4.4 CARDIAC SYNCOPE

Question 1

Pathophysiology

Answer 1

(1) Syncope is a sudden, transient loss of consciousness associated with inability to maintain postural tone
(2) Most commonly caused by an inciting event which decreases CO leading to decreased O2 delivery to the brain
(3) Most common etiologies are:
(a) Vasovagal reflex mediated: pain or fear
(b) Orthostatic hypotension: uncompensated drop in CO when assuming upright posture. Defined as a decrease of SBP > 20 mmHg and increase in HR > 10 beats/min. Commonly caused by volume depletion and drugs
(alpha or beta-blockers, Calcium channel blockers).
(c) Cardiac Syncope: Divided into structural cardiopulmonary lesions vs
dysrhythmias
1) Structural: valvular, hypertrophic cardiomyopathy (IHSS), AMI, PE
2) Dysrhythmias: Bradycardia, AV block, V-tach, A-fib, PSVT, WPW

Question 2

Symptoms/Physical Findings

Answer 2

(1) Prodromal symptoms: blurring of vision, dizziness, pallor, nausea, vomiting, diaphoresis, seeing stars/spots
(2) Positive tilt test: orthostatic syncope
(3) Rectal exam to evaluate for GI bleeding
(4) Cardiac syncope: listen for murmurs, S3, S4

Question 3

Differential Diagnosis

Answer 3

(1) Vasovagal
(2) Dysrhythmia
(3) Infection
(4) Dehydration
(5) Electrolyte abnormalities (hypokalemia, hypomagnesium, hyperkalemia)
(6) Seizure
(7) PE
(8) AMI
(9) CHF
(10) Hemorrhage (most commonly a GI bleed)
(11) Medication induced
(12) Cardiac malignancy
(13) Aortic aneurysm/dissection
(14) Large CVA

Question 4

Labs/Studies/EKG

Answer 4

(1) CBC
(2) Chemistry (to rule out electrolyte abnormalities)
(3) EKG: to evaluate for dysrhythmias
(4) Echocardiogram: to evaluate for cardiomyopathy, valvular disease

Question 5

Treatment

Answer 5

(1) Treat underlying cause of syncope:
(a) Cardiac: treat arrhythmia, AMI, CHF, etc.
(b) Orthostatic: give IV fluid bolus
(2) ABCs, IV, O2, Monitor
(3) Evaluate and treat signs of trauma
(4) Evaluate and treat signs of hemorrhage
(5) Continue to monitor patient until cardiac origin is ruled out OR if you
cannot rule it out then transfer to higher level of care.

Question 6

Initial Care

Answer 6

(1) Obtain history from patient and witnesses
(2) Emphasis on events leading up to LOC, characteristics of LOC, symptoms and duration, neurologic and cardiac symptoms, presence of incontinence of urine
(3) Determine etiology of syncope trying to rule out cardiac syncope

Question 7

Complications

Answer 7

(1) Cardiac dysrhythmias
(2) Cardiac arrest
(3) Death