Inappropriate Sinus Tachycardia Research Articles

Insights from preclinical ultra high-density electroanatomical sinus node mapping

Although sinus node modification by catheter ablation is an established therapy for the treatment of inappropriate sinus tachycardia, there is incomplete understanding of sinus node anatomy and function but also limited electroanatomical mapping data. Recently, an automatic, ultra high-resolution mapping system has been presented to accurately and quickly identify right atrial (RA) geometry and activation patterns but detailed assessment of sinus node activation has not been performed which was one aim of this study. Preclinical experiences are compared with previous sinus node mapping studies in animals and humans, and potential clinical implications for catheter ablation are discussed. In anaesthetized and ventilated 14 pigs, 30 endocardial and 2 eipcardial RA maps were generated using the Rhythmia™ mapping system without complications and earliest activation sites (EAS) and sinus break-out (SBO) were determined. At baseline, EAS and SBO were located anterior to the middle (n = 6) or lower third (n = 8) of the crista terminalis exhibiting a unicentric activation pattern in all cases. Conduction pathways were directed anterior, posterior, superior, or inferior with substantial inter-individual variation in direction, pathway distance, and conduction time. Orciprenaline, propranolol, or amiodarone shifted endocardial activation with considerable variation between animals with inconsistent patterns. Multicentric activation was found in one case after orciprenaline infusion. Sequential endocardial and epicardial high-density mapping of the RA was performed in two animals and showed a high congruence of the sinus node activation in the endo- and the epicardial map. Ultra high-density mapping allows fast, simple, and very detailed assessment of sinus node activation. Future studies are clearly needed to evaluate novel mapping and ablation strategies for an improved understanding of sinus node disease and better outcomes.

Differences in cardiac autonomic function contributes to heart rate abnormalities in POTS and IST.

Our objective was to examine the differences in cardiac autonomic function in Postural Tachycardia Syndrome (POTS) versus inappropriate sinus tachycardia (IST). Subjects (IST, n = 8; POTS, n = 12) were studied using standard measurements of the autonomic reflex screen, baroreflex function and spectral analysis. Data was compared to age/gender-matched controls (n = 20). The components of the autonomic reflex screen did not differ between groups. The exception was the significant but expected difference in postural heart rate increment on head-up tilt in POTS (47.9 ± 13.8; n = 12) compared to IST (30.9 ± 9.7; n = 8; p = 0.008). Accordingly the Orthostatic Intolerance Scale showed significantly greater orthostatic symptoms in POTS (2.6 ± 0.5; n = 12) versus IST patients (0.4 ± 0.5; n = 8; p < 0.001). Conversely, IST patients had a significantly higher resting heart rate (96 ± 12; n = 8) when compared to POTS patients (73 ± 12; n = 12; p = 0.001). There was a significant difference in vagal baroreflex sensitivity (BRSv) in POTS (8.21 ± 2.3, n = 12) compared to IST patients (5.30 ± 2.94, n = 8, p = 0.036) during the Valsalva maneuver. Only POTS subjects showed a significant increase in sympathovagal balance (LF/HF) with tilt (FFT, 8.29 ± 6.38; AR, 7.84 ± 5.24) compared to the supine position (FFT, 2.25 ± 1.75; AR, 1.99 ± 1.38; p < 0.05) for both frequency domains. Differences in cardiac autonomic function contribute to changes in positional and non-positional heart rate in postural tachycardia syndrome versus inappropriate sinus tachycardia. These findings shed further light on the autonomic dysfunction underlying POTS and IST.

Ein Herz ohne Drehzahlbegrenzung

We report the case of a 38-year patient who presented in our outpatient clinic for cardiac evaluation and assessment as volunteer firefighter. The patient had an asymptomatic sinustachycardia, which was diagnosed at the age of 15. After we excluded secondary etiologies, as well as a postural orthostatic tachycardia syndrome (POTS) diagnosis of inappropriate sinus tachycardia (IST) was confirmed. A metoprolol therapy was established, however to resistant tachycardia, we suggested a combined therapy of Bisoprolol and Ivabradin, which resulted successfully in normocard sinus rhythm.

COMPARATIVE SAFETY AND EFFICACY EVALUATION OF IVABRADINE, METOPROLOL AND ITS COMBINATION IN MANAGEMENT OF INAPPROPRIATE SINUS TACHYCARDIA IN CORONARY ARTERY BYPASS GRAFT PATIENTS

Post-Operative Inappropriate Sinus Tachycardia (IST) is common After Coronary Artery Bypass Graft (CABG) surgery requiring treatment to reduce heart rate (HR). If untreated, increases incidence of complications including post-operative stroke. A total of 151 patients undergoing CABG surgery at a

DI-059 Use, effectiveness and safety of ivabradine in paediatric patients

BackgroundIvabradine is authorised for the treatment of coronary artery disease and chronic heart failure with systolic dysfunction in adult patients, but there is little information on its efficacy and safety...

Epicardial/Endocardial Sinus Node Ablation After Failed Endocardial Ablation for the Treatment of Inappropriate Sinus Tachycardia

Success of endocardial sinus node (SN) ablation for refractory inappropriate sinus tachycardia (IST) is limited by the epicardial location of the SN and potential damage to the phrenic nerve (PN). An epicardial approach may overcome these limitations. IST patients who failed endocardial ablation underwent an epicardial approach. Percutaneous pericardial access was obtained with a double wire technique for PN protection (i.e., with a balloon catheter), if needed. Earliest sinus activation was mapped and ablated with remapping for changes in P-wave morphology or sinus rate. The endpoint was total SN ablation (patients with atrial pacing [AP]); otherwise the target was a >25% decrease in sinus rate and inversion of P-wave axis. Five patients (all female, age 36 ± 4 years) underwent ablation. Two had prior AP, and 1 elected to have SN ablation and pacemaker during the same procedure. Three had prior endocardial ablation limited by PN proximity. Baseline sinus rate was 119 ± 20 bpm. After 35.2 ± 21.3 lesions (22.4 ± 21.7 epicardial, 12.8 ± 21.3 endocardial), 4 were in junctional rhythm, 1 in atrial rhythm at 90 bpm. This latter patient had symptom recurrence and underwent combined minimally invasive surgical/catheter SN cryoablation. Atrial tachycardia subsequently occurred and was successfully ablated. The only significant complication was pericarditis (3 patients). At last follow-up (30.4 ± 18.4 months), all had symptom resolution. Two were AP >99%, 1 was AP 54%. Two remain in ectopic atrial rhythm with controlled rates. Combined epicardial/endocardial SN ablation is a viable approach for patients with severely symptomatic IST after a failed endocardial attempt.

Management of inappropriate sinus tachycardia

Inappropriate sinus tachycardia (IST) is a condition characterised by unusually fast heart rates at rest and/or minimal physical activity or both. The mechanisms of IST are not well understood and individuals suffering with the condition can present with an array of incapacitating symptoms. Although IST is a benign arrhythmia, it can have profound effects on quality of life. Diagnosis is a process of elimination and treatment may include drugs, lifestyle adjustment, and in some circumstances catheter ablation. Cardiac nurses should consider IST as a diagnosis in patients presenting with incessant palpitation and tachycardia in the presence of an otherwise normal ECG.

Inappropriate sinus tachycardia — ailment or disease?

We present a case of a 36-year-old female patient with a long history of persistent palpitations, limited exercise tolerance, and pre-syncope. ECG recordings revealed long lasting episodes of inappropriate sinus tachycardia (IST). IST is characterised by persistent cardiac arrhythmias with sinus P waves in the ECG, and an exaggerated response to a minimal physical effort or stress. Using 24-h Holter definition the average heart rate in patients with IST should be > 90 bpm or daytime heart rate > 100 bpm. The syndrome is associated neither with structural heart disease nor with any reversible causes of sinus tachycardia (i.e. fever, anemia, infection, hyperthyroidism, drug abuse). Therefore the diagnosis is generally one of exclusion. Beta-blockers are most frequently used as first line therapy. Other potentially effective drugs are nondihydropyridine calcium antagonists or ivabradine. The prognosis in patients with IST is very good but in some cases the symptoms can be severe and debilitating.

Long term outcomes of ivabradine in inappropriate sinus tachycardia patients: appropriate efficacy or inappropriate patients?

Long term outcomes of ivabradine in inappropriate sinus tachycardia patients: appropriate efficacy or inappropriate patients?

Disclosing the extensive crystal chemistry of Ivabradine hydrochloride, in its pure and solvated phases

Powder diffraction data are presented for Ivabradine hydrochloride (pure and solvated forms), a drug marketed worldwide for symptomatic treatment of angina pectoris and inappropriate sinus tachycardia. [Ivrabradine: 3-[3-({[(7S)-3,4-dimethoxy bicyclo[4.2.0]octa-1,3,5-trien-7-yl]methyl}(methyl)amino)propyl]-7,8-dimethoxy-2,3,4,5-tetrahydro-1H-3-benzazepin-2-one]. Many are the different (polymorphic or solvated) phases claimed in the scientific or forensic literature. We have here prepared monophasic samples of six different ivabradine hydrochloride species. Exposure to water vapours, at room temperature, of the anhydrous δ-d form generated pure powders of the tetrahydrate form (the β-form). Two different anhydrous forms (β-d and α) were prepared by gentle, or extensive, heating of the β and δ-d forms, respectively. Acetonitrile and acetone solvates (hereafter called δ1- and δ2-forms) were obtained by precipitation methods from concentrated solutions. Diffraction data were collected on laboratory equipment with Ni-filtered CuKα radiation; cell parameters and space groups were determined from ab initio indexing procedures using the SVD algorithm.

Highlights in clinical autonomic neurosciences: Treatment insights for postural tachycardia syndrome and inappropriate sinus tachycardia

The authors sought to investigate whether 24-hour urinary sodium excretion could be an indicator of the effectiveness of salt supplementation in children with postural tachycardia syndrome (POTS). The patient group comprised 30 children with POTS, and the control group comprised 10 healthy children. Serum sodium and 24-hour urinary sodium excretion were measured in all children, and the relationship between 24-hour urinary sodium and symptom severity was analyzed in the 30 patients. At 1 month after initiation of salt supplementation, the receiver operating characteristic curve was used to explore the probability of correctly discriminating responders to salt supplementation fromnonresponders using 24-hour urinary sodium excretion as an indicator. Patients with POTS had lower 24-hour urinary sodium excretion than controls (P = 0.022). Symptom severity was negatively correlated with 24-hour urinary sodium excretion (OR, −0.754; P b 0.001). The receiver operating characteristic curve demonstrated a sensitivity of 77% and specificity of 93% for correct prediction of responders and nonresponders to salt supplementation when a 24-hour urinary sodium excretion of 124 mmol/24 h was used as the cutoff value.

Noninvasive Assessment of Autonomic Cardiovascular Activity in Patients With Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia (IST) is a clinical syndrome characterized by excessive resting heart rate (HR) or disproportional HR increase during exercise. The etiology of IST has not been fully elucidated and remains controversial. The aim of the present study was to assess autonomic function by means of noninvasive tests and commonly available electrocardiographic methods in a series of consecutive patients with symptomatic IST. Twenty-four patients (37 ± 12 years; 20 women) with IST were enrolled. Six cardiovascular reflex tests were performed: (1) HR variation during slow deep breathing, (2) 30-to-15 ratio during active standing, (3) blood pressure response to standing, (4) cold face test, (5) Valsalva maneuver, and (6) blood pressure response to sustained handgrip. Intrinsic HR was calculated and compared with HR after pharmacologic denervation. Additionally, spontaneous baroreflex sensitivity and 24-hour HR variability indices were analyzed. In IST patients, intrinsic HR was significantly higher compared with control subjects. Most cardiovascular autonomic tests revealed abnormal or borderline results, particularly those reflecting mainly parasympathetic function. The spontaneous baroreflex gain was significantly reduced in IST patients. After controlled orthostatic stress and during Valsalva maneuver, impaired baroreflex function was observed. The sympathovagal balance from HR variability was preserved, but altered activity in both bands of frequency domain analysis was recorded. In conclusion, IST is a heterogenic syndrome with enhanced sinus node automaticity modulated by complex alterations of autonomic tone.

Central hyperadrenergic state after lightning strike

To describe and review autonomic complications of lightning strike. Case report and laboratory data including autonomic function tests in a subject who was struck by lightning. A 24-year-old man was struck by lightning. Following that, he developed dysautonomia, with persistent inappropriate sinus tachycardia and autonomic storms, as well as posttraumatic stress disorder (PTSD) and functional neurologic problems. The combination of persistent sinus tachycardia and episodic exacerbations associated with hypertension, diaphoresis, and agitation was highly suggestive of a central hyperadrenergic state with superimposed autonomic storms. Whether the additional PTSD and functional neurologic deficits were due to a direct effect of the lightning strike on the central nervous system or a secondary response is open to speculation.

Interaction between Cardioverter Defibrillator and Enhanced External Counterpulsation Device

Potential interference between implanted cardiac devices and other medical instruments is an important concern. Therefore, we aimed to investigate the possible device interaction between implantable cardioverter defibrillators (ICDs) and external enhanced counterpulsation (EECP) treatment. Twenty-one patients with an implanted ICD or cardiac resynchronization therapy with defibrillator (CRT-D) were enrolled into the study. EECP had applied as two sessions of 5 minutes. Data from device interrogations before and after the first EECP session and during second EECP session were recorded and analyzed for signs of possible device interaction. There was no sign of inappropriate sensing or noise during EECP session. There was no difference regarding electrode impedance, pacing, and sensing values before and after EECP. There was a statistically significant difference regarding heart rates during EECP therapy between rate response off and on modes (68.69 ± 5.92 beats/min and 90.32 ± 11.05 beats/min, respectively P = 0,001). In four patients with CRT-D and unipolar left ventricular pacing, counterpulsation could not be done because of QRS sensing problems. EECP seems to be a safe treatment modality in patients with implanted ICD and CRT-D devices. It should be kept in mind that in those patients with CRT-D, rate responsive mode is on; inappropriate sinus tachycardia can be seen during EECP therapy. Also in patients with CRT-D using a unipolar sensing mode, problems of QRS complex sensing by the EECP may occur and, therefore, this effects synchronization and success of EECP therapy.

Hyperpolarization‐Activated Cyclic Nucleotide‐Gated Channels and Ventricular Arrhythmias in Heart Failure: A Novel Target for Therapy?

Arrhythmias are a common and often fatal complication of heart failure accounting for 50% to 70% of cardiac deaths due to tachyarrhythmic mechanisms.[1][1] In the failing heart, disturbances in cardiac rhythm are the likely result of cardiac remodeling consisting of structural and/or

Feasibility of using ivabridine in adult congenital heart disease patients

Beta Blockers have been the main agent to control the heart rate in Fontan patients. Ivabridine which is a selective SA node inhibitor has been used in adult cardiac patient with successful result in controlling heart rate for those who did not respond to beta blockers alone. This agent has not been reported to be used in adult congenital heart disease patients. To determine the feasibility of using ivabridine in patient with adult congenital heart disease and inappropriate sinus tachycardia who failed to respond to beta blockers. 3 patients all with single ventricle physiology were on maximum tolerable dose of Beta Blockers, with inappropriate sinus tachycardia started on ivabridine. Average follow up was 52 weeks with regular holter monitor. Pro-BNP, 6 min walk test, and echocardiography at baseline and 24 weeks of follow up. Physical examination and interrogation for any detected side effect was done on each visit. At baseline the average heart rate was 100 ± 4 BPM, ivabridine started on with target dose 7.5 mg BD. The mean average heart rate at 12 weeks was 83 BPM, 78 BPM on 24 weeks, and 85 BPM on 52 weeks. There was no reported side effect by the patients or an effect on single ventricle function. ivabridine can be used in single ventricle patients to reduce the heart rate in conjunction with beta blockers. However larger study is needed to assess its isolated long term effect on a diseased sinus node.

Long‐Term Outcomes of Ivabradine in Inappropriate Sinus Tachycardia Patients: Appropriate Efficacy or Inappropriate Patients

Inappropriate sinus tachycardia (IST) is characterized by persistent and disproportional elevation of heart rate (HR). Ivabradine has been successfully used in some patients. Twenty-four patients (18 women, 41 ± 13 year olds) were diagnosed with IST according to current guidelines criteria. Patients were treated with 5-7.5 mg of ivabradine twice a day. Twenty-four-hour Holter recordings and the SF-36 Health Survey were performed at 6 months to evaluate both HR control and clinical status. Holter recordings before and after 6 months on treatment showed a significant reduction in the average maximal HR of 155 ± 18 beats/min versus 132 ± 16 beats/min, mean HR of 97 ± 6 beats/min versus 79 ± 8 beats/min (mean daytime HR of 103 ± 8 beats/min vs 84 ± 10 beats/min) and minimal HR of 58 ± 12 beats/min versus 48 ± 7 beats/min (Wilcoxon analysis, P < 0.05). The SF-36 mean score showed a significant improvement on ivabradine treatment (57 ± 23 vs 76 ± 20), with a better physical and mental status scores (56 ± 25 vs 74 ± 22 and 58 ± 24 vs 78 ± 18, respectively) (Wilcoxon analysis, P < 0.001). Mean dose of ivabradine was 5.8 ± 1.4 mg. No episodes of severe bradycardia or syncope were reported. After 1 year, patients were asked to stop treatment to reevaluate the situation. Twenty patients were on treatment and only 10 patients accepted to stop ivabradine. Only two patients (20%) remained on IST criteria. IST patients treated with ivabradine showed both HR normalization and quality-of-life improvement maintained in the long-term follow-up. Stopping ivabradine after 1 year unexpectedly showed that HR remained in the normal limits in 80% of the patients.

NEED OF EPICARDIAL INSTRUMENTATION TO OPTIMIZE THE ABLATION SITE FOR SINUS NODE MODIFICATION

Catheter ablation of inappropriate sinus tachycardia (IST) is a challenging procedure due to the proximity of the sinus node to the phrenic nerve, and the predominant epicardial location of the sinus node structure. We report a consecutive series of patients undergoing ablation of IST and

‘Inappropriate’ Sinus Tachycardia: Does the 100 Beats Per Min cut-off matter?

Sinus tachycardia is commonly encountered in clinical practice and when persistent, can result in significant symptoms and impaired quality of life, warranting further evaluation. On the other hand, a growing body of epidemiological and clinical evidence has shown that high resting heart rate (HR) within the accepted normal range is independently associated with increased risk of all-cause and cardiovascular mortality. However, higher HR as a risk factor for adverse cardiovascular outcomes is frequently underappreciated. In this review, we focus on two challenging problems that span the spectrum of abnormally fast sinus HR. The first section reviews inappropriate sinus tachycardia, a complex disorder characterized by rapid sinus HR without a clear underlying cause, with particular emphasis on current management options. The latter section discusses the prognostic significance of elevated resting HR and reviews clinical evidence aimed at modifying this simple, yet highly important risk factor.

Ivabradine in Combination With Metoprolol Succinate in the Treatment of Inappropriate Sinus Tachycardia

Inappropriate sinus tachycardia (IST) is a clinical syndrome characterized by excessive resting heart rate (HR) or a disproportional increase in HR during exercise. β-blocker or calcium channel-blocker therapy is often noneffective or not well tolerated. The HR reduction on ivabradine is similar to β-blockers but in some patients its efficacy to resolve all IST-related symptoms is limited. The aim of the study was to assess the efficacy and safety of combining ivabradine with metoprolol succinate in patients with refractory highly symptomatic IST. Twenty patients (36 ± 10 years; 16 women) with IST were enrolled. All patients received metoprolol succinate 95 mg single dose during the first month of the study. After 4 weeks of treatment with metoprolol, ivabradine was administered as adjuvant therapy up to 7.5 mg twice daily. Holter monitoring and treadmill stress test were performed at baseline, after 4, and 8 weeks of the study, respectively. We observed significant and similar reduction in resting HR both for metoprolol and for combined therapy compared to the baseline. The mean HR during daily activity was significantly lower on ivabradine and metoprolol compared to monotherapy with β-blocker. The combined treatment yielded a significant increase in exercise capacity as assessed by treadmill stress test. After 4 weeks of combined therapy a significant reduction in IST-related symptoms, measured by means of the European Heart Rhythm Association score, was observed. Combining ivabradine with metoprolol is an effective and well-tolerated treatment option for IST in patients with refractory to monotherapy.