1. Anatomy
    2. 1. Mediastinum
    2. The Heart Development
    3. Pericardium
    4. Features of the Heart
    5. Arterial Supply of Heart
    6. Venous Drainage of the Heart
    7. Conducting System of Heart
    8. Nervous System of Heart
    9. Foetal Circulation and Changes at Birth
    10. Microscopic Structure of Heart
    11. Arteries
    12. Arch of Aorta
    13. Descending Thoracic Artery
    14. Abdominal Aorta
    15. Subclavian Artery
    16. Axiallary Artery
    17. Internal Thoracic Artery
    18. Brachial Artery
    19. Radial Artery
    20. Ulnar Artery
    21. Palmar Arches
    22. External Iliac Artery
    23. Internal Iliac Artery
    24. Femoral Artery
    25. Popliteal Artery
    26. Posterior Tibial Artery
    27. Anterior Tibial Artery
    28. Dorsalis Pedia Artery
    29. Common Carotid Artery
    30. External Carotid Artery
    31. Internal Carotid Artery
    32. Veins
    33. Internal Jugular Vein
    34. External Jugular Vein
    35. Superior Venacava
    36. Inferior Venacava
    37. Brachiocephali vein
    38. Subclavian vein
    39. Axillary vein
    40. Cephalic vein
    41. Basilic vein
    42. Azygous vein
    43. Hemiazyous vein
    44. Accessory Hemiazyoug Vein
    45. Internal Hemiazygous Vein
    46. Internal Iliac Vein
    47. Femoral Vein
    48. Popliteal Vein
    49. Long Saphenous Vein
    50. Small or Short Saphenous Vein
    51. Hepato-portal System
    52. Lymphatic System
    53. Spleen
    54. Thymus
    55. Thoracic duct
  2. Pharmacology
    3. 56. Congestive Heart Failure
    57. Therapy of Arrhythmiasis
    58. Angina pectoris
    59. Therapy of Hypertension
    60. Therapy of Shock
    61. Haemostatic Agents
    62. Therapy of Thromboembolic Disorder
    63. Thrombolytic or Fibrinolytics
    64. Antifibrinolytics
    65. Antiplatelet Drugs
    66. Therapy of Iron Deficiency Anemia
    67. Therapy of Megaloblastic Anaemia
    68. Hypolipidemic Drugs and Plasma Expanders
  3. Physiology
    4. 69. Properties of Myocardial Cells
    70. Heart - A Mechanical Pump
    71. Cardiac Cycle
    72. Electrocardiogram (ECG)
    73. Cardiac Output (CO)
    74. Haemodynamics of Circulation
    75. Heart Sounds
    76. Arterial Pulse
    77. Blood pressure
    78. Regional circulation
    79. Cardiovascular chanes during exercise
    80. Edema Dropsy of fluid retention
    81. Shock
    82. Hematology
  4. Pathology
    5. 83. Anaemia
    84. Hypertension
    85. Hypertensive Heart Disease
    86. Ischemic Heart Disease
    87. Angina pectoris
    88. Myocardial infarction
    89. Rheumatic Fever and Rheumatic Heart Disease (RHD)
    90. Acute Pericarditis
    91. Myocarditis
    92. Infective Endocarditis (IE)
    93. Congenital Heart Disease
    94. Cardiomyopathies
    95. Arteriosclerosis
    96. Atherosclerosis
    97. Inflammatory Disease of Blood Vessels
    98. Aneurysms and Dissection
    99. Congestive Heart Failure
    100. Iron Deficiency Anaemia
    101. Megaloblastic anaemia
    102. Pancytopenia
    103. Leucocytosis and Leucopenia
    104. Aplastic anaemia
    105. Haemolytic anaemia
    106. Hereditary Spherocytosis
    107. Haemoglobinipathies
    108. Thalassemia syndrome
    109. Sickle Cell Disease
    110. Leukaemia
    111. Leukemoid reaction
    112. Lymphadenitits
    113. Hodgkin lymphoma
    114. Non-hodgkin lymphoma
    115. Myeloproliferative disorders
    116. Myelofibrosis
    117. Multiple myeloma
    118. Bleeding disorders
    119. Coagulation disorders
    120. any
    121. Blood grouping
  5. Microbiology
    6. 122. Introduction of Blood borne infections
    123. Infective Endocarditis
    124. Brucella
    125. Rickettsiae
    126. Leishmania donovani
    127. Plasmodium
    128. Wuchereria bancrofti
  6. Biochemistry
    7. 129. Metabolism in Blood Cells
    130. Iron metabolism
    131. Haemoglobin
    132. Lipoprotein metabolism
    133. Biochemical aspect of MI
Anatomy
2. The Heart Development
FORMATION OF PRIMARY AND SECONDARY HEART FIELD
Primary Heart Field
graph TD 1["<b>Progenitor Heart Cells</b> lie in the epiblast, immediately <br>adjacent to the cranial end of the primitive streak."] 2["Migrate through the primitive streak into the <br><b>Splanchnic layer of lateral plate mesoderm</b>"] 3["Form horseshoe-shaped cluster of <br>cells called the <b>Primary Heart Field</b>"] 1 --> 2 2 --> 3
Derivatives of Primary Heart Field
  1. Part of right ventricle
  2. Left ventricle
  3. Atria

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Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above.

Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above.

◈ Derivatives of Secondary Heart Field:
  1. Outflow tract (Truncus arteriosus and Conus cordis)
  2. Part of the right ventricle
Secondary Heart Field
SHF develops later than PHF and resides in Splanchnic mesoderm ventral to the posterior pharynx
Derivatives of Secondary Heart Field
  1. Outflow tract (Truncus arteriosus and Conus cordis)
  2. Part of the right ventricle
Functions
  1. Lengthening of the outflow tract.
  2. Exhibits laterality such that right side contribute to left of the outflow tract and vice-versa.
DEVELOPMENT OF CARDIOGENIC AREA AND PERICARDIAL SAC
graph TD 1["PHF are induced by underlying pharyngeal<br> endoderm to form <b>Cardiac myoblasts</b> <br>and <b>Blood islands</b>."] 2["They form blood cells and vessels by the<br> process of<b> Vasculogenesis</b>."] 3["Islands unite to form a horseshoe-shaped <br>endothelial-lined tube surrounded by myoblasts."] 4["<b>Cardiogenic region</b>"] 1 --> 2 2 --> 3 3 --> 4
FORMATION AND POSITION OF THE HEART TUBE
  1. Initially, the central portion of the cardiogenic area is anterior to the oropharyngeal membrane and the neural plate.
  2. Growth of CNS, Cephalic and lateral folding of the embryo.
  3. Movement of Cardiogenic area first to cervical region and then to thorax.
  4. Merging of the caudal regions of the paired cardiac tube except at the caudalmost which becomes right and left horn of sinus venosus.
LENGTHENING OF CARDIAC TUBE
  1. Lengthening of Cardiac tube occurs by addition of cells from SHF to outflow tract region which forms the parts given above.
Clinical Correlates
Inhibition of cardiac tube
  1. Double Outlet Right Ventricle (DORV) (Both the aorta and pulmonary artery arise from the right ventricle.
  2. Ventricle Septal Defect (VSD)
  3. Tetralogy of Fallot
  4. Pulmonary atresia
  5. Pulmonary stenosis
Regulation of SHF
graph TD 1["Regulated by <b>Neural crest cells</b>"] 2["Control concentration of FGGs in the area."] 3["Pass nearby the SHF in the pharyngeal arches."] 4["Septate the outflow tract."] 1 --> 2 1 --> 3 3 --> 4
CARDIAC LOOPING
Bending of ventricular part (cephalic part)
Direction of shifting
  1. Ventrally
  2. Caudally
  3. Right
Shape given to Heart tube
U-shaped
Shifting of Atrial (caudal) portion
Direction of shifting
  1. Dorsocranial
  2. Left
Shape given to Heart tube
S-shaped
Local expansions of Heart tube
Bulbus cordis
Truncus arteriosus
Forms Aorta and Pulmonary trunk
Conus cordis
Forms smooth part/ outflow tract of both right and left ventricles
Proximal 1/3 part
Forms rough or trabeculated part of right ventricle.
Primitive ventricle
Forms rough or trabeculated part of left ventricle.
Primitive atria
Forms rough or trabeculated part of right and left atria.
Sinus venosus
Body of sinus venosus
Forms smooth part of both right and left atria.
Horn of sinus venosus
Left horn
All these retrogresses and remnant forms part of coronary sinus.
Common cardinal vein
Forms Coronary sinus and the Oblique vein of left atrium.
Anterior Cardinal vein
Posterior Cardinal vein
Umbilical vein
Proximal part disappears, while distal part forms Ductus venosus
Vitelline vein
Regresses
Right horn
Common cardinal vein
Forms part of Superior venacava.
Anterior Cardinal vein
Posterior Cardinal vein
Umbilical vein
Forms terminal part of Inferior venacava.
Vitelline vein
Regresses
Shifting of Conotruncal portion of the heart tube
Right side of pericardial cavity to left side.
Clinical Correlates
Dextrocardia
  1. Dextrocardia is a condition where the heart lies on the right side of the thorax instead of the left.
  2. It occurs when the heart loops to the left instead of the right.
  3. The defect is induced during gastrulation, when laterality is established.
    4. ◈ Associated with:
    ■ Situs inversus: Complete reversal of asymmetry in all organs.
    ■ Laterality sequences: Only some organ positions are reversed.
DEVELOPMENT OF THE SINUS VENOSUS
  1. Left to Right shunting of blood
    1. Development of azygous system
    2. Obliteration of left cardinal veins and becoming the tributaries of right cardinal veins
  2. Shifting of sino-atrial orifice to the right
    1. Rapid development of right sided septum of sinuatrial orifice
  3. Vertical placement of sino-atrial orifice
  4. Development of valvular folds, the right and left venous valves
  5. Dorsocranial fusion of valves to form Septum spurium.
  6. Right sinus horn incorporated into the wall of the atrium
  7. Fusion of left venous valve and the septum spurium with the developing atrial septum
  8. Complete disappearance of superior portion of the right venous valves
  9. Fate of inferior portion of right venous valves
    1. Valves of coronary sinus
    2. Valves of the inferior venacava
  10. Crista terminalis forms the dividing line between the original trabeculated part and smooth part of right atrium.
FATE OF ENDOCARDIAL CUSHION
Atrioventricular endocardial cushion
  1. Atrio-ventricular parts
    1. Atrio-ventricular septa
    2. Atrioventricular canals
    3. Atrioventricular valves
    ◈ Formation of septum intermedium:
    1. Developed by fusion of ventral and dorsal endocardial cushions.
    2. Divides the canal into righ and left A-V orifices
  2. Atrial septa
  3. Membranous part of Ventricular septa
    4. ◈ Abnormalities: Atrial and Ventricular septal defect
Conotruncal endocardial cushion
  1. Aortic channel
  2. Pulmonary channel
    3. ◈ Abnormalities:
    1. Transposition of the great vessels
    2. Common truncus arteriosus
    3. Tetralogy of Fallot
ATRIAL CHAMBER
Inter-atrial septum development
Septum primum
  1. The first portion of the septum primum is a sickle-shaped crest growing from the roof of the common atrium into the lumen.
  2. The two limbs of this septum extend forward the endocardial cushions in the atrioventricular canal.
    3. ■ Ostium primum:
    1. The opening between the lower rim of the septum primum and the endocardial cushions is the ostium primum.
    2. With further development, extensions of the superior and inferior endocardial cushions grow along the edge of the septum primum, closing the ostium primum.
    ■ Ostium secundum:
    1. Before closure of ostium primum, however, cell death produces perforations in the upper portion of the septum primum.
    2. Coalescence of these perforations forms the ostium secundum, ensurign free blood flow from the right to the left primitive atrium.
Septum secundum
  1. Later, a new crescent-shaped fold appears from the roof known as Septum secundum.
  2. Its anterior limb extends downward to the septum in the atrioventricular canal.
  3. The free concave edge of the septum secundum begins to overlap the ostium secundum.
    4. ■ Foramen ovale:
    1. The opening left by the septum secundum is called the Foramen ovale.
    2. When the upper part of the septum primum gradually disappears, the remaining part becomes the valve of the foramen ovale.
Changes after birth
    ■ Closing of the foramen ovale: After birth, when lung circulation begins and pressure in the left atrium increases, the valve of the foramen ovale is pressed against the septum secundum, obliterating the foramen ovale and separating the right and left atria.
    ■ Probe patency: In about 20% of cases, fusion of the septum primum and septum secundum is incomplete, and a narrow oblique cleft remains between the two atria known as Probe patency.
Right atrium development
Smooth part
Develops from sinus venosus
Rough part
Develops from primitive atrium
Left atirum development
Smooth part
Develops from sinus venosus
Rough part
Develops from primitive atrium
VENTRICULAR CHAMBER
Inter-ventricular septum development
Muscular part
  1. First there is a formation of bulbo-ventricular cavity by fusion of conus and primitive ventricle, so the bulboventricular sulcus disappears.
  2. This cavity contains lower dilated part and upper conical part.
  3. A muscular interventricular septum grows from the floor of bulboventricular cavity and divides ventricles into two halves.
  4. It grows towards septum intermedium (AV cushion).
  5. When the muscular ventricular septum ceases to grow, a incomplete muscular septum is formed.
  6. The two ventricles still communicate with each other through the interventricular foramen that lies cranial to the muscular interventricular foramen.
Bulbar part
  1. The formation of bulbar part of IV septum is associated with the septation of outflow tract of heart tube.
  2. There are formation of the subendocardial tissue in the conus part of bulbus cordis called the right and left trunco-conal or Bulbar ridges.
  3. But these ridges are also invaded by neural crest cells. Thus the cushion tissue of the outflow tract consists of both endocardium-derived cushion tissue and neural-crest cell derived cushion tissue.
Membranous part
Fills the gap of interventricular foramen
Derived from
AV cardiac cushion
Anterior portion
Separates right and left ventricles
Posterior portion
Separates right atrium and left ventricles
Right and left bulbar ridge
Note
Inter-atrial and inter-ventricular septum doesn't lie in same plane.
Clinical Correlates
Ventricular Septal Defects
Muscular VSDs
  1. Less serious form.
  2. Resolves as the child grows.
Membranous VSDs
  1. More serious form.
  2. Often associated with abnormalities in partitioning of the conotruncal region.
  3. Depending on the size of the opening, blood carried by the pulmonary artery may be 1.2 to 1.7 times as abundant as that carried by the aorta.
Tetralogy of Fallot
  1. Tetralogy of fallot is the unequal division of the conus resulting from anterior displacement of the conotruncal septum.
  2. It is the most common abnormality of the conotruncal region.
  3. It is not fatal
  4. Occurrence rate is 9.6/10,000 births.
Cardiovascular alterations produced by it
  1. D ⟶ Ventricular Septal Defect
  2. R ⟶ Right Ventricular Hypertrophy
  3. O ⟶ Overriding Aorta
  4. P ⟶ Pulmonary stenosis
Persistent (common) truncus arteriosus
  1. Persistent truncus arteriosus is the defect having no division of the outflow tract.
  2. It occurs when the conotruncal ridges fail to form such division.
  3. Pulmonary artery arises some distance above the origin of the undivided truncus.
  4. Since the ridges also participate in formation of the interventricular septum, the persistent truncus is always accompained by a defective interventricular septum.
  5. The undivided truncus thus overrides both ventricles and receives blood from both sides.
  6. Occurrence rate is 0.8/10,000 births.
Transposition of the great vessels
  1. Transposition of the great vessels is the condition in which the aorta originates from the right ventricle, and the pulmonary artery originates from the left ventricle.
  2. Causes: Failure of conotruncal septum to follow its normal spiral course and runs straight down.
  3. Occurrence rate: 4.8/10,000 births
DiGeorge sequence
DiGeorge sequence is characterized by a pattern of malformations that have their origin in abnormal neural crest development.
Defects
  1. Facial defects
  2. Thymic hypoplasia
  3. Parathyroid dysfunction
  4. Cardiac abnormalities involving the outflow tract
    1. Persistent truncus arteriosus
    2. Tetralogy of Fallot
Valvular stenosis
Cause
Fusion of semilunar valves for variable distance
Incidence
Approx 3 to 4 / 10,000 births
Pulmonary arterial valvular stenosis
  1. The trunk of the pulmonary artery is narrow or even atretic.
  2. The patent oval foramen then forms the only outlet for blood from the right side of the heart.
  3. The ductus arteriosus, always patent, is the only access route to the pulmonary circulation.
Aortic valvular stenosis
  1. Fusion of the thickened valves may be so complete that only a pinhole opening remains.
  2. The size of the aorta itself is usually normal.
Aortic valvular atresia
  1. Complete fusion of the semilunar aortic valves is called Aortic valvular atresia.
  2. The aorta, Left ventricle, and Left atrium are markedly underdeveloped.
  3. The abnormality is usually accompained by an open ductus arteriosus, which delivers blood into the aorta.
Ectopia cordis
Ectopia cordis is the condition of the heart lying on the surface of the chest.
Cause
Failure of the embryo to close the ventral body wall.
Right ventricular development
Smooth part
Develops from conus cordis
Rough part
Develops from proximal 1/3 part of bulbous cordis
Left ventricular development
Smooth part
Develops from conus cordis
Rough part
Develops from primitive ventricle
TRUNCUS ARTERIOSUS
  1. A spirally arranged aorto-pulmonary septum divides the truncus into ascending aorta and pulmonary trunk.
  2. This septum rotates clock-wise from below upwards, Thus
    1. In lower part of septum, pulmonary trunk lies in front of aorta.
    2. In middle part, pulmonary trunk lies on the left side of aorta.
    3. In upper part, pulmonary trunk lies behind the aorta.
Note
  1. The upper end of truncus arteriosus is divided into right and left limbs and each limb is connected to corresponding dorsal aorta by 6 aortic arches.
  2. Upper 5 pairs of aortic arches are connected to the ascending aorta and 6th pair of arch is annexed with the pulmonary trunk.
DERIVATIVES OF AORTIC ARCHES
Table: Derivatives of the Aortic Arches
Arch
Arterial Derivatives
Right side
Left side
I
Maxillary arteries
II
  1. Hyoid
  2. Stapedial arteries
III
  1. Common carotid
  2. First part of the Internal carotid arteries
    3. Note
    Remainder of the internal carotid arteries are derived from the dorsal aorta; the external carotid arteries sprout from the third aortic arch.
IV
Right subclavian artery (Proximal portion)
Note
The distal portion of the right subclavian artery, as well as the left subclavian artery, form from the seventh intersegmental arteries on their respective sides.
Arch of the aorta from the left common carotid to the left subclavian arteries
Note
The proximal portion of the aortic arch is derived from the left horn of the aortic sac; the right horn of this sac forms the brachiocephalic artery.
V
VI
Right pulmonary artery
  1. Left pulmonary artery
  2. Ductus arteriosus
Table: Derivatives of the Aortic Arches
Data
Content
Right side
Left side
Mandible
Maxillary arteries
FOETAL CIRCULATION
Changes at birth
  1. Lungs start functioning
    1. Umbilical vein form Ligamentum teres.
    2. Ductus venosus form Ligamentum venosus.
    3. Foramen of ovale closes.
    4. Ductus arteriosus form Ligamentum arteriosus.
    5. Umbilical artery forms Medial umbilical ligament.
  2. Placenta is delivered and removed.

Question Answers

Q.

Developmentant of right atrium with relevant congenital anomalies.

(4 + 1= 5)

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Q.

Development of truncus arteriosus with relevant congenital anomalies.

(3= 3)

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Q.

Give the embryological basis of: Atrial Septal Defect

(3= 3)

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Q.

Write short notes on: Development of right atrium of heart.

(5= 5)

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Q.

Write short notes on: Derivatives of fourth branchial arch arteries.

(4= 4)

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Q.

Name different parts of developing heart tube. Explain the development and congenital anomalies associated with internal septum.

(2 + 4= 6)

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Q.

Name the different parts of development of heart tube. Write about the development of ventricular septum and its congenital anomaly.

(8= 8)

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Q.

Describe the development and congenital anomalies of the heart.

(4 + 2= 6)

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Q.

Mention in brief the interatrial septal development.

[2055]

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