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60 year old woman with hx of obesity and DM type 2 experienced a…
60 year old woman with hx of obesity and DM type 2 experienced a myocardial infarction causing permanent damage to papillary muscle of left ventricle, resulting a failure of the mitral (bicuspid/left AV) valve to close. BP is 95/55, respiration is 30 breaths/minute, pulse is 125 bpm. Breathing is labored and gurgling sounds heard during assessment.
Anatomy of the heart
Internal has 4 chambers
2 superior atria- receiving chambers for blood. contributes little to propulsion of blood thru the heart. have Auricles to increase total volume of atria.
Right Atrium- receives de-oxygenated blood from body via
-Superior Vena Cava- from body regions superior to diaphragm
-Inferior Vena Cava- from body inferior to diaphragm
-Coronary Sinus- returns blood from coronary veins
Anterior is smooth welled, posterior contains ridges called pectinate muscles.
Christa terminalis seperates anterior and posterior regions of right atrium
Left Atrium- receives oxygen rich blood from lungs.
Pectinate muscles only in Auricles. Four pulmonary veins return blood from lungs.
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2 inferior ventricles- discharging chambers. Makes up most of the volume of the heart. Thicker walls than atria. Actual pumps of the heart.
-Trabeculae carneae- irregular ridges of muscle on ventricular wall
-Papillary muscles- project into ventricular cavity, anchors chordae tendineae that are attached to heart valves
Right ventricle- pumps blood into pulmonary trunk. Blood goes into lungs for gas exchange. Blood is de-oxygenated
Left ventricle- ejects blood into aorta (largest artery in body) and out to the body. Blood is oxygenated
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Chordae tendineae- Anchor cusps of AV valves to paillary muscles that hold cusps in closed position and prevent flaps from collapsing into aorta.
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Valves- ensures unidirectional blood flow through the heart. open & close in response to pressure changes. made of cusps
Cusps- flaps of endocardium reinforced by connective tissue cores
2 types of valves
Atrialventricular- one located at each atrial-ventricular junction. prevents blood from going back into atria when ventricles contract.
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Semilunar valves- prevents back flow from major arteries back into ventricles. Semilunar valves are made of 3 cusps that roughly resemble a half-moon/crescent
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Surface features-
Coronary sulcus- (atrioventricular groove) encircles junction of atria and ventricles
Anterior interventricular sulcus- anterior position of interventricular septum
Posterior interventricular sulcus- landmark on posteroinferior surface
Pathway of blood through the body:
- Aorta
- Arteries
- Arterioles
- Capillaries
- Veins
- Venules
- Vena Cava
- Right Atrium
- Right AV/Tricuspid valve
- Right Ventricle
- Right Semilunar Valve/Pulmonary Valve
- Pulmonary Arteries
- Lung Capillaries
- Pulmonary Veins
- Left Atrium
- Left AV/Bicuspid Valve/Mitral Valve
- Left Ventricle
- Left Semilunar valve/ Aortic Semilunar Valve
- Aorta
Valves prevent backflow of blood in the heart. They keep blood from getting stuck and sitting in one location in the heart
Papillary muscles hold valves in closed position and prevent AV valve flaps from entering atria.
Heart Sounds- 2 Sounds "Lub-Dub" associated with closing of valves. Pause after "dub" and before "lub" indicates heart relaxation
"Lub"- first sound closing of AV valves at beginning of ventricular systole. Bicuspid (left) closes slightly before tricuspid (righ)
"Dub"- second sound, closing of semilunar valves at beginning of vetricular diastole
heart rate- "pulse"- the number of times a heart beats per minute. normal adult range is 60-100 bpm
Stroke volume- blood volume pumped out by one ventricle with each contraction
Cardiac output- the amount of blood pumped out by each ventricle in one minute
Mean Arterial Pressure (MAP)- the pressure that propels the blood to the tissues. roughly equal to diastolic pressure plus one third of pulse pressure
Systolic pressure- pressure generated by ventricular contraction
Diastolic pressure- pressure maintained as the heart relaxes
pulse pressure- difference between systolic and diastolic pressure
preload- the degree to which cardiac muscle cells are stretched just before they contract
afterload- the pressure that ventricles must overcome to eject blood
periphral resistance- the resistance of arteries to blood flow. resistance decreases with dialation, increases with constriction
cardiac reserve- difference in resting and maximum cardiac output.
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Heart rate and respiration correlate with each other. If the heart starts to beat faster, respiration rate increases to keep up with the blood flowing through the lungs. If respiration rate has to keep up with increased heart rate so that the carbon dioxide in the blood can be exchanged for fresh oxygen. If respirations do not increase, the blood will not be oxygenated properly
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AGE
As people age, hardening of arteries occurs. While this is normal, it does not help patient's condition
Valves of the heart stiffen with age. Heart muscles also degenerate as people age. So, without the other existing conditions, this patients heart was already not in top shape.
Because of the aging of the heart, its valves and its muscles, it has a hard time beating quickly in times of stress or physical activity
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Effects on Body
There is potential that this episode could cause damage to the kidneys from lack of adequately oxygenated blood.
Damaged kidneys can contribute to high blood pressure from enzymes released. This puts patient at risk for further heart attacks. Damaged kidneys can also contribute to edema
Damaged kidneys cannot absorb extracellular fluid to be gotten rid of by the body. Blood begins to pool in the extremities due to the heart not being able to function appropriately.
As kidney function starts to degrade, the potential for the patient to develop altered mental status increases. With kidneys failing, they are not getting rid of waste products effectively and this is starting to effect brain function.
The nervous system, specifically the sympathetic nervous system, keeps releasing triggers to get the heart to beat faster. This causes the ventricles, which are already damaged, to contract less effectively. The total cardiac output starts to go down.
Increased heart rate by the nervous system triggers quicker respiration rate. The patient will feel short of breath and require AT LEAST oxygen therapy, at most intubation. in order to keep her O2 saturation compatible with life. The patient will sound like she is gasping for air.