Reasonable caution, by minimizing the time spent in close proximity with the charging cables, is still advised as the occurrence of very rare events cannot be excluded from our results.

Targeted Treatment of Inappropriate Sinoatrial Node Tachycardia Based on Electrophysiological and Structural Mechanisms

The purpose of this review is to determine the causal mechanisms and treatment of inappropriate sinoatrial tachycardia (IST), defined as a non-physiological elevation in resting heart rate. IST is defined as a resting daytime sinus rate >100 beats/minute and an average 24-hour heart rate >90 beats/minute. Potential causal mechanisms include sympathetic receptor hypersensitivity, blunted parasympathetic tone, or enhanced intrinsic automaticity within the sinoatrial node (SAN) pacemaker-conduction complex. These anomalies may coexist in the same patient. Recent ex-vivo near-infrared transmural optical imaging of the SAN in human and animal hearts provides important insights into the functional and molecular features of this complex structure. In particular, it reveals the existence of preferential sinoatrial conduction pathways that ensure robust SAN activation with electrical conduction. The mechanism of IST is debated because even high-resolution electroanatomical mapping approaches cannot reveal intramural conduction in the 3-dimensional SAN complex. It may be secondary to enhanced automaticity, intranodal re-entry, or sinoatrial conduction pathway re-entry. Different pharmacological approaches can target these mechanisms. Long-acting β blockers in IST can act on both primarily increased automaticity and dysregulated autonomic system. Ivabradine targets sources of increased SAN automaticity. Conventional or hybrid ablation may target all the described abnormalities. This review provides a state-of-the-art overview of putative IST mechanisms. In conclusion, based on current knowledge, pharmacological and ablation approaches for IST, including the novel hybrid SAN sparing ablation, are discussed.

Post-COVID-19 syndrome. SARS-CoV-2 RNA detection in plasma, stool, and urine in patients with persistent symptoms after COVID-19

BackgroundThere is a paucity of knowledge on the long-term outcome in patients diagnosed with COVID-19. We describe a cohort of patients with a constellation of symptoms occurring four weeks after diagnosis causing different degrees of reduced functional capacity. Although different hypothesis have been proposed to explain this condition like persistent immune activation or immunological dysfunction, to date, no physiopathological mechanism has been identified. Consequently, there are no therapeutic options besides symptomatic treatment and rehabilitation.MethodsWe evaluated patients with symptoms that persisted for at least 4 weeks after COVID-19. Epidemiological and clinical data were collected. Blood tests, including inflammatory markers, were conducted, and imaging studies made if deemed necessary. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) reverse transcription polymerase chain reaction (RT-PCR) in plasma, stool, and urine were performed. Patients were offered antiviral treatment (compassionate use).ResultsWe evaluated 29 patients who reported fatigue, muscle pain, dyspnea, inappropriate tachycardia, and low-grade fever. Median number of days from COVID-19 to positive RT-PCR in extra-respiratory samples was 55 (39–67). Previous COVID-19 was mild in 55% of the cases. Thirteen patients (45%) had positive plasma RT-PCR results and 51% were positive in at least one RT-PCR sample (plasma, urine, or stool). Functional status was severely reduced in 48% of the subjects. Eighteen patients (62%) received antiviral treatment. Improvement was seen in most patients (p = 0.000) and patients in the treatment group achieved better outcomes with significant differences (p = 0.01).ConclusionsIn a cohort of COVID-19 patients with persistent symptoms, 45% of them have detectable plasma SARS-CoV-2 RNA. Our results indicate possible systemic viral persistence in these patients, who may benefit of antiviral treatment strategies.

Severe Post-COVID-19 dysautonomia: a case report

BackgroundThe emergence of dysautonomia as a consequence of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2; or COVID-19) is becoming more prevalent. We have seen evidence in several post-COVID patients and in the literature of varying degrees of autonomic dysfunction. Symptoms, among others, include inappropriate tachycardia, sweating, anxiety, insomnia and blood pressure variability from the effects of excessive catecholamine, as well as cognitive impairment, fatigue, headaches and orthostatic intolerance from decreased brain perfusion.Case presentationWe present a case of severe dysautonomia in a previously healthy 27-year-old runner. About five weeks after her initial mild COVID-19 infection, the patient began to develop weakness, which progressed into severe post-exertional fatigue, slowed cognition, headaches, blurred vision and generalized body aches. She also endorsed palpitations, especially when getting up from a seated or lying position as well as with mild exertion. She became reliant on her husband for help with her activities of daily living. Exam was significant for orthostasis; laboratory workup unremarkable. Over the following months, the patient’s symptoms have improved slowly with fluid and sodium intake, compression stockings and participating in a graduated exercise program.ConclusionsDysautonomia as a consequence of infection with COVID-19 is becoming increasingly discussed, especially as more patients recover from COVID-19. This is a case of a non-hospitalized patient with a mild initial presentation and significant, debilitating dysautonomia symptoms. More research on its pathophysiology, especially in relation to a precedent viral insult, as well as its treatment, is needed.

The long COVID: Findings of 24 rhythmic Holter in patients suffering from palpitations

IntroductionMany patients showed long COVID syndrome after recovery from the CORONAVIRUS – SARS infection (40–50%). Many patients showed palpitations and we do not know the cause of these palpitations.Patients and methodsThis is an observational study including patients showing palpitations after recovery from the COVID-19. We analyzed the results of 24 hours recording as well as echocardiographic findings and we analysed the correlation between myocardial strain and rhythms disorders.ResultsAmong 2338 COVID-19 patients, 45% showed long COVID symptoms at 30 days, 7% patients suffered from palpitations. We noted an inappropriate sinusal tachycardia in 60% of cases, 3 cases of ventricle disorders arrhythmia disorders. Longitudinal strain was significantly lower in patients who showed arrhythmia in the 24 recordings than in patients with normal 24 hours rhythm recordings.ConclusionThere is correlation between rhythmic disorders and myocardial damages in patients who showed COVID-19.

Abstract 11329: Prospective Analysis of Vascular Resistance in Patients with Persistent Tachycardia and or Dyspnea on Exertion in the Post Acute Sequela of Covid-19 Syndrome

Introduction: The cause of tachycardia and dyspnea on exertion (DOE) in the Post Acute Sequelae CoV-2 syndrome (PASC) has yet to be identified. While endothelial invasion of the virus is well documented, how that might explain PASC is unknown. Hypothesis: Covid induced changes in vascular signaling to autonomic regulatory centers can induce sinus tachycardia and DOE. Methods: In a prospective, observational study, we enrolled 18 PASC patients who reported DOE or inappropriate tachycardia. All patients had normal left ventricular function, CXR, Hgb and thyroid studies. None had preexisting autonomic dysfunction. Vascular resistance was assessed by echocardiographic measurement of aortic-vascular impedance (Zva)=(systolic BP + mean Ao valve gradient)/stroke volume index. Ambulatory heart rate monitoring and head-up tilt table testing (HUTT) were performed. Results: Consecutively enrolled patients (18) were studied (17 females, ages 27 to 64). None had a significant aortic valve gradient. Zva was elevated in 17 of 18 patients. Ambulatory monitoring revealed episodes of symptomatic sinus tachycardia. Higher average daily heart rates correlated significantly with higher Zva levels (fig1). The 14 patients with DOE trended to higher average Zva levels than the 4 patients without dyspnea (4.13 +- 0.85 vs 3.5 +- 0.24, P=0.14). Of the 17 patients who had HUTT, 16 demonstrated patterns of orthostatic intolerance consistent with excess sympathetic tone including both postural orthostatic tachycardia and neurogenic cardiac syncope. Conclusions: PASC associated sinus tachycardia and HUTT abnormalities result from excess sympathetic tone. Covid-19 vascular injury as evidenced by abnormal Zva values may result in abnormal vascular signaling to autonomic regulatory centers. Resultant increases in sympathetic output may produce inappropriate sinus tachycardia, vasomotor dysregulation and DOE via peripheral vasoconstriction.

Inappropriate tachycardia at rest as a consequence of atrial preference pacing algorithm

Inappropriate tachycardia at rest as a consequence of atrial preference pacing algorithm

Inadequate, inappropriate sinus-node tachycardia. An old cardiac arrhythmia in a new perspective

Introduction: The inadequate, inappropriate sinus-node tachycardia is not a rare clinical syndrome, defined as a non-paroxysmal, increased sinus-rate at rest, and/or inadequate response to physical and/or emotional stress, and palpitations. Aim: The aim of this study was to describe our experiences with the investigations of our inappropriate sinus-node tachycardia patients. Method: In the last years, 104 patients (92 women, 12 men, mean age: 31 ± 10 years) were treated with this cardiac arrhythmia entity. All patients underwent 12 leads ECG, chest X-ray, echocardiography, Holter-monitoring and transtelephonic ECG observations. The quality of life score was estimated by using the European Heart Rhythm Association scale. Results: Patients had no structural heart disease (physical examination ECG, chest X-ray, echocardiography were normal), the laboratory values (TSH, blood count) were within normal limits, but the resting heart rates were repeatedly high (102 ± 8/min). The results of Holter recording (expressed as minimal-maximal [average] heart rate/min) without drug therapy showed high heart rate values (59 ± 8, 160 ± 14 [94 ± 6]/min). The standard bicycle ergometry showed an average loading capacity of 124 ± 23 watt (heart rate: control: 99 ± 12/min, top: 167 ± 13/min) with early, inadequate sinus tachycardia. To disclose the episodes of paroxysmal supraventricular tachycardia, beside the Holter-monitoring transtelephonic ECG system was used. This diagnostic modality was very useful for the exclusion of paroxysmal supraventricular tachycardia episodes during the palpitation symptoms. Out of 104 patients, 4 patients (3.8%) showed familiar occurrence, another 16 patients (15.2%) had previous slow-pathway radiofrequency ablation due to atrioventricular nodal reentry tachycardia. Conclusions: Based on our clinical observations, it can be pointed out that inappropriate sinus-node tachycardia syndrome (1) occurs mainly in young women, mostly in students, inducing decreased quality of life scores (EHRA score: 2.3 ± 0.4); (2) the prevalence in our outpatient clinic was 0.7%; (3) the patient population is not homogeneous: familiar or postablation occurrence is possible in some patients; (4) transtelephonic ECG has been proved to be very useful to disclose episodes of paroxysmal supraventricular tachycardia in these patients. Orv Hetil. 2019; 160(37): 1464-1470.

Modern Security Screening And Electromagnetic Interference with Cardiac Implantable Devices: A Cross-Sectional Study

Background: The prevalence of patients with cardiac implantable electronic devices (CIEDs) is increasing and many of these patients will undergo security screening during travel. Currently, patients with CIEDs are advised to request manual security checks as there are concerns about device malfunction due to electromagnetic interference (EMI). The aim of this study was to evaluate the EMI effects and safety of the new security screening millimetre-wave body scanners (MWBSs) for patients with CIEDs. Method: We selected a population of 302 patients with a CIED presenting for routine review at the German Heart Centre, Munich. CIED programming was optimised for the detection of EMI occurrence and high-voltage therapy was disabled. Electrocardiography-monitored patients were then scanned using the body scanner at the recommended distance, as well as in close proximity to the scanner simulating accidental exposure. CIED interrogation was then performed to review for EMI effects. Results: There were no episodes of inhibition of pacing, upper-rate tracking, inappropriate tachycardia detection, or spontaneous device reprogramming. There was no change in pacing or sensing thresholds, or lead impedance measurements after scanning with the MWBS. No CIEDs were identified by the MWBS during the study. Conclusion: No EMI events were detected during the use of MWBSs suggesting that their use is safe and there is no need for specific protocols or precautions. Patients with a CIED need not disclose medical information regarding their device at security checkpoints.

The Endogenous Lusitropic and Chronotropic Agent, B-Type Natriuretic Peptide, Limits Cardiac Troponin Release in Cancer Patients with an Early Impairment of Myocardial Relaxation Induced by Anthracyclines.

We have reported that cancer patients treated with anthracycline-based or nonanthracycline chemotherapy developed an early impairment of myocardial relaxation at echocardiography or persistent elevations of the cardiac hormone B-type natriuretic peptide (BNP). Post-hoc pharmacologic analyses showed that BNP elevations were induced by impaired relaxation and caused positive lusitropic effects that maintained normal relaxation. High BNP levels and impaired relaxation were therefore characterized as mutually exclusive manifestations of diastolic dysfunction, but high BNP levels resulted in positive chronotropism and inappropriate tachycardia. Some patients developed increased circulating levels of cardiac troponin I isoform (cTnI), a marker of cardiomyocyte necrosis. Here we have characterized whether cTnI elevations correlated with diastolic dysfunction that manifested as impaired relaxation or a high level of BNP. The effects of high BNP levels on cTnI elevations were also characterized. We show that impaired relaxation or high BNP levels were significantly more frequent in patients with cTnI elevations. High BNP levels diminished the plasma peak and area under the curve of cTnI, but this result was accompanied by inappropriate tachycardia. cTnI elevations occurred only in patients treated with anthracyclines; moreover, the association of impaired relaxation or high BNP levels with cTnI elevations was significantly more frequent in doxorubicin-treated patients compared with patients treated with its analog, epirubicin. These findings describe cause-and-effect relations between impaired relaxation and cardiomyocyte necrosis, illuminate the role of anthracycline analogs, denote that the beneficial effects of BNP in relieving impaired relaxation and cardiomyocyte necrosis are counterbalanced by inappropriate tachycardia. Patients showing troponin elevations and impaired relaxation or high BNP levels should be treated with lusitropic drugs that lack a positive chronotropism.

Resolution of Postural Orthostatic Tachycardia Syndrome After CT-Guided, Percutaneous T2 Ethanol Ablation for Hyperhidrosis

Postural orthostatic tachycardia syndrome is characterized by orthostatic intolerance. Orthostasis (or other mild physical stress) triggers a cascade of inappropriate tachycardia, lightheadedness, palpitations, and often fainting. The underlying defect is sympathetic dysregulation of the heart, which receives its sympathetic tone from the cervical and upper thoracic sympathetic ganglia. Primary hyperhidrosis is also thought to be the result of sympathetic dysregulation. We present the case of a patient treated with CT-guided, percutaneous T2 EtOH sympatholysis for craniofacial hyperhidrosis. The patient also suffered from postural orthostatic tachycardia syndrome for many years and was unresponsive to treatment. Immediately after sympatholysis, the patient experienced resolution of both craniofacial hyperhidrosis and postural orthostatic tachycardia syndrome.

Respiratory Distress in an Infant: An Uncommon Cause for a Common Complaint

BackgroundRespiratory distress and tachycardia are common presenting complaints in infants and young children, and evaluation typically focuses on respiratory infections. Tachydysrhythmias causing heart failure are rare and can be difficult to diagnose in young children, but are reversible if recognized and treated early. Case ReportWe discuss a 7-week-old female infant who presented with respiratory distress and persistent tachycardia. Evaluation revealed severe cardiac dysfunction with an underlying atrial flutter discovered on electrocardiography after adenosine administration. Rate control by synchronized electrocardioversion resulted in resolution of symptoms and restoration of cardiac function, confirming the diagnosis of atrial flutter–induced cardiomyopathy. Why Should an Emergency Physician Be Aware of This?Persistent or inappropriate tachycardia in a young child should not be dismissed and underlying dysrhythmia should be considered.

Malignant hyperthermia deaths related to inadequate temperature monitoring, 2007-2012: a report from the North American malignant hyperthermia registry of the malignant hyperthermia association of the United States.

AMRA (adverse metabolic or muscular reaction to anesthesia) reports submitted to The North American Malignant Hyperthermia Registry of the Malignant Hyperthermia Association of the United States from 1987 to 2006 revealed a 2.7% cardiac arrest and a 1.4% death rate for 291 malignant hyperthermia (MH) events. We analyzed 6 years of recent data to update MH cardiac arrest and death rates, summarized characteristics associated with cardiac arrest and death, and documented differences between early and recent cohorts of patients in the MH Registry. We also tested whether the available data supported the hypothesis that risk of dying from an episode of MH is increased in patients with inadequate temperature monitoring. We included U.S. or Canadian reports of adverse events after administration of at least 1 anesthetic drug, received between January 1, 2007, and December 31, 2012, with an MH clinical grading scale rank of "very likely MH" or "almost certain MH." We excluded reports that, after review, were judged to be due to pathologic conditions other than MH. We analyzed patient demographics, family and patient anesthetic history, anesthetic management including temperature monitoring, initial dantrolene dose, use of cardiopulmonary resuscitation, MH complications, survival, and reported molecular genetic DNA analysis of RYR1 and CACNA1S. A one-sided Cochran-Armitage test for proportions evaluated associations between mode of monitoring and mortality. We used Miettinen and Nurminen's method for assessing the relative risk of dying according to monitoring method. We used the P value of the slope to evaluate the relationship between duration of anesthetic exposure before dantrolene administration and peak temperature. We calculated the relative risk of death in this cohort compared with our previous cohort by using the Miettinen and Nurminen method adjusted for 4 comparisons. Of 189 AMRA reports, 84 met our inclusion criteria. These included 7 (8.3%) cardiac arrests, no successful resuscitations, and 8 (9.5%) deaths. Of the 8 patients who died, 7 underwent elective surgeries considered low to intermediate risk. The average age of patients who died was 31.4 ± 16.9 years. Five were healthy preoperatively. Three of the 8 patients had unrevealed MH family history. Four of 8 anesthetics were performed in freestanding facilities. In those who died, 3 MH-causative RYR1 mutations and 3 RYR1 variants likely to have been pathogenic were found in the 6 patients in whom RYR1 was examined. Compared to core temperature monitoring, the relative risk of dying with no temperature monitoring was 13.8 (lower limit 2.1). Compared to core temperature monitoring, the relative risk of dying with skin temperature monitoring was 9.7 (1.5). Temperature monitoring mode best distinguished patients who lived from those who died. End-tidal CO2 was the worst physiologic measure to distinguish patients who lived from those who died. Longer anesthetic exposures before dantrolene were associated with higher peak temperatures (P = 0.00056). Compared with the early cohort, the recent cohort had a higher percentage of MH deaths (4/291 vs 8/84; relative risk = 6.9; 95% confidence interval, 1.7-28; P = 0.0043 after adjustment for 4 comparisons). Despite a thorough understanding of the management of MH and the availability of a specific antidote, the risk of dying from an MH episode remains unacceptably high. To increase the chance of successful MH treatment, the American Society of Anesthesiologists and Malignant Hyperthermia Association of the U.S. monitoring standards should be altered to require core temperature monitoring for all general anesthetics lasting 30 minutes or longer.

Telemonitoring for arrhythmias on rural outpatients: Feasibility and results on 167 patients

Background and purpose Cardiac arrhythmias are undiagnosed because of their frequent transient and asymptomatic characteristic. This observational study on 167 patients assesses diagnosis and therapeutic advantages of electrocardiogram (ECG) remote monitoring on an at-risk population living in rural areas. Patients referred for ECG ambulatory monitoring were put on continuous recording to detect cardiac arrhythmias. Methods A total of 167 patients referred for evaluation of cardiac arrhythmia underwent simultaneous ECG ambulatory recording with a Holter monitor. Arrhythmias were automatically detected and the tracings transmitted by phone to a secure server for heart rate (HR) analysis. This study main objective was to evaluate the detection of 6 different kinds of arrhythmias including supraventricular tachycardia, atrial fibrillation (AF)/flutter, pause longer than 3 seconds atrioventricular block, ventricular tachycardia or inappropriate sinusal tachycardia. Results One hundred and sixty-seven patients with sinus rhythm. Thirty-nine percent men and 61% women, mean age of 64-years-old. Nine percent had already experienced a stroke and 7% suffered coronary disease. Thirty-five percent were taking an anti-arrythmic and 17% were taking anticoagulant. CHADS2Vasc2 = 2. Monitoring lasted 11 days, 11 hours per day, 248 ECG were transmitted. Recorded changes are: – absence of abnormality (44%); – onset of AF (31%); – discovery of regular sinusal tachycardia (25%) treated with heart rate control medications. Screening and early detection of AF is one of the strategy main priorities to optimise anti-arrhythmia and anticoagulant treatment in real time. Early results show that 4 patients have an indication of implant placement and 3 for radiofrequency ablation. Both system and method are a quick and interesting solution to data transfer between medical experts and local family practitioners in order to take the most appropriate decisions. Conclusion A long-term single-lead monitoring in detection of arrhythmia events on referred patients for ECG ambulatory monitoring is a simple method. The quality of life of rural population and retired people who require medical attention without moving could be significantly improved in term of diagnosis, treatment and drug prescriptions to prevent stroke.

Analysis of malignant hyperthermia results in Padua and Siena

Background Malignant Hyperthermia is pharmacogenetic disease triggered by some anaesthetics such as halogenated gases and non depolarizing muscle relaxant. The diagnosis of malignant hyperthermia susceptibility may be done by 1) relevant clinical signs observed during the crisis, 2) the in vitro contracture test (IVCT) with caffeine-halothane according to the European and the American Malignant Hyperthermia Group protocols and/or 3) the search for mutations of RYR 1 and CACNA1S genes. The IVCT identified three categories of patients: a) MHS (malignant hyperthermia susceptible), b) MHE (malignant hyperthermia equivocal) and c) MHN (non susceptible). A gene mutation may be defined as diagnostic only if it can be defined as “causative mutations” capable to alter the protein function in a cell culture test. The patients carrying “no causative” mutations must carry out the IVCT to confirm a susceptibility condition. Usually, the first investigated patients, the probands, have had an abnormal reactions during trigger anaesthesia such as early signs (inappropriately elevated CO2, inappropriate tachycardia and/or arrhythmia and muscle signs like masseter spasm or generalized muscle rigidity) or late signs (rapid increase in core body temperature, high value of CK etc). If the anaesthesia report has been well done it is possible to attribute a Larach Clinical Grading Scale that classifying the reactions as” almost certain” (more than 50 scores) or very rare “almost never” with 0 scores. The susceptible probands may be also genetically studied and the relatives warned of the genetic risk of an autosomal dominant trait. The problems for the physicians may be relevant when the probands have a raw score range from 20 to 34 or more, and the IVCT results is negative (MHN). Although negative patients may be happy to result negative, they remain worried regarding anaesthesia own and of their relatives. The worry for General Anesthesia (GA) does not disappear with a negative test and it may be very difficult explaining that other possible causes may be involved in MH like reactions. In some MHN probands it may be easier to find an explanation, as it is possible an alternative diagnosis or because.... the not clear or wrong anaesthetic report but what about the others. In some of similar cases, we decide to perform a genetic analysis and in one patient MHN patient we found a “no causative mutation”. At this point the question is 1) can be assure the MHN patients regarding GA with trigger agents? 2) Are there other possible investigations to give more assurance to such patients? 3) genetic testing should be prescribed also in the MHN probands? We present the data of our MH laboratories highlighting the IVCT and genetic results obtained on our probands and the suggestions and information that we give to the MHN probands as well as some questions to the auditorium.

Approximation of electrocardiogram T wave by using Gaussian mixtures and automatic measurement of QT interval

Results: Active fixation leads were used in 120 (90%) patients, and passive fixation leads were used in 14 (10%) patients. Local injury current was observed in 121 events (28.8%) and was detected more frequently after appropriate (43 [60.6%] events) and inappropriate (56 [64.4%] events) ICD shocks, as compared with appropriate (8 [9.2%] events) and inappropriate (3 [4.7%] events) antitachycardia pacing (ATP) or nonsustained ventricular tachycardia (11 [9.9%] events; analysis of variance, P ≤ .0001]. Appearance of LIC was a changeable phenomenon; that is, LIC was frequently observed after one, but not another, appropriate ICD shock in the same patient. Significant LIC was observed after 61% of events with single ICD shock, 83% of events with 2 shocks, 50% of events with 3 shocks, and 100% of events with 4 or more shocks (analysis of variance, P = .658). Type of ICD therapy (ICD shock vs ATP) was the most significant predictor of LIC (ATP:β-coefficient =−0.81; 95%confidence interval [CI], −1.19 to 0.44; P ≤ .0001), along with cycle length of tachycardia (β-coefficient = −0.0117; 95% CI, −0.0167 to −0.0068; P≤; .00001) and shock energy (β-coefficient = 0.024; 95% CI, 0.003–0.045; P = .025). Conclusion: Appropriate and inappropriate ICD shocks are frequently characterized by the development of LIC in patients with structural heart disease. Type of electrical ICD therapy, shock energy, and cycle length of ventricular arrhythmia are important determinants of LIC.

Differentiation of ventricular and supraventricular tachycardias based on the analysis of the first postpacing interval after sequential anti-tachycardia pacing in implantable cardioverter-defibrillator patients

Current discrimination algorithms do not completely avoid inappropriate tachycardia detection. This study analyzes the discrimination capability of the changes of the first postpacing interval (FPPI) after successive bursts of anti-tachycardia pacing (ATP) trains in implantable cardioverter-defibrillator (ICD)-recorded tachycardias. We included 50 ICD patients in this prospective study. We hypothesized that the FPPI variability (FPPIV) when comparing bursts with different numbers of beats would be shorter in ventricular tachycardias (VTs) compared with supraventricular tachycardias (SVTs). The ATP (5-10 pulses, 91% of tachycardia cycle length) was programmed for tachycardias >240 ms. Anti-tachycardia pacing was delivered during 37 sinus tachycardias (STs) in an exercise test, 96 induced VTs in an electrophysiological study, and 198 spontaneous episodes (144 VTs and 54 SVTs). The FPPI remained stable after all ATP bursts in VT but changed continuously in SVT; when comparing bursts of 5 and 10 pulses, the FPPIV was shorter in VT (34 +/- 65 vs.138 +/- 69, P<.0001, in all T and 12 +/- 20 vs. 138 +/- 69, P<.0001, in T>or=320 ms) than in SVT. In T>or=320 ms an FPPIV<or=50 ms between bursts of 5 and 10 pulses classified correctly 100% of VTs and 90% of SVTs. Anti-tachycardia pacing terminated 66% of induced VTs, 60% of spontaneous VTs, and 20% of spontaneous SVTs and induced no VT during spontaneous or exercise induced SVT. Five induced and two spontaneous VT episodes were accelerated. Analysis of FPPIV after ATP discriminates ICD-detected T. Successive bursts (of ATP) trains at 91% of tachycardia cycle length are safe, despite being delivered before rhythm classification.

Can a standardized ICD programming approach match physician tailored programming in preventing shocks post ICD implantation?

Introduction: ICD shocks are a major cause of morbidity following device implantation. Shocks can be reduced by programming enhancements that prevent inappropriate supraventricular tachycardia detections and by the use of antitachycardia pacing (ATP) to painlessly terminate monomorphic ventricular tachycardias. However, physicians may not use these features. The EMPIRIC trial hypothesized that a standardized set of VT/VF detection and therapy settings would be at least as effective in preventing shocks as individually tailored programming by an electrophysiologist.

Induction Ovens and Electromagnetic Interference: What Is the Risk for Patients with Implantable Cardioverter Defibrillators?

Electromagnetic fields may interfere with normal implantable cardioverter defibrillator (ICD) function. Although the devices are effectively shielded and use exclusively bipolar leads, electromagnetic interference (EMI) remains a concern when patients are exposed to several household appliances. The aim of this study was to evaluate potential EMI risk of induction ovens, which are increasingly common in private households. In vitro measurements of an induction oven for private households GK 43 TI (V-Zug, Inc., Zug, Switzerland) showed that heating is regulated by increasing operating time from level 1 (100 ms/sec) to 5 (continuous operation). From levels 5 to 9 the magnetic field increases. Nineteen patients with left-sided implants of single- and dual-chamber ICD systems (8 Medtronic, 7 Guidant, and 4 St. Jude Medical) (18 males, 1 female), age (mean +/- SEM) 58 +/- 3 years, were included in this study. All patients were examined in standing position, bent over the cooking pot (minimal distance to the induction coil 25 cm), and with the cooking pot put eccentrically over the induction field at three different cooking levels (level 2, 5, and 9). The tests were repeated touching the cooking pot with one hand. Ventricular sensitivity was left unchanged. Ventricular tachycardia therapies were turned off in Medtronic and Guidant devices and ventricular sensing was continuously monitored in St. Jude Medical devices during testing. Interrogation of the devices after exposure did not show any inappropriate tachycardia detection, oversensing, or reprogramming. In conclusion, ICD patients can be reassured that EMI is unlikely to affect their devices if induction ovens are used in their kitchens.