Critical-Cardiac

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Cardiac - E 1 BAPTIST HEALTH School of Nursing NSG 4017: Critical Care Nursing Nursing Management of Patients with Altered Cardiovascular Function Georgia Seward

I.

Anatomy and physiology review A. Layers B. Chambers C. Heart valves D. Flow of blood E. Blood supply of myocardium 1. RCA 2. L Main 3. LAD 4. Circumflex F. Cardiac cycle 1. Systole 2. Diastole G. Cardiac output and cardiac index - SV x HR. CI = CO /body surface area. 1. Preload 2. Afterload H. Cardiac pressures p. 1557 of Black and Hawks 1. R atrium 2. R ventricle 3. Pulmonary artery 4. L atrium 5. L ventricle I. Electrophysiology 1. Properties of heart a. Excitability - ability to respond - Na and K b. Automaticity (rhythmicity) - ability to initiate impulse spontaneously and repetitively without neurohormonal influence (1) SA node 60-100 bpm (2) atria 60-100 (3) AV node 40-60 (4) Ventricles 20-40 c. Contractility - extracellular calcium required! Then triggers more calcium from sarcoplasmic reticulum. Significance: Ca channel blockers alter cardiac rate but not skeletal muscle contraction. d. Refractoriness - inability to respond to new stimulus while still in state of depolarization - can shorten as HR increases

Cardiac - E 2 (1) ventricles - absolute refractoriness - .25 to .3 sec (2) ventricles - relative refractoriness - .05 sec e. Conductivity - move electrical impulses along and across cell membranes of muscle mass but not through fibrous bands. SA node AV node - delay is .07 Bundle of His and bundle branches a. R bundle b. L bundle - 2 fascicles (branches) Purkinje fibers

2. 3. 4.

5. II.

III.

IV.

Monitor waves - p. 120 in Urden. A. P B. QRS C. T D. PR Interval (PRI) E. ST segment 1. Depressed 2. Elevated Rate A. Using monitor paper B. Six second strip Rhythms - p. 123, Urden, Stacy, and Lough A. Normal sinus rhythm 1. Rate 2. Rhythm 3. P wave 4. PRI 5. QRS complex a. Shape b. Width (duration) 6. Etiology 7. Treatment B. Sinus bradycardia 1. Rate 2. Rhythm 3. P wave 4. PRI 5. QRS complex a. Shape b. Width 6. Etiology

Cardiac - E 3 Treatment - atropine, pacer (see p. 1691 in Black) - look for pacer spike (p 1696), Oxygen Sinus tachycardia 1. Rate 2. Rhythm 3. P wave 4. PRI 5. QRS complex a. Shape b. Width 6. Etiology - FEVER, shock, pain, meds (including dopamine), hormones (epi) 7. Treatment - varies by cause. Channel blockers, beta blockers, oxygen! Sinus dysrhythmia - variance of NSR with respiratory cycle Premature Atrial Contraction (PACs) 1. P wave - shape varies 2. QRS complex - < .12 Paroxysmal supraventricular tachycardia (PSVT) - begins and ends suddenly 1. Rate - 150 - 250 2. Rhythm - regular 3. P waves - rate may be too fast to see P wave 4. PRI - normal 5. QRS - normal 6. Etiology - caffeine, nicotine, digitalis, mitral prolapse, CHF 7. Treatment - Adenocard (adenosine) - antiarrhythmic (slows the conduction in the AV node), vagal maneuver, Ca channel blockers, digitalis, and cardioversion. Atrial flutter - several P waves called flutter waves for each QRS Atrial fibrillation 1. Rate a. Atrial- 350 to 600 fibrillatory waves b. Ventricular - 60 to 100 = controlled; >100 = uncontrolled 2. Rhythm - irregularly irregular ventricular complex 3. P wave - fibrillations 4. PRI - absent 5. QRS - normal 6. Etiology - various sites in atria 7. Treatment a. Convert electrically or chemically (amiodarone, calcium channel blockers, beta blockers, dig) b. Control the rate with medication c. NOTE: mural thrombi 7.

C.

D. E.

F.

G. H.

Cardiac - E 4 I. Premature ventricular contractions (PVCs) 1. Rate - underlying rhythm 2. Rhythm - Early QRS complex 3. P wave - absent or after PVC 4. PRI - absent 5. QRS - > 0.12 - wide with bizarre shape a. Unifocal b. Multifocal 6. Etiology - myocardial ischemia (may be secondary to MI, especially anterior), electrolyte (especially K & Ca) imbalance, hypoxia, acidosis, heart disease, meds. 7. Physiology - ectopic focus, impulse spreads through unusual pathways 8. Treatment - treat...
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