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C4 Cardiology and Cardiac Surgery
Differential Diagnoses of Common Presentations Toronto Notes 2019
• cardiovascularinnervation
■ sympathetic nerves
◆ innervate the SA node, AV node, ventricular myocardium, and vasculature
◆ SA node (β1) increased activity leads to increased heart rate via more frequent impulse from
pacemaking cells (increased chronotropy - increased HR)
◆ cardiac muscle (β1) fibres increase contractility (inotropy - leads to increased SV)
◆ stimulation of β1- and β2-receptors in the skeletal and coronary circulation causes vasodilatation
■ parasympathetic nerves
◆ innervate the SA node, AV node, and atrial myocardium but few vascular beds
◆ at rest, vagal tone dominates the tonic sympathetic stimulation of the SA node and AV node
resulting in slowing of pacemaker activity (leading to a heart rate at rest slower than the intrinsic
heart rate) and conduction (i.e. reduced dromotropy – if only affecting AV node conduction)
◆ parasympathetics have very little impact on total peripheral vascular resistance
Differential Diagnoses of Common Presentations
Note: bold text indicates most common, underlined text indicates life threatening condition Chest Pain
• cardiac
■ MI/angina, myocarditis, and pericarditis/Dressler’s syndrome
• pulmonary
■ PE, pneumothorax/hemothorax, tension pneumothorax, pneumonia, empyema, pulmonary
neoplasm, bronchiectasis, and TB • gastrointestinal
■ esophageal: GERD, esophageal rupture, spasm, esophagitis, ulceration, achalasia, neoplasm, and Mallory-Weiss syndrome
■ other structures: PUD, gastritis, pancreatitis, and biliary colic • mediastinal
■ lymphoma, thymoma • vascular
■ dissecting aortic aneurysm, aortic rupture • surfacestructures
• costochondritis
• ribfracture
• skin(bruising,herpeszoster)
• breast
• anxiety/psychosomatic
Loss of Consciousness
1. Causes of true syncope (impaired cerebral perfusion)
• inadequatecirculatingvolume(bleeding,hypovolemiawithorthostasis) • obstructiontobloodflow
■ tamponade
■ pulmonary embolism
■ severe pulmonary hypertension
■ severe obstructive valve disease (mitral and aortic stenosis) (see Arrhythmias, C16) ■ left ventricular outflow obstruction (HCM) (see Arrhythmias, C16)
• suddenlossofcardiacoutput
■ ventricular tachycardia/VF
■ severebradycardia(AVblock/AVdyssynchrony)
• reflexmediated/reflexdysfunction
■ vasovagal (most common)
■ situational (micturition, cough, carotid hypersensitivity)
■ autonomic dysfunction (often associated with neurologic diseases)
2. Loss of consciousness NOT due to impaired cerebral perfusion
• seizure
• hypoglycemia
• severehypoxiaorhypercarbia • psychiatric
• cerebrovascularevents
Local Edema
• venousorlymphaticobstruction
■ thrombophlebitis/deep vein thrombosis, venous insufficiency, chronic lymphangitis, lymphatic
tumour infiltration, filariasis • inflammation/infection