Basics in anatomy and physiology of the heart

1. Anatomy and Physiology of the
Heart
DR. N. PRAVEEN
MD., DM (CARDIOLOGY)

2. Contents
 Anatomy of the heart
 Physiology of the heart
 Conduction system of the heart
 Arterial and Venous system
 Cardiac auscultation

4.  Normally located in the middle and slightly to the left side of the thoracic
cavity on the diaphragm between 3rd and 5th ribs.
 Weighs about 325 gm is males and about 275 gm in females.

5. Heart has ….
 Base
 Apex
 Anterior
 Posterior

7. It has …
 Four chambers
 Right Atrium
 Right Ventricle
 Left atrium
 Left ventricle

9. Right Atrium
 Receives venous blood from whole of
the body via the superior vena cava
(SVC) at its upper end and inferior vena
cava (IVC) at its lower end.
 It pumps into Right ventricle (RV)
through the tricuspid valve during the
ventricular diastole.
 Right atrial appendage – arises from the
antero superior part of the right atrium. It
is to the left of the ascending aorta.
 Sulcus terminalis – shallow vertical
groove along the right heart border
between SVC and IVC.
 RA and SVC junction – Sino atrial
node.

10. Right ventricle
 Triangular shaped or
crescent shaped
 Opens into pulmonary artery
through pulmonary valve
 Most anterior chamber
 RV wall measures 4-5 mm in
thickness.
 Three portions – inflow ,
outflow and apical trabecular
portion or body of RV.

11. Left atrium
 Posterior most chamber
 Receives oxygenated blood
from pulmonary veins
 Pulmonary veins open into
LA from the posterior wall
 Left atrial appendage is
anterior.

12. Left ventricle
 Bullet shaped
 Blunt tip forms the apex
of the heart
 LV wall is 8-15 mm in
thickness.

13. Three layers
 Outer Epicardium
 Middle Myocardium
 Inner Endocardium
 And a covering Pericardium

14. Pericardium
 The pericardial sac has two layers,
 a serous layer and
 a fibrous layer.
 It encloses the pericardial cavity which
contains pericardial fluid.
 The pericardium fixes the heart to the mediastinum, gives
protection against infection, and provides the lubrication for
the heart.
 The pericardial sac normally contains up to 50 mL of fluid.

15. Epicardium
 Outer most layer of the heart.
 Visceral layer of pericardium.

16. Myocardium
 Thicker middle layer of the heart
 Composed of individual heart
muscle cells called as
cardiomyocytes.
 Joined together by intercalated
disks
 Encased by collagen and other
substances forming the
extracellular matrix
(INTERSTITIUM).

17. Endocardium
 Its cells are embryologically and biologically similar to the
endothelial cells that line blood vessels.

18. Applied anatomy
 Pericarditis
 Pericardial effusion
 Pericardial window
 Pericardiectomy
 Constrictive Pericardits
 Myocarditis
 Interstitial myocarditis
 Infective endocarditis
 Epicardial pacing
 Myocardial biopsy

19. Four valves
 Mitral valve
 Aortic valve
 Tricuspid valve
 Pulmonic valve

20.  Mitral and tricuspid valves are called as ATRIOVENTRICULAR
valves.
 Mitral valve has two leaflets. (Anterior and Posterior)
 Tricuspid valve has three leaflets (Anterior, Septal and Posterior)
 Aortic and Pulmonary valves are called as SEMILUNAR valves.
 Aortic valve has three cusps right coronary cusp, left coronary cusp
and non coronary cusp.
 Pulmonic valve has three cusps.

23. Applied anatomy
 Mitral stenosis
 Mitral Valve prolapse
 Mitral regurgitation
 Tricuspid stenosis
 Tricuspid regurgitation
 Aortic stenosis
 Aortic regurgitation
 Pulmonic stenosis
 Pulmonic regurgitation

24. Two great arteries
 Aorta
 Pulmonary artery

25. Chest x ray correlation

26. Physiology of heart
 Systole - contraction
 Diastole – relaxation
 Atrial systole
 Atrial diastole
 Ventricular systole
 Ventricular diastole
 Systole is 0.3 sec
 Diastole is 0.5 sec
 Total cardiac cycle is 0.8 sec

28. Applied physiology
 Contraction of muscles occurs due to calcium influx.
 Increased contractility – positive inotropes – dobutamine
 Decreased contractility - negative inotropes – digoxin, beta
blockers
 Increased relaxation – lusitropic
 Decreased heart rate – chronotropic – calcium channel blockers
 Increased conduction – bromotropic

30. Cardiac output
 CO = SV X HR
 For a resting adult
CO = 70mL/beat x75beats/min
= 5250 mL/min
= 5.25 L/min

31. Stroke volume
 Regulation of stroke volume is by three factors
 PRELOAD
 CONTRACTILITY
 AFTERLOAD

32. Preload
 Stretch of cardiac muscle prior to
contraction.
 Frank-starling law
 Preload is propotional to End Diastolic
Volume
 If HR is more than 160 beats/min stroke
volume declines due to short filling time.

33. Contractility
 It is the strength of contraction
at any given preload.
 Positive and Negative
inotropics.
 Stimulation of sympathetic
division of ANS leads to positive
inotropic effect
 Inhibition of sympathetic
division of ANS leads to
negative inotropic effect

34. Afterload
 The pressure that must be overcome before a semilunar
valve can open is termed the afterload.
 Increase in afterload causes decrease in stroke volume
 HTN and atherosclerosis increases the afterload.

35. Sympathetic effect
 Releases norepinephrine

36. Parasympathetic Effect
 Left vagus nerve
 Releases acetylcholine
 Predominates during resting state

37. Conduction system of the heart

39. Vascular System
 Provide conduits for blood to travel from the heart to nourish
the body.
 Carry cellular wastes to the excretory organs.
 Return blood to the heart for recirculation.

40. Arterial System
 Delivers blood to various
tissues for nourishment
 Transport of cellular wastes
 Contribute to thermal
regulation

41. Arterial System
 Blood pressure
- force of blood exerted against the vessel walls
= CO x Peripheral Vascular Resistance
- regulated by:
 autonomic nervous system (ANS)
 kidneys (renin-angiotensin-aldosterone)
 endocrine system (catecholamines, kinins,
serotonin, histamine)

42. Palpation of arteries

43. Blood Pressure
 Systolic:
- amount of pressure/force generated by LV to distribute
blood into the aorta with each contraction of the heart
- it is between 90 – 135 mmHg (120)
- affected by CO and arterial distention.
 Diastolic:
- amount of pressure/force sustained by the arteries during
the relaxation phase of the heart
- ability of the heart to rest while filling with blood
- affected by peripheral vascular resistance
- it is between 60 – 85 mmHg (80)

44. Blood Pressure
 Written as SBP /DBP
 Units mm Hg
 Mean Blood Pressure – {DBP + 1/3
PP}
 Pulse pressure – SBP - DBP

45. Classification of Hypertension

46. Venous System
 Series of veins located
adjacent to arterial system
 Veins collect blood from
the capillaries & terminal
arterioles
 Acts as reservoir for blood
 Low-pressure, collapsible
system that work against
effects of gravity

47. Jugular Venous Pulse

48. Cardiac auscultation
Heart Sounds
 Produced from blood turbulence caused by closing of the heart
valves
 S1 – atrioventricular valve closure LUB
 S2 – semilunar valve closure DUB
 S3 – rapid ventricular filling
 S4 – atrial systole
 S3 is physiological less than 30 years of age.
 S4 is usually pathological.

53. AS murmur

54. AR murmur

56. Thank you