Perfusion & Dysrhythmias — Study Notes (Part 1)

Structured by: What is it? What does it look like (signs & symptoms)? How do I diagnose it? How do I treat/manage it (chemical, electrical, surgical, nursing)?

0) High-Yield Foundations

Focused Cardiac Assessment

Chart review, history, complete med list (Rx/OTC/herbals).
Vitals: BP (pulse pressure = SBP–DBP), HR/rhythm, RR, Temp, SpO₂.
Inspect/palpate: skin color/temperature, cap refill, JVD, edema.
Auscultate: heart (APTM) & lung sounds.
Monitoring: 3-lead/5-lead telemetry; 12-lead ECG when indicated.
Labs/imaging: electrolytes (K⁺, Mg²⁺), troponin (if ischemia), CXR, echo per order.
Priorities: maintain CO & O₂, identify reversible causes, prevent complications, reduce anxiety, teach family.

ECG Essentials

P = atrial depolarization; PR = AV conduction; QRS = ventricular depolarization.
ST monitors ischemia/infarction; T = repolarization; U may appear in hypokalemia.
Small box = 0.04 s; 5 small = 0.20 s; 1-min strip ≈ 1500 small boxes.
Isoelectric line = baseline reference for ST deviation.

Rate & Regularity

Regular: 1500 ÷ small boxes (R–R) or 300 ÷ large boxes.
Irregular: count QRS in 6 s × 10.

Lead Placement & Artifact

Prep skin (clean/dry), clip hair, minimize movement to reduce artifact.

1) Normal Sinus Rhythm

What is it?

Normal SA-node rhythm with intact AV conduction.

What does it look like?

Usually asymptomatic.
ECG: P before each QRS, regular R–R, rate 60–100 bpm, PR 0.12–0.20 s, narrow QRS.

Diagnosis & Management

Confirm by 12-lead ECG; no specific treatment needed.
Nursing: routine monitoring and education on healthy habits.

2) Sinus Bradycardia

What is it?

SA node rate < 60 bpm; physiologic (athletes/sleep) or pathologic (vagal tone, meds, ischemia).

What does it look like?

Asymptomatic or dizziness, syncope, hypotension, cool/pale skin, SOB, exercise intolerance.
ECG: P before each QRS, regular, rate < 60.

Diagnosis

ECG plus review for causes: β-blockers, CCBs, digoxin, ischemia, ↑ICP, hypothyroid, hypothermia.

Treatment/Management

Chemical: If unstable: atropine; correct reversible causes, rewarm, adjust meds.
Electrical: Transcutaneous pacing if atropine ineffective; transvenous pacing as needed.
Surgical: Permanent pacemaker for persistent symptomatic cases.
Nursing: Oxygen, IV access, continuous monitor, prepare for pacing, patient teaching.

3) Sinus Tachycardia

What is it?

SA node rate > 100 bpm; physiologic response to stressors or disease.

What does it look like?

Palpitations, SOB, chest discomfort, anxiety, or asymptomatic.
ECG: P before QRS, regular rhythm, rate > 100 (100–160 typical).

Diagnosis

ECG, review for fever, hypovolemia, anemia, hypoxia, pain, anxiety, stimulants, thyrotoxicosis.

Treatment/Management

Chemical: Treat underlying cause; β-blocker or CCB if persistent/symptomatic.
Electrical: Cardioversion if unstable.
Nursing: Monitor, IV access, address cause (fluids, O₂, cooling, calm environment).

4) Sinus Arrhythmia

What is it?

Physiologic rhythm variation with respiration (HR ↑ inspiration, ↓ expiration).

What does it look like?

Usually asymptomatic.
ECG: Sinus P before QRS, repeating R–R variation with breathing.

Treatment

None required; reassurance only.

5) First-Degree AV Block

What is it?

Delayed AV conduction; each impulse conducts but PR interval prolonged (> 0.20 s).

What does it look like?

Usually asymptomatic.
ECG: Constant PR prolongation, 1:1 conduction.

Diagnosis & Management

ECG; review meds (β-blockers, CCBs, digoxin); correct electrolytes.
Observe; no treatment unless symptomatic.

6) Medication-Associated QT Prolongation

What is it?

Delayed ventricular repolarization causing torsades de pointes risk.

What does it look like?

Often asymptomatic until syncope/palpitations; can lead to arrest.
ECG: QTc > 440 ms; notched or abnormal T-waves.

Treatment

Stop offending drug; correct K⁺/Mg²⁺/Ca²⁺.
IV magnesium for torsades; pacing if refractory.
Nursing: Telemetry, med reconciliation, electrolyte trending.

7) Electrolyte-Driven Dysrhythmias (Potassium)

What is it?

Conduction and repolarization disturbances from abnormal potassium.

What does it look like?

Hyperkalemia: Peaked T, wide QRS, sine-wave, weakness.
Hypokalemia: Flat T, U wave, PVCs/VT, fatigue, cramps.

Treatment

HyperK⁺: IV calcium, insulin/dextrose, β-agonist, diuretics/dialysis.
HypoK⁺: Replace K⁺ ± Mg²⁺.
Nursing: Monitor telemetry, repeat labs, administer safely via pump.

8) Myocardial Ischemia/Infarction

What is it?

Reduced or blocked coronary flow causing injury or infarction.

What does it look like?

Chest pain, SOB, diaphoresis, nausea, anxiety.
ECG: ST depression/T inversion (ischemia), ST elevation (injury), Q waves (infarct).

Diagnosis

12-lead ECG, troponins, echo, risk factors, CXR.

Treatment

Aspirin, nitrates, β-blocker, antiplatelet, statin, oxygen if SpO₂ < 90%.
PCI (preferred for STEMI); fibrinolytics if PCI unavailable.
Nursing: Activate STEMI alert, prepare for cath, monitor, manage pain/anxiety.

9) Artifact / Lead Misplacement

What is it?

False signals due to poor electrode contact or motion.

What does it look like?

Erratic baseline, no symptoms, inconsistent P morphologies.

Treatment

Re-prep skin, reapply electrodes, check cables, warm patient if shivering.

10) Devices

Pacemaker

Treats symptomatic bradycardia or conduction blocks.

Post-op arm precautions; incision care; device ID card.
Teach: pulse checks, report syncope, redness, fever.

Implantable Cardioverter-Defibrillator (ICD)

Detects and treats ventricular arrhythmias; may also pace.

Occasional shocks expected; multiple shocks = urgent eval.
Avoid magnets; maintain follow-up visits.

11) Bedside Algorithm

Assess patient (ABCs, perfusion). Unstable → follow ACLS.
Determine regular vs irregular rhythm.
Calculate rate (300/1500 methods or 6-sec ×10).
Evaluate P waves, PR, QRS, ST/T changes.
Name rhythm, find causes, treat per stability.
Monitor for arrest, HF, thromboembolism.
Educate and plan follow-up.

12) Functional Assessment

Six-minute walk test: stop for chest pain, severe SOB, syncope, abnormal BP, or dysrhythmias.

End of notes.