While syncope may seem benign, it makes up a reasonably high number of 911 calls. There are 3 major causes of syncope; 2 of which are relatively non-threatening, and one category that has a high mortality. So take it seriously.
Orthostatic Syncope:
When we change position from sitting/lying to standing, gravity does what it is good at and causes the blood to move toward the lower extremities. This causes a sudden, transient drop in systolic blood pressure. In a healthy individual, baroreceptors in the carotid arch pick up this drop and activate compensatory vasoconstriction and tachycardia. This means that SPB is restored to baseline in seconds. However, in patients with pre-existing hypotension, dehydration, or those on beta-blockers, these compensatory mechanisms may not be active; at least not sufficiently to correct rapid changes in SBP. The result is a brief drop in cerebral perfusion pressure, and loss of consciousness. This lasts anywhere from 10-15 seconds, with a spontaneous return to GCS 15.
Reflex-mediated (vasovagal) syncope:
In this case, there is increased vagal nerve stimulation, during activities such as prolonged standing in a hot environment, valsalva maneuver (bearing down), or exposure to intense pain, or fear. The result is a drop in SBP, sudden LOC, and then return to GCS 15 in 10-15 seconds.
Both of the above conditions are normal body responses and usually do not require significant intervention in the medical setting. Supportive care and a good history are all that is needed unless secondary injuries occur.
CARDIOGENIC SYNCOPE: This is what we worry about.
There are 2 very obvious things we need to look for on the ecg of a syncopal patient:
1. Ischemia
2. Arrhythmias
There are also 4 additional things we should be looking for; 2 genetic problems, and 2 interval-opathies
Genetic causes/structural causes:
1. Hypertrophic cardiomyopathy: This is evidenced much like LVH, with large amplitude QRS
complexes, in addition to Q waves in the lateral leads.( Lead I, avL, V5 and V6) YOU MUST
HAVE BOTH to diagnose hypertrophic cardiomyopathy.
2. Brugada syndrome:This involves a sodium channel abnormality. The ecg presents with
abnormalities in leads V1 and V2. The QRS will have a pseudo-rSR morphology with coved J
point elevation, followed by T wave inversion.
Interval related problems:
1. WPW: This is evidenced by a triad of short PR, widened QRS, and a delta wave.
2. Long QT syndrome: There is a formula but you can eyeball this one. The normal QT
interval should be less than half the R to R interval. If it is greater, there is a very good chance
that the patient's syncope is the result of R on T phenomenon. This can lead to torsades. DONT
MISS THIS.
Missing any of the above causes can lead to patient DEATH. A thorough history of previous syncopal events, and any family history of sudden death, should be elicited.
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