Normal Cardiac Anatomy & Physiology - Echo Notebook

CV System Overview

• CV system functions: \text{transport blood, gases, nutrients & waste; prevent infection; thermoregulation; fluid balance} rt as a two-sided pump:

  • Left heart: receives oxy blood from pulmonary circuit; pumps to systemic circuit; maintains blood pressure (BP).

  • Right heart: receives deoxy blood from systemic circuit; pumps to pulmonary circuit.

• Heart location basics:

  • Base: superior, rotates posterior, toward the right.

  • Apex: inferior, rotates anterior, toward the left.

• Pericardium & heart wall:

  • Pericardium: fibrous layer + serous layer (parietal and visceral).

  • Heart wall: epicardium, myocardium, endocardium.

  • Pericardial effusion accumulates in the pericardial space.

NORMAL CARDIAC ANATOMY & PHYSIOLOGY (Key Concepts)

• Circulatory connections: connection of systemic and pulmonary circuits via the heart to perform the CV functions.

• Cardiac cycle basics: diastole (relaxation & filling) vs systole (contraction & ejection).

• Coronary, venous, and conduction systems provide nourishment, return, and rhythm to the heart.

CHAMBERS, VESSELS & VALVES

• Chambers:

  • 2 atria (RA, LA) and 2 ventricles (RV, LV).

  • Atrial appendages (RAA, LAA) and fossa ovalis in IAS.

  • Interventricular septum (IVS) separates ventricles; LV walls thicker than RV.

• Valves:

  • Atrioventricular (AV) valves: Tricuspid (TV) between RA & RV; Mitral (MV) between LA & LV.

  • Semilunar (SL) valves: Pulmonary (PV) between RV & PA; Aortic (AOV) between LV & AO.

  • MV leaflets: PMVL (posteromedial) and AMVL (anterior) with chordae tendineae & papillary muscles.

  • TV leaflets: anterior, medial/septal, posterior.

• Great vessels & flow origins:

  • Superior vena cava (SVC) and Inferior vena cava (IVC) drain into RA.

  • Pulmonary veins (PV4) drain into LA.

  • Aorta (AO) and pulmonary artery (PA) exit the heart via SL valves.

ORDER OF FLOW THROUGH THE HEART

• Sequence (start at SVC):

  • SVC → RA → TV → RV → PV → PA → Lungs → PV4 → LA → MV → LV → AOV → AO.

• Notes:

  • Right heart receives systemic venous return; left heart receives pulmonary venous return.

  • Pulmonary veins carry oxygenated blood back to LA.

VALVES: STRUCTURE & FUNCTION

• AV valves (TV, MV):

  • Largest leaflets; diastolic valves open during filling.

  • MV leaflets: PMVL & AMVL; chordae tendineae & papillary muscles prevent prolapse.

  • MV area (MVA): $4-6\ \mathrm{cm^2}$; MV velocity: $0.6-1.3\ \mathrm{m/s}$.

• SL valves (PV, AOV):

  • 3 cusps each; systolic valves open to allow ejection.

  • AOV area (AVA): $1-1.7\ \mathrm{cm^2}$; AOV velocity: $1-1.7\ \mathrm{m/s}$.

  • PV velocity: $0.6-0.9\ \mathrm{m/s}$.

• Valve annulus, tissue, chordae, papillary muscles are critical for function.

VALVE AREAS & SPEEDS (Quick Reference)

• MV: area $MVA = 4-6\ \mathrm{cm^2}$; velocity $0.6-1.3\ \mathrm{m/s}$

• TV: TVA $7-9\ \mathrm{cm^2}$; velocity $0.3-0.7\ \mathrm{m/s}$

• PV: area notated with velocity $0.6-0.9\ \mathrm{m/s}$

• AOV: area $AVA = 1-1.7\ \mathrm{cm^2}$; velocity $1-1.7\ \mathrm{m/s}$

PRESSURE & CARDIAC CYCLE (Essentials)

• Chamber pressures (typical ranges):

  • RA mean/mean: $2-8\ \mathrm{mmHg}$; RA O2 sat: $75\%$

  • RV systolic: $15-25\ \mathrm{mmHg}$; RV diastolic: $2-8\ \mathrm{mmHg}$

  • PA systolic: $15-25\ \mathrm{mmHg}$; PA diastolic: $4-12\ \mathrm{mmHg}$; PA mean: often $15-25\ \mathrm{mmHg}$

  • LAP (LA pressure): mean $2-12\ \mathrm{mmHg}$; LA O2 sat: $98\%$

  • LV systolic: < $120\ \mathrm{mmHg}$; LV diastolic: $3-12\ \mathrm{mmHg}$

  • AO systolic: < $120\ \mathrm{mmHg}$; AO diastolic: < $80\ \mathrm{mmHg}$; AO O2 sat: $98\%$

• Cardiac cycle phases (simplified):

  • Diastole: AV valves open; rapid filling, diastasis, atrial kick.

  • Isovolumic relaxation time (IVRT): ventricles relax with no volume change.

  • Systole: SL valves open; ejection occurs.

  • Isovolumic contraction (IVCT): ventricles contract with closed valves, volume constant.

CARDIAC FUNCTION & INFLUENCES

• Cardiac output (CO) relation:

  • $\mathrm{CO} = \mathrm{HR} \times \mathrm{SV}$

  • $\mathrm{SV} = \mathrm{EDV} - \mathrm{ESV}$

  • $\mathrm{CI} = \dfrac{\mathrm{CO}}{\mathrm{BSA}}$

• Preload (EDV/EDP): relates to initial fiber stretch; Frank-Starling law.

• Afterload: resistance heart must pump against; higher afterload increases myocardial work.

• Inotropic (contractility) and chronotropic effects regulate force and rate.

• Post-extrasystolic potentiation (PESP): preload changes after extra beats affect contractility.

AUTONOMIC NERVOUS SYSTEM & MEN

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• Sympathetic: increases HR and contractility.

• Parasympathetic: decreases HR.

PHYSIOLOGY OF CONDUCTION & EKG

• Conduction system components:

  • SA node: primary pacemaker; paced rate ~$60-100\ \text{bpm}$; near the border of SVC & RA.

  • AV node: slows conduction to allow ventricular filling; pacemaker rate ~$40-60\ \text{bpm}$ if SA fails.

  • Bundle of His: travels through IVS; divides into R & L bundles to ventricles.

  • Purkinje fibers: spread depolarization to ventricles.

• EKG basics:

  • P wave: atrial depolarization.

  • QRS complex: ventricular depolarization.

  • T wave: ventricular repolarization.

  • R–R interval: normal is $3-5\ \text{large boxes}$ (roughly $60-100\ \text{bpm}$).

  • PR interval: < $1\ \,text{large box}$ (< $0.2\ \text{s}$).

• Electrical-mechanical relationship: electrical events (EKG) align with mechanical events (contraction/relaxation) via a delay.

CONDUCTION SYSTEM RATES (SPECIAL NOTES)

• SA node pace: $60-100\ \text{bpm}$

• AV node pace: $40-60\ \text{bpm}$

• Purkinje/ventricular pacemaking if needed: down to $20-40\ \text{bpm}$

CORONARY CIRCULATION & DOMINANCE

• Coronary arteries originate from the aortic root sinuses:

  • Right coronary artery (RCA)

  • Left coronary artery (LCA)

• Dominance depends on which artery supplies the posterior descending artery (PDA): most individuals are right-dominant; others are left-dominant or codominant.

QUICK REFERENCE: POPULAR NUMBERS & TERMS (Reminders)

• Blood pressure categories (as listed in the source):

  • Normal: \text{Systolic} = 120, \text{Diastolic} < 80

  • Elevated: 120-129, <80

  • Stage 1 HTN: $130-139 or 80-89$

  • Stage 2 HTN: $140+ or 90+$

  • HTN crisis: as described in the material

• Common units: $\mathrm{mmHg}$ for pressures, $\mathrm{cm^2}$ for valve areas, $\mathrm{m/s}$ for velocities.

• Basic relationships to recall during last-minute review:

  • $\mathrm{CO} = \mathrm{HR} \times \mathrm{SV}$

  • $\mathrm{SV} = \mathrm{EDV} - \mathrm{ESV}$

  • $\mathrm{CI} = \dfrac{\mathrm{CO}}{\mathrm{BSA}}$

• Primary chamber pressure cues:

  • RA: $2-8\ \mathrm{mmHg}$ (mean)

  • RV systolic: $15-25\ \mathrm{mmHg}$

  • PA systolic: $15-25\ \mathrm{mmHg}$; PA diastolic: $4-12\ \mathrm{mmHg}$

  • LAP / LV diastolic: $2-12\ \mathrm{mmHg}$

  • LV systolic: < $120\ \mathrm{mmHg}$

  • AO systolic: < $120\ \mathrm{mmHg}$

• Chamber roles:

  • RA: reservoir for systemic & coronary venous return; aids RV filling

  • LA: reservoir; passageway to LV; LA appendage (LAA) can be thrombus-prone

  • LV: main pump with thick walls; LVOT & LV inflow tract

• Valve terminology quick cues:

  • MV leaflets: PMVL & AMVL; 2 commissures; chordae tendineae & papillary muscles

  • TV leaflets: anterior, medial/septal, posterior

  • AV valves open during diastole; SL valves open during systole

REFERENCES TO VOCABULARY (for quick recall)

• Base vs Apex定位: base superior/posterior; apex inferior/anterior

• Pericardial space location for effusion: around the heart within the pericardial cavity

• Conduction nodes: SA node, AV node, Bundle of His, Purkinje fibers