Syncope

Following are differential diagnoses for patients presented with syncope.

Cardiac

• Congestive heart failure

• Cardiac tamponade secondary to pericardial effusion

• Arrhythmias

  • Inherited ventricular arrhythmias (eg, boxer, Doberman pinscher, German shepherd dog)

  • Supraventricular or ventricular arrhythmias secondary to underlying cardiac disease

  • Sick sinus syndrome (eg, miniature schnauzer, dachshund, West Highland white terrier, cocker spaniel)

  • Bradyarrhythmias

    • High-grade atrioventricular block (usually geriatric large-breed dogs)

    • Complete or third-degree atrioventricular block

    • Atrial standstill (hyperkalemia should be ruled out)

• Outflow obstruction (eg, subaortic stenosis, pulmonic stenosis, heartworm infection)

• Congenital heart disease resulting in right-to-left shunting from concurrent pulmonary hypertension or complex heart disease (eg, reverse patent ductus arteriosus, reverse atrial septal defect, reverse ventricular septal defect, Tetralogy of Fallot)

• Hypertrophic cardiomyopathy

• Vasovagal syncope

• Left atrial tear due to degenerative mitral valve disease

• Dilated cardiomyopathy

Respiratory

• Hypoxia

• Pulmonary hypertension

• Pulmonary thromboembolism

• Pneumonia

• Neoplasia

• Upper airway obstruction (eg, tracheal or laryngeal collapse, laryngeal paralysis, geriatric onset laryngeal paralysis polyneuropathy, foreign body)

Hypertensive

• Adrenal disease (eg, pheochromocytoma)

• Renal disease

Hypotensive

• Hypovolemia

• Septic shock

• Cardiogenic (rare)

Hematologic

• Anemia

• Hyperglobulinemia (eg, multiple myeloma, lymphoma)

• Polycythemia

*At the time of writing, Dr. Nakamura was affiliated with Coast-to-Coast Cardiology.