Project background
Syncope is a bordeline symptom related to the cardiovascular, internal medicine and neurologic pathology. Its prognostic ranges from mild to severe beeing related to the underlying cause as well as to the appropriate therapeutic approach. If the syncope is caused by an arrhythmia or a structural cardiac disease the treatment aims the amelioration of the lesion but if the syncope is associated with no structural heart disease further interdiciplinary examinations are needed and the therapeutic approach is not yet well defined.
In this project, a multidisciplinary team-cardiologist, internist, neurologist, phisyologist- will investigate by comparative analysis the pathophisyological mechanisms of the neurocardiogenic or vasovagal syncope which is associated with no structural heart disease. We also aim to investigate the diagnostic value of the tilt table testing and to perform a classifiction of the hemodynamic respose patterns focused on the orthostatic hypotension.another target is to evaluate by a randomized, blind, crossover study the efficacy of a new tratment method which use the external counterpressure aplied over the capacitance vessels of the legs and of the abdomene by elastig garmets in order to increase the venous return to the heart.
The objectives are to use of the tilt test in order to identify the underlying mechanism of syncope, to provide new interdisciplinary protocols and classifications aimed to a better managememt of the syncope patient and to investigate the efficacy of a new treatment method of the orthostatic hypotension in acute and during follow up phase, based on the improvement of the quality of life. The results of this study will be compared and merged with those of international refferal centers for syncope to which the project director is strongly related by a long-lasting and comprehensive cooperation, leading to increased knoweledge and new therapeutical protocols.
Determination of efficiency of the tilt testing in stating the mechanism that is base of the syncope
The syndrome of the neurally mediated syncope represent the most frequent cause of syncope; their physiopathologic real cause is represented by a transitory spoiling of the vegetative mechanisms of hemodynamic control. Their investigation, in the cases of assessment of patients with syncope, needs the utilization of devices that are able to identify or “disclose” the existence of such functional disturbances (Goldschalger, 2003).
There are a lot of research studies related to the utility of the tilt testing as a tool in the diagnosis procedure of identification of vasovagal pathology. Although there are numerous protocols for its performance, which differ in technical details, they usually imply an accommodation stage in dorsal position followed by a “passive” stage at an angle of 60°-70° for a time span of 20 to 45 minutes. Provided there is lack of positive response, an “active” stage may be inserted, when a challenging agent is administered, usually nytroglicerin, applied sublingually, out of comfort reasons (Benditt 1996).
The utilization of a 45 minute period is frequently described in the literature and is recommended by the current guides in diagnosis and treatment. It corresponds to the average time of the syncope’s appearance ± 2xDS of Fitzpatrick’s study on TT without medication challenge. The angle of 60° was chosen on the basis of the recommendations issued by the European Society of Cardiology (Fitzpatrick, 1991).
The tilt test represents the only available tool at present that can bring about a syncopal event in the presence of the physician. Besides the clinical information offered in this way, the tilt testing helps the patient to recognize the way in which the vasovagal syncope manifests itself, thus helping to avoid further episodes (Podoleanu, 2003).
As far as the reproducing of the tilt test is concerned, it has been found that its repetition to the same patient does not always determine the same hemodynamic modifications, which questions the efficacy of the tilt test in choosing the optimum therapeutic approach (Foglia 1999).
As far as the TT sensitivity is concerned (namely the percentage of patients with historic antecedents of syncope in whose cases the TT induces syncope), it must be mentioned that this is difficult to appreciate due to the degree of objectivity of the patient or the physician. Even in cases in which the patient has syncopal antecedents, it is sometimes difficult to state if the syncope induced by the TT is similar with that in the historic antecedent.
This is why literature comprises studies that report a TT sensitivity varying between 30% and 85% (Abi-Samra, 1988; Shen, 1999). These variantions are also influenced by the protocols utilized related to the period of time and to the tilt angle of the table, respectively of the utilization of the medication challenge. There are also significant differences between the criteria of selection of patients: the existence of uniques syncopal event in the antecedents or multiple events, riguroua initial assessment or flexible intitial assessment, exclusion of other syncope causes, patients’ age, associated affections.
The specific character of the TT (namely the percentage of controlled asymptomatic subjects in whose cases syncope is not induced) described by literature varies, less than the sensitivity, in a range between 70% and 90% (Benditt, 1996; Fenton, 2000).