1. Cardiac Cycle 2. Tabulate Inspection, Palpation, Percussion, Auscultation findings for : - MS - MR - AS - AR - TS - TR - PS - PR - ASD - VSD - TOF - PDA
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1. THE CARDIAC CYCLE
(Sources: Costanzo Physiology 7e; Guyton & Hall Textbook of Medical Physiology)
The cardiac cycle encompasses all mechanical and electrical events from the beginning of one heartbeat to the beginning of the next. At 72 bpm, one complete cycle = ~0.833 sec. It is divided into 7 phases:
Phases of the Cardiac Cycle
Phase A - Atrial Systole
- Trigger: P wave (atrial depolarization)
- Events: Atria contract → LA pressure rises → final "top-up" of ventricular filling through open mitral valve → LV volume increases slightly
- Venous pulse: a wave (reflected rise from LA into veins)
- Heart sound: S4 (not audible normally; heard in ventricular hypertrophy/reduced compliance)
- Valves: Mitral + tricuspid OPEN; aortic + pulmonic CLOSED
Phase B - Isovolumetric Ventricular Contraction (IVC)
- Trigger: QRS complex (ventricular depolarization)
- Events: Both ventricles contract → LV pressure rises sharply → mitral valve closes (LV pressure exceeds LA pressure) → ALL valves closed → ventricular volume is CONSTANT (no ejection yet)
- Heart sound: S1 (closure of mitral + tricuspid valves; mitral component louder)
- Duration: ~0.05 sec
Phase C - Rapid Ventricular Ejection
- Trigger: ST segment
- Events: LV pressure exceeds aortic pressure → aortic valve OPENS → rapid ejection of ~70% of stroke volume → ventricular volume decreases sharply → aortic pressure rises to peak (~120 mmHg)
- Heart sound: None normally (ejection sounds may be heard in certain pathologies)
- Valves: Aortic + pulmonic OPEN
Phase D - Reduced Ventricular Ejection
- Trigger: T wave (ventricular repolarization begins)
- Events: Ventricles begin to relax → ejection rate slows → remaining ~30% of stroke volume ejected → LV volume reaches its minimum (end-systolic volume, ~50 mL) → aortic pressure starts to fall as blood runs off to periphery
- Heart sound: None
Phase E - Isovolumetric Ventricular Relaxation (IVR)
- Trigger: After T wave
- Events: Ventricles relax → LV pressure falls below aortic pressure → aortic valve CLOSES → incisura (dicrotic notch) on aortic pressure curve → all valves closed again → ventricular volume remains constant (minimum)
- Heart sound: S2 (closure of aortic + pulmonic valves; A2 before P2)
- Duration: ~0.08 sec
Phase F - Rapid Ventricular Filling
- Trigger: After IVR
- Events: LV pressure falls below LA pressure → mitral valve OPENS → rapid passive filling (pressure gradient drives blood from LA → LV) → LV volume increases rapidly → ventricular pressure stays low
- Heart sound: S3 (may be physiologic in children/young adults; pathologic in heart failure if heard in adults >40 y)
- Venous pulse: y descent (LA empties rapidly)
Phase G - Reduced Ventricular Filling (Diastasis)
- Events: Filling slows as pressure gradient equalizes → slow continued filling → LA and LV pressures equalize → cycle ends just before next P wave
Key Summary Table - Cardiac Cycle
| Phase | Valves | LV Volume | LV Pressure | ECG | Heart Sound |
|---|---|---|---|---|---|
| Atrial Systole | MV open, AoV closed | ↑ (slightly) | Slight ↑ | P wave | S4 |
| Isovolumetric Contraction | ALL closed | Unchanged | ↑ rapidly | QRS | S1 (MV closes) |
| Rapid Ejection | AoV open | ↓ rapidly | ↑ to peak | ST segment | - |
| Reduced Ejection | AoV open | ↓ to minimum | Starts ↓ | T wave | - |
| Isovolumetric Relaxation | ALL closed | Unchanged | ↓ rapidly | After T | S2 (AoV closes) |
| Rapid Filling | MV open | ↑ rapidly | Low, stable | - | S3 |
| Diastasis | MV open | ↑ slowly | Equalizes | - | - |
MV = Mitral valve; AoV = Aortic valve
Wiggers Diagram - Key Points
- End-Diastolic Volume (EDV): ~120-130 mL
- End-Systolic Volume (ESV): ~50-60 mL
- Stroke Volume (SV): EDV - ESV = ~70 mL
- Ejection Fraction (EF): SV/EDV = ~55-65%
- Cardiac Output: HR × SV = 72 × 70 mL ≈ 5 L/min
2. CLINICAL FINDINGS IN CARDIAC CONDITIONS
Abbreviations Key
INSPECTION | PALPATION | PERCUSSION | AUSCULTATION
- JVP = Jugular venous pressure | Apex = Apical impulse | S1/S2 = Heart sounds | OS = Opening snap
- LV = Left ventricle | RV = Right ventricle | TAR = Tracheal deviation | LH = Liver
VALVULAR HEART DISEASE
MS - Mitral Stenosis
| Domain | Findings |
|---|---|
| Inspection | Malar flush (mitral facies - due to low CO and cutaneous vasodilation) |
| Palpation | Apex - tapping (undisplaced, "palpable S1") |
| Percussion | Cardiac dullness not significantly displaced (LV small/normal) |
| Auscultation | S1 - loud, accentuated (leaflet excursion is large before snapping shut) |
Memory tip: MS = Loud S1, Opening Snap, Mid-diastolic rumble, Pre-systolic accentuation
MR - Mitral Regurgitation
| Domain | Findings |
|---|---|
| Inspection | Dyspnea, fatigue |
| Palpation | Apex - displaced laterally and downward (LV dilatation) |
| Percussion | Increased area of cardiac dullness to left (LV enlarged) |
| Auscultation | S1 - soft or absent (leaflets fail to coapt normally before closure) |
AS - Aortic Stenosis
| Domain | Findings |
|---|---|
| Inspection | Pale; narrow pulse pressure |
| Palpation | Apex - sustained/heaving, not significantly displaced (concentric LVH) |
| Percussion | Cardiac dullness not greatly enlarged (concentric hypertrophy without dilation initially) |
| Auscultation | Ejection systolic (crescendo-decrescendo) murmur at 2nd RICS, radiates to carotids; harsh/rough quality; peaks in mid-to-late systole in severe AS |
AR - Aortic Regurgitation
| Domain | Findings |
|---|---|
| Inspection | Wide pulse pressure (systolic HTN + low diastolic); water-hammer/collapsing pulse (de Musset's sign - head bobbing; Quincke's sign - capillary pulsations in nail bed; Traube's sign - pistol shot sounds over femoral artery) |
| Palpation | Apex - displaced inferolaterally (volume overload → LV dilatation) |
| Percussion | Increased area of cardiac dullness to left (markedly enlarged LV - "cor bovinum") |
| Auscultation | Early diastolic murmur (EDM) - decrescendo, high-pitched, blowing; best heard at LLSB (3rd LICS) with patient leaning forward, breath held in expiration |
TS - Tricuspid Stenosis
| Domain | Findings |
|---|---|
| Inspection | Raised JVP with prominent a wave (forceful atrial contraction against stenosed valve) |
| Palpation | Liver pulsatile (presystolic pulsation) |
| Percussion | Hepatomegaly (percuss liver dullness) |
| Auscultation | Mid-diastolic murmur at lower LSB (4th LICS) |
TR - Tricuspid Regurgitation
| Domain | Findings |
|---|---|
| Inspection | Raised JVP with giant cv wave (systolic venous pulsation; "v" wave fuses with "c") |
| Palpation | Liver pulsatile in systole (systolic hepatic pulsation) |
| Percussion | Hepatomegaly |
| Auscultation | Pansystolic murmur at lower LSB (LLSB, 4th LICS) |
PS - Pulmonary Stenosis
| Domain | Findings |
|---|---|
| Inspection | Usually asymptomatic until severe |
| Palpation | Right parasternal heave (RV pressure overload → RV hypertrophy) |
| Percussion | Cardiac dullness relatively normal |
| Auscultation | Ejection systolic (crescendo-decrescendo) murmur at 2nd LICS (pulmonary area), radiates to left shoulder |
PR - Pulmonary Regurgitation
| Domain | Findings |
|---|---|
| Inspection | Usually asymptomatic unless severe or due to PH |
| Palpation | Right parasternal heave (if PH and RV overload) |
| Percussion | Relatively normal |
| Auscultation | Graham-Steell murmur (if due to PH) - early diastolic, high-pitched, blowing, decrescendo; at 2nd LICS, increases with inspiration; begins with P2 |
CONGENITAL HEART DISEASE
ASD - Atrial Septal Defect
| Domain | Findings |
|---|---|
| Inspection | Often asymptomatic in childhood |
| Palpation | Right parasternal heave (RV volume overload) |
| Percussion | Dullness shifted right (LA + RA enlargement) |
| Auscultation | Fixed wide splitting of S2 (hallmark) - splitting does not vary with respiration (equalization of RV filling between inspiration and expiration due to atrial communication) |
VSD - Ventricular Septal Defect
| Domain | Findings |
|---|---|
| Inspection | Small VSD (maladie de Roger): asymptomatic |
| Palpation | Systolic thrill at lower LSB (3rd-4th LICS) - best palpable finding |
| Percussion | Increased area of cardiac dullness (biventricular enlargement in large VSDs) |
| Auscultation | Pansystolic murmur at lower LSB (3rd-4th LICS); harsh; radiates across precordium |
TOF - Tetralogy of Fallot
(4 components: PS + VSD + Overriding aorta + RVH)
| Domain | Findings |
|---|---|
| Inspection | Central cyanosis from birth (R→L shunt through VSD) |
| Palpation | Right parasternal heave (RVH) |
| Percussion | "Boot-shaped" heart on CXR (not percussion, but anatomy: upturned apex from RVH, concave PA segment) |
| Auscultation | Ejection systolic murmur at upper LSB (RVOT obstruction murmur) |
PDA - Patent Ductus Arteriosus
| Domain | Findings |
|---|---|
| Inspection | Small PDA: asymptomatic |
| Palpation | Hyperdynamic apex (LV volume overload) |
| Percussion | Cardiac dullness increased to left (LV + LA enlargement in significant PDA) |
| Auscultation | Continuous ("machinery") murmur - Gibson's murmur; best heard at left infraclavicular area/2nd LICS; peaks at S2 (maximum L→R gradient is during systole and early diastole); heard throughout systole AND diastole, hence "continuous" |
Quick Reference Summary Table
| Condition | Key Murmur | Timing | Best Heard | Special Signs |
|---|---|---|---|---|
| MS | Mid-diastolic rumble + pre-systolic accentuation | Diastole | Apex (LLD position) | Loud S1, OS, Malar flush |
| MR | Pansystolic | Systole | Apex → axilla | Soft S1, S3, displaced apex |
| AS | Ejection systolic (cresc-decresc) | Systole | 2nd RICS → carotids | Ejection click (bicuspid), Soft A2, S4, pulsus parvus et tardus |
| AR | Early diastolic decrescendo | Diastole | LLSB (lean forward) | Austin-Flint, collapsing pulse, wide PP |
| TS | Mid-diastolic (↑ inspiration) | Diastole | LLSB | Prominent a wave in JVP, OS |
| TR | Pansystolic (↑ inspiration) | Systole | LLSB | Giant cv wave, pulsatile liver |
| PS | Ejection systolic | Systole | 2nd LICS | EC decreases on inspiration, wide S2 split |
| PR | Early diastolic (Graham-Steell) | Diastole | 2nd LICS | Loud P2 (if PH) |
| ASD | Ejection systolic (pulm flow) | Systole | 2nd LICS | Fixed wide S2 split |
| VSD | Pansystolic (harsh) | Systole | 3rd-4th LICS | Systolic thrill, loud P2 if Eisenmenger's |
| TOF | Ejection systolic (RVOT) | Systole | Upper LSB | Single S2, cyanosis, squatting, clubbing |
| PDA | Continuous "machinery" | Systole + Diastole | 2nd LICS/infraclavicular | Differential cyanosis (Eisenmenger's), bounding pulse |
Sources: Costanzo Physiology 7e; Guyton & Hall Textbook of Medical Physiology; Harrison's Principles of Internal Medicine 22e; Braunwald's Heart Disease; Fuster and Hurst's The Heart 15e; Goldman-Cecil Medicine
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