9.1 Cardiac Assessment, ECG Interpretation & Common Arrhythmias
Key Takeaways
- Systematic cardiac assessment requires structured inspection of Jugular Venous Pressure (JVP >3 cm above the sternal angle indicates fluid overload), palpation of the point of maximal impulse (PMI), and auscultation of heart sounds (S1, S2, S3 gallop, S4, and heart murmurs).
- Standard 12-lead ECG placement demands precise anatomical landmarking, including lead V1 at the 4th intercostal space right sternal border and lead V4 at the 5th intercostal space midclavicular line.
- A 5-step ECG rhythm interpretation method (Rate, Rhythm, P wave, PR interval [0.12–0.20s], QRS duration [<0.12s]) allows rapid identification of ischemic ST-segment changes and lethal dysrhythmias.
- Atrial Fibrillation requires immediate ventricular rate control, thromboembolic stroke risk stratification using the CHA₂DS₂-VASc score under Singapore MOH guidelines, and appropriate oral anticoagulation therapy.
- Pulseless Ventricular Tachycardia and Ventricular Fibrillation are shockable cardiac arrest rhythms requiring immediate CPR, early unsynchronized defibrillation (200J biphasic), and ACLS pharmacotherapy per NRFAC standards.
9.1 Cardiac Assessment, ECG Interpretation & Common Arrhythmias
Cardiovascular nursing requires structured physical examination, precise diagnostic lead placement, and systematic electrocardiography (ECG) interpretation. Registered nurses practicing in acute care and cardiac units across Singapore must rapidly synthesize clinical findings with electronic waveform data to detect dysrhythmias and initiate evidence-based emergency protocols.
Physical Cardiovascular Assessment
A comprehensive physical examination of the cardiovascular system follows a logical sequence: Inspection, Palpation, and Auscultation.
1. Inspection & Jugular Venous Pressure (JVP)
Inspection evaluates skin color, capillary refill time (<2 seconds), peripheral edema, and Jugular Venous Pressure (JVP), which estimates right atrial pressure:
- Positioning: Position the patient supine with the head of the bed elevated at 30 to 45 degrees.
- Landmarking: Measure the vertical distance from the highest point of internal jugular venous pulsation to the sternal angle of Louis.
- Clinical Significance: A vertical height greater than 3 cm above the sternal angle indicates elevated right atrial pressure, seen in right-sided heart failure, volume overload, hypervolemia, or cardiac tamponade.
2. Palpation
- Point of Maximal Impulse (PMI): Located at the 5th intercostal space (ICS) at the left midclavicular line (MCL). Lateral displacement indicates left ventricular enlargement or cardiomegaly.
- Thrills & Heaves: A thrill is a palpable vascular vibration associated with a loud murmur (Grade IV or higher). A heave is a sustained precordial impulse felt at the left sternal border indicating right ventricular hypertrophy.
3. Auscultation
Auscultation requires systematic evaluation across five anatomical areas using both the diaphragm and bell of the stethoscope:
| Anatomical Area | Chest Location | Primary Sounds & Murmurs Evaluated |
|---|---|---|
| Aortic Area | 2nd ICS, Right Sternal Border | S2 sound; Aortic Stenosis murmur |
| Pulmonic Area | 2nd ICS, Left Sternal Border | S2 splitting; Pulmonic Stenosis murmur |
| Erb's Point | 3rd ICS, Left Sternal Border | S1 & S2 integration; Aortic Insufficiency |
| Tricuspid Area | 4th ICS, Left Sternal Border | S1 sound; Tricuspid Regurgitation murmur |
| Mitral (Apical) Area | 5th ICS, Left Midclavicular Line | S1 sound, S3 gallop, S4 gallop; Mitral disorders |
- Normal Heart Sounds: S1 ('lub') marks mitral and tricuspid valve closure at systole onset. S2 ('dub') marks aortic and pulmonic valve closure at diastole onset.
- Extra Heart Sounds: S3 (Ventricular Gallop) is a low-frequency early diastolic sound reflecting elevated left ventricular filling pressures and heart failure. S4 (Atrial Gallop) occurs late in diastole, caused by atrial contraction against a stiff, non-compliant ventricle.
12-Lead ECG Placement & Lead System
Standard 12-lead ECG monitoring provides a 3-dimensional view of cardiac electrical activity. Precise lead placement prevents diagnostic errors such as false ST-segment shifts.
Precordial (Chest) Lead Placement
- V1: 4th Intercostal Space (ICS) at the Right Sternal Border.
- V2: 4th Intercostal Space (ICS) at the Left Sternal Border.
- V3: Positioned midway between lead V2 and lead V4.
- V4: 5th Intercostal Space (ICS) in the Left Midclavicular Line.
- V5: 5th Intercostal Space (ICS) in the Left Anterior Axillary Line.
- V6: 5th Intercostal Space (ICS) in the Left Midaxillary Line.
Special Lead Configurations
- Right-Sided ECG (V3R–V6R): Indicated in acute inferior wall MI (ST elevation in II, III, aVF) to detect Right Ventricular Infarction (V4R ST elevation). Nitrates and diuretics are avoided in RV MI due to strict preload dependence.
- Posterior ECG (V7–V9): Indicated when isolated ST depressions appear in V1–V3, placing leads along the posterior axillary (V7), scapular (V8), and paravertebral (V9) lines at the 5th ICS.
Systematic 5-Step ECG Interpretation Framework
Nurses apply a standardized 5-step framework to evaluate ECG rhythm strips:
- Step 1: Calculate Heart Rate: Divide 300 by the number of large 5 mm boxes between consecutive R-R intervals (300-150-100-75-60-50), or count QRS complexes in a 6-second strip and multiply by 10.
- Step 2: Assess Rhythm Regularity: Evaluate R-R interval consistency to determine if the rhythm is regular, regularly irregular, or irregularly irregular.
- Step 3: Analyze P Waves: Verify presence, upright morphology in Lead II, and 1:1 ratio with QRS complexes.
- Step 4: Measure PR Interval: Normal range is 0.12 to 0.20 seconds (3 to 5 small boxes). Prolongation (>0.20s) signifies First-Degree AV Block.
- Step 5: Measure QRS Duration & ST Segment: Normal QRS duration is <0.12 seconds (<3 small boxes). ST elevation ≥1 mm in 2 contiguous limb leads or ≥2 mm in precordial leads indicates acute transmural infarction (STEMI).
Common Arrhythmias & Clinical Management
Arrhythmia management follows National Resuscitation and First Aid Council (NRFAC) and Singapore MOH Clinical Practice Guidelines.
1. Atrial Fibrillation (AFib)
- ECG: Absent P waves, fibrillatory baseline, irregularly irregular ventricular response.
- Risks: Loss of atrial kick reduces cardiac output by 20–30%. Stasis of blood in the left atrial appendage increases stroke risk.
- Interventions: Administer IV Metoprolol or IV Diltiazem for rate control. Stratify stroke risk using the CHA₂DS₂-VASc score under Singapore MOH guidelines; a score ≥2 in men or ≥3 in women mandates oral anticoagulation (DOACs: Apixaban, Dabigatran, Rivaroxaban; or Warfarin INR 2.0–3.0). Perform synchronized cardioversion (50–100J) if unstable.
2. Ventricular Tachycardia (VT)
- ECG: Rapid rate (100–250 bpm), wide QRS complexes (>0.12s), absent P waves.
- Nursing Action: CHECK FOR A PULSE IMMEDIATELY.
- Pulseless VT: Treated as cardiac arrest. Initiate CPR, call Code Blue, attach defibrillator, and deliver an unsynchronized shock at 200J (biphasic). Give IV Adrenaline 1 mg Q3–5min and IV Amiodarone 300 mg per NRFAC protocols.
- Stable VT with Pulse: Administer IV Amiodarone 150 mg infusion over 10 minutes.
- Unstable VT with Pulse: Perform immediate synchronized cardioversion (100J) under sedation.
3. Ventricular Fibrillation (VF)
- ECG: Chaotic, irregular rhythm without recognizable waves; zero cardiac output.
- Management: High-quality CPR (100–120 compressions/min) + immediate unsynchronized defibrillation (200J biphasic).
4. Asystole & Pulseless Electrical Activity (PEA)
- Management: UNSHOCKABLE RHYTHMS. Do NOT defibrillate. Initiate high-quality CPR and IV Adrenaline 1 mg Q3–5min. Search for reversible causes using the 5 Hs and 5 Ts (Hypovolemia, Hypoxia, Hydrogen ion, Hypo/Hyperkalemia, Hypothermia; Tension pneumothorax, Tamponade, Toxins, Thrombosis PE, Thrombosis MI).
SNB Standards & Patient Safety
Under the SNB Code for Nurses and Midwives (2023), nurses must maintain alarm management standards to prevent alarm fatigue. Acute rhythm changes must be documented on a printed telemetry strip and escalated immediately to the medical officer using the ISBAR (Identify, Situation, Background, Assessment, Recommendation) communication tool.
When performing a standard 12-lead ECG on an adult patient, where should the nurse place the V4 electrode?
A patient in the coronary care unit suddenly displays Ventricular Tachycardia on the telemetry monitor. The nurse assesses the patient and confirms the absence of a carotid pulse. What is the immediate priority nursing action according to NRFAC resuscitation standards?
A nurse is managing a patient with newly diagnosed Atrial Fibrillation. According to Singapore MOH Clinical Practice Guidelines, which clinical tool is routinely utilized to assess thromboembolic stroke risk and determine the necessity for oral anticoagulation therapy?