syncope is a very common symptom and it represents an important public health problem because it leads to traumatic lesions , worsens quality of life ; it is one of the most common causes of inability and it is associated with elevated health care costs ( 1 , 17 ) . syncope is defined as a sudden and transitory loss of consciousness and orthostatic position associated with a fast , spontaneous and complete regain of consciousness . lypotimia is defined as a sudden weakness , incapacity to maintain the orthostatic position , visus block out and near loss of consciousness . vasovagal syncope is the most common cause of syncope and it represents about 1040% of all the causes ( 19 ) . vasovagal syncope physiopathology : when we step over from the clinostatic to orthostatic position about 800 ml of blood goes into the subdiaphragmatic part of the body with a reduction in preload into the right ventricle . in patients with vasovagal syncope the mechanoceptors located in the heart and in the carotid bulb send an exaggerated signal to the cerebral trunk with an alterated sympathovagal response and vasodepression ( 3 ) . the head - up tilt test ( hutt ) is the most efficacious test in studying the vasovagal reaction . in addition , ecg monitoring is very important in discovering the cause of syncope both with traditional ecg 24-hr and the r - test , and with ecg monitoring over a period of 7 days . the aim of our study was to verify the diagnostic value of the hutt in patients suspected of vasovagal syndrome and of the r - test in patients with unexplained syncope . in our syncope unit , from 20022005 , there were 211 patients symptomatic for syncope and/or lypotimia suspicious for vasovagal syndrome . mean age was 41.5 yrs ( range 1865 yrs ) ; 88 patients were male and 123 were female . fifty - eight patients had one or more lypotimic episodes in anamnesis and 153 patients had one or more syncopal episodes . some patients had already undergone other diagnostic tests for syncope such as holter ecg monitoring , echocardiogram , electrophysiological study , electroencephalogram , encephalic ct , and upper aortic trunk doppler . after a detailed description of the test modality , the patients had to give their informed consent . patients should fast for at least 2 hr before the test . in order to monitor arterial blood pressure ( bp ) , we adopted the f500 system , a versatile non - invasive beat - to - beat monitoring system . it captures the continuous bp waveform , and automatically computes up to 15 important beat - to - beat hemodynamic parameters including cardiac output ( co ) , stroke volume ( sv ) , total peripheral resistance ( tpr ) , pulse rate variability ( prv ) and baroreflex sensitivity ( brs ) . ecg monitoring at 25 mm / sec in 12 derivations is obtained in the basal position after the supine position phase , every 3 min and every time it was necessary . we used a tilt table with a foot board support to achieve the upright position smoothly and rapidly , and to reset the supine position quickly ( < 10 sec ) when the test is completed to avoid the consequences of a prolonged loss of consciousness . this protocol provides a supine pre - tilt phase of at least 5 min when no venous cannulation is performed and at least 20 min when cannulation is undertaken ; tilt angle is 6070. passive phase is a minimum of 20 min and a maximum of 45 min . if the passive phase has been negative 400 g of nitroglicerin spray is used sublingually ; the drug challenge phase is about 1520 min . the end - point of the test is defined as the induction of syncope or a progressive and symptomatic fall in bp for at least 3 min or until a value of 60 mmhg in systolic bp is achieved or the completion of the planned duration of tilt including drug stimulation ( 15 , 16 , 18 ) . type 1 mixed response : heart rate falls at the time of syncope but the ventricular rate does not fall to < 40 beats / min or falls to < 40 beats / min for < 10 sec with or without asystole of <3 sec . type 2a cardio inhibition without a systole : heart rate falls to a ventricular rate < 40 beats / min for > 10 sec , but asystole of > 3 sec does not occur . type 2b cardio inhibition with a systole : a systole occurs for > 3 sec . type 3 vasodepressor : heart rate does not fall > 10% from its peak at the time of syncope . forty - five patients with syncope and a negative response to hutt , after a negative 24-hr holter ecg , underwent an ecg ambulatory registration with the r - test that registers ecg over a period of 7 days , and to give an analysis with dedicated software for specific event monitoring . the r - test ( evolution novacor - cardioline ) is a compact and lightweight ergonomic recorder ( 45 g batteries included , 60  48  28 mm ) suspended around the neck like a medallion ; it is maintained by an auto - adjustable cable , a particularly ergonomic configuration which drastically limits movement artefacts ; its advanced miniaturized electronics are capable of real time qrs acquisition and processing . it stores only significant events ; therefore , avoiding the generation of huge data files usually associated with long - term ecg monitoring . the number and type of events recorded , as well as the pre- and post - event time are entirely programmable , allowing either specific screening for the confirmation of a suspected pathology or a wider search field in the absence of strong clinical evidence . voluntary registration is possible during the specific symptom ; in addition , this recorder includes a pre- and a post - registration of specific events . the r - test evolution is equipped with a new acquisition system favoring the cm5 lead , for excellent results in arrhythmia detection and st shift measurement in case  the user interface on pcs ( rtsoft ) is a model of user friendliness . patient i d is directly sent to and stored in the recorder before it starts , for enhanced data treatment safety . transfer of the recorded data , display of all the events as well as the heart rate curve and event histograms are immediate , allowing a global overview . each strip can also be zoomed in on separately for a detailed analysis . in our syncope unit , from 20022005 , there were 211 patients symptomatic for syncope and/or lypotimia suspicious for vasovagal syndrome . mean age was 41.5 yrs ( range 1865 yrs ) ; 88 patients were male and 123 were female . fifty - eight patients had one or more lypotimic episodes in anamnesis and 153 patients had one or more syncopal episodes . some patients had already undergone other diagnostic tests for syncope such as holter ecg monitoring , echocardiogram , electrophysiological study , electroencephalogram , encephalic ct , and upper aortic trunk doppler . after a detailed description of the test modality , the patients had to give their informed consent . patients should fast for at least 2 hr before the test . in order to monitor arterial blood pressure ( bp ) , we adopted the f500 system , a versatile non - invasive beat - to - beat monitoring system . it captures the continuous bp waveform , and automatically computes up to 15 important beat - to - beat hemodynamic parameters including cardiac output ( co ) , stroke volume ( sv ) , total peripheral resistance ( tpr ) , pulse rate variability ( prv ) and baroreflex sensitivity ( brs ) . ecg monitoring at 25 mm / sec in 12 derivations is obtained in the basal position after the supine position phase , every 3 min and every time it was necessary . we used a tilt table with a foot board support to achieve the upright position smoothly and rapidly , and to reset the supine position quickly ( < 10 sec ) when the test is completed to avoid the consequences of a prolonged loss of consciousness . this protocol provides a supine pre - tilt phase of at least 5 min when no venous cannulation is performed and at least 20 min when cannulation is undertaken ; tilt angle is 6070. passive phase is a minimum of 20 min and a maximum of 45 min . if the passive phase has been negative 400 g of nitroglicerin spray is used sublingually ; the drug challenge phase is about 1520 min . the end - point of the test is defined as the induction of syncope or a progressive and symptomatic fall in bp for at least 3 min or until a value of 60 mmhg in systolic bp is achieved or the completion of the planned duration of tilt including drug stimulation ( 15 , 16 , 18 ) . type 1 mixed response : heart rate falls at the time of syncope but the ventricular rate does not fall to < 40 beats / min or falls to < 40 beats / min for < 10 sec with or without asystole of <3 sec . type 2a cardio inhibition without a systole : heart rate falls to a ventricular rate < 40 beats / min for > 10 sec , but asystole of > 3 sec does not occur . type 2b cardio inhibition with a systole : a systole occurs for > 3 sec . type 3 vasodepressor : heart rate does not fall > 10% from its peak at the time of syncope . forty - five patients with syncope and a negative response to hutt , after a negative 24-hr holter ecg , underwent an ecg ambulatory registration with the r - test that registers ecg over a period of 7 days , and to give an analysis with dedicated software for specific event monitoring . the r - test ( evolution novacor - cardioline ) is a compact and lightweight ergonomic recorder ( 45 g batteries included , 60  48  28 mm ) suspended around the neck like a medallion ; it is maintained by an auto - adjustable cable , a particularly ergonomic configuration which drastically limits movement artefacts ; its advanced miniaturized electronics are capable of real time qrs acquisition and processing . it stores only significant events ; therefore , avoiding the generation of huge data files usually associated with long - term ecg monitoring . the number and type of events recorded , as well as the pre- and post - event time are entirely programmable , allowing either specific screening for the confirmation of a suspected pathology or a wider search field in the absence of strong clinical evidence . voluntary registration is possible during the specific symptom ; in addition , this recorder includes a pre- and a post - registration of specific events . the r - test evolution is equipped with a new acquisition system favoring the cm5 lead , for excellent results in arrhythmia detection and st shift measurement in case  the user interface on pcs ( rtsoft ) is a model of user friendliness . patient i d is directly sent to and stored in the recorder before it starts , for enhanced data treatment safety . transfer of the recorded data , display of all the events as well as the heart rate curve and event histograms are immediate , allowing a global overview . among the patients , 113 were positive to the hutt and 98 were negative . in the positive group , 87 were females and 26 were males ( median age 32  10 yrs ) , while in the negative group 36 were female and 62 were male ( median age 61  10 yrs ) . of the 45 patients who underwent the r - test , five patients were symptomatic for syncope : in three cases there was a registration of complete atrial ventricular block with idio - ventricular rhythm and in two cases there was evidence of major pauses > 3 sec ( fig . r - test : results for hypokinetic arrhythmias . among the patients submitted to the r - test , 19 patients presented with hyper kinetic arrhythmias ( seven patients with ventricular ectopic beats ( fig . 2 ) , five patients with supra - ventricular ectopic beats , four patients with short traits of parossistic supra - ventricular tachycardia and three patients with short traits of atrial fibrillation ) ( figs . syncope is a syndrome consisting of a relatively short period of temporary and self - limited loss of consciousness caused by a transient reduction in blood flow to the brain ( most often the result of systemic hypotension ) . syncope comprises part of a subset of clinical conditions in which loss of consciousness is transient ; other conditions in this group , which are not syncope and should be clearly distinguished from syncope , include , for example , seizure disorders , post - traumatic loss of consciousness and cataplexy ( 4 ) . syncope accounts for up to 3% of emergency room visits and 6% of hospital admissions . the framingham study reported that approximately 3% of individuals have a syncopal episode during their lives , although lifetime incidence in the elderly can be as high as 23% . mortality is generally low , but can be up to 33% at 1 yr in patients with a cardiac aetiology ( 5 ) . diagnosis can be made difficult by the intermittent nature of the symptoms , the large number of potential aetiologies , and the lack of a gold standard for clinical investigation . the cost of the investigation of recurrent unexplained syncope can be high , particularly if a relatively benign cause of syncope is overlooked in the process of excluding life - threatening disorders . recurrences are common after the index event , occurring in up to one - third of patients . the search for an underlying cause in patients with syncope often poses a clinical dilemma and even after extensive evaluation , the specific cause can remain unknown in up to 50% of patients . in selected patients , the diagnostic yield can be improved with the use of specialized studies such as head - up tilt testing . head - up tilt testing is a widely accepted tool in the investigation of syncope , particularly where there is no evidence of structural heart disease ( 6 ) . initial evaluation with anamnesis , clinical examination , ecg and bp in clinostatic and orthostatic positions screens the patients suspected of vasovagal syncope and cardiogenic syncope . with an initial evaluation a neurogenic reflex can be suspected with indicative data and when other syncope causes have been excluded , independent from tilt - table test results . patients with positive tilt - table test results and those with a negative response ( indefinite syncope ) have similar characteristics and prognosis , so it seems they belong in the same population . the key remains in selecting the appropriate patients for each investigation , such as by the presence of a prodrome of autonomic symptoms in those with suspected vasovagal syncope ( 7 ) . the absence of a gold standard diagnostic test for vasovagal syncope makes the calculation of the exact specificity and sensitivity of the tilt test difficult , particularly in view of the variable methodology used in the different groups reporting results . the ability of the test to differentiate patients from healthy controls is nonetheless established with specificity generally up to 90% and sensitivity ranging between 32% and 85% with the median closer to the upper number ( 8) . the diagnostic value of the hutt in our group of patients is lower than that in the literature data , possibly due to the low pre - test probability . more rigorous application of the guidelines is necessary to optimize the usefulness of the hutt . recent studies have seen how a correct and specific anamnesis is able to discover with a high diagnostic value patients affected by vasovagal syndrome ( 11 , 13 ) . however , the tilt test has a higher sensibility in young female patients ( 10 ) . sheldon et al ( 11 ) tested the sensitivity and specificity of a preliminary questionnaire about the characteristics of the syncopal episodes and every question was assigned a positive or negative score . the point score correctly classified 90% of patients , diagnosing vasovagal syncope with 89% sensitivity and 91% specificity ; so it is true that a targeted anamnesis could make a diagnosis without the tilt test ( 14 ) . the availability of implantable cardiac loop recorders is a significant advance in helping to clarify the situation in patients with unexplained syncope ( 9 ) . not unsurprisingly , many patients have been found to have a diagnosis different from that presumed from their history and other investigations as evidenced in the issue-2 study . the issue-2 study with the early application of a loop recorder in patients with unexplained syncope demonstrated that in a minority of patients during syncope recurrences there are tachy or bradyarrhythmias , supraventricular or ventricular that are responsible for syncopal episodes . in our study , the r - test was able to detect an arrhythmic cause of syncope in some patients with negative hutt and negative traditional holter ecg monitoring . in our opinion , r - test ecg monitoring for a period of 7 days , with the possibility of repeating the test , could be a preliminary test to determine the use of the implantable loop recorder in patients with unexplained syncope . it is a very simple method that also reduces the management costs of the unexplained syncope population ( 12 ) .
the diagnostic value of the head - up tilt test ( hutt ) in discovering vasovagal syndrome depends on the pre - test probability . 
 an accurate anamnesis and clinical examination screens the patients indicated for the hutt . in patients with unexplained syncope , 
 the r - test is an alternative procedure to discover its cause . in our study 
 , we evaluated the diagnostic significance of the hutt in a group of 211 patients and of the r - test in a subgroup of 45 patients with negative hutt results and with negative traditional holter ecg monitoring ( 24 hr ) .