Pericardium and Heart Anatomy

Pericardium and Heart Overview

• The presentation covers the pericardium and the heart

The Pericardium

• It is a conical fibro-serous sac, located in the middle mediastinum
• Situated behind the sternum and the 2nd to 6th costal cartilages
• In front of the border of the 5th to 8th thoracic vertebrae
• Components: An outer fibrous sac (open) pierced by blood vessels and an inner serous sac (closed)
• The heart is intra-fibrous but extra-serous

Introduction to the Pericardium

• Fibro-serous and conical in shape
• Lateral walls are covered externally by mediastinal pleura
• Serous pericardium includes parietal and visceral layers

Pericardial Cavity and Layers

• Pericardial cavity exists between the two layers of serous pericardium
• It has a capillary layer of fluid
• Serosal pericardium is lined by mesothelium
• Fibrous pericardium is made of compact collagenous tissue

Fibrous Pericardium Relations

• Above: tunica adventitia of great vessels
• Below: fuses with the central tendon and left half of musculature of diaphragm
• Anteriorly: attached to the sternum by sternopericardial ligaments
• Posteriorly: related to structures of posterior mediastinum
• Laterally: mediastinal surfaces of lungs

Piercing Structures

• Ascending aorta
• Superior Vena Cava (SVC) and Inferior Vena Cava (IVC)
• Right and Left Pulmonary Arteries
• Four pulmonary veins
• All receive a prolongation except the IVC.

Serosal Pericardium

• Located within the fibrous pericardium
• Consists of 2 layers: parietal and visceral
• Pericardial cavity contains a capillary layer of fluid (50ml (300ml))
• Two tubes establish continuity between parietal and visceral layers
• Reflections take the form of complex tubes around the Asc Aorta, Pulmonary trunk, SVC, IVC and pulmonary veins

Pericardial Sinuses: Transverse and Oblique

• Transverse sinus is between arterial and venous ends of the primitive heart
• Formed by degeneration of central cells of dorsal mesocardium
• Borders of transverse sinus: Ascending Aorta & Pulmonary trunk anteriorly, and SVC & upper border of the Left atrium posteriorly
• Oblique sinus is a cul-de-sac behind the left atrium, formed by the absorption of pulmonary veins
• Borders of oblique sinus: Right pair of pulmonary veins & IVC on the right side, left pair of pulmonary veins on the left side

Fold of Marshall

• Triangular fold of serous pericardium
• Extends from the left pulmonary artery to the left superior pulmonary vein
• Contains a fibrous ligament, a remnant of the left duct of Cuvier (left common cardinal vein)

Blood Supply

• Fibrous and Parietal layer: Internal thoracic, Musculophrenic, Descending thoracic aorta (bronchial, Oesophageal, and superior phrenic) arteries; Internal thoracic and Azygous veins
• Visceral layer: Coronary arteries; Coronary sinus

Nerve supply

• Fibrous and Parietal: Phrenic nerve (sensory)
• Visceral layer: Vagus and Sympathetic (vasomotor) nerves

Points to note

• The oblique sinus lies behind the left atrium
• The transverse sinus lies above and in front of the left atrium

Clinical aspects

• Transverse Sinus
• Pericardial tamponade occurs with >300ml fluid leading to diastolic capacity, lower CO, PR, and VP
• Paracentesis (Aspiration/Tapping) can be performed via subcostal (Costoxiphoid angle) or parasternal route (4th or 5th ICS) for Intracardiac Injections

Pericarditis & Cardiac Tamponade

• Pericarditis includes inflammation, chest pain, and rough serous pericardium
• Pericardial effusion and inflammatory diseases can cause this
• Non-inflammatory effusion can occur with congestive heart failure
• Cardiac Tamponade is compression on the heart due to excessive fluid in the pericardial sac
• This leads to decreased cardiac output
• Is caused by Hypothyroidism, physical trauma, pericarditis, myocardial rupture

The heart

• The heart is a hollow organ situated in the middle mediastinum and covered by the pericardium
• Size is that of a clenched fist
• Consists of 4 chambers: atria and ventricles
• Atria are separated by inter-atrial septum and ventricles by inter-ventricular septum
• Right heart deals with deoxygenated blood for pulmonary circulation
• Left heart deals with oxygenated blood for systemic circulation.

Heart Measurements

• Apex to base: 12 cm
• AP diameter: 6 cm
• Widest transverse diameter: 8 to 9 cm
• Transverse diameter is 1/3 or <1/2 of thorax
• Weight: Males -280-340gm. Females-230-280

Presenting Parts and Apex

• Apex, base, 3 surfaces- sternocostal, diaphragmatic & left surfaces
• 3 borders- right, inferior & left border
• Apex points down, forwards & to the left in the 5th intercostal space - 9 cm from mid

Surface Features: Apex, Base, Surfaces

• Apex: Present in the left 5th intercostal space, 9 cm from midline to inferomedial left nipple and by left ventricle
• Base: Mainly formed by the left atrium and partly by the right atrium. Present opposite the bodies of 5th to 8th thoracic vertebrae
• Surfaces: Anterior (sternocostal), Inferior (diaphragmatic), left and right

Sternocostal Surface

• Directed forwards & upwards, separated from base by right border, diaphragmatic surface by inferior border & left surface by left border.
• Formed of the anterior surface of right ventricle(2/3), the anterior surface of the left ventricle (1/3), partly left auricle, right atrium and its auricle
• Atrio-ventricular groove lodges the right coronary artery & is crossed by the anterior cardiac vein
• Anterior Interventricular groove lodges the anterior Interventricular branch of left coronary artery and great cardiac vein

Diaphragmatic or Inferior Surface

• Flat, 2/3 by the left ventricle, 1/3 by the right ventricle
• Separated from the sternocostal surface by the inferior border, base by posterior part of the atrio-ventricular groove
• Posterior Interventricular groove lodges the posterior Interventricular branch of the right coronary artery
• Relations: Perocardium, central tendon & diaphragm,cardiac impression of liver & fundus

Left Surface of Heart

• Upwards, backwards & to the left
• Constructed mainly by left ventircle and partly by left atrium

Grooves of the Heart

• Inter-atrial groove exists between the 2 atria
• Interventricular groove separates the ventricles and it is anterior with interventricular artery and great cardiac vein, and posterior has posteriorinterventricular artery and middle cardiac vein

Atrio-ventricular Groove (Coronary Sulcus)

• Has 2 Parts-- Anterior and Posterior
• In the anterior part is the Right part that contains trunk of the right coronary artery that runs between the right atrium and right ventricle
• In the posterior part that has the left part that contains coronary circumflex artery, runs between the left auricle and ventricle
• Groove also between Base and diaphragmatic surface and contains the coronary sinus and anastomosis of right & left coronary arteries

Points to note

• Apex formed only by left ventricle
• Basel formed only by the two atria
• Right border formed only by light atrium
• Diaphragmatic surface formed only by the 2 ventricles

2/3 and 1/3 Features

• Base made of - 2/3 left, 1/3 right atrium
• Diaphragmatic surface- 2/3 left, 1/3 right ventricle
• Sterno-costal surface- 2/3 right, 1/3 left ventricle
• Entire heart- 2/3 to left of midline, 1/3 to right

Right Atrium

• Behind and to the right of the right ventricle and separated externally by the right atrioventricular groove
• It forms- Entire right border, 1/3 of base of the heart, part of the sterno-costal surface
• Extent ranges: Orifice of SVC- 3rd right costal cartilage to Orifice of IVC- 6th right costal cartilage

Right Atrium Features

• Quadilateral chamber extends from 3rd to 6th right costal cartilages
• Right auricle, Sulcus terminalis are the external features
• Internal: Anterior rough part- atrium pumper (pectinatepart), Posterior part is smooth- sinus venarum, separated smooth muscular called crista terminalis

Interior of the Right Atrium Details

• Consists of 2 distinct parts: the posterior smooth part (Sinus Venarum that receives the termination of large veins) and the anterior rough part (Atrium Proper, developed from the right half of the primitive atrium)
• Both are distinctly separated by the Crista Terminalis Structure

Sinus Venarum (Posterior wall):

• Consists of the Opening of SVC, IVC with Eustachian valve; opening of Coronary sinus with Thebesian Valve
• Foramina Venarum Minimarum- through whitch venae cordis minimi opens into right atrium
• Atrium proper (Anterior wall) and Crista terminalis with musculi pectinati

Walls of the Atrium Details

• Septal wall: Fossa ovalis and Limbus Fossa Ovalis
• Triangle of Koch with Torus aorticus

Interior of Right Ventricle

• Composed of 2 parts: Rough inflowing part (ventricular proper) and Outflowing smooth part (Infundibulum)
• The Supraventricular crest is responsible for separating these regions
• Inflow contains Tricuspid orifice with chordae tendinae
• Trabaculae Carneae: Ridges -Supraventricular crest, Bridges- Septomarginal trabaculae
• Papillary muscles: Anterior-larger, Posterior-intermediate, Septal- Small
• Outflow Part (Conus Arteriosus) contains conical, smooth walls
• Apex infundibulum presents pulmonary orifice

Left Atrium

• Forms anterior boundary for oblique sinus and the wall is primarily smooth
• Smooth wall receives the 4 pulmonary veins posteriorly
• Anteriorly opens into left ventricle via mitral orifice
• Semilunar fold on the septa wall
• Interiorly most of the wall is smooth except in the auricle where musculi pectinati is present

Interior of the Left Ventricle

• Rough inflow includes - Bicuspid orifice with valve complex, Chordae tendinae and Trabaculae carneae with Muscles that are Anterior - Large and Posterior- small
• Smooth outflow parts includes - Aortic Vestibule leads into aortic orifice that developed by bulbous cordis

Orifices of the heart

• The tricuspid valves is best heard over right half the lower end from the body of sternum
• The mitral valve is best heard over the apex beat at the fifth intercostal space
• The pulmonary valve is heard over the medial end of the 2nd left intercostal space
• Aortic the valve is heard over 2nd right intercostal space

The Heart’s Fibrous Skeleton

• Consists of 4 connected rings that surround the 4 valve orifices including the pulmonary (P), aortic (A), mitral (M), tricuspid (T)
• Rings give muscle attachment to the atria and ventricles
• Support the valves and give attachments to the vessels incl aorta /trunk and have Trigonum fibrosum between orifices

Skeletal Structures and Support

• A tendon infundibulum connects the pulmonary orifice to the aortic orifice.
• The Trigonum fibrosum dextrum lies between the mitral and tricuspid orifices.
• Triangular rings also between aortic and mitral

Rings of the Heart

• Annuli are the rings of collagenous around 4 orifices
• Aortic has collagenous scallops, and fibrous trigone
• Mitral has Right and left fibrous trigone with coronaria that connects by sulcul tissue
• Pulmonary has collagenous scallops on 1 posterior
• Right or tricuspid has fibrous trigone with coronaria connected by sulcul tissue

Conducting System of Heart

• Specialty cardiac myocytes are used
• Musculature use muscular connection for conducting separate systens
• Conducting include node and bundle and fibers

Additional Information

• Dextrocardia is when primitive heart points ot the right on mutation
• Situs inversus viscerum mutations chromosome
• Ectopia cordis is improper side folding

Defects in the Interatrial Septum (ASD)

• Probe patency of the Foramen Ovale (F.O.) results in functional and anatomic closure ~25% of cases
• Persistent Foramen Secundum: Cyanosis caused by a right-to-left shunt due to high blood pressure or anatomical variation
• Prenatal closure of F. Ovale: Rare, Hypertrophy on the right side of heart + Death shortly the birth

Defect in the Bulbus Cordi

• Fallot's tetralogy: 9% of all congenital disease of heart, pulmonary stenosis, hypertrophy of the rt ventricle, misalignment of AA and Patent
• Interventricle occurs

Angina & Myocardial

• Angina Pectoris: Blood cut off for Ischemia from an occuluted Major A
• Angina Caused by the stenosis
• Factors include Family risk and cholesterol Hypertension; diabities and pain is felt in those area
• Results in necrosis or MI, including heart diseases, and the left descending
• The coronary bypass

Cardiac Pain

• Cardiac Pain is referred to to spinal segments incl predaordium
• Includes Tachycardia, Bradycardia, Arrhythmia
• It includes chest and coronary pain to arteries and branches including (Vagus) and sympathetic

Vessels to Heart

• The Arterial vessel includes 2 vessels Incl RA and LT including endothelial
• Not always and end point and functionally
• Can have occlusion on branches and spinal segments in the vessels and chest
• Can also have incl Myocarditis, endocarditis and pericarditis

Right Coronary Artery - Course and Distribution

• Arises from the right anterior aortic sinus, emerging between pulmonary trunk & right auricle
• Winds around inferior border to posterior aspects
• Terminates by anastomosing with the left coronary .
• Supplies for Rt: the atrium, part of ventricle, interventriuclar septum, and Whole conducting system of the heart except left branch of AV bundle

Branches of the Right Coronary

• Marginal Branch, posterior, nodal, right artrial, Infundibular, terminal.

Pathway of the Left Coronary Artery

• From the left posteriomr
• Gives anterior and conitnues
• Branches into arteries
• Terminal, pulmonary vessels

Ventricle Dominance

• Ventricel can right (90%) or to left (10%) based on genetic disposition.

Heart Chambers

• Most blood drains into the sinus from atrias through largest the vein
• This happens form anterior wall and guared
• There's great, small vessels and atrium to artery
• Can have ischemia due to the coronary disesases and vessels closing including the infarction with angina
• In some case the descenden can cause incompletion of the anginas
• This is du e to and conduction of the cardiac.

Nerves

• Nerves are created by (T1-T5) and is either Sympathetic or Parasympathetic cardiac plexus
• Sympathetic releases arteries when there and pain is less and heart rate is lower
• Parasympathetic occurs coronary when heart rate is slow with blood flow