Pregnancy in postural orthostatic tachycardia syndrome

INTRODUCTION: Postural orthostatic tachycardia syndrome (POTS) is a rare disease characterized by syncope, sinus tachycardia, and orthostasis due to autonomic dysfunction. METHODS AND RESULTS: Two women aged 26 and 24 years with severe POTS became pregnant. Both women experienced hyperemesis gravidarum with subsequent marked improvement in their POTS symptoms until 6 months gestation, when their syncope and sinus tachycardia caused clinical decompensation. Both patients delivered healthy babies at 37 weeks by elective cesarean section. CONCLUSION: In long-term follow-up, both women reported improvement in their prepartum symptoms. We describe the first report, to our knowledge, of two successful pregnancy outcomes in severe POTS, including the first report of midodrine use in pregnant women.     

Cardiac Arrest Caused by Trigeminal Neuralgia

A 67-year-old man with a 12-year history of trigeminal neuralgia experienced multiple fainting episodes preceded by right facial pain. One episode resulted in cardiac arrest with successful resuscitation. Pacemaker insertion prevented further episodes of syncope despite the occurrence of pain. The fainting episodes and cardiac arrest are believed to be unusual manifestations of trigeminal neuralgia.     

Intravenous nitrates for pharmacological stimulation during head-up tilt testing in patients with suspected vasovagal syncope and healthy controls

Nitrates may be used for pharmacological stimulation during tilt testing for the diagnosis of vasovagal syncope. In this study we assessed the diagnostic value of intravenous nitrates during tilt testing in patients with a typical history of vasovagal syncope. Twenty patients and 23 controls were tilted at 700 for a maximum duration of 30 minutes. After a 10-minute baseline supine phase, the test started with a continuous nitrate infusion at 1 microg/kg/min and increased every 5 minutes by 1 microg/kg/min, to a maximum of 6 microg/kg/min at the end of the test. The test was ended if the subjects developed a positive response (syncope or presyncope). Nineteen patients (95%) and 17 (74%) of the controls had a positive response. At test end sensitivity was 95%, but specificity was 26% and accuracy was 58%. Receiver operator characteristics (ROC) analysis revealed a maximum accuracy of 79% at 18 minutes, with a sensitivity of 80% and a specificity of 78%. Intravenous nitrates during tilt testing in patients with typical clinical criteria of vasovagal syncope is highly effective in provoking vasovagal syncope. Based on the ROC analysis, a maximum accuracy of 79% was attained at 18 minutes (at a dose of 4 microg/kg/min), suggesting a good diagnostic performance when tilt duration is limited to this point. A positive result requiring more than 18 minutes of stimulated tilting should be interpreted with caution, due to the accompanying considerable decrease of specificity.     

Progressive central hypovolaemia in man—resulting in a vasovagal syncope?

Summary. Hypotensive functional haemorrhage induced by venous pooling of blood in the legs has been reported to be characterized by a vasovagal reaction. In the present study these observations were extended by determination of the hormonal profile developed during progressive central hypovolaemia and an emotionally induced vasovagal syncope. In six subjects venous pooling resulted in normotensive central hypovolaemia, in one subject hypotensive central hypovolaemia was induced, and one subject experienced an emotionally induced vasovagal syncope. During normotensive central hypovolaemia heart rate increased from 58 ± 4 to 76 ± 4 beats min^-1 (P<0·05) and cardiac output fell from 6·1 ± 0·4 to 4·1 ± 0·21 min^-1. Pulse pressure and central venous pressure decreased from 64 ± 4 to 53 ± 4 mmHg, and from 8 ± 2 to 3 ± 2 mmHg, respectively. Adrenalin and noradrenalin increased from 87 ± 10 to 120 ± 20 pg/ml and from 196 ± 33 to 370 ± 50 pg/ml, respectively. Angiotensin II increased from 13 ± 4 to 36 ± 6 pg/ml and aldosterone from 63 ± 9 to 180 ± 27 pg/ml. In hypotensive central hypovolaemia the decrease in mean arterial pressure was accompanied by a decrease in heart rate and increments in the plasma concentrations of pancreatic polypeptide, indicating increased vagal activity and β-endorphin, while plasma noradrenalin was unchanged. In emotionally induced syncope heart rate decreased to cardiac arrest for 13 s, associated with increments in the plasma concentrations of pancreatic polypeptide and β-endorphin. It is concluded (1) that normotensive functional haemorrhage in man is associated with increased sympathetic activity and (2) that the qualitatively similar observations obtained during an emotionally and a hypovolaemic-induced hypotensive episode indicate that the hypotensive functional haemorrhage is characterized by a vasovagal reaction.     

血管迷走性晕厥患者直立倾斜试验反应类型转变的机制

目的 探讨血管迷走性晕厥(VVS)患者直立倾斜试验(HUTT)反应类型发生转变的机制.方法 2003-06～2008-04在我院晕厥专科门诊就诊或住院的以不明原因晕厥或晕厥先兆为主诉的患者50例,年龄7-53岁[平均(14.82±8.55)岁],男性15例,女性35例,HUTT检查为阳性,诊断为VVS.经健康教育与药物干预治疗后,随诊并追踪复查HUTT.HUTT采用基础直立倾斜试验(BHUT)及舌下含化硝酸甘油直立倾斜试验(SNHUT),比较初诊检查与重复检查的HUTr反应类型.结果 第一次HUTT复查50例中有5例(10%)HUTT反应类型发生改变,第二次HuTT复查10例中有2例(20%)HUTT反应类型发生改变.HUTT反应类型发生转变见于心脏抑制型转变为混合型、血管抑制型转变为混合型、混合型转变为心脏抑制型、混合型转变为血管抑制型.结论 VVS患者随访过程中HUTT反应类型可发生转变,HUTT反应类型转变的机制受患者自主神经功能状态、干预治疗方法及患者的耐受性等多因素影响.     

Susceptibility to neuromediated syncope after acute myocardial infarction

BACKGROUND: Syncope after acute myocardial infarction (AMI) is a common clinical problem. It may be hypothesised that remodelling and neurohormonal changes following AMI may predispose to neuromediated syncope. DESIGN: To address this issue we prospectively evaluated the incidence of positive results of head-up tilt-table testing in 40 patients following AMI and 40 age and sex matched controls without a history of syncope. The mechanisms of tilt-induced changes in autonomic tone were assessed using spectral analysis of heart rate variability. The patients were followed-up for one year. RESULTS: Positive results of tilt-test occurred in 4 (10%) controls and 13 (33%) AMI patients (P = 0.01). No significant differences in sympathovagal interaction (assessed by a low frequency/high frequency ratio) were detected between the groups before tilting (2. 9 +/- 1.9 vs. 3.1 +/- 2.2; NS). However, dynamic changes of this parameter differed significantly during the first 5 symptomless minutes of the active phase of tilt-test. The ratio increased in the majority of controls (87%) and decreased in the majority of patients (62%) (P < 0.0001). During one year follow-up, syncope or presyncope occurred in 10 (25%) AMI patients but did not occur in any control subject (P < 0.001). The sensitivity, specificity and predictive accuracy of an early tilt-test after AMI for the prediction of syncope or presyncope was 70%, 80% and 78%, respectively. CONCLUSION: Patients after AMI are prone to neuromediated reactions. Sympathetic withdrawal seems to be the most likely mechanism of syncope. The role of tilt testing for identification of patients susceptible to syncope or presyncope after AMI needs further investigation.     

Abnormality of the left ventricular sympathetic nervous function assessed by I-123 metaiodobenzylguanidine imaging in pediatric patients with neurocardiogenic syncope

The purpose of this study was to assess the left ventricular sympathetic nervous system function in the patients with neurocardiogenic syncope (NCS) using I-123 metaiodobenzylguanidine (MIBG) imaging of the heart, and to compare the plasma noradrenaline (NA) and MIBG results of tilt positive and tilt negative patients following a head-up tilt test (HUT). The study included 30 patients. Their physical and laboratory examinations did not show a pathology that may be the cause of their syncope. HUT test was positive in 13 patients and negative in 17 patients. Plasma NA concentrations were higher in the HUT positive than the HUT negative group at the beginning and at the 10th minute of the test. Specific I-123 MIBG uptake assessed as the cardiac to mediastinal activity ratio in the delayed image was significantly higher in HUT positive group. The higher levels of MIBG uptake and plasma NA observed in HUT positive patients may reflect the greater capacity of NA storage in cardiac adrenergic neuronal tissue in patients with NCS. The results of this study support the critical role of autonomic nervous system in the pathophysiology of NCS and the excessive sympathetic nervous stimulation as the trigger of paradox reflex.     

A randomized and controlled pilot trial of beta-blockers for the treatment of recurrent syncope in patients with a positive or negative response to head-up tilt test

The aim of this study was to assess the efficacy of lipophilic beta-blockers in preventing recurrent neurocardiogenic syncope and the value of head-up tilt test (HUT) in predicting response to therapy. The efficacy of beta-blockers in recurrent syncope is controversial. The value of HUT in predicting efficacy of therapy has not been investigated. Fifty-six patients (44+/-18 years, 36 women) with recurrent syncope (> 1 event in the last 6 months) of suspected neurocardiogenic origin were included in the study. Independent of the response to HUT, patients were randomized to receive metoprolol or propanolol at the maximal tolerated dose (28 patients, group A, 86+/-23 vs 98+/-29 mg/d) or no pharmacological therapy (28 patients, group B). The primary endpoint was the first recurrence of syncope. During the 1-year of follow-up, 20 patients of group A and 8 of group B had no recurrence. In group A, of 20 patients without recurrences 12 had a positive and 8 a negative HUT result while of 8 patients with recurrences 5 had a positive and 3 a negative response to HUT. In the group B, of 20 patients with recurrences 10 had a positive and 10 a negative HUT result while of 8 patients without recurrences 4 had a positive and 4 a negative response to HUT. In a multivariate Cox-regression analysis, medical therapy was the only independent factor for predicting recurrence of syncope (P = 0.004); HUT had no influence in this regard (P = 0.773). In conclusion, lipophilic beta-blockers appear efficacious in preventing recurrent syncope of suspected neurocardiogenic origin. The efficacy of therapy seems to be not predicted by HUT.     

Asystole induced by partial seizures: a rare cause of syncope

The clinical distinction between cardiovascular and epileptic causes of loss of consciousness is sometimes difficult, but becomes challenging when a primary epileptic seizure secondarily causes an asystole. Epilepsy can be correlated to severe bradycardia or asystole. The syndrome is called the ictal bradycardia syndrome. Ictal bradycardia and asystole have been implicated in the etiology of sudden unexpected death in epileptic patients (SUDEP). We present a case of traumatic syncope during an epileptic disorder ab esordio and we discuss the related literature.     

Head-Up Tilt Test in Patients with High Pretest Likelihood of Neurally Mediated Syncope: An Approximation to the "Real Sensitivity" of this Testing

This study was designed to examine the "true sensitivity" of a specific head-up tilt (HUT) testing protocol using clinical findings. The HUT protocol used 45 minutes at 60 degrees for the baseline portion and intermittent boluses of 2, 4, and 6 micrograms of isoproterenol in the second phase. Eighty-eight patients (40 men and 48 women; mean age of 33.8 +/- 16 years) with recurrent syncope and high pretest likelihood of neurally mediated syncope were included. The following were considerated as high pretest likelihood criteria: (1) at least two syncopal episodes; (2) no structural heart disease and normal baseline ECG; (3) age < 65 years; (4) a typical history of neurally mediated syncope, triggering factors plus premonitory signs; and (5) short duration of symptoms and fast recovery without neurological sequelae. Fifty-four patients (61%) had a positive tilt test (34/88 baseline [39%] and 20/50 with isoproterenol [40%]). The shorter time interval between the last syncopal episode and baseline HUT test was the only predictor for a positive response (P < 0.003). Conversely, this time interval was not predictor of positive responses during isoproterenol-tilt testing. In conclusion: (1) we claim a "sensitivity" for this combined protocol of 61%; and (2) our results indicate that patients with syncope of unknown origin must be tilted nearest as possible to the last syncope to increase the positive responses of HUT test.