Cardiac Reference
Quick-reference material for licensed nurses and students. Values are drawn from commonly cited clinical guidelines and nursing references — always verify against your facility protocols. About our editorial standards · Report a correction
Normal Hemodynamic Values
| Parameter |
Normal Range |
Units |
| CO |
4–8 |
L/min |
| CI |
2.5–4.0 |
L/min/m² |
| SVR |
800–1200 |
dyn·s/cm⁵ |
| PVR |
150–250 |
dyn·s/cm⁵ |
| CVP |
2–6 |
mmHg |
| PAP systolic |
15–25 |
mmHg |
| PAP diastolic |
8–15 |
mmHg |
| PAP mean |
10–20 |
mmHg |
| PCWP |
6–12 |
mmHg |
| MAP |
70–105 |
mmHg |
| EF |
55–70 |
% |
Heart Sounds
| Sound |
Location |
Description |
| S1 |
Apex (mitral area) |
Closure of AV valves (mitral, tricuspid); marks start of systole; "lub" |
| S2 |
Base (aortic, pulmonic areas) |
Closure of semilunar valves (aortic, pulmonic); marks start of diastole; "dub" |
| S3 (ventricular gallop) |
Apex |
Early diastole; rapid ventricular filling; may indicate HF in adults |
| S4 (atrial gallop) |
Apex |
Late diastole; atrial contraction into stiff ventricle; may indicate hypertrophy |
| Murmurs |
Varies |
Classified by timing (systolic/diastolic), location, intensity (1–6), pitch, quality |
EKG/ECG Basics
Normal Intervals
| Interval |
Normal Range |
| PR interval |
0.12–0.20 s |
| QRS |
<0.12 s |
| QT interval |
0.36–0.44 s |
Common Rhythms
| Rhythm |
Rate |
Regularity |
Description |
| Normal Sinus |
60–100 |
Regular |
Normal; P before each QRS, PR <0.20s |
| Sinus Brady |
<60 |
Regular |
Slow but normal conduction |
| Sinus Tach |
>100 |
Regular |
Fast but normal conduction |
| A-fib |
Variable |
Irregularly irregular |
No P waves; chaotic atrial activity |
| A-flutter |
Variable (often 150) |
Regular or variable |
Sawtooth flutter waves |
| SVT |
150–250 |
Regular |
Narrow QRS; often P buried in QRS |
| V-tach |
100–250 |
Regular |
Wide QRS; no P waves; life-threatening |
| V-fib |
— |
Chaotic |
No organized rhythm; CPR + defibrillation |
| Asystole |
— |
— |
Flat line; no electrical activity |
| PEA |
Any |
Any |
Organized electrical activity but no pulse |
Cardiac Enzymes Timeline
| Marker |
Onset |
Peak |
Duration |
| Troponin I |
2–4 hours |
12–24 hours |
5–10 days |
| CK-MB |
3–6 hours |
12–24 hours |
2–3 days |
| Myoglobin |
1–2 hours |
4–8 hours |
24 hours |
Coronary Arteries
| Artery |
Supplies |
| LAD (Left Anterior Descending) |
Anterior wall |
| LCx (Left Circumflex) |
Lateral wall |
| RCA (Right Coronary Artery) |
Inferior wall |
References
Public cardiovascular and hemodynamic references.
Medical Disclaimer
The content on this page is provided for educational and quick-reference purposes only and does not constitute medical advice. It is not a substitute for professional clinical judgment, your facility's protocols, or the guidance of a qualified licensed healthcare provider. Always verify dosages, reference ranges, and protocols against current evidence-based clinical guidelines and institutional policy before providing care. rnref.com makes no warranty regarding the accuracy or completeness of this information and is not liable for clinical decisions made based on it. See our Terms of Service, Privacy Policy, and Accessibility Statement.