Page 96 - Critical Care Notes

4223_Tab02_045-106 29/08/14 10:00 AM Page 90

CV

Hemodynamics of Dysrhythmias
Atrial Dysrhythmias
Atrial dysrhythmias are caused by increased automaticity in the atria. The
patient may complain of palpitations or “heart racing.” Loss of atrial contraction
→ shortens diastole → loss of atrial kick (25%–30% of CO) → ↓ CO →↓ coro-
nary perfusion → ischemic myocardial changes. Atrial flutter or fibrillation can
lead to a pulmonary embolus, stroke, or MI. These patients should be taking
anticoagulants. Calculation for Atrial Fibrillation Stroke Risk found at: http://www
.mdcalc.com/cha2ds2-vasc-score-for-atrial-fibrillation-stroke-risk/
Surgical ablation via a Cox-Maze procedure during mitral valve repair or
replacement has been shown to be an effective treatment for atrial fibrillation.
Causes
■ Amphetamines
■ Cocaine
■ Decongestants
■ Hypokalemia
■ Hyperthyroidism
■ COPD
■ Pericarditis
■ Digoxin toxicity
■ Hypothermia
■ Alcohol intoxication
■ Pulmonary edema
Ventricular Dysrhythmias
Ventricular dysrhythmias are caused by increased automaticity in the ventricles.
PVCs can be manifested as complaints of “heart skipping a beat.” This dysrhyth-
mia can lead to bradycardia →↓ CO →↓ BP and eventually VT, VF, and death.
Bradycardia
Bradycardia is defined as a heart rate less than 60 bpm. ↓ HR →↓ CO →↓ BP
→↓ perfusion to brain, heart, kidneys, lung, and skin.
Causes
■ Vomiting
■ Gagging
■ Valsalva maneuver
■ ETT suctioning

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