Dexmedetomidine does not reduce emergence agitation in adults following orthognathic surgery.

BACKGROUND: Patients undergoing orthognathic surgery are at high risk of developing emergence agitation. We hypothesised that a single-dose of dexmedetomidine would reduce emergence agitation in adults with nasotracheal intubation after orthognathic surgery. METHODS: Seventy adults (20-45 years old) undergoing orthognathic surgery were randomly assigned to two groups. Patients received intravenous dexmedetomidine 1 µg/kg (dex group) or normal saline (control group) for 10 min at the end of surgery. Remifentanil was infused at 0.02 µg/kg/min during emergence in both groups. The severity of emergence agitation was assessed with the Richmond agitation-sedation scale. Cough, haemodynamic and respiratory profiles, pain, and time to eye opening were evaluated. RESULTS: The incidence of emergence agitation was not different between dex group and control group (38% vs. 47%, P = 0.45). However, severe cough during emergence was reduced in the dex group (P = 0.04). Tachycardia during emergence and recovery phases was attenuated in the dex group. The verbal numeric rating of pain was lower in the dex group. There were no differences in respiratory rate between the two groups. Time to eye opening was prolonged in the dex group. CONCLUSION: The addition of a single dose of dexmedetomidine (1 µg/kg) to low-dose remifentanil infusion did not attenuate emergence agitation in intubated patients after orthognathic surgery compared with low-dose remifentanil infusion alone. However, single-dose dexmedetomidine suppressed coughing, haemodynamic changes, and pain during emergence and recovery phases, without respiratory depression. Delayed awakening might be associated with this treatment.

A comparison of fospropofol to midazolam for moderate sedation during outpatient dental procedures.

Moderate intravenous (IV) sedation combined with local anesthesia is common for outpatient oral surgery procedures. An ideal sedative agent must be safe and well tolerated by patients and practitioners. This study evaluated fospropofol, a relatively new sedative/hypnotic, in comparison to midazolam, a commonly used benzodiazepine, for IV moderate sedation during oral and maxillofacial surgery. Sixty patients were randomly assigned to either the fospropofol or the midazolam group. Each participant received 1 µg/kg of fentanyl prior to administration of the selected sedative. Those in the fospropofol group received an initial dose of 6.5 mg/kg, with 1.6 mg/kg supplemental doses as needed. Those in the midazolam group received initial doses of 0.05 mg/kg, followed by 0.02 mg/kg supplemental doses. The quality of sedation in each patient was evaluated with regard to (a) onset of sedation, maintenance, and recovery profile; (b) patient and surgeon satisfaction; and (c) hemodynamic stability and adverse effects. The fospropofol group demonstrated shorter physical recovery times than midazolam patients, taking a mean of 11.6 minutes versus 18.4 minutes for physical recovery (P = .007). Cognitive recovery comparison did not find any difference with a mean of 7.5 minutes versus 8.8 minutes between the 2 drug groups (P = .123). The fospropofol group had a higher rate of local anesthetic injection recall (90.5 vs 44.4%, P = .004). Other parameters of recall were comparable. Two adverse effects demonstrated significance, with more patients in the midazolam group experiencing tachycardia (48.2 vs 9.4%, P = .001), and more patients in the fospropofol group experiencing perineal discomfort (40.6 vs 0, P < .001). No significant difference was found in any other measures of sedation safety, maintenance, or satisfaction. Fospropofol, when administered intravenously by a dentist anesthesiologist at the indicated dose in this study, appears to be a safe, well-tolerated alternative to midazolam for intravenous moderate sedation during minor oral surgery procedures.

Sleep bruxism, an autonomic self-regulating response by triggering the trigeminal cardiac reflex.

Sleep bruxism, an intensified manifestation of rhythmic masticatory muscle activity, characterized by tooth grinding or clenching during sleep, lacks a definitive physiological purpose. This paper posits that physiologically, sleep bruxism is an autonomic self-regulatory response to nighttime occurrences of tachycardia stemming from the brain experiencing microarousals during sleep. Sleep bruxism by triggering the trigeminal cardiac reflex leads to bradycardia. Rhythmic masticatory muscle activity-sleep bruxism, thereby, serves to slow the heart rate when brain microarousals cause tachycardia.

Diurnal variation in the salivary melatonin responses to exercise: relation to exercise-mediated tachycardia.

Salivary melatonin concentration is an established marker of human circadian rhythmicity. It is thought that melatonin is relatively robust to the masking effects of exercise. Nevertheless, the extent and even the direction of exercise-related change is unclear, possibly due to between-study differences in the time of day exercise is completed. Therefore, we aimed to compare melatonin responses between morning and afternoon exercise, and explore the relationships between exercise-related changes in melatonin and heart rate. At 08:00 and 17:00 hours, seven male subjects (mean ± SD age, 27 ± 5 years) completed 30 min of cycling at 70% peak oxygen uptake followed by 30 min of rest. Light intensity was maintained at ~150 lx. Salivary melatonin (ELISA) and heart rate were measured at baseline, 15 min during exercise, immediately post-exercise and following 30 min recovery. Melatonin was ≈15 pg ml(-1) higher in the morning trials compared with the afternoon (P = 0.030). The exercise-related increase in melatonin was more pronounced (P = 0.024) in the morning (11.1 ± 8.7 pg ml(-1)) than in the afternoon (5.1 ± 5.7 pg ml(-1)). The slope of the heart rate-melatonin relationship was significantly (P = 0.020) steeper in the morning (0.12 pg ml(-1) beats(-1 )min(-1)) than in the afternoon (0.03 pg ml(-1) beats(-1 )min(-1)). In conclusion, we report for the first time that the masking effect of moderate-intensity exercise on melatonin is approximately twice as high in the morning than the afternoon. The much steeper relationship between heart rate and melatonin changes in the morning raises the possibility that time of day alters the relationships between exercise-mediated sympathetic nervous activity and melatonin secretion.

Significance of cannabis use to dental practice.

The illicit use of the three main forms of cannabis-marijuana, hash, hash oil-pose certain obstacles and challenges to the dental professional. There are a number of systemic, as well as oral/head and neck manifestations, associated with cannabis use. Dentists need to be aware of these manifestations in order to take whatever precautions and/or modifications to the proposed treatment that might be necessary.

Efficacy and safety of oral propranolol premedication to reduce reflex tachycardia during hypotensive anesthesia with sodium nitroprusside in orthognathic surgery: a double-blind randomized clinical trial.

PURPOSE: The present study sought to determine whether premedication with oral propranolol 10 mg before hypotensive anesthesia with sodium nitroprusside could reduce reflex tachycardia, the amount of sodium nitroprusside used, and blood loss during hypotensive anesthesia for orthognathic surgery. PATIENTS AND METHODS: A total of 60 patients undergoing bimaxillary surgery were studied in a prospective, randomized, and double-blind study of oral propranolol 10 mg or placebo as premedication before hypotensive anesthesia with sodium nitroprusside. Hemodynamic variables, the amount of sodium nitroprusside used, and blood loss were statistically analyzed. RESULTS: The heart rate and amount of sodium nitroprusside used were highly significantly less (P < .01) in the propranolol group, but no significant difference was found in blood loss between the 2 groups. No clinically significant complications were observed in either group. CONCLUSION: Premedication with oral propranolol 10 mg before hypotensive anesthesia with sodium nitroprusside is safe and effective to reduce reflex tachycardia and the amount of sodium nitroprusside used.

Cryoablation of accessory pathways in the coronary sinus in young patients: a multicenter study from the Pediatric and Congenital Electrophysiology Society's Working Group on Cryoablation.

INTRODUCTION: This is a multicenter retrospective study evaluating the immediate- and mid-term outcomes of cryoablation of accessory pathways in the coronary sinus in children or in patients with congenital heart disease. METHODS AND RESULTS: Twenty-one patients (median age 13.0 years, range 2-40) from six institutions were included. The accessory pathways were concealed in 11 and manifest in 10. Of 12 patients who had coronary sinus angiography, two had large coronary sinus diverticula, one had a dilated coronary sinus due to a left superior vena cava to coronary sinus, and one had a "pouch" at the mouth of the coronary sinus. Six patients underwent ablation procedures with cryoablation alone, while in the remaining 15 patients, both cryoablation and radiofrequency ablation were utilized. The ablation procedure included left-sided endocardial mapping via a retrograde or transseptal approach in 13 (62%). Procedural success was achieved with cryoablation in the coronary sinus in 15/21 (71%). Four patients (19%) had successful radiofrequency ablation at the right or left posterior septum. Two patients (10%) had unsuccessful procedures. Of the 15 patients with initially successful cryoablation procedures, six (40%) had arrhythmia recurrences at a median of 17 days (range 1-120). Recurrences could not be explained by differences in patient or procedural variables. CONCLUSION: Cryoablation in the coronary venous system in young patients is feasible but associated with a high arrhythmia recurrence rate. Cryoablation techniques and/or equipment need to be improved in order to safely create more permanent lesions in this arrhythmia substrate.

Risk factors for neurogenic pulmonary edema in patients with severe hand, foot, and mouth disease: A meta-analysis.

OBJECTIVE: To investigate the risk factors for neurogenic pulmonary edema (NPE) in patients with severe hand, foot, and mouth disease (HFMD) and to provide evidence for the prevention and treatment of NPE. METHODS: Several databases were searched (from inception to 2017) to identify case-control studies on risk factors for NPE among patients with severe HFMD. Data were analyzed via meta-analysis. The combined odds ratio (OR) and 95% confidence interval (CI) were calculated using fixed-effects and random-effects models, and a sensitivity analysis and evaluation of publication bias was also performed. RESULTS: A total of 14 studies involving 557 cases (severe HFMD with NPE) and 1450 controls (severe HFMD) were included. Results for the categorical variables were as follows: hyperglycemia (OR 10.25, 95% CI 4.82-21.76), tachycardia (OR 6.21, 95% CI 3.02-12.75), hypertension (OR 3.79, 95% CI 2.90-4.95), respiratory rhythm abnormality (OR 7.86, 95% CI 2.46-25.12), drowsiness (OR 8.11, 95% CI 4.26-15.44), vomiting (OR 8.96, 95% CI 3.83-20.96), limb tremors (OR 8.96, 95% CI 3.83-20.96), atypical rash (OR 4.27, 95% CI 2.83-6.45). No significant publication bias was found for the different factors. CONCLUSIONS: Drowsiness ranks first among risk factors for NPE in children with severe HFMD, followed by vomiting, tachycardia, hypertension, breathing rhythm changes, limb tremors, atypical rash, and hyperglycemia.

Surgical treatment of a giant unruptured aneurysm of the noncoronary sinus of Valsalva: a case report.

BACKGROUND: A sinus of Valsalva aneurysm is a rare cardiac anomaly which may be acquired or congenital. The main associated symptoms are conduction disturbances, myocardial ischemia, and syncopes. CASE PRESENTATION: In this report we describe a 52-year-old Albanian woman from Kosovo with an unruptured aneurysm of 74×60 mm of the noncoronary sinus of Valsalva presenting dyspnea, jugular distension, and tachycardia due to cardiac compression. She underwent successful closure of the orifice and sinus remodeling with a Dacron patch. CONCLUSION: To the best of our knowledge this is the largest reported isolated unruptured aneurysm of the coronary sinus causing severe compression of the cardiac chambers undergoing successful surgical correction.

Comparison of endocardial and epicardial programmed stimulation for the induction of ventricular tachycardia.

Twenty-seven patients who had pairs of stainless steel wire electrodes placed on the right and the left ventricle during cardiac surgery underwent both epicardial and endocardial programmed ventricular stimulation to assess the inducibility of ventricular tachycardia. Twenty-six of the patients had coronary artery disease and were studied to evaluate map-guided surgery for treatment of ventricular arrhythmias. Burst ventricular pacing and up to three ventricular extrastimuli coupled to two drive train cycle lengths were delivered from the right and left ventricular epicardial wire electrodes and from endocardial catheter electrodes placed at the apex and outflow tract of the right ventricle. Ventricular tachycardia was reproducibly induced in three patients by both endocardial and epicardial stimulation. In one patient ventricular tachycardia was reproducibly induced by epicardial stimulation, but nonreproducible, nonsustained ventricular tachycardia was induced by endocardial stimulation. Ventricular tachycardia remained inducible by both endocardial and epicardial stimulation in three instances (two patients) during drug therapy. A negative study (less than 10 consecutive ventricular beats induced) was obtained in 23 patients by both endocardial and epicardial stimulation. The patients were followed up for 12 to 43 months (average 31). Sudden death or documented ventricular tachycardia occurred in two of the three patients with a positive study by both endocardial and epicardial stimulation. Nineteen (83%) of the 23 patients with concordantly negative studies remained free of arrhythmias. On the basis of concordant results of endocardial and epicardial stimulation (p = 0.001) these results suggest that epicardial stimulation of the right and the left ventricle is an acceptable method to assess the postoperative inducibility of ventricular tachycardia.(ABSTRACT TRUNCATED AT 250 WORDS)

Two cases with HSS/DRESS syndrome developing after prosthetic joint surgery: does vancomycin-laden bone cement play a role in this syndrome?

We report two cases of hypersensitivity syndrome/drug reaction with eosinophilia and systemic symptoms (HSS/DRESS) syndrome following systemic and local (via antibiotic laden bone cement (ALBC)) exposures to vancomycin. Both cases developed symptoms 2-4 weeks after the initiation of treatment. They responded to systemic corticosteroid treatment and were cured completely. Various drug groups may cause HSS/DRESS syndrome, and vancomycin-related cases do not exceed 2-5% of the reported cases. Almost all of these cases developed the syndrome following systemic exposure to vancomycin. ALBC seems to be the safer antibiotic administration method, as systemic antibiotic levels did not reach a toxic threshold level. However, local administration may not always be sufficient for bone-related/joint-related infections; these infections may require systemic antibiotics as well. As HSS/DRESS syndrome can mimic infectious diseases, it must be considered during differential diagnosis before suspecting failure of treatment and initiation of a different antibiotic course.

Postural tachycardia syndrome: clinical features and follow-up study.

OBJECTIVE: To define the clinical features and outcome of postural tachycardia syndrome (POTS). MATERIALS AND METHODS: In this cross-sectional study of the autonomic symptom profile, inclusion criteria were orthostatic heart rate increment of 30 beats/min or greater, orthostatic symptoms, completion of a standardized autonomic test battery, and follow-up of 18 months or longer. We used 2 instruments. The first part was a structured and validated autonomic symptom profile (108 patients). The second part was a structured questionnaire focused on autonomic status on prospective follow-up (40 patients) (mean +/- SD follow-up, 67+/-52 months). RESULTS: Most patients had frequent, persistent, and at least moderately severe symptoms for less than 5 years. The following orthostatic symptoms occurred in more than 75% of subjects: light-headedness or dizziness, lower extremity or diffuse weakness, disequilibrium, tachycardia, and shakiness. Nonorthostatic symptoms included dry eyes or mouth, gastrointestinal complaints of bloating, early satiety, nausea, pain, and alternating diarrhea and constipation. Half of the patients reported an antecedent illness presumed to be of viral origin. On follow-up, 80 % of patients were improved, 60% were functionally normal, and 90% were able to return to work. Patients who had an antecedent event appeared to do better than those with spontaneous POTS. Salt supplementation and beta-blockers were the most efficacious therapies. CONCLUSION: In the majority of patients, POTS is self-resolving, especially in those with a triggering event.

A dentoalveolar abscess in a pediatric patient with ketoacidosis caused by occult diabetes mellitus: a case report.

Oral health professionals are frequently asked to evaluate patients with routine odontogenic infections. These patients can sometimes present with systemic signs and symptoms, including fever, malaise, tachycardia, and dehydration. It is important for the astute clinician to understand the possible associated systemic diseases that may be contributing to odontogenic infections. We present here an interesting case of a pediatric patient with a routine canine space infection who exhibited classic clinical signs and symptoms of diabetic ketoacidosis.

Ambulant 24-hour blood pressure and heart rate of dentists.

PURPOSE: To investigate blood pressure fluctuations in dentists during their daily activities, including dental procedures, in comparison with a non-dentist population. MATERIALS AND METHODS: A pilot study on blood pressure and heart rate fluctuations was performed which involved 26 dentists working at a university clinic. A 24-hour blood pressure registration was obtained using the Oxford Monitoring System. RESULTS: In the dentist group, both blood pressure and heart rate were found to be significantly higher during work than during leisure activities. In the control group, no significant difference in blood pressure was recorded between these periods. This study also showed the feasibility of ambulant 24-hour blood pressure registration on dentists during daily activity. Our results ethically justify a more intensive cardiovascular study involving a larger number of dentists working in private practice in order to establish whether our results are valid for the dental practitioner in general.

Attenuation of the hemodynamic responses to endotracheal intubation with preinduction intravenous labetalol.

Endotracheal intubation following anesthesia induction frequently produces hypertension and tachycardia. This study evaluated the efficacy of preinduction IV labetalol for attenuating the hemodynamic responses to intubation following thiopental and succinylcholine induction of anesthesia. Two hours after diazepam (10 mg by mouth), 60 patients were randomized in a double-blind manner and received IV saline or labetalol at doses of 0.25, 0.5, 0.75, or 1 mg/kg in a parallel design study. Five minutes later, thiopental (4 mg/kg) and succinylcholine (1 mg/kg) were administered, and the trachea was intubated in 2 minutes. Nitrous oxide (70%) anesthesia was maintained for 10 minutes. Hemodynamic parameters were grouped and analyzed for significance (p less than 0.05) by two-way repeated measures analysis of variance and t-test with Bonferroni adjustments. Baseline group demographics and hemodynamics were comparable. All doses of labetalol significantly attenuated the rate-pressure product increase immediately postintubation versus placebo. There was a dose-dependent attenuation of the increases in heart rate and the systolic, diastolic, and mean blood pressures versus placebo following intubation. IV labetalol at doses up to 0.75 mg/kg offers an effective pharmacologic means of attenuating preoperative hemodynamic responses to endotracheal intubation.

ECG effects of aerobic dance: a study of five exercise-conditioned young women.

Monitoring of the heart rate of five healthy well-conditioned women during an aerobic dance routine showed that maximum rates were within acceptable limits for exercise tachycardia except in one subject, who had paroxysmal supraventricular tachycardia that subsequently converted to sinus tachycardia. Thus, although aerobic dance seems a benign form of exercise, it can be intense enough to trigger dysrhythmias. Before recommending or approving it for any patient, the physician should take into consideration the person's age, health, and physical fitness level.

[Mechanisms of action of antidepressants: new data from Escitalopram]. / De nouvelles données pour appréhender les mécanismes d'action des antidépresseurs: l'apport du Escitalopram.

A first improvement in the treatment of depression was achieved in 1970-80 with the development of selective serotonin reuptake inhibitors (SSRI) because these drugs, which are as potent antidepressants as the tricyclics, are devoid of most of the secondary effects of the latter drugs (orthostatic hypotension, weight gain, dry mouth, etc, mainly caused by their capacity to block alpha1-adrenergic, H1 histaminergic and muscarinic receptors). However, SSRI did not solve all the problems inherent to the treatment of depression because (i) approximately 30% of depressed patients do not respond to these drugs, and (ii) their antidepressant effect becomes really significant only after 3-4 weeks of treatment, like that observed with tricyclics. A further improvement in the development of antidepressant drugs has recently been made with the synthesis of the S enantiomer of citalopram, called Escitalopram. Indeed, this active enantiomer is the most selective among all SSRI available to date, including citalopram. In addition, the potency of Escitalopram to inhibit serotonin reuptake (K(i)=2,1 nM) and to induce antidepressant-like effects in relevant animal paradigms (forced swimming test; chronic mild stress; stress-induced ultrasonic vocalization) is markedly increased as compared with citalopram and other SSRI. In particular, in the forced swimming test, which is especially relevant for assessing the potential antidepressant properties of drugs, Escitalopram was shown to be at least 15 fold more potent than any other SSRI to delay helplessness-induced immobility of rats. Even more interestingly, under chronic treatment conditions, Escitalopram was found to be significantly more rapid than any other antidepressant (tricyclics such as imipramine, SSRI such as fluoxetine) to restore sucrose intake in rats subjected to chronic mild stress, suggesting a reduced delay in its antidepressant action. This was indeed fully confirmed in humans as only 1-2 weeks of treatment with Escitalopram was enough to significantly reduce MADRS score in depressed subjects, compared to 3-4 weeks with any other antidepressant drug. These unique properties led to further investigations of the pharmacological profile of Escitalopram. It thus appeared that, at equipotent doses, the S enantiomer was significantly more efficient than citalopram (racemate) to increase the extracellular levels of serotonin within the frontal cortex of freely moving rats bearing a locally implanted microdialysis probe. Further experiments showed that R-citalopram counteracted the capacity of Escitalopram to enhance extracellular 5-HT levels, thereby explaining why the racemate had only a limited action in this regard. In addition, behavioural studies (stress-induced ultrasonic vocalization test) also showed that R-citalopram exerts effects opposite to those (antidepressant--and anxiolytic--like effects) of Escitalopram. The reason for these differences between the two enantiomers might concern the secondary molecular targets at which citalopram acts, but with affinities at least two orders of magnitude less than for the serotonin transporter. Indeed, R-citalopram has a 7-10-fold higher affinity for H1 histaminergic (K(i)=180 nM) and alpha1-adrenergic (K(i)=560 nM) receptors than Escitalopram (respective K(is) > or = 2 000 nM), and this difference might contribute not only to the better selectivity of the latter enantiomer for its therapeutically relevant target (i.e. the serotonin transporter) but also to its improved capacity to enhance central 5-HT neurotransmission. On the other hand, the global affinity of Escitalopram (K(i)=200-430 nM) for both subtypes of sigma receptors (sigma1 and sigma2) is higher than that of R-citalopram (and of the racemate citalopram; K(i)=200-1 500 nM), and this might also strengthen the antidepressant and anxiolytic effects of the S enantiomer because behavioural studies showed that selective sigma1 and sigma2 agonists are endowed with both antidepressant--and anxiolytic-like properties in relevant animal models. However, to date, the exact nature (agonist or antagonist) of the action of Escitalopram at sigma receptors is not known yet, and this question has to be addressed in future investigations. Altogether, these data open novel perspectives for both a better treatment of depressive disorders and a better knowledge of the neurobiological mechanisms underlying antidepressant therapy, and, possibly, depression itself.

The dangers of jimson weed and its abuse by teenagers in the Kanawha Valley of West Virginia.

Jimson weed (Datura stramonium, a member of the Belladonna alkyloid family) is a plant growing naturally in West Virginia and has been used as a home remedy since colonial times. Due to its easy availability and strong anticholinergic properties, teens are using Jimson weed as a drug. Plant parts can be brewed as a tea or chewed, and seed pods, commonly known as "pods" or "thorn apples," can be eaten. Side effects from ingesting jimson weed include tachycardia, dry mouth, dilated pupils, blurred vision, hallucinations, confusion, combative behavior, and difficulty urinating. Severe toxicity has been associated with coma and seizures, although death is rare. Treatment consists of activated charcoal and gastric lavage. Esmolol or other beta-blocker may be indicated to reduce severe sinus tachycardia. Seizures, severe hypertension, severe hallucinations, and life-threatening arrhythmias are indicators for the use of the anticholinesterase inhibitor, Physostigmine. This article reviews the cases of nine teenagers who were treated in hospitals in the Kanawha Valley after ingesting jimson weed. We hope this article will help alert primary care physicians about the abuse of jimson weed and inform health officials about the need to educate teens about the dangers of this plant.

[Stable ventricular tachycardia in arrhythmogenic dysplasia of the right ventricle in sportsmen]. / Stabil'naia zheludochkovaia takhikardiia pri aritmogennoi displazii pravogo zheludochka u sportsmenov.

Right ventricular arrhythmogenic dysplasia (RVAD) is a typical asymptomatic arrhythmogenic cardiopathy in athletes, which is occasionally concurrent with normal ventricular function and life-threatening arrhythmias. A total of 32 athletes (28 males and 4 females, mean age, 23 years, mean follow-up, 6.7 years) were examined for severe cardiac arrhythmias with left bundle branch block. The conclusive diagnosis of RVAD was established from clinical, echocardio-, and angiographic evidence. The protocol of the examination involved Holter monitoring, loading tests, electrophysiological study, two-dimensional echocardiography, cardiac angiography of the right and left ventricles, coronary angiography. The most severe arrhythmias were observed in athletes whose mean age was 23.4 years, 20 patients had sustained ventricular tachycardia (it occurred only in 19 who were indulging in sports), 6 presented with transient ventricular tachycardia, and 1 had ventricular fibrillation. They all had been considered fit for sports. The disease proceeded severely in 16 of 32 athletes (in 13 of 16 while indulging in sports), the conditions close to syncope were seen in 9 patients (8 had sustained ventricular tachycardias and 1 had transient ventricular tachycardias), syncopes were observed in 5 patients (sustained ventricular tachycardias).