Clinical Observation Of Tilt Table Test

Objective:1. The characteristics of haemodynamic changes of patients with positive tilt table test (TTT) were analyzed, to explore the possible mechanism and positive classification criteria.2. The characteristics of haemodynamic changes before and after syncope in TTT were analyzed, to explore when the test should be terminated if the patients have a positive reaction and its impact on the classification of positive results.3. Patients with a pacemaker to prevent the recurrence of vasovagal syncope (VVS) were followed up to observe the role of the pacemaker in the prevention of VVS.Methods:The data of patients undergoing TTT in our hospital from2007to2012was analyzed. And the patients with a pacemaker to prevent the recurrence of VVS were followed up.Results:1. The observation of haemodynamics.1.1From the patients were tilted up to the VVS attacked, the positive reaction occurred in22±10min in passive phase and in6(median) min in nitroglycerin sensitized phase. Before heart rate (HR) decreased, there was an increase>10%than HR at the time of upright in89.1%patients with positive TTT. When the positive patients returned to the supine position, HR of171(58.4%) patients increased (Increased Group), while it decreased in116(39.6%) patients (Decreased Group), and no change in the remaining6(2.0%) patients. The diastolic blood pressure (BP) in Decreased Group was lower than in Increased Group at the time of upright (P<0.05) at the time of patients felt uncomfortable and at the termination of TTT.1.2In the groups "BP drops before HR"、"BP drops after HR" and "BP drops coincides with HR", the distribution is no difference between passive phase and nitroglycerin sensitized phase. Patients in "BP drops after HR" group had lower HR and higher BP at the termination of TTT (P<0.05)1.3Domestic classification significantly reduced the proportion of cardioinhibitory and mixed type compared with VASIS classification. There was no difference in the drop of HR between positive patients in passive phase and in nitroglycerin sensitized phase. But the drop of HR in negative patients is larger in nitroglycerin sensitized phase than in passive phase (P<0.05). Use14%as the criterion to determine heart rate reflex drop had a higher correct rate in passive phase, and22%in the nitroglycerin sensitized phase.2. When syncope occurred, patients had lower HR and BP compared with the moment they got to positive criteria (P<0.05). In the167patients occurred syncope,62(37.1%) lost consciousness when they got to positive criteria. The remaining105patients reproduced syncope in several minutes after they got to positive criteria. The time from positive criteria to syncope is1(1) min. The longest time is8minute and95%syncope occurred in4minutes.3. The syncope episodes reduced significantly in15patients who received a pacemaker. There was only1syncope episodes in1(6.7%) patient within5-63months. But9(60%) patients had presyncope episodes.Conclusions:1. Conclusions of haemodynamic observation:1.1The withdrawn of sympathetic activity is not the only mechanism of VVS in Decreased Group. An abnormal vasodilatation maybe plays an important role in it.1.2Patients in "BP drops after HR" group had lower HR and higher BP, the cause maybe is that these patients had a fast drop in HR and a lighter degree of vasodilatation.1.3It is established in this investigation that the VASIS classification has better meaning for therapy. But for the type of vasodepressor, the following criteria maybe is more suitable:HR does not drop more than14%(passive phase) and22%(nitroglycerin sensitized phase) compared to the peak at the time of syncope.2. We suggest a new criterion for the termination of TTT:①syncope with hypotension or bradycardia. ②presyncope and HR drops to less than40bpm and the drop lasts more than10seconds, or there is asystole that lasts more than3seconds.③presyncope and systolic BP≤80mmHg and(or) diastolic BP≤50mmHg, or HR<50bpm, lasts more than4min。3. Although pacemaker can’t avoid the reproduction of VVS, it can prevent the occurrence of syncope. Set up the parameters properly is the most important thing to make the pacemaker work well.