Lecture 5: Cardiology Flashcards
What are the divisions of the mediastinum?
- Superior mediastinum
2. Inferior mediastinum
- Anterior mediastinum- in front of the heart
- Posterior mediastinum- behind the heart
- Middle mediastinum- da heart
What separates the superior mediastinum from the anterior mediastinum?
Sternal angle
What separates the anterior mediastinum from the posterior mediastinum?
Heart
What occupies the middle mediastinum?
Heart
What occupies the superior mediastinum?
Great vessels and thymus
Features of the heart
- Two sided
- Four chambers
- Self-initializing
4. Self-adjusting
Right side of heart gets deoxygenated blood from superior and inferior vena cava–> lungs to be oxygenated.
L side of the heart gets O2 rich blood from the lungs and pumps it to the body via the aorta.
What are the layers of the heart?
- Epicardium- outmost layer made up of visceral serous pericardium
- Myocardium- thick layers of cardiac muscle, below the epicardium
- Endocardium- thin internal endothelial and subendothelial layer that lines the insideof the chambers of the heart and valves.
- Fibrous skeleton of the heart
CN: What is a myocardial infarction?
Lack of blood blow to the myocardium, often caused by a blockage in the coronary artery.
Coronary atherosclerosis is a buildup of lipids inside the coronary arteries that decreases the size of the lumen, increasing the liklihood of a blockage.
CN: What is angina pectoris?
Angina pectoris is pain that originates in the heart but is referred to the left upper limb. It causes stragling pain in the chest.
Cause is often a obstructed coronary artery that causes ischemia in the myocardium.
What is the fibrous skeleton of the heart?
Dense collagenous fibers that:
- Is an attachment point for the myocardium
- Holds open cuspid valves
- Holds open the AV and semilunar orifices.
- Serves an electrically insulated barrier between the atria and ventricle.
What is the electrically insulated barrier between the atria nad ventricle that the fibrous skeleton of the heart makes?
Membranous atrioventricular septum
What are the borders of the heart?
- Left- left margin (left ventricle)
- Inferior- right margin (right ventricle)
- Superior (R and L atria and has the exit point for the aorta and pulmonary trunk).
- Right (right atrium)
What is the ligamentum arteriosum?
Remnants of the embryological ductus arteriosus, which shunted blood from the pulmonary trunk to the aorta to bypass the nonfunctional lungs.
It communicates between the pulmonary trunk–>aortic arch.
-L recurrent laryngeal n. of the vagus n loos around the aortic arch and the ligamentum arteriosum then goes to the larynx.
CN: compression of the L recurrent laryngeal nerve
L recurrent laryngeal N goes under the ligamentym arteriosym.
Because it creates a weak spot in the aorta, it is prone to aneurisms, which can compress the nerve and make it hard to speak
What are the internal features of the RIGHT ATRIUM?
- Sinus venarum–> smooth, thin wall muscle
- Pectinate muscle of the R atrium --> rough muscular wall. right auricle
- Interatrial septum–> smooth walle between the two atria and located AROUND fossa ovalis. Interatrial septum is surrounded by the sinus venaris
- Valve for the opening for the coronary sinus
- Crista terminalis will seperate the rough and smooth wall.
What is the embryonic remnant of the foramen ovalis?
Fossa ovalis
What is the coronary sinus?
How the coronary veins drain back into the heart
CN: Atrial septal defects
Atrial septal defects occur when the foramen ovalis does not close completely.
15-20% of adults have a small opening in their foramen ovale, which is not bad because the left atrium contracts harder than the right, so very little blood goes from the right–> left atrium.
Larger openings in the interatrial septum allow oxygen rich blood to mix with oxygen depleted.
What is the purpose of the foramen ovalis?
It allows blood to pass from 1 atrium–> another.
What is the right atrioventricular orifice?
The passage from the right atrium –> right ventricle
Tricuspid valve and attachment of the cusps
Separates the right atrium from the right ventricle.
It has 3 cusps: anterior cusp, posterior cusp and the septal cusp.
Chordae tendinae attach the three cusps–> papillary muscle.
To be a papillary muscle, they must chordae tendinae attached to them.
What are the internal features of the right ventricle?
- Tricuspid valve
- Trabecula carneae–> rough wall in the ventricles. Includes the septomarginal trabeculum (moderator band).
- Conus arteriosus- smooth wall that leads to the pulmonary trunk
- Septomarginal trabeculum-
- Pulmonary valve
Pulmonary valve
A semilunar valve that seoerates the right ventricle from the pulmonary trunk.
1. Right cusp
2. Left cusp
3. Anterior cusp
The pulmonary sinus is the space between the wall of the pulmonary trunk and the cusps of the valve.
What is a cardiac catheterization?
Insert a catheter into the femoral vein–> inferior vena cava, allowing you to see the RIGHT ATRIUM, RIGHT VENTRICLE, PULMONARY TRUNK and PULMONARY ARTERIES.
Describe theleft atrium
- Left atrium is thicker than the right atrium.
- Connected to the left ventricle via the left atrioventricular orifice, which has the bicusid valve in it.
- The left atrium has almost NO pectinate muscle (besides the left auricle). It is mostly sinus venarum.
- 4 pulmonary veins empty into the left aatrium.
Describe the left ventricle
Thick wall.
Bicuspid (mitral) valve seperates the left atrium from the left ventricle; made up of a anterior and posterior cusp.
Chordae tendinae attach the two cusps to the anterior papillary m and the posterior papillary m.
Aortic vestibule is a smooth-walled and leads to the aortic valve–> aorta
What is the smooth portion of that leads from the left ventricle–> aorta?
Aortic vestibule
What separates the two ventricles?
Interventricular septum.
It has a membranous part and a musclar part.
The membranous part is RIGHT near the aortic vestible. DR. Keime is obsessed with it.
CN: Ventricular septal defects
Defects to the interventricular septum allow oxygenated blood and deoxygenated blood to mix.
Aortic valve
Aortic valve is the origin to coronary arteries. It is a semilinar valve with a
- [Right cusp]
- [Left cusp]
- Posterior (non-coronary) cusp
Aortic sinuses are the spaces behind the valve.
The aortic valve is the host to coronary arteries. What would happen if blood went directly to the coronary arteries?
They would brust because they’re too small.
When the valves close, backflow of the blood due to revoil of the aorta causes the coronary arteries to fill and it is sent at a much LOWER PRESSURE.
What is the spread of excitation through the heart?
- SA node (our pacemaker) is in the right atrium . It spontaneously depolarizes
- Depolarization is spread through the atrial muscle because the walls are so thin.
- Impulse reaches the AV node at the bottom of the right atrium, which acts as a conduction station to the ventricles. The AV node causes a delay in conduction.
- Depolarization travels from AV node–> bundle of his (atrioventricular bundle)–> L and R bundle branches
- Depolarization is then distrubted to the ventricles via purkinje fibers (subendocardial branches).
Bundle of Hiss is also called the
atrioventricule bundle
Purkinje fibers are also called
Subendocardial branches
CN: Cardiac pacemaker
Cardiac pacemakers produce regular electrical impulse to the ventricles via electrodes that are inserted through
a large vein –> superior vena cava–> right atrium–> tricuspid valve–> endocardium of the trabecula carnae of the RIGHT VENTRICLE
CN: Atrial fibrillation
Atrial cardiac muscles twitch irregularly, causing the ventricles to respond at irregular intervals.
Fucks up circulation.
CN: Ventricular fibrillation
Irregular twitching of the ventricles, causing the heart to not pump blood. Heart is debrillated (stopped) in the hopes that they heart will beat regularly again.
CN: Cardiac referred pain
Ischemia stimulates visceral pain sensory fibers in the heart of the Autonomic Nervous system. These visceral sensory fibers often share a spinal ganglion with the somatic sensory fibers of areas such as the upper limb and superior lateral chest wall. Anginal pain is typically referred to the area innervated by the Left Medial Brachial Cutaneous nerve, the left substernal area, left pectoral area and medial aspect of the left upper limb are often involved in this variety of referred pain.
What are the two types of pericardium?
- Serous (membranous)
- Fibrous (tough and fibrous)
Types of serous pericardium
- Parietal serous pericardium - on the inside of the fibrous pericardium
- Visceral serous pericardium (epicardium) - adheres to the heart and makes up the epicardium
CN: What is the surgical signficance of the transverse pericardial sinus?
The space allows cardiac surgeons to access the area posterior to the aorta and pulmonary trunk to clam or insert the tubes of a bypass machine into the large vessels.
CN: Pericarditis
- Inflammation of the pericardium, which can make the pericardium rough and cause friction against each other and the heart.
- This friction is called pericardial friction rub and can be seen heard with a stethoscope.
- If it is not treated, the pericardium can calcify.
CN: Pericardial effusion
Inflammation of the pericardium can result in fluid or pus in the pericardial sac, compressing the heart.
Compression of the heart is called cardiac tamponade.
CN: Percardiocentisis
Performed to drain blood, fluid or pus from the pericardial sac.
Thus, it treats cardiac tamponade.
Pt John comes in with fluid in his pericardial sac. What is this called and how do we treat?
- Cardiac tamponade
- Pericardiocentisis
What are the two pericardial sinuses?
- Transverse pericardial sinus
- Oblique pericardial sinus
What sinus can things get stuck behind?
Oblique pericardial sinus.
