Transient loss of consciousness Diagnostic and therapeutic challenges

In part 1 of this thesis we describe diagnostic strategies employed in specialized outpatient clinics to diagnose patients with syncope, so called syncope units, in the Netherlands. We found that there is much homogeneity among syncope units, but that protocols for autonomic function tests differ between centres. Thereafter we researched the diagnostic yield of history taking and autonomic function tests and the accuracy of these tests. We found that history taking is the most important diagnostic tool, yielding a diagnosis in 95% of the patients. Autonomic function tests increased certainty in the diagnosis but only yielded diagnoses in patients in whom history taking did not yield any diagnosis.
In part 2 of this thesis we reviewed the literature regarding pacemaker therapy for patients presenting with vasovagal syncope. Vasovagal syncope can result in bradycardia and asystole. To prevent syncope, pacemaker therapy has been tried for many years, with conflicting results. As the vasovagal reflex does not only consist of cardio-inhibition, but also of vasodilation which can not be prevented with pacing, they often do not prevent syncope. In a subset of patients with severe, sudden vasovagal syncope with profound asystole, pacemakers might give patients more time from prodromes to actual syncope, thereby preventing trauma due to a fall.
In part 3 we sought to evaluate the diagnostic criteria for carotid sinus hypersensitivity. We analysed patients who underwent carotid sinus massage and analysed, using beat-to-beat haemodynamic measurements, the parameters significantly correlated with symptoms. The current criteria consist of the fall in systolic blood pressure and asystole. However we found that the lowest systolic blood pressure reached is actually significantly associated with symptoms.