Complete remission with histamine blocker in a patient with intractable hyperadrenergic postural orthostatic tachycardia syndrome secondary to long coronavirus disease syndrome

The COVID-19 pandemic caused by the novel severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has emerged as a global public health concern and its sequels have barely started to outcrop. A good percentage of patients who suffered from COVID-19 are prone to develop long-COVID or post-COVID condition (PCC), a multisystemic, heterogeneous, chronic disorder. Patients with PCC may experience diverse manifestations, of which cardiovascular and neurological symptoms are among the most frequently reported. Indeed, dysautonomia presented as orthostatic intolerance has gained room following recent reports linking postural orthostatic tachycardia syndrome (POTS) with PCC. Disturbances in heart rate (HR) and blood pressure (BP) during postural changes are the cornerstones of orthostatic intolerance seen in patients suffering from PCC. A subtype of POTS, hyperadrenergic POTS, has been widely studied because of its association with mast cell activation syndrome (MCAS). Although a causative relationship between PCC, hyperadrenergic POTS, and MCAS remains unrevealed, these syndromes can overlap. We want to propose here a correlation produced by a close-loop mechanism with positive feedback established after SARS-CoV-2 infection in a previously healthy young patient.

Postural Tachycardia Syndrome and COVID-19: Focus on Ivabradine Therapy

In this article we discuss the association of postural orthostatic tachycardia syndrome (POTS) with coronavirus-19 (COVID-19), ivabradine's unique mechanism of action, and its use in POTS patients. We highlight the pathophysiology and common etiologies of POTS, including preceding viral infections, vaccines, trauma, surgeries, and other stressors. COVID-19, a viral illness, has been associated with POTS through a variety of mechanisms that are not yet well understood. The initial management strategy for POTS is largely nonpharmacological, focusing on increasing venous return to the heart through physical therapy or other exercise activities. Ivabradine is a selective inhibitor of the funny sodium channels within the sinoatrial node. This unique mechanism of action allows for the reduction of heart rate without any effect on the heart's ionotropic activity. With an increase in the number of POTS cases, especially during the COVID pandemic, the importance of utilizing new medications and management strategies for POTS becomes imperative. Though ivabradine is currently only approved for the management of patients with coronary artery disease and heart failure by the Food and Drug Administration (FDA), it has also proven to be effective at reducing symptoms among patients with refractory POTS, and thus, should be considered for the management of patients who do not respond to initial treatment strategies.

Randomized controlled trial of intravenous immunoglobulin for autoimmune postural orthostatic tachycardia syndrome (iSTAND)

OBJECTIVE

This study assesses response to intravenous immunoglobulin (IVIG) in presumed autoimmune postural orthostatic tachycardia syndrome (POTS).

BACKGROUND

POTS may be associated with autoimmune disorders, serum autoantibodies, or recent infection. Uncontrolled case studies suggest that IVIG is beneficial for treating autoimmune POTS. No previous randomized controlled trials have been conducted.

METHODS

This single-site randomized controlled trial compared IVIG with intravenous albumin infusions. Albumin comparator ensured blinding and control for effects of volume expansion. Eligible patients with POTS had COMPASS-31 total weighted score ≥ 40 and met predetermined criteria suggesting autoimmunity. Over 12 weeks, participants received eight infusions (0.4 gm/kg each). Four infusions were given weekly followed by four infusions every other week. Primary outcome measure was improvement in COMPASS-31 2 weeks after final infusion.

RESULTS

A total of 50 participants consented; 30 met inclusion criteria and received study drug (16 IVIG and 14 albumin; 29 female). Group baseline characteristics were well matched; 27 participants completed treatment protocol. Change in COMPASS-31 did not differ between groups (median change [IQR]; IVIG: -5.5 [-23.3, 2.5] versus albumin: -10.6 [-14.1, -4.7]; p-value = 0.629). The IVIG group had a higher response rate (46.7% versus 38.5%), but this was not statistically significant. Adverse events were common but usually mild and did not differ between treatment groups.

CONCLUSIONS

This small randomized controlled trial of IVIG in POTS found no statistical difference in response compared with albumin infusion. Both groups showed improvement possibly related to volume expansion or other effects obscuring group differences. These findings inform development of future immunomodulatory clinical trials in POTS.

Establishment and validation of a multivariate predictive model for the efficacy of oral rehydration salts in children with postural tachycardia syndrome

BACKGROUND

The therapeutic effectiveness of the empirical and unselected use of oral rehydration salts (ORS) on postural tachycardia syndrome (POTS) is not satisfactory in children. Therefore, looking for suitable predictors of the therapeutic effects of ORS before treatment is extremely necessary to implement individualised treatment for paediatric patients with POTS.

METHODS

A retrospective case-control analysis of 130 patients (aged 5-18 years) who suffered from POTS with a 3-month treatment of ORS was conducted. A nomogram model was developed in the training set (n = 87) to predict the therapeutic response to ORS. Univariate analysis and logistic regression were applied to select the most useful predictors. ROC curves were applied to evaluate the discriminative performance of the nomogram model. The nomogram was then evaluated by calibration curves and the Hosmer-Lemeshow (H-L) test. The results were further validated using 1000 bootstrap resamples. External validation was performed in an independent validation set (n = 43).

FINDINGS

Among the ten variables with significant differences between the responders and non-responders in univariate analysis, five variables were found to be independently associated factors for ORS therapeutic efficacy among POTS children in the further logistic regression, including mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean arterial pressure (MAP) at the first minute of the upright position, urine specific gravity (SG), and P-wave voltage peaking ratio (PWP). The nomogram model was established in the training set (AUC 0.926 [95% CI: 0.865-0.988], yielding a sensitivity of 87.8% and a specificity of 86.8%). The calibration curves showed good agreement between the prediction of the nomogram and actual observation in both the training and validation sets. The nomogram also effectively predicted the external validation set (sensitivity 82.1%, specificity 73.3%, and accuracy 79.1%).

INTERPRETATION

We established a feasible and high-precision nomogram model to predict the efficacy of ORS, which would help implement individualised treatment for children with POTS.

FUNDING

This study was supported by National High-Level Hospital Clinical Research Funding (Multi-centre Clinical Research Project of Peking University First Hospital) (2022CR59).

Novel pharmacotherapeutic options for the treatment of postural orthostatic tachycardia syndrome

INTRODUCTION

Postural tachycardia syndrome (POTS) is a disorder characterized by a constellation of symptoms including lightheadedness, fatigue, and palpitations when upright, associated with an increase in the heart rate (HR) of > 30 beats per minute when changing from a lying down to standing position or head-up tilt position and not associated with orthostatic hypotension. The causes as well as the management of POTS are not quite fully understood.

AREAS COVERED

We performed a literature review on the diagnosis and management of POTS, and this article includes an overview of novel pharmacotherapeutic options for the treatment of (POTS), although an effective treatment has not been established.

EXPERT OPINION

POTS is a clinical syndrome characterized by a constellation of symptoms that are nonspecific. No single etiology or unified hypothesis could be identified. In fact, multiple pathophysiological mechanisms have been proposed, and none of the suggested medications have been approved by the FDA for this indication. Further understanding of the autonomic nervous system and its adjustment to standing position is needed to provide better management strategies.

Adrenal gland response to adrenocorticotropic hormone is intact in patients with postural orthostatic tachycardia syndrome

BACKGROUND

Many patients with postural orthostatic tachycardia syndrome (POTS) are hypovolemic with plasma volume deficits of 10-30 %. Some also have low levels of aldosterone and diminished aldosterone-renin ratios despite elevations in angiotensin II, pointing to potential adrenal dysfunction. To assess adrenal gland responsiveness in POTS, we measured circulating levels of aldosterone and cortisol following adrenocorticotropin hormone (ACTH) stimulation.

METHODS

While on a low Na+ diet (∼10 mEq/day), 8 female patients with POTS and 5 female healthy controls (HC) received a low dose (1 μg) ACTH bolus following a baseline blood sample. After 60 min, a high dose (249 μg) infusion of ACTH was administered to ensure maximal adrenal response. Venous aldosterone and cortisol levels were sampled every 30 min for 2 h.

RESULTS

Aldosterone increased in both groups in response to ACTH but was not different between POTS vs. HC at 60 min (53.5 ng/dL [37.8-61.8 ng/dL] vs. 46.1 ng/dL [36.7-84.9 ng/dL]; P = 1.000) or maximally (56.4 ng/dL [49.2-67.1 ng/dL] vs. 49.5 ng/dL [39.1-82.8 ng/dL]; P = 0.524). Cortisol increased in both groups in response to ACTH but was not different in patients with POTS vs. HC at 60 min (39.9 μg/dL [36.1-47.7 μg/dL] vs. 39.3 μg/dL [35.4-46.6 μg/dL]; P = 0.724) or maximally (39.9 μg/dL [33.9-45.4 μg/dL] vs. 42.0 μg/dL [37.6-49.7 μg/dL]; P = 0.354).

CONCLUSIONS

ACTH appropriately increased the aldosterone and cortisol levels in patients with POTS. These findings suggest that the response of the adrenal cortex to hormonal stimulation is intact in patients with POTS.

Salt supplementation in the management of orthostatic intolerance: Vasovagal syncope and postural orthostatic tachycardia syndrome

Salt supplementation is a common non-pharmacological approach to the management of recurrent orthostatic syncope or presyncope, particularly for patients with vasovagal syncope (VVS) or postural orthostatic tachycardia syndrome (POTS), although there is limited consensus on the optimal dosage, formulation and duration of treatment. Accordingly, we reviewed the evidence for the use of salt supplementation to reduce susceptibility to syncope or presyncope in patients with VVS and POTS. We found that short-term (~3 months) salt supplementation improves susceptibility to VVS and associated symptoms, with little effect on supine blood pressure. In patients with VVS, salt supplementation is associated with increases in plasma volume, and an increase in the time taken to provoke a syncopal event during orthostatic tolerance testing, with smaller orthostatic heart rate increases, enhanced peripheral vascular responses to orthostatic stress, and improved cerebral autoregulation. Responses were most pronounced in those with a baseline sodium excretion <170 mmol/day. Salt supplementation also improved symptoms, plasma volume, and orthostatic responses in patients with POTS. Salt supplementation should be considered for individuals with recurrent and troublesome episodes of VVS or POTS without cardiovascular comorbidities, particularly if their typical urinary sodium excretion is low, and their supine blood pressure is not elevated. The efficacy of the response, in terms of the improvement in subjective and objective markers of orthostatic intolerance, and any potential deleterious effect on supine blood pressure, should be routinely monitored in individuals on high salt regimes.

Improvement of hyperadrenergic postural orthostatic tachycardia syndrome (POTS) with methylated B vitamins in the setting of a heterozygous COMT Val158Met polymorphism

A middle-aged woman was diagnosed with postural orthostatic tachycardia syndrome based on her clinical symptoms, elevated norepinephrine levels and positive tilt-table test. The patient was refractory to conventional treatment and improved only after she was treated with methylated B vitamins for her heterozygous catechol-O-methyltransferase Val158Met polymorphism.

Baseline left ventricular ejection fraction associated with symptom improvements in both children and adolescents with postural tachycardia syndrome under metoprolol therapy

BACKGROUND

Postural tachycardia syndrome (POTS) is a common childhood disease that seriously affects the patient's physical and mental health. This study aimed to investigate whether pre-treatment baseline left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) values were associated with symptom improvement after metoprolol therapy for children and adolescents with POTS.

METHODS

This retrospective study evaluated 51 children and adolescents with POTS who received metoprolol therapy at the Peking University First Hospital between November 2010 and July 2019. All patients had completed a standing test or basic head-up tilt test and cardiac echocardiography before treatment. Treatment response was evaluated 3 months after starting metoprolol therapy. The pre-treatment baseline LVEF and LVFS values were evaluated for correlations with decreases in the symptom score after treatment (ΔSS). Multivariable analysis was performed using factors with a P value of <0.100 in the univariate analyses and the demographic characteristics.

RESULTS

A comparison of responders and non-responders revealed no significant differences in demographic, hemodynamic characteristics, and urine specific gravity (all P > 0.050). However, responders had significantly higher baseline LVEF (71.09% ± 4.44% vs. 67.17% ± 4.88%, t = -2.789, P = 0.008) and LVFS values (40.00 [38.00, 42.00]% vs. 36.79% ± 4.11%, Z = -2.542, P = 0.010) than the non-responders. The baseline LVEF and LVFS were positively correlated with ΔSS (r = 0.378, P = 0.006; r = 0.363, P = 0.009), respectively. Logistic regression analysis revealed that LVEF was independently associated with the response to metoprolol therapy in children and adolescents with POTS (odds ratio: 1.201, 95% confidence interval: 1.039-1.387, P = 0.013).

CONCLUSIONS

Pre-treatment baseline LVEF was associated with symptom improvement after metoprolol treatment for children and adolescents with POTS.

Postural orthostatic tachycardia syndrome (POTS) occurring during treatment for breast cancer

Postural orthostatic tachycardia syndrome (POTS) is a common condition of orthostatic intolerance in response to changes in position. We report a case of a middle-aged woman presenting with a new onset of POTS likely due to chemotherapy for treatment of breast cancer. She was started on a trial of a beta blocker, which was effective in controlling her symptoms and heart rate. The objective of this report was to encourage clinicians to consider POTS as a differential diagnosis, while managing patients with symptoms of orthostatic intolerance.

[Postural orthostatic tachycardia syndrome]

Postural orthostatic tachycardia syndrome (POTS) is a condition where the patient experiences tachycardia (a rise in heart rate of at least 30 beats per minute, 40 in people between the ages of 12 and 19) upon assuming the upright position, in the absence of orthostatic hypotension (a fall in systolic blood pressure of more than 20 mmHg). The majority of patients are young women. Symptoms are experienced frequently during standing, and include dizziness, fatigue, palpitations, tremulousness, blurred vision and sometimes syncope - although presyncope is more common. The diagnosis requires that symptoms have been present for at least six months and lack another medical explanation. The pathophysiology is believed to be multifactorial; peripheral sympathetic denervation, excessive sympathetic drive, hypovolemia and deconditioning have been reported in POTS. Patient education is fundamental in the management of POTS, including information regarding symptoms and exacerbating factors as well as methods for increasing arterial pressure. Exercise is believed to be effective. Several drugs can be used to relieve symptoms, although none of them are licensed for the treatment of POTS. We describe a case that illustrates that POTS can be debilitating, which requires awareness of the condition among clinicians.

Efficacy of Propranolol, Bisoprolol, and Pyridostigmine for Postural Tachycardia Syndrome: a Randomized Clinical Trial

Postural tachycardia syndrome (POTS) is a form of dysautonomia which presents with complex symptoms including orthostatic intolerance. Several medications are prescribed for POTS; however, the efficacy of sustained medical treatment has not been well-investigated. Here, we conducted a 2 × 2 factorial design, randomized, clinical trial of a 3-month medical treatment regimen in POTS patients. Patients were randomly allocated to 4 treatment groups (Group 1: propranolol; Group 2: bisoprolol; Group 3: propranolol + pyridostigmine; Group 4: bisoprolol + pyridostigmine). The orthostatic intolerance questionnaire (OIQ), Beck depression inventory-II (BDI-II), and short-form health survey (SF-36) were conducted at baseline, 1 and 3 months after treatment. Seventy-seven patients who completed the 3-month follow-up were analyzed. In total, every clinical score improved significantly after medical treatment. The OIQ score was significantly lower than that at baseline (18.5 ± 6.7) after 1 month (12.5 ± 4.5, P < 0.01), which decreased further after 3 months (7.8 ± 5.7, P < 0.01). The OIQ score improvements were consistent across every treatment group. In the subgroup analysis of 59 patients who did not receive antidepressants, the BDI-II score significantly decreased after treatment, regardless of the regimen. Physical components of the SF-36 improved after 3 months in every group, while mental components improved only in Group 3. The amount of changes in each score was similar among groups throughout the comparisons. Sustained medical treatment is beneficial to POTS patients, not only for orthostatic intolerance symptoms but also for depression and diminished quality of life, even without prescriptions for antidepressants. The efficacy of each regimen in POTS patients was comparable.

TRIAL REGISTRATION

NCT02171988.

Postural orthostatic tachycardia syndrome and the potential role of mast cell activation

Though a sizeable amount of data connects mast cell activity to the neurologic system, less is known about the true clinical implications of this relationship. Even less is understood about treatment strategies in those with both allergic and neurologic complaints. This is particularly true in postural orthostatic tachycardia syndrome (POTS), a common type of dysautonomia, where patients are burdened by symptoms of orthostatic cerebral hypoperfusion and several other comorbidities that are likely influenced by autonomic tone. Some patients describe characteristic allergic symptoms, in the absence of typical IgE mediated triggers, and also improvement with traditional mast cell directed medications. Further work is necessary to determine whether these anecdotal observations are valid. The answer to this question will likely be addressed as the mechanisms of POTS are better characterized, which may include a phenotype with distinct mast cell involvement.

A Case of Narcolepsy Type 2 and Postural Tachycardia Syndrome Secondary to Lesions of the Thalamus and Amygdala

ABSTRACT

Although there are reports of narcolepsy type 1 caused by lesions of the central nervous system, there are far fewer reports of narcolepsy type 2 (NT2) caused by discrete brain lesions. We report a case of a patient in whom NT2 was diagnosed after a viral illness, and inflammatory lesions in the right thalamus and amygdala were found. In addition, symptoms of autonomic impairment developed and postural tachycardia syndrome was subsequently diagnosed in this patient. To our knowledge this is the first reported case of NT2 resulting from central nervous system lesions in these discrete locations, as well as the first reported case of postural tachycardia syndrome associated with narcolepsy.

Acute on Chronic Ivabradine Overdose: a Case Report

Ivabradine is a newly approved medication which reduces the heart rate by antagonizing the If channel. We report a case of intentional overdose on ivabradine. A 26-year-old female presented after taking 250 mg ivabradine. On arrival, her vital signs and neurologic exam were unremarkable. Within 30 min, her heart rate decreased to 31 bpm, but she remained normotensive with no change in mentation. Her bradycardia resolved after treatment with atropine. She experienced two further bradycardic episodes responsive to atropine; the second episode was associated with hypotension, responsive to a fluid bolus. For the remainder of her hospitalization, she remained hemodynamically stable without further interventions. She was dispositioned to the psychiatry service approximately 36 h post-ingestion with a heart rate of 67 bpm. Laboratory analysis confirmed a serum ivabradine concentration of 525 ng/mL, greater than 50 times the mean level in therapeutic trials. Proposed treatments for ivabradine include activated charcoal, atropine, isoproterenol, and intravenous pacing. Further study is needed to identify ideal treatment modalities.

[Predictive value of baseline plasma midregional fragment of pro-adrenomedullin level on long-term outcome of postural tachycardia syndrome children treated with midodrine hydrochloride]

OBJECTIVE

To explore the predictive value of baseline plasma midregional fragment of pro-adrenomedullin level (MR-proADM) on long-term survival of postural tachycardia syndrome (POTS) children treated with midodrine hydrochloride.

METHODS

Fifty-three children (male 26, mean age (14.5 ± 4.5) years old) with POTS were included in this study, and all of them were diagnosed as POTS in our department from December 2007 to January 2010. Fifty-three children with POTS were divided into two groups according to the baseline plasma content of MR-proADM. Group I consisted of 35 POTS children with plasma content of MR-proADM > 61.5 ng/L, and the group II consisted of 18 POTS children with plasma content of MR-proADM ≤ 61.5 ng/L. The mean follow-up time was (67 ± 7) months. The orthostatic intolerance symptom score and the symptom free survival were compared between the 2 groups.

RESULTS

At the 60 months follow-up, the symptom score of children in group I was significantly lower than that in group II (χ(2) = 4.985, P < 0.05). At 72 months follow up, the symptom score was similar between the 2 groups (χ(2) = 0.004, P > 0.05) while the symptom free survival of group I was significantly higher than that in group II (χ(2) = 4.566, P < 0.05).

CONCLUSION

The baseline plasma MR-proADM level is value in predicting the long-term survival of POTS children treated with midodrine hydrochloride.

[Postural orthostatic tachycardia syndrome]

Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition of dysautonomia and suspected autoimmunity characterized by abnormal increments in heart rate upon assumption of the upright posture accompanied by symptoms of cerebral hypoperfusion and sympathoexcitation. An increase in heart rate equal to or greater than 30 bpm or to levels higher than 120 bpm during a head-up tilt test is the main diagnostic criterion. Management includes both non-pharmacological and pharmacological treatment focusing on stress management, volume expansion and heart rate control.

Plasma C-type natriuretic peptide as a predictor for therapeutic response to metoprolol in children with postural tachycardia syndrome

POTS is a global public-health disease, but predictor for therapeutic response to metoprolol in children with POTS is lacking. This study was designed to investigate predictive value of plasma C-type natriuretic peptide (CNP) in the therapeutic efficacy of metoprolol on postural tachycardia syndrome (POTS) in children. Totally 34 children with POTS and 27 healthy children were included in the study. The head-up test or head-up tilt test was used to check heart rate and blood pressure from supine to upright in subjects. A double antibody (competitive) sandwich immunoluminometric assay was used to detect plasma CNP. Metoprolol was used to treat children with POTS. The difference in plasma concentrations of CNP between responders and non-responders was compared. An ROC curve was used to analyze plasma CNP to predict efficacy of metoprolol on POTS in children. Plasma CNP in children with POTS was significantly higher than that of healthy children [(51.9 ± 31.4) vs. (25.1 ± 19.1) pg/ml, P <0.001]. Plasma CNP in responders to metoprolol was significantly higher than non-responders [(59.1 ± 33.5) vs. (34.8 ± 16.7) pg/ml, P = 0.037] before treatment. The ROC curve showed that area under the curve was 0.821 (95% CI 0.642–0.999). The cut-off value of plasma CNP > 32.55 pg/ml yielded a sensitivity of 95.8% and specificity of 70% in predicting therapeutic efficacy of metoprolol on POTS children. Plasma CNP might serve as a useful predictor for the therapeutic efficacy of metoprolol on POTS in children.

Difference between supine and upright blood pressure associates to the efficacy of midodrine on postural orthostatic tachycardia syndrome (POTS) in children

Postural orthostatic tachycardia syndrome (POTS) is common, and has a serious impact on children's quality of life. Midodrine hydrochloride, an α1-adrenoreceptor agonist, is an effective treatment. The study was designed to examine the therapeutic efficacy of midodrine hydrochloride by quantifying changes in blood pressure during the head-up test (HUT), in children with POTS. Overall, 104 out of 110 children with POTS were treated with midodrine hydrochloride and successfully followed-up. Systolic blood pressure (SBP) and diastolic blood pressure (DBP) changes were analyzed during the HUT. In a retrospective analysis, a receiver operating characteristic (ROC) curve was used to analyze the therapeutic predictive value of pre-treatment changes in SBP, DBP, and a combination of both, from the supine position to standing, in the subjects. The increase of SBP and DBP from the supine position to standing in responders were significantly lower than that of the non-responders. The ROC curve showed that midodrine hydrochloride for children with POTS would be predicted to be effective when the pre-treatment increase of SBP was ≤ 0 mmHg, or when the pre-treatment increase of DBP was ≤ 6.5 mmHg (from the supine position to standing), yielding a sensitivity of 72% and specificity of 88%. The area under the curve was 0.744 and 0.809, respectively. Hence, the results suggested that looking at the changes in blood pressure during the HUT was useful in predicting the response to midodrine hydrochloride in children with POTS.

[Postural orthostatic tachycardia syndrome]

Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition of dysautonomia and suspected autoimmunity characterized by abnormal increments in heart rate upon assumption of the upright posture accompanied by symptoms of cerebral hypoperfusion and sympathoexcitation. An increase in heart rate equal to or greater than 30 bpm or to levels higher than 120 bpm during a head-up tilt test is the main diagnostic criterion. Management includes both non-pharmacological and pharmacological treatment focusing on stress management, volume expansion and heart rate control.

Clinical features and management of postural tachycardia syndrome in children: a single-center experience

BACKGROUND

The incidence of postural tachycardia syndrome (POTS) has been increasing in children and adolescents, while clinical characteristics of POTS in the pediatric population are not fully understood.

METHODS

An observational study was performed in 150 pediatric patients aged between 5 and 18 years who underwent head-up tilt test (HUTT) with the diagnosis of POTS at Peking University First Hospital from March 2008 to August 2013. Demographic data, clinical presentation, autonomic parameters, laboratory findings, and treatments were recorded.

RESULTS

POTS in children commonly occurred in the age of 7-14 years. Dizziness (84.00%) was the most common symptom, followed by weakness (72.00%) and orthostatic syncope (62.67%). Positive family history of orthostatic intolerance (OI) was found in 24.64% of children with POTS. And 33.09% of them had preceding infection history as precipitating events. Ten percent of them suffered from orthostatic hypertension. Hyperadrenergic status was documented in 51.28% of 39 patients who were tested for the standing norepinephrine levels. More than half of POTS patients, with 24-hour urinary sodium level <124 mmol/24 hours, were suitable for treatment of salt supplementation. At least 25.74% of POTS patients were of positive acetylcholine receptor (AChR) antibody. Low iron storage in children with POTS was relatively rare. Most patients responded well to treatments, 43.51% of patients recovered, while 7.63% of them had relapse after symptoms disappeared.

CONCLUSIONS

POTS is a relatively common condition with complex pathophysiology and heterogeneous clinical manifestation. A comprehensive therapeutic regimen is recommended for the treatment.

A prospective, 1-year follow-up study of postural tachycardia syndrome

OBJECTIVE

To prospectively evaluate patients who met standard criteria for postural tachycardia syndrome (POTS), at baseline and 1-year follow-up, using standard clinical and laboratory methods to assess autonomic function.

METHODS

Fifty-eight patients met the study criteria (orthostatic symptoms and a heart rate increment of ≥ 30 beats/min on head-up tilt) and completed 12 months of follow-up. All patients were enrolled and completed the study from January 16, 2006, through April 15, 2009. Patients underwent standardized autonomic testing, including head-up tilt, clinical assessment, and validated questionnaires designed to determine the severity of autonomic symptoms.

RESULTS

Patients were predominantly young females (n=49, 84%), with 20 patients (34%) reporting an antecedent viral infection before onset of symptoms. More than one-third (37%) no longer fulfilled tilt criteria for POTS on follow-up, although heart rate increment on head-up tilt did not differ significantly at 1 year (33.8 ± 15.1 beats/min) compared with baseline (37.8 ± 14.6 beats/min) for the entire cohort. Orthostatic symptoms improved in most patients. Autonomic dysfunction was mild as defined by a Composite Autonomic Severity Score of 3 or less in 55 patients (95%) at baseline and 48 patients (92%) at 1 year.

CONCLUSION

To our knowledge, this is the first prospective study of the clinical outcomes of patients with POTS. Orthostatic symptoms improved in our patients, with more than one-third of patients no longer fulfilling tilt criteria for POTS, although the overall group change in heart rate increment was modest. Our data are in keeping with a relatively favorable prognosis in most patients with POTS.

[Therapies for postural tachycardia syndrome in children]

OBJECTIVE

This study was designed to compare the short-term and long-term effects of oral rehydration salts, oral rehydration salts plus metoprolol or oral rehydration salts plus midodrine hydrochloride on the treatment of postural tachycardia syndrome (POTS) in children.

METHOD

A total of 118 children with POTS were divided into oral rehydration salts group (n = 39), metoprolol group (oral rehydration salts plus metoprolol, n = 10) or midodrine hydrochloride group (oral rehydration salts plus midodrine hydrochloride, n = 69). The patients were followed up in clinics or over telephone for 3 - 18 months, with a mean of (11.7 ± 4.1) months. The symptom scores were recorded before treatment, after 3 months and at the end of the follow-up. Reduction of the score by 2 points or more was considered that the treatment was effective. The effective rate in 3 months was applied to evaluate short-term effects of 3 different therapies by chi-square test. Taking futility as events, Kaplan-Meier curves were drawn to compare long-term effects of the 3 different therapies in treating POTS in children.

RESULT

No significant differences among the 3 groups were found in sex, age, body height, weight, the symptom scores before treatment or hemodynamic variables. Oral rehydration salts, metoprolol and midodrine hydrochloride improved clinical symptoms after 3 months. The symptom scores of the 3 groups before treatment and after 3 months were 2.4 ± 3.2 vs. 5.5 ± 2.9, 2.2 ± 3.0 vs. 6.1 ± 3.0 and 1.9 ± 1.6 vs. 5.9 ± 2.7, respectively. The difference was significant (P < 0.05). Descending order of the short-term effective rate was 91.3% in midodrine hydrochloride group, 80.0% in metoprolol group and 74.4% in oral rehydration salts group. The difference was significant (χ(2) = 5.85, P < 0.05). All the 3 different therapies improved clinical symptoms at the end of follow-up. The symptom scores were 2.6 ± 3.2 vs. 5.6 ± 2.9, 2.5 ± 3.1 vs. 6.1 ± 3.0 and 2.2 ± 2.1 vs. 6.0 ± 2.7, respectively. (P < 0.05). The result of the Kaplan-Meier curves showed that the long-term effect of midodrine hydrochloride was significantly superior to metoprolol group and oral rehydration salts group (P < 0.05). There was no significant difference between the latter two groups.

CONCLUSION

Oral rehydration salts plus midodrine hydrochloride or plus metoprolol improved the efficacy of drugs in children with POTS. And the efficacy of midodrine hydrochloride was superior to that of metoprolol.

Successful use of ivabradine in a case of exaggerated autonomic dysfunction

We present a 30-year-old male with complex and predominantly cardiovascular autonomic dysfunction. He had frequent syncopal attacks and paroxysmal atrial fibrillation (PAF). Physical, electrocardiographic, and echocardiographic findings were unremarkable. Syncopal attacks were precipitated by emotional stress, upright position, and micturition. Electrocardiograms obtained immediately after syncopal events revealed PAF with a low ventricular rate, which spontaneously returned to sinus rhythm without any medication. Syncopal events were suggestive of postural orthostatic tachycardia syndrome (POTS), were induced during upright position, and were associated with a sudden increase in heart rate to approximately 140 beats per minute and a sudden drop in blood pressure. Syncope was also induced during carotid sinus massage (CSM) in the upright position. It was thought that cardiac autonomic dysfunction, with POTS as the main component, was responsible for this clinical condition. Syncopal episodes increased in frequency during treatment with metoprolol. Treatment with ivabradine (5 mg twice a day) resulted in disappearance of syncopal episodes both during upright position and CSM. During six months of follow-up, the patient remained asymptomatic without syncope or atrial fibrillation.

[Effect of selective alpha1 receptor agonist in the treatment of children with postural orthostatic tachycardia syndrome]

OBJECTIVE

The study was designed to examine the effect of selective alpha1 receptor agonist midodrine hydrochloride in the treatment of children with postural orthostatic tachycardia syndrome.

METHODS

Fifty-five children (23 male, 32 female, age 5 - 19 yrs, mean age 12.3 +/- 3.1 yrs) who came from Peking University First Hospital were included in the study and clinical investigations as well as standing test, basic head-up tilt test and sublingual nitroglycerin-provocated head-up tilt test under quiet circumstance were conducted. They were randomly divided into treatment group (with midodrine hydrochloride and oral rehydration salt treatment) and control group (with oral rehydration salt treatment only). At last, the disease-free rate, improvement rate and effective rate of symptoms, and the rate of HUT from positive to negative response were compared between control group and treatment group. SPSS 10.0 software was used for the statistical analysis of these data.

RESULTS

The symptom improvement rate in treatment group was significantly higher than that of control group after three and six weeks of treatment (100.0% vs. 42.4%, P < 0.001; 100.0% vs. 42.4%, chi2 = 19.352, P < 0.001). The disease-free rate at follow-up end-point in treatment group was significantly higher than that of control group (77.3% vs. 27.3%, chi2 = 13.239, P < 0.001). The effective rate at follow-up end-point in treatment group was also significantly higher than that of control group (100.0% vs. 36.4%, chi2 = 22.647, P < 0.001). The rate of HUT changing from positive to negative response between two groups after three weeks of treatment was not significantly different (31.8% vs. 12.1%, P > 0.05), but it was significantly different (81.0% vs. 48.5%, P < 0.05) after six weeks of treatment.

CONCLUSION

Selective alpha1 receptor agonist midodrine hydrochloride is effective in the treatment of children with postural orthostatic tachycardia syndrome.