Setting: ED
CC: “She passed out!”
VS: R: 14 breaths/minute; BP:124/75 mm Hg; P:76 beats/minute; T: 97.5°F
HPI: A 65-year-old woman is brought to the ED by ambulance after losing consciousness in church. The patient was in her usual state of health until she woke up lying on her back in church. She was transferred to a stretcher and brought to the ED. The onset of loss of consciousness (LOC) was sudden. She cannot recall how long it lasted, but friends say it was only for a few minutes. When she awoke, she knew where she was immediately. Currently, she feels fine.
PMHX:
Osteoarthritis
Diverticulosis
Medications:
Acetaminophen one to two times a day
PE:
General appearance: older woman sitting up on stretcher looking her stated age; comfortable; not diaphoretic
Cardiovascular: no murmur
Neurological: normal
ROS:
Denies chest pain, dyspnea, headache
Denies bowel or bladder incontinence
She “felt shaky and sweaty” before the episode. She “felt very hot.”
As you move the clock forward 5 to 10 minutes and take an interval history, you will find that the vast majority of cases of syncope do not change. Syncope is extremely common, and in the majority of patients, the etiology is never found. The most important part of syncope evaluation is the history.
Why do atrial arrhythmias generally not lead to syncope?
a. The rate is not fast enough.
b. Atrial systole eventually occurs.
c. Stroke volume remains intact.
d. Vasoconstriction compensates.
e. α1-Receptors upregulate.
Answer c. Stroke volume remains intact.
Only 10% to 15% of cardiac output is dependent on the atrial contribution to ventricular filling. Loss of atrial systole leaves stroke volume intact in most cases. VT markedly decreases cardiac output and ventricular fibrillation eliminates it.
Here are the two key questions and the examination for syncope:
1. Was the loss of consciousness gradual or sudden?
If gradual (patients are shaky, sweaty, lowering themselves to the ground or to a seated position),
Hypoglycemia
Hypoxia
Drug toxicity or alcohol
Vasovagal
If sudden (patients feel fine, then wake up on the floor),
Neurological or seizure
Cardiac: arrhythmia or obstructive disease
2. Was regaining of consciousness gradual or sudden?
If gradual,
Seizure: Patients are “post-ictal” in that they need time to become normal over a few minutes to hours.
If sudden (“like a light switch turned off and on”),
Cardiac: arrhythmia, ischemia, structural
3. Examination
Arrhythmia rarely reveals an abnormality on cardiac examination.
Murmurs: hypertrophic obstructive cardiomyopathy (HOCM) versus aortic stenosis versus mitral stenosis
Initial Orders:
ECG
Telemetry monitoring
CK-MB, troponin
Echocardiogram
Head CT
CHEM-7
Urine toxicology screen (some cases)
Patients with syncope do not need to be placed in the ICU just for syncope. They only need the ICU if ventricular arrhythmia is found. Admit the patient to the regular hospital ward but order telemetry. Ninety percent of mortality with syncope is from a cardiac problem. You can view your syncope case as (exclude MI and arrhythmia) for those patients with no clear etiology at the beginning. If your case presents a person who is shaky and sweaty with a documented low glucose (<60 mg/dL), then you do not have to place the person on telemetry or order echocardiography. If your case is clearly hypotensive from pulmonary embolus, they need TPA and should be admitted to the ICU.
Syncope can be either considered one of the most complicated conditions with a broad differential or one of the simplest with the same list of tests for almost everyone.
If there is no clear etiology from the patient’s history, order
• ECG and telemetry
• Echocardiogram
• CK-MB, troponin
• Head CT
It is very unlikely to have a significant obstructive lesion with no murmur on examination.
As with many patients with syncope, as you move the clock forward 2 to 4 hours, there is no change in status, no new symptoms, and the tests return as normal.
ECG: normal sinus rhythm with no ST- or T-wave abnormalities
Echocardiogram: mild MR, no wall motion abnormalities
CK-MB, troponin, head CT: normal
Continue to advance the clock on CCS until the tests are all normal. Keep the patient in the hospital for 24 hours of telemetry monitoring.
Do not order any consultations for syncope patients unless a cardiac abnormality is found.
Regurgitant lesions do not cause syncope.
Do not order carotid Doppler ultrasounds in syncope.
Why does carotid stenosis not cause syncope?
a. It is too gradual in onset.
b. The posterior circulation supplies the brainstem.
c. Anterior circulation flows to the reticular activating system.
d. Vertebrobasilar circulation comes straight off the carotid.
Answer b. The posterior circulation supplies the brainstem.
The “sleep–wake” center for the brain is in the brainstem. Anterior or carotid circulation does not supply the brainstem. A patient can have a 100% occlusion of both carotid arteries and not lose consciousness. The patient may develop a stroke of the middle and anterior cerebral artery circulation, but will not lose consciousness.
Only posterior circulation (vertebral and basilar artery) occlusion causes syncope.
Stenosis lesions rapidly decrease stroke volume and cardiac output.