Douglas Wolfe

Usefulness of fluoxetine hydrochloride for prevention of resistant upright tilt induced syncope

Recurrent vasovagally mediated episodes of hypotension and bradycardia are a common cause of recurrent syncope that can be identified by head‐upright tilt table testing. Although the use of beta blockers, transdermal scopolamine, disopyramide, and fludrocortisone may be helpful in preventing further episodes, some patients are intolerant of or respond poorly to each of these agents. Following anecdotal observations, we investigated the utility of fluoxetine (a serotonin re‐uptake antagonist) in preventing head‐upright tilt induced hypotension/bradycardia in patients unresponsive to or intolerant of standard therapy. Sixteen patients (7 men and 9 women, mean age 42 ± 21 years) with recurrent syncope and positive head‐upright tilt studies (refractory to normal therapy) were placed on fluoxetine and restudied 5–6 weeks afterward. Three patients were intolerant of the medication. Of the 13 patients who underwent repeat tilt studies, seven patients (53% of the patients retested or 44% of the total group) were rendered tilt table negative, and, over a mean follow‐up period of 19 ± 9 months, have remained asymptomatic. We conclude that fluoxetine may be an effective therapy in patients with recurrent vasovagally mediated syncope refractory to other forms of therapy.

Head-upright tilt-table testing in evaluation and management of the malignant vasovagal syndrome

Vasovagally mediated cardiac asystole has been proposed as a potential cause of sudden cardiac death. To assess this possibility and identify characteristics that define patients with vasovagally mediated asystole, head-upright tilt-table testing was performed in 50 consecutive patients (26 women and 24 men, mean age 42 +/- 10 years) with recurrent unexplained syncope. The upright tilt-table test was performed in the fasting state for 30 minutes, with or without the use of intravenous isoproterenol (1 to 3 micrograms/min). The production of ventricular asystole lasting greater than 4 seconds was considered a positive result. All patients with tilt-induced asystole received therapy with either beta blockers, disopyramide, transdermal scopolamine or atrioventricular permanent pacing, the efficacy of which was evaluated with serial tilt-table tests. Reproducible tilt-induced asystole occurred in 10 patients (7 men and 3 women, mean age 23 +/- 12 years) (7 patients during baseline tilt, and 3 during isoproterenol infusion). Analysis of this group revealed that they had significantly more frequent and severe syncopal episodes (3 patients had episodes needing bystander cardiopulmonary resuscitation) than did those patients with tilt-induced syncope without asystole. All patients who had tilt-induced asystole eventually became tilt-table negative with therapy (4 with beta blockers, 2 with disopyramide, and 4 with atrioventricular permanent pacing), and over a mean follow-up of 21 +/- 6 months no further syncopal episodes occurred. It is concluded that patients with recurrent tilt-induced asystole represent a distinct subgroup that has recurrent severe syncope that may mimic or result in sudden cardiac death. Thus, the predischarge electrophysiologic study could predict late outcome with recurrence of preexicitation or supraventricular tachycardia in patients who had undergone surgical ablation of the accessory pathway with an overall predictive accuracy of 95% (107 of 113 patients), negative predictive value of 96% (103 of 107), and positive predictive value of 67% (4 of 6).

The Use of Head-Upright Tilt Table Testing in the Evaluation and Management of Syncope in Children and Adolescents

GRUBB, B.P., et al.: The Use of Head‐Upright Tilt Table Testing in the Evaluation and Management of Syncope in Children and Adolescents. Recurrent syncope in an otherwise healthy child or adolescent is a common anxiety provoking disorder. Vasovagally mediated hypotension and bradycardia are believed common, yet difficult to diagnose, causes of syncope in this age group. Upright tilt table testing has been suggested as a potential method to test for vasovagal episodes. This study evaluated the utility of this technique in the evaluation and management of recurrent syncope in children and adolescents. Thirty patients with recurrent unexplained syncope were evaluated by use of an upright tilt table test for 30 minutes, with or without an infusion of isoproterenol (1 to 3 μg/min given intravenously), in an attempt to produce hypotension, bradycardia, or both. There were 15 males and 15 females, mean age 14 ± 6 years. Each of the tilt positive patients received therapy with either fluorohydrocortisone, beta blockers, or transdermal scopolamine. Syncope occurred in six patients (20%) during the base line tilt and in 15 patients (50%) during isoproterenol infusion (total positives 70%). All initially positive patients were rendered tilt negative by therapy. Over a mean follow‐up period of 20 months, no further episodes have occurred. We conclude that tilt table testing is a useful and effective test in the evaluation of unexplained syncope in childhood.

Reproducibility of Head Upright Tilt Table Test Results in Patients with Syncope

Head upright tilt table testing is a promising technique for the evaluation and management of vasovagal (neuroregulatory) syncope. In order to determine the day‐to‐day reproducibility of results using this technique we performed head upright tilt table testing (with or without graded isoproterenol infusion) in 21 patients (12 males, 9 females, mean age 34 ± 19.1 years). During the first tilt study a total of 14 patients experienced syncope (six during baseline tilt, mean tilt time 15.8 ± 7 minutes, eight following tilt with graded isoproterenol infusion, mean tilt time 17.7 ± 9 minutes) while seven were negative. During the second tilt study (performed 3–7 days following the first study) the results of the first study were duplicated in 19 patients (90%) (six during baseline tilt, mean time 17.5 ± 8 minutes, eight following graded isoproterenol infusion, mean time 15.9 ± 7 minutes), however the level of provocation required to provoke syncope differed from that needed in the initial test in five patients (24%). We conclude that the results of head upright tilt table testing with graded isoproterenol infusions can be duplicated in 90% of patients, although some day‐to‐day variability exists in the degree of provocation necessary to elicit a positive response.

Cerebral syncope : loss of consciousness associated with cerebral vasoconstriction in the absence of systemic hypotension

Transcranial Doppler (TCD) ultrasonography done during headupright tilt induced neurocardiogenic syncope has demonstrated that cerebral Vasoconstriction occurs concomitant with (or precedes) loss of consciousness. This article demonstrates evidence that cerebral blood flow changes alone (vasoconstriction), in the absence of systemic hypotension, may result in syncope. Five patients (4 men, 1 woman; mean age 41 ± 17 years) with recurrent unexplained syncope were evaluated by use of an upright tilt table test for 45 minutes with or without an infusion of low dose isoproterenol. TCDoppler ultrasonography was used to assess middle cerebral artery systolic velocity (Vs); diastolic velocity (Vd); mean velocity (Vm); and pulsatility index (PI = Vs = Vd/Vmean). Syncope occurred in five patients during the baseline tilt and in one patient during isoproterenol infusion. During tilt induced syncope, at an average mean arterial pressure of 89 ± 16 mmHg, TCD sonography showed a 2%± 10% increase in systolic velocity; a 51%± 27% decrease in diastolic velocity; and a 131 %± 87% increase in pulsatility index. One patient underwent continuous electroencephalographic recording during tilt, which demonstrated diffuse slow wave activity (indicating cerebral hypoxia) at the time of syncope concomitant with the aforementioned TCD changes in the absence of systemic hypotension. These fndings reflect an increase in cerebrovascular resistance secondary to arteriolar vasoconstriction distal to the insonation point of the middle cerebral artery, that occurred concomitant with loss of consciousness and in the absence of systemic hypotension. We conclude that in some individuals abnormal baroreceptor responses triggered during orthostatic stress may result in a derangement of cerebral autoregulation leading to cerebral vasoconstriction with resultant cerebral hypoxia in the absence of systemic hypotension.

Fluoxetine hydrochloride for the treatment of severe refractory orthostatic hypotension

OBJECTIVE To evaluate the usefulness of fluoxetine hydrochloride in the treatment of patients with severe refractory orthostatic hypotension. DESIGN Prospective, nonrandomized study. PATIENTS Five patients (3 men, 2 women with a mean age of 67 +/- 7 years with chronic symptomatic orthostatic hypotension resistant to or intolerant of other therapies. METHODS Symptoms and orthostatic responses were recorded in the baseline state. Fluoxetine hydrochloride 20 mg orally once daily was started and patients were reevaluated after 6 to 8 weeks of therapy. RESULTS All patients demonstrated orthostatic hypotension (20 mm Hg or greater decline in systolic blood pressure) associated with symptoms (eg, dizziness, vertigo, near syncope) in the baseline state. After 6 to 8 weeks of fluoxetine therapy, 2 patients reported resolution of all symptoms, 2 had a marked reduction in symptoms, and 1 patient experienced no effect. Orthostatic responses were attenuated in 4 of the 5 patients (80%). CONCLUSION Fluoxetine hydrochloride may be an effective therapy for some patients with recurrent severe orthostatic hypotension refractory to other forms of therapy.

Tilt table testing in the evaluation and management of athletes with recurrent exercise-induced syncope.

Recurrent idiopathic exercise-related syncope in the young athlete is often a challenging and frustrating condition. Vasovagally mediated hypotension and bradycardia is believed to be a common, but difficult to prove, cause of this form of syncope. This study evaluated the usefulness of head-upright tilt table testing in the evaluation and management of young athletes with recurrent idiopathic exercise-related syncope. Twenty-four trained young athletes (12 male, 12 female mean age 18 +/- 3.4 yr) with recurrent unexplained exercise-related syncope were evaluated by use of an upright tilt table test for 30 min, with or without an infusion of isoproterenol (1-3 micrograms.min-1 given intravenously) in an effort to provoke bradycardia, hypotension, or both. Ten control patients with no history of syncope were also studied. Syncope occurred in 10 patients (41%) during the baseline tilt and in nine patients (37%) during the isoproterenol infusion (total positives 79%). Seventeen patients who had positive test results eventually became tilt table negative with pharmacotherapy, and over a mean follow-up period of 23 +/- 7 months, no further syncopal episodes have occurred. Two patients refused pharmacotherapy and have continued to experience syncope. We conclude that head-upright tilt table testing combined with isoproterenol infusion is useful in the diagnosis of vasovagal syncope in young athletes with recurrent exercise related syncope, and in the evaluation of prophylactic pharmacotherapy.

Recurrent Unexplained Syncope in the Elderly: The Use of Head-Upright Tilt Table Testing in Evaluation and Management

To investigate the usefulness of head‐upright tilt table testing for vasovagal episodes in the evaluation and management of elderly patients with recurrent idiopathic syncope.

Adaptive Rate Pacing Controlled by Right Ventricular Preejection Interval for Severe Refractory Orthostatic Hypotension

A 72‐year‐old African‐American man with frequent recurrent syncope was found to have severe refractory orihostatic hypotension with concomitant supine hypertension. Pharmacotherupy was successful in controlling his supine hypertension but was unable to resolve his severe orihostatic hypotension. Temporary fixed rate tachypacing was only minimally effective in preventing syncope during upright tilt, while variable rate pacing based on degree of blood pressure fall was far superior. Following these observations, an adaptive rate pacing system controlled by right ventricular preejection interval was implanted (Precept DR Model 1200). The system adequately sensed the patients fall in blood pressure when sitting or standing and augmented its rate accordingly, thus preventing syncope. While supine, the pacing rate fell to 60 ppm, thereby, avoiding an exacerbation of his concomitant supine hypertension. Over a 3‐nionth follow‐up period, he has had no further orthostatic or syncopal episodes. We conclude that adaptive rate pacing using right ventricular preejection interval may be an effective treatment for severe refractory orthostatic hypotension.

Head-Upright Tilt-Table Testing: A Useful Tool in the Evaluation and Management of Recurrent Vertigo of Unknown Origin Associated with Near-Syncope or Syncope

Recurrent idiopathic vertigo associated with near-syncope and syncope is a common perplexing problem, some cases of which are considered autonomically mediated (vasovagal). Upright-tilt-table testing has emerged as a potential method to test for vasovagal episodes. This study evaluated the use of this technique in the evaluation and management of patients with recurrent idiopathic vertigo associated with near-syncope or syncope. Twenty-one patients with recurrent unexplained vertigo and syncope/near-syncope and 11 control subjects were evaluated by use of an upright-tilt-table test for 30 minutes, with or without a graded isoproterenol infusion (1 to 4 μg/min given intravenously), in an attempt to provoke hypotension, bradycardia, or both, which reproduced the patients symptoms. The patients included 10 men and 11 women (mean age, 51 ± 16 years). Eleven controls with no history of vertigo were also studied. Transcranial Doppler sonography was used to assess cerebral arteriolar blood flow during tilt. All tilt-positive patients were placed on therapy with either β-blockers, disopyramide, or transdermal scopolamine, the effectiveness of which was determined with another tilt-table study. Symptoms occurred in seven patients (33%) during the baseline tilt and in eight patients (38%) during isoproterenol infusion (total positives, 71%). Transcranial Doppler sonography demonstrated a 225% ± 192% increase in pulsatility index and a 70% ± 29% increase in resistance index (indicative of cerebral arteriolar vasoconstriction) at the time of vertigo. No control subject experienced syncope during this test. Each tilt-positive patient eventually became tilt-negative with therapy, and over a mean follow-up period of 26 months, no further episodes have occurred. We conclude that head-upright tilt-table testing may be a valuable tool in the evaluation of recurrent idiopathic vertigo associated with near-syncope or syncope and in the evaluation of pharmacotherapy.