CP5 - The Heart Handout notes and lecture notes Flashcards
what is the average heart rate for adults?
lifetime?
• In the average adult, the heart beats an average of 70 times per minute at rest (50 times per minute for marathon runners), which adds up to 100,800 beats a day, every day of the year, for a lifetime (close to 80 years).
How much blood does the heart pump per day?
• The heart pumps more than 1800 gallons of blood throughout the body each day.
How much does the heart weigh?
how strong is it?
• The heart weighs about 300 grams in males and 250-275 grams in females. To understand the strength of the heart muscle and the amount of work it does: during the course of a lifetime, this organ could lift a 30-ton object 30,000 feet in the air.
What are variables that Contribute to the Development of Heart Disease?
elaborate.
- Aging: Aging is inevitable and beyond our control.
- Disease: We have many different ways of manipulating and treating diseases including drugs, surgery, and heart transplants. (* The very first surgery performed to insert a heart valve in this country was performed at the Georgetown Hospital!)
- Life style: Often this is the most important factor in any disease and many diseases are self-inflicted by using the wrong kind of diet, and life style, e.g., smoking, lack of exercise, drinking alcohol, etc. The exception to the alcohol rule is drinking red wine. There are many known benefits from drinking eight fluid ounces of red wine a day, including cardiovascular benefits and reducing the risk of Alzheimer’s disease and cancer.
in industrialized nations heart disease is ranked the _____ killer
what propertion of people have some form of CVD?
congenital and acquired heart diseases are what____ in industrialized nations
how long has heart disease been the #1 killer?
How are these deaths compared to other causes?
• Heart disease is the number one killer in all industrialized nations, especially the United States.
- 1 in 5 males and females has someform of cardiovascular disease
- congenital and acquired diseases of the heart are leading cause of morbidity and mortality in teh US and other developed nations
- since 1900 CVD is number 1 killer in US every year (except for 1918)
- CVD claims almost 10,500 more deaths than the 6 next leading causes of death
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Does heart disease only affect middle aged men?
- The myth that heart disease only affects middle-aged men must be dispelled.
- Most women believe that breast cancer is the number one cause of death among women. However, 1 in 9 women a year develop breast cancer while 1 in 4 women a year die from heart disease.
How many death per year in the US?
how much of sudden death mortality does heart disease account for?
what percentage of victims are males between ages of 45-64?
what percentage of all sudden cardiac deaths occur in who?
are their enough hearts available for transplant?
- 1 million deaths in the US per year
- 90% of sudden death mortality in the US (can’t think of better/pain-free way to die!)
- 90% of victims are males between the ages of 45 to 64
- 75% of all sudden cardiac death occurs in men
- Not enough hearts are available for transplant!
what are the Four Components of the Cardiovascular System?
- Heart.
- Vascular system: a closed system of living tubes that transport and distribute blood to the periphery, and then collects it and returns it to the right side of the heart.
- Volemia: the circulating blood volume that fills up the vascular system at a given pressure.
- Pulmonary microcirculation: a gas-exchange system between the blood and the surrounding environment.
What is a clinician trying to figure out when a patient comes in with a cardiovascular problem?
When a patient comes in with a cardiovascular problem, the clinician will ask, “Where in the cardiovascular system is the problem? Is it the heart, or the tubing system, … etc.” In other words, there are many things (hundreds) that can go wrong with each component of the cardiovascular system. A problem arising in any of these four components can throw your whole cardiovascular system out of whack.
Mediastinum
The space at the center most portion of the thorax, between the lungs, after removing the sternum
What can the mediastinum be divided into?
any subdivisions?su
The mediastinum can be divided into several regions anatomically
- Superior – From the angle of Louis = sternal angle (T4/5) superiorly to the superior thoracic aperture.
- Inferior – From the angle of Louis inferiorly to the diaphragm. This space can be further subdivided into three regions.
a. Anterior – Doesn’t contain much
b. Middle – The heart and associated structures
c. Posterior – Some structures found in the superior mediastinum extend to the posterior mediastinum as well
What is the pericardial sac?
- Pericardial Sac : Covering surrounding heart. Consists of two layers:
what is the fibrous pericardium?
what is the major function of the pericardium?
Fibrous Pericardium: the outermost layer. It’s a tough connective layer. Superiorly the fibrous pericardium is attached to the great vessels and inferiorly it rests upon the center tendon of the diaphragm.
Major function = protect the heart from sudden overfilling!
- Fused to tunica adventitia of great vessels
- bound to central tendon of diaphragm
- attached to posterior surface of sternum
what is the Serous pericardium?
what are its layers?
what is in between the pericardia?
Serous Pericardium: smooth inner two layers parietal and visceral, just like the pleura of the lungs!
- Parietal –> outer layer lining the inner surface of the fibrous pericardium
- Visceral (epicardium) –> inner layer, covering the external surface of the heart
- There is a potential space in between the 2 serous layers. It’s generally filled with a tiny amount of fluid to lubricate the 2 surfaces, but it’s doesn’t become a true space unless pathological conditions ensue. (analogous to the pleural space)
What are possible causes of pathological conditions?
- Pericarditis- inflammation of the pericardium
- Possible causes: Virus or bacteria (prophylaxis treatment by dentists)
- Pericardial effusion – the potential space becomes a real space with build up of fluid
- Cardiac Tamponade – pericardial effusion –>heart compressed because fibrous pericardium cannot stretch!
- Cardiomegaly – heart becomes larger
- Hemopericardium – blood in the pericardial cavity (acute condition), must be drained –> pericardiocentesis (draining procedures)
What are the cardiac sinuses?
What are the 2 spaces called? what are they bound by?
Why are they significant during coronary bypass surgery?
Cardiac Sinuses: two spaces created by the reflections of the serous pericardium. The borders of the two cardiac sinuses are where the visceral pericardium extends off the surface of the heart to become continuous with the parietal pericardium. (NOT CONNECTED)
a. Oblique Pericardial Sinus – bound by reflections of serous pericardium inferior to the level of pulmonary veins, posterior to the heart
b. Transverse Pericardial Sinus – bound by reflections of serous pericardium superior to the level of pulmonary veins, posterior to the pulmonary trunk and ascending aorta
Note: Location of transverse pericardial sinus is exploited during coronary by-pass surgery. Surgical clamp is introduced into the space and blood flow of aorta and pulmonary trunk stopped momentarily before great vessels are connected to bypass machine.
“if they were connected, the blood in pericardium would dissipate, but it doesn’t, so you have cardiac temponade
Under what context are the nomenclature of the heart and its contents defined?
The nomenclature of the heart and its contents are defined within the context of the heart in its normal anatomical position in the mediastinum.
Describe the anterior view of the heart:
- Opening the pericardial sac exposes the anterior view of the heart.
- The right ventricle takes up most of this view.
- Immediately to the right of the right ventricle, a portion of the right atrium and its appendix (auricle) are observed.
- To the left of the right ventricle, it is possible to see a small section of the left ventricle.
- The roots of the three Great Vessels (i.e. superior vena cava, ascending aorta and pulmonary trunk) are inside the pericardium and can also be observed. In fact, the heart is suspended in the pericardial sac by the roots of these vessels.
Describe the orientation of the pericardium with that of the superiror vena cava
-The top of the pericardium (or root) blends with the tunica adventitia of the superior vena cava near its midpoint. Thus, the upper half of the superior vena cava is outside the pericardium (extra pericardial), while the lower half is contained within the pericardium.
what area would you palpate when trying to feel the epicardium?
-Palpation of the sternal angle at the junction between the manubrium and the body of the sternum in the midline of the body points to the uppermost level of the pericardium.
what are the ventricles separated by in the surface of the heart?
The atria and ventricles are separated by what?
What resides within these sulci?
- Examination of the surface of the heart with the heart in its anatomical position reveals that the right ventricle is separated from the left ventricle by a sulcus (groove), and the two ventricles are further separated from the atria by another sulcus.
- Within these sulci reside the coronary arteries that provide circulation to the heart muscle itself.
What is a sulcus?
- what is the groove between the atria and the ventricles circumscribing the entire organ called?
- what is the groove between the ventricles. Present on both anterior and posterior surfaces of the heart called?
a. Sulcus: Surface grooves produced by tissue folding during the embryonic development
i. Coronary (atrioventricular) Sulcus – groove between the atria and the ventricles circumscribing the entire organ
ii. Interventricular Sulcus – groove between the ventricles. Present on both anterior and posterior surfaces of the heart
what are the coronary arteries?
what are their branches and where do they travel?
Coronary Arteries : Two major branches that appear as a crown (hence their name) on the heart, if looking from above
i. Left Coronary Artery – gives rise to two arteries
- Left Anterior Descending (LAD) or Anterior Interventricular Artery -in the anterior interventricular sulcus, traveling inferiorly
- Circumflex Branch – in the atrioventricular sulcus, traveling posteriorly
ii. Right Coronary Artery – lodged in the atrioventricular sulcus, gives rise to two or three major branches
- Sinoatrial Node Branch or Nodal branch – traveling superiorly to the SA node, near origin of right coronary artery.
- Right Marginal Branch – traveling anteriorly/inferiorly along the surface of right ventricle
- Posterior Interventricular Branch (PIB) – traveling in the posterior interventricular sulcus
- Atrioventricular nodal branch arises from right coronary in about 80-85% of people
What does the dominance of the heart mean?
and what is it defined by?
what is the percentage?
The artery that gives rise to the posterior interventricular branch defines the dominance of the heart.
Most people (85%) are believed to have right dominant heart.
i.e. If the posterior Interventricular artery arises from the left coronary artery, the heart is said to be left heart dominant!
What are the 4 coronary veins?
c. Coronary Veins : generally more superficial compared to the arteries, 4 major branches
i. Great Cardiac Vein – large, in the anterior interventricular sulcus (accompanies LAD)
ii. Middle Cardiac Vein – medium, in the posterior interventricular sulcus (Accompanies posterior interventricular artery)
iii. Small Cardiac Vein – small, along the inferior margin of the heart (accompanies R. marginal branch)
iv. Anterior Cardiac Veins – on anterior border of right atrium and ventricle, drain directly into right atrium
Where do the cardiac veins ultimately drain?
Where does this run along?
where does it empty? Where is that in relation to the IVC?
what is an exception to this?
In general, all the named cardiac veins ultimately drain into the coronary sinus, which runs along the posterior atrioventricular sulcus and empties into the right atrium, medially to the inferior vena cava.
The anterior cardiac veins are the only exception as they drain directly into the right atrium.
How can you check if you have a coronary artery stenosis?
describe the procedure
- One of the ways to assess whether a circulatory problem exists in the coronary vessels is to perform an angiogram.
- An angiogram is an imaging technique used to assess the blood flow through any artery (in this case the coronary arteries).
- The coronary angiogram is accomplished by injecting a contrasting dye into the coronary vessels. The dye will only spread through the coronary arteries if there is no blockage (or clot) within the lumen of the vessel.
- In order to reach the coronary arteries, a catheter is inserted into the femoral artery and passed in a retrograde fashion back through the aorta into the coronary arteries. Thus, the coronary angiogram is a very invasive procedure.
Accumulation of what may completely block a coronary artery?
What is implicated as being a major contributor and/or risk factor of this?
Coronary Artery Pathology
The chronic accumulation of plaque within the lumen of coronary arteries may ultimately completely block a coronary artery.
-High blood cholesterol is implicated as being a major contributor and/or risk factor to plaque formation in coronary arteries (although it is not the only one) .
what is Myocardial ishchemia?
what sx’s does it cause?
Myocardial ischemia
(blockage of coronary artery circulation) results in angina pectoris (paroxysmal pain the chest), often radiating to the arms (referred pain from the left upper limb).
what is the sensation of angina pectoris?
Angina pectoris is the sensation caused by myocardial ischemia and is usually described as pressure, discomfort, or feeling of chocking in the left chest or substernal region that radiates to the left shoulder and arm as well as the neck, jaw and teeth, abdomen, and back.
The pain may also radiate to the right arm. This radiating pattern is an example of referred pain in which visceral afferents from the heart enter the upper throracic spinal cord with somatic afferents, both converging in the spinal cord’s dorsal horn. interpretation of the visceral pain ma be confused with somatic sensations from the same cord levels.
What eventually happens if coronary circulation is blocked to a particular area?
If the coronary circulation is completely blocked to a particular area of the heart, then the heart tissue can undergo ischemic necrosis (prolonged absence of blood to an area leading to tissue death).
What treatments were developed for Coronary artery disease?
what are more recent treatments?
In the mid 1960’s, pioneering surgery for coronary artery disease entailed the grafting of a piece of the saphenous vein from the thigh to by-pass the blocked artery. (must remember to change orientation of the veins due to valves)
More recently, arterial graphs, e.g., internal thoracic arteries have been employed for the graphs with better long term results. (only 2 available before you have to harvest veins)
- This diverts blood from the mammary gland to the coronary artery. (mammary gland has redundant blood supply)
What is another treatment for CAD that has had even more success?
what are they coated with?
Even greater success to alleviate coronary artery disease has been achieved with the use of stents. Most, if not all, stents today are coated with anticoagulants that further improve the long term success of the implanted devices.
describe the arrangement of the heart in the anatomical position.
The heart consists of four chambers, two atria and two ventricles. In the anatomical position, the chambers of the heart are arranged such that they form a horizontal cross.
describe the arrangement of the heart on a horizontal section of the heart
On a horizontal section of the heart, the right ventricle is anterior and the left atrium is immediately behind it, both lying on the same anteroposterior line in the midline of the body.
In turn, the right atrium and the left ventricle form a transverse line across the plane established by the right ventricle and left atrium.
what does the heart look like on MRI images?
This anatomical arrangement of the heart chambers is responsible for the typical appearance observed in MRI images of heart. Recall that in an MRI patient structures are observed as if one were to be located at the feet of the patient looking upwards. Thus, from such a view, the right atrium appears on the left side and the left ventricle appears to be on the right side. From this perpendicular arrangement, it is clear that the right ventricle should really be called the ANTERIOR CHAMBER of the heart and the left atrium should be known as the POSTERIOR CHAMBER.
What does the arrangement of the heart imply about how common injuries occur?
What is it called when a contusion to the heart can cause a rupture causing the pericardial sac to fill?
This arrangement of the heart also leads to an understanding of how common injuries to heart occur, e.g., during car crashes. If a driver is not wearing his seat belt and the car crashes, he/she may slam into the steering wheel, crushing the anterior portion of the chest, i.e., the right ventricle. Indeed, this is the most common place to see cardiac contusions in automobile accidents. Sometimes these contusions can be so severe that they can cause the heart to rupture, and the pericardial sac fills with blood, a condition called CARDIAC TEMPONADE
what is hemopericardium?
What is cardiac temponade?
causes?
symptoms?
What is done to treat this?
- what does the tx accomplish
The presence of any amount of blood in the pericardial cavity is known as hemopericardium, but if the amount of blood is large enough to strangle the heart and prevent it from filling up with blood in diastole, then the condition is known as cardiac tamponade.
Causes:
- Ruptured aortic aneurism
- Ruptured myocardial infarct
- Penetrating injury
Symptoms:
- Variable degrees of shock or in extemis
- neck veins are distended
- heart sounds are distant
- decreased arterial and pulse pressures often exist but not pathognomonic
- venous pressure elevated (pathognomonic)
- pericardial tap at larrey’s point (diagnostic and decompressive)
What is the treatment for cardiac temponade?
The immediate life-saving treatment is to stick a long needle under the xyphoid process and into the pericardial sac to suck the blood out.
What are the Right Atrium components?
describe each.
1) . Pectinate muscles: horizontal rough inner surface of the anterior wall of the atrium, allows for atrial contraction
2) . Fossa ovalis: a remnant of foramen ovale, thinnest part between the two atria
3) . Cristae terminalis: a longitudinal ridge running superior to inferior on the lateral border of the atrium, separating anterior and posterior walls
4). Vessels that drain into right atrium: • Superior vena cava • Inferior vena cava • Coronary sinus • Anterior cardiac veins
