Heart Sounds, Murmurs, and Hemodynamic Cardiac Cycles

Comprehensive vocabulary flashcards covering heart sounds, auscultation landmarks, abnormal splitting patterns, murmurs, systolic and diastolic parameters, and cardiac cycle hemodynamics.

Stethoscope Auscultation Areas

The four standard thoracic landmarks for evaluating heart sounds: Aortic area ($2\text{nd}\text{--}3\text{rd}$ right interspace), Pulmonic area ($2\text{nd}\text{--}3\text{rd}$ left interspace), Tricuspid area (left lower sternal border), and Mitral area (apex).

First Heart Sound ($S_1$)

A high-frequency sound ("LUB") caused by the closure of the atrioventricular (mitral and tricuspid) valves at the onset of systole; loudest near the apex or mitral area. Loudness and timing are determined by distance between valve leaflets at the start of systole, leaflet mobility, and the rate of rise of ventricular pressure.

Second Heart Sound ($S_2$)

A low-frequency sound ("DUB") caused by the closure of the semilunar valves, consisting of an aortic component ($A_2$) and a pulmonary component ($P_2$).

Physiological Splitting

Normal respiratory variation in $S_2$ where $A_2$ and $P_2$ are fused during expiration and split during inspiration; inspiration lowers intrathoracic pressure, increasing venous return to delay $P_2$, while decreasing venous return to the left ventricle causes earlier $A_2$.

Widened Splitting

An abnormal splitting pattern characterized by delayed pulmonic valve ($P_2$) closure that persists during expiration with only slight respiratory variation, commonly caused by right bundle branch block (RBBB) due to slow contraction or pulmonic stenosis due to slow ejection.

Fixed Splitting

A wider than normal split of $S_2$ with no respiratory variation, caused by right-sided volume overload that leads to a persistent low-resistance state delaying $P_2$ closure, classic for an atrial septal defect (left-to-right shunt).

Paradoxical Splitting

An abnormal splitting pattern where a split $S_2$ is heard on expiration and disappears on inspiration due to reversed order of valve closure ($P_2$ precedes $A_2$); caused by delayed left ventricular contraction or prolonged ejection time such as in left bundle branch block (LBBB) or advanced aortic stenosis.

Ejection Click

An extra systolic heart sound caused by aortic or pulmonic valve stenosis, generated when stenotic valve leaflets reach their elastic limit during opening.

Mid/Late Systolic Click

An extra systolic heart sound caused by mitral valve prolapse (MVP) or tricuspid valve prolapse (TVP), produced as the leaflets prolapse back into the atrium.

Opening Snap (OS)

A sharp, high-pitched extra diastolic sound heard in mitral stenosis or tricuspid stenosis, generated by the abrupt opening of rigid valve leaflets.

Third Heart Sound ($S_3$)

A low-pitched early diastolic "rumbling" sound (ventricular gallop) occurring during rapid ventricular filling. Normal in children and young adults due to chordae tendineae tensing in a healthy ventricle; abnormal in middle-aged or older patients due to volume overload slapping into a dilated ventricle.

Fourth Heart Sound ($S_4$)

A low-pitched late diastolic "vibrations" sound (atrial gallop) corresponding with the "a" kick, caused by atrial contraction into a stiff, non-compliant ventricle; typically denotes left ventricular hypertrophy or ischemia.

Summation Gallop

The acoustic phenomenon occurring during tachycardia when shortened diastole causes $S_3$ and $S_4$ to fuse into a single sound.

Pericardial Knock

A rare early diastolic sound caused by ventricular filling halting abruptly due to the inability of the heart to expand against a hardened, calcified pericardial sac in severe constrictive pericarditis.

Cardiac Murmur

Any sound produced by turbulent blood flow within the heart or blood vessels, caused by flow across an obstruction (stenotic valve), regurgitant flow, increased flow (e.g., pregnancy), shunts, or ejection into a dilated chamber.

Murmur Intensity Grading (Systolic)

A six-grade numerical scale for murmurs: Grade 1 (very faint, may not be heard everywhere), Grade 2 (quiet, but heard immediately), Grade 3 (moderately loud), Grade 4 (loud, may have palpable thrill), Grade 5 (very loud, definite thrill, heard with light application of stethoscope), and Grade 6 (very loud, heard with stethoscope lifted off chest).

Continuous Murmur

A murmur that extends throughout systole and diastole without interruption, exhibiting a crescendo-decrescendo shape across the cardiac cycle, classically caused by patent ductus arteriosus (PDA).

To-and-Fro Murmur

A combination of distinct systolic and diastolic murmurs (such as aortic stenosis and aortic regurgitation, or pulmonic stenosis and pulmonic regurgitation) where sound occurs in both phases but does not extend continuously through all of diastole.

Systolic Function

The ability of the ventricles to efficiently eject blood into the systemic and pulmonary vasculature via myocardial thickening and inward motion ("the squeeze"), representing contractility and inotropic state.

Stroke Volume (SV)

The volume of blood ejected with each ventricular contraction, typically approximately $60\text{--}100\,\text{ml}$ per beat; calculated as $\text{SV} = \text{EDV} - \text{ESV}$.

Wall Motion Terminology (WMA)

Echocardiographic descriptions of regional myocardial contractility: hyperkinetic (excessive motion), hypokinetic (decreased motion), akinetic (no movement or thickening), and dyskinetic (paradoxical outward systolic movement).

Cardiac Output (CO)

The volume of blood pumped per minute, calculated as $\text{CO} = \text{SV} \times \text{HR}$. Normal resting value is typically $4\text{--}8\,\text{L/min}$, increasing dynamically up to $20\,\text{L/min}$ or higher during exercise.

Cardiac Index (CI)

A hemodynamic parameter that normalizes cardiac performance to an individual's body surface area ($\text{BSA}$), calculated as $\text{CI} = \frac{\text{CO}}{\text{BSA}}$; the normal range is $3\text{--}4\,\text{L/min/m}^2$.

Ejection Fraction (EF)

The percentage or fraction of left ventricular volume ejected during systole, averaging a normal range of $55\text{--}75\%$. Calculated via M-mode/2D formulas as $\text{EF} = \frac{\text{LVIDd}^2 - \text{LVIDs}^2}{\text{LVIDd}^2} \times 100\%$.

Fractional Shortening (FS)

A linear 1-D dimension estimation of left ventricular systolic function ("EF without the squaring"), normally $25\text{--}45\%$, calculated as $\text{FS} = \frac{\text{LVIDd} - \text{LVIDs}}{\text{LVIDd}} \times 100\%$.

Preload

The stretch placed on myocardial fibers before contraction at end-diastole; determined by total blood volume, venous return, valves, atrial contraction, respiration, heart rate (filling time), and PR interval.

Frank-Starling Principle

The physiological relationship stating that the greater the ventricular end-diastolic volume (preload), the greater the force of the subsequent systolic contraction.

Afterload

The tension or resistance against which the ventricles must pump to eject blood into the systemic or pulmonary circulation; shares an inverse relationship with stroke volume and is increased in hypertension and aortic stenosis.

Diastolic Function

The ability of the ventricles to relax and fill to an adequate volume without an abnormal increase in intracavity filling pressures across four sequential phases: IVRT, rapid filling, diastasis, and atrial kick.

Mitral Inflow Doppler Profile

Pulsed-wave Doppler waveform of left ventricular filling, featuring the E wave representing early rapid passive filling ($80\%$ of ventricular filling) and the A wave representing late active filling from atrial contraction ($20\%$ of ventricular filling).

Isovolumic Relaxation Time (IVRT)

The phase of early diastole between semilunar (aortic) valve closure and atrioventricular (mitral) valve opening, where ventricular pressure decreases precipitously without any change in volume.

Isovolumic Contraction

The phase of early mechanical systole between atrioventricular (mitral) valve closure and semilunar (aortic) valve opening, during which all cardiac valves are closed and ventricular pressure rises steeply at constant volume.

Diastasis

The quiescent middle phase of diastole during which pressures in the atrium and ventricle approach equilibrium, resulting in minimal blood inflow before atrial contraction occurs.

Atrial Kick

The active final phase of diastole following the ECG P-wave, in which atrial contraction contributes the final $20\%$ of left ventricular end-diastolic volume.

Normal Left Heart Pressure Ranges

Standard hemodynamic pressures: Aorta is $120/80\,\text{mmHg}$, Left Ventricle is $120/10\,\text{mmHg}$, and Left Atrium is $3\text{--}12\,\text{mmHg}$.

QT Interval

The segment on the electrocardiogram extending from the start of the Q-wave to the end of the T-wave, corresponding temporally to ventricular electrical activity and mechanical systole.