determinants and assessment of cardiac function
examples are: acute coronary syndrome, global hypoxia disorders, [e.g., severe pulmonary disease]; myocarditis, cardiomyopathy and depressant effects of many narcotic and anesthetic agents
afterload can be increased by arteriole vasocontriction and semilunar valve failure. examples are: stimulation of sympathetic nervous system, drugs that vasoconstrice [epinephrine, norepinephrine] and pulmonic or aortic valve stenosis
there are four primary coronary arteries: the left main coronary artery; left anterior descending artery, left circumflex artery; and the right coronary artery
as the arteries cross the epicardial surface, small feeder arterioles penetrate the chamber walls, giving rise to a dense network of thousands of capillaries per square millimeter called arteriosinusoidal channels, this ensures that each cardiac muscle cell is in contact with a bordering capillary
The coronary perfusion pressure [CPP] is derived by subracting the pulmonary artery wedge pressure from the diastolic blood pressure. the CPP should be maintained above 50 mm Hg to provide adequate blood flow to the myocardium
autoregulation maintains CPP at a fairly constant level within an aortic pressure range of 40 to 130 mm Hg.
medium veins and venules are referred to as capacitance vessels because they hold large volumes of blood
capillaries form a complex interconnected network known as a capillary bed that links the arterioles with the venules
the left ventricle is often referred to as the workhorse of the heart because it must provide adequate pumping power to perfuse organs and tissues
cardiac muscle has more mitochondria to make energy via aerobic metabolism and more myoglobin to story oxygen. this is important because cardiac muscle is almost completely dependent on aerobic metabolism for energy
coronary collateral channels: provide an alternate route for myocardial tissue perfusion, the become important when coronary arteries occlude, and they are a complication of coronary artery disease
cardiac output is the amount of blood pumped by the heart each minute. normal CO varies significantly for individuals depending on body size [body surface area].
contractility is increased by sympathetic nervous system stimulation and the drug effects of epinephrine, norepinephrine, dobutamine, dopamine, and digitalis
contractility is decreased by parasympathetic nervous system stimulation; hypoxia or ischemia, myocardial disease and drug effects
blood flow through the coronary arteries and perfusion of the myocardium is regulated primarily by aortic pressure
coronary blood flow is greatest just after closure of the aortic valve and gradually slows during diastole
afterload is the risistance against which the ventricle pump blood. an optimal amount of resistance is necessary for the system to work properly.
if afterload increases, stroke volume decreases because the ventricle is meeting increased resistance and cannot effectively pump out its volume.
if blood pressure has fallen below the preset value, the medulla stimulates the heart rate to increase and the arterioles [and veins to a lesser extent] to constrict.
if blood pressure has risen above the preset level it will slow down the heart rate and trigger vessel dilation
exercise ECG, commonly known as a stress test evaluates heart muscle and its blood supple during physical stress exercise. it can identify myocardial ischemia that may not be present at rest.
if for some reason the patient cannot tolerate exercise, stress to the heart muscle is simulated with the anministration of dobutamine, a positive inotropic drug
drugs that decrease heart rate include beta blockers and calcium channel blockers
increased preload caused by increased blood volume can be cause by heart or kidney failure, fluid overload from I V therapy, increased aldosterone secretion and excess dietary sodium
cardiac muscle contraction depends on an influx of calcium; however, cardiac muscle does not store calcium, so serum calcium levels are important to monitor
it is important for the nurse to recognize that when a patient's serum calcium is low contractility is reduced.
in a person complaining of dizziness a radial pulse would give a better indication than an apical pulse of the adequacy of peripheral perfusion.
preload for the right ventricle is assessed by evaluating the systemic venous system. increased preload to the right heart typically manifest as signs of too much fluid in the peripheral tissues and organs as fluid backs up form the right side of the heart
the volume of blood pumped with each heartbeat is called the stroke volume.
preload is the amount of stretch in the myocardial fibers at the end of diastole and represents the volume of blood in the ventricle at the end of diastole
the pulse pressure is the difference between diastolic and systolic blood pressures. if reflects how much the heart is able to raise the pressure in the arterial system with each beat.
pulse pressure increases when stroke volume increases or in arteriole vasoconstriction. pulse pressure drips with decreased stroke volume or vasodilation [e.g., some shock states]. the normal pulse pressure is approximately 30 to 40 mm Hg.
heaves and lifts also indicate ventricular hypertrophy on either side.
severely depressed cardiac function may cause pulsus alternans, or alternating weak and strong pulses in a regular rhythm.
signs of increased left ventricular preload: dyspnea, cough, S3, S4 heart sounds
signs of decreased left ventricular preload: usually the same as decreased right preload [flat jugualr veins, dry mucous membranes, orthostatic hypotension, poor skin turgor [immediate sign]; possible muffling of S1 and S2
signs of increased right ventricular prelaod: jugular vein distension, ascites, hepatic engorgement [enlarged, tender to palpation] and peripheral edema
signs of decreased right ventricular preload: flat jugular veins, dry mucous membranes, orthostatic hypotension, poor skin turgor [immediate sign]
signs of increased systemic afterload include cool, clammy extremities. these signs may indicated that peripheral arterioles are constricted. Nonhealing wounds and thick brittle nails are indicators of chronic poor perfusion of the extremities
signs of decreased systemic afterload include warm, flushed extremities, which may indicate peripheral vasodilation.
the TEE provides a more definitive representation of the heart, producitng imnages of intracardiac structures and the entire thoracic aorta.
the TEE produces high quality images of both atrial chambers and is the procedure of choice to detect clots in the left atrium, atrial septal defects, infections of valve leaflets, and valve dysfunction
the medium arteries also known as muscular arteries, have a tunica media that contains more smooth muscle than elastic fibers. they deliver blood to the muscles and organs and are sometimes referred to as distribution arteries
the arterioles are the smalles arteries and consist of only two layers, the tunica media and tunica intima. the arterioles are referred to as resistance vessels because they play a critical role in the regulation of blood flow and blood pressure
the parasympathetic nervous system decreases cardiac output by slowing the heart rate and decreasing cardiac contractility and vasodilation.
the autonomic nervous system is also responsible for the baroreceptor reflex, which is largely responsible for maintaining a steady state blood pressure at the individual's preset level
collateral circulation usually develops to compensate for chronic low output heart disease, such as heart failure, over a long period and is seen in patients with chronic cardiovascular disease. these channels become important when the large arteries occlude.
the collateral channels, if present, can enlarge to provide an alternate route for blood and oxygen to myocardial tissues, which can diminish or eliminate myocardial tissue damage from poor perfusion, as seen in myocardial infarction
the semilunar valves have no supportive structures and are dependent on pressure gradients on either side of the valves for opening and closing. the closure of the semilunar valves can be auscultated as the second [S2] heart sound
the coronary arteries begin in the ascending aorta, close to the aortic valve. This location provides the heart with arterial blood that contains the richest oxygen concentration.
the heart is nestled within the mediastinum directly behind the sternum between the right and left lungs. with the majority of the heart apex lying in the left chest
the heart is protected by the anterior and posterior bony structures of the thorax
stabilization is provided by fibers in the tunica external layer that interlace with bordering tissues. the tunica externa is thicker in veins than in arteries
the larger arteries are also know as elastic arteries. the comprise the major arteries, such as the aorta and its major branches and the trunk of the pulmonary artery.
the right atrium accepts venous [oxygen poor] blood coming into the heart from the superior and inferior vena cavae and the coronary sinus
the left atrium accepts arterial [oxygen rich] blood form the lungs via the pulmonary veins
the right heart has the tricuspid valve, consisting of three flaps, or cusps, that open and close. it separates the right atrium from the right ventricle
the left heart has the mitral valve, which has tow cusps [bicuspid] and separate the left atrium from the left ventricle. the closure of the AV valves can be auscultated as the first [S1] heart sound.
serial CK-MB measurement resulting in an elevation or upward trend is a cardiac marker for acute myocardial infarction or heart attack.
the major limitatin of CK-MB is that levels do not start to rise until 4 hours after the onset of myocardial damage. this can delay diagnosis and treatment of myocardial infarction
The stress test is discontinued when a predetermined heart rate is reached and maintained signs of insufficient cardiac output appear, or ECG changes occur
the nurse conducting the stress test must be familiar with cardiac dysrhythmias and emergency procedures and must ensure that emergency medications and a defibrillator are readily available
arterioles are called resistance vessels because they regulate blood flow and blood pressure
the primary purpose of capillary beds is to interact with the adjacent environment
the cardiopulmonary system is composed of the heart, lungs, a vast network of blood vessels and blood. Its purpose is to take in and deliver oxygen and nutrients to the organs and tissues and remove metabolic products from elimination from the body
the pulmonary circuit includes the right side of the heart the pulmonary arteries, the lungs, and the pulmonary capillaries. it ends with the pulmonary veins where they join the left atrium.
the purpose of the pulmonary circuit is to facilitate pulmonary [external] gas exchange.
the pulmonary circuit is a low pressure system; it requires only sufficient pressures to pump blood through the lungs and back into the left heart
the pulmonary veins have no valves. if pressures in the left heart increase [e.g., heart failure], blood can back up through the pulmonary veins and into the lungs, causing increased pulmonary vascular pressures and pulmonary edema
the systemic circuit begins with the left side of the heart [left atrium] and ends with the superior and inferior vein cavae where they join the right atrium
a major purpose of the pulmonary circuit is to facilitate external gas exchange
the systemic circuit is a high pressure system
the endocardium is the innermost layer of the heart and is continuous with the endothelium [inner layer] of the blood vessels; like the blod vessels, it is composed of squamous cell epithelium
the thick middle layer, the moycardium, forms the bulk of the heart wall. it is composed of contractile muscle fibers, called myofibrils, that are unique in the way they conduct electrical impulses
the tunica media is thicker in arteries than in veins, which gives arteries the ability to instantly adjust their lumen size in response to ventricular systole [artery diameter expands] and diastole [artery diameter contracts]
the tunica externa [or adventitia] is the outermost layer surrounding the vessel and is composed of connective tissue. Its functions are to protect and stabilize the vessels
the systemic circuit is a high pressure system; the heart must pump using sufficient pressure to perfuse the organs and tissues
the tunica intima [or interna] line the inside of the vessel and is the only layer that directly interfaces with the blood rushing through the vessels. it consists of endothelium, the squamous cell epithelium that lines the entire circulatory system
ultrasound technology can be used to assess and diagnose cardiomyopathies, valvular function, cardiac tumors, and left ventricular function. An estimate of ejection fraction is also obtained
transthoracis echocardiograms are noninvasive tests that can be performed at the bedside or in the outpatient setting by a technician. the patient is usually placed in a semi fowler, left lateral, or supine position
troponin is a protein found in cardiac and skeletal muscle. it is part of a protein complex that binds myosin and actin, the myofilaments that regulate contraction
troponin can appear in the blood as early as 1 to 3 hours after symptoms onset and is a sensitive indicator of early myocardial infarction regardless of when chest pain began. it has a higher sensitivity and specificity for identifying even minor myocyte necrosis than CK-MB
during and immediately after the procedure, the nurse monitors for complications, which include respiratory depression and aspiration. movement of the probe in the esophagus may stimulate the vagus nerve, resulting in bradycardia or hypotension.
vital signs are monitored as the patient awakens from the procedures. the patient recovers in 1 to 2 hours.
one way that the renin agniotensin aldosterone system alters blood pressure in that angiotensin 2 stimulates the release of aldosterone
when baroreceptors sense a blood pressure that is below the individual's normal preset level, it will trigger increased heart rate and vasodilation
baroreceptors are special nerve endings located in the walls of certain large vessels [e.g., aortic arch, aorta, vena cava, and carotid sinus] and the atria. these receptors are sensitive to changes in pressure at their locations
when pressure changes at a baroreceptor changes at a baroreceptor, it sends a signal to the medulla to trigger one of two actions:
B-type natriuretic peptide [BNP] is a neurohormone released from the ventricular myocardium in response to increased preload [increased ventricular wall tension and pressure within the myocardium.
when released, BNP causes urinary excretion of sodium and diuresis and counteracts the water retaining effects of the RAAS. this results in a reduction of preload.
angiotensin 2 also stimulates the adrenal cortex to release aldosterone, a mineralocorticoid hormone that causes renal retention of sodium and water, resulting in increased circulating blood volume with subsequent increase in arterial blood pressure.
when the actions of the RAAS have increased blood pressure sufficiently to regain normal kidney perfusion pressures, the RAAS shuts down
the greater the volume of blood in the ventricle, the greater the amount of stretch that the fibers experience.
within limits, the heart pumps the amount of blood it receives with each beat. this is know as the frank starling law of the heart. in other words, as preload increases, so does stroke volume and vise versa
other laboratory test may be ordered to provide additional supportive data, including C-reactive protein, B-type natriuretic peptide, and lipid profile
C-reactive protien [CRP] is a peptide released by the liver in response to systemic inflammatin, infection, and tissue damage. it is a normal part of the inflammatory response, playing an important role in fighting infection or injury.
an enlarged cardiac siluouette may be evidence of cardiac tamponade or dilated cardiomyopathy
MRI is prohibited in patients with cardiac pacemakers
decreased contractility is manifested by diminished pulse pressure
cool clammy extremities indicate possible increased afterload for the left ventricle
the elctrophysiology study [EPS] is used to classify and locate cardiac arrhythmias
a 35 year old patient who is 6 feet tall and weights 435 pounds is receiving inotropic medications to improve cardiac output. Cardiac index would be the best to evaluate the efficacy of the medications
changes in skin color are a late sign of hemodynamic compromise, as is clubbing of the fingers.
a cooling of the skin is brought about by the vasoconstriction of the arterioles as blood is shunted to the internal organs. a decrease in CO may be the cause
afterload is decreased with arteriole vasodilation by depression of sympathetic nervous system, drugs that vasodilate [e.g., nitroglycerine], septic shock, anaphylactic shock, or spinal cord injury
a normal cardiac output is between 4.0 to 8.0 L/min
the nurse is caring for a patient who has increased afterload. the patient is most likely to exhibit decreased stroke volume and hypertension
a patient has decreased cardiac output form decreased myocardial contractility. the nurse would anticipate treatment with digoxin, oxygen, calcium, and dobutamine
a patient is admitted to the unit with multiple trauma resulting in significant blood loss. during asses, the nurse notes low blood pressure and signs of low cardiac output. Based of these two findings, the nurse would expect peripheral resistance to increase.
a patient is admitted with unstable angina, elevation of serum troponin levels requires the most immediate action by the nurse.
a patient is being evaluated after accidentally overdosing on antihypertensive meidcation.. the nurse would anticipate low urine output
a patient with a history of palpitations reports feeling that her heart is skipping beats. if the patient reports feeling light headed it would warrant immediate intervention by the nurse.
a patient with a heart rate of 150 would have decreased cardiac output
a patient with a normal heart has developed increased preload. this will result in increased stroke volume
the patient may be anticoagulated with heparin during cardiac catheterization to prevent stroke, which can occur during prolonged procedures from the embolization of clots that form on the interventional catheter
a variety of femoral artery access complications can develop during the procedure, including laceration of the vessel, hematoma, pseudoaneurysm, acute vessel closure/thrombus, and others.
if the venous valves are not working correctly for example, in a person who has varicose veins, is paralyzed, or is not active, the blood pools in the extremities rather than moving forward to the heart
any considiton that increases intraabdominal pressure [e.g., morbid obesity, ascites, or abdominal carpartment syndrome] can result in complete or partial collapse of abdominal veins if the intraabdominal pressure exceeds venous pressures
the kidneys alter blood pressure through the RAAS mechanism and through retention of water. blood flow through the kidneys diminishes as arterial blood pressure drops, resulting in a reduced glomerular filtration rate [GFR].
as GFR decreases, so does uring output, with resultant water retention, increased circulating blood volume, and increasing blood pressure
in the absence of infectin or injury, serum CRP levels should be negligible, [normal range is 0 to 1.0 mg/dL in the healthy adult]
atherosclerosis is considered to be a chronic inflammatory process and studies shave shown CRP levels increase with the atherosclerotic disease process. there is strong evidence suggesting that CRP levels correlate with degree of risk for heart disease
increased preload may develop with kidney injury
blood pressure is the amount of pressure exerted against blood vessel walls by circulating blood as it is pumped throughout the body
the major purpose of the heart valves is to prevent the backward flow of blood
cardiac cycle is the heart muscle activities during one complete heartbeat
consious [moderate] sedaton is used with the TEE. prior to the procedure, the nurse reviews the patient's chart, obtains, a detailed history, and inserts a peripheral intravenous catheter. suction equipment should be available in case the patient vomits
during the procedure, the nurse administers sedation, monitors vital signs and pulse oximetry saturations every 3 to 5 minutes, adjusts fluid and oxygen, and documents the patient's condition.
there are tow forms of echocardiogram: transthoracic and transesophageal
echocariograms are particularly useful for visualizing blood, cardiac valves, the myocardium, and the pericardium
ohm's law: pressure equals flow times resistance.
flow and resistance compensate to maintain blood pressure. flow in the cardiovascular system is cardiac output, resistance is afterload, and pressure is arterial blood pressure [ABP]. therefore, ABP is the produce of CO and afterload.
capillaries begin with a precapillary sphincter that expands and constricts the entryway into the capillary to control the rate and volume of blood flow
flow through the capillaries is not continuous; the precapillary sphincters open and close in a cyclic fashion, resulting in intermittent blood flow and increasing the time available for the exchange of gases, fluids, and other molecules
after completion of the electrophysiology study, the catheters are removed. firm pressure is applied for 10 to 20 minutes to the insertion site to achieve hemostasis. the entire procedure can last 1 to 5 hours.
following the EPS, the patient must remain in supine position with the affected leg straight for up to 4 to 6 hours per institution policy to prevent bleeding from the insertion site
it is imperative that the nurse and other team members monitor the patient's access site and distal pulses closely during the procedure to recognize early development of these and other complications
if a lesion is discovered, a percutaneous coronary intervention [PCI] is generally performed. this intervention is called an angioplasty or percutaneous transluminal angioplasty [PCTA].
BAS is calculated using the patient's height and weight. the correction is called the cardiac index and is calculated by dividing CO by BSA
in all, there are four determinants of cardiac output: heart rate, perload, afterload, and contractility.
retention of blood in the right side of the heart as in heart failure or cor pulmonale increases right atrial pressure and subsequently produces jugular vein distention as a result of backlfow through the vena cava.
in assessing for venous distention, the head of the bed is elevated to approximately 45 degrees. the patient's head is turned slightly away from the examiner. a penlight is used to shine a light tangentially across the neck
factors that decrease contractility have a negative inotropic effect. because hypoxemia decreases contractilty, it is an example of a negative inotrope
in high acuity settings, positive inotripc drugs are often used to augment cardiac output by improving myocardial contractility
the nurse in the prep area is responsible for initial assessment and history, vital signs, initiating intravenous access, and placing electrocardiogram leads. a thorough review of the patient's medications and allergies is required. informed consent must be obtained
in preparation for the procedure, 325 mg of aspirin is given to patients with suspected or known coronary artery disease to decrease the risk of clot formation during the procedure.
nursing responsibilities may include dimming of the lights in the room and ensuring patient privacy and warmth
in preparation for the transesophageal echocardiogram [TEE] procedure, an ultrasound probe is inserted orally into the patient's esophagus and advanced until it is close to the heart
contractility is the ability of a muscle cell to become shorter given a suitable stimulus. When referring to the heart, it is the force of myocardial contraction and reflects the ability of the heart muscle to work independently of preload and afterload i.e., the heart's ability to function as a pump
increased calcium release allows for greater interaction between actin and myosin filaments, resulting in greater contraction.
the smooth surface of the endothelium reduces friction and prevents clotting and damage to blood cells as blood flow by.
the tunica media, or middle layer is composed of smooth muscle with loose connective tissue and elastic fibers.
the law only applies within a certain range. Until a critical point is reached, as preload increases, so does stroke volume, an optimal preload results in optimal stroke volume. Past this point, an increase in preload results in a decrease in stroke volume
too much preload cause excessive stretching of the myocardial fibers; the ventricles cannot effectively contract, resulting in a decreased stroke volume
after a cardiac cath, the must must monitor for bleeding
transthoracis echcardiogram is used to evaluate structures within the heart, such as the septum and valves
the S in PQRST stands for associated symptoms
troponin appears in the blood within 3 hours of myocardial cell death
the findings from this study help to determine if the patient would benefit from further interventions such as drug therapy, implanted pacemaker or implantable cardio-defibrillator, or ablation [destruction of tissue of the arrhythmia source
under fluoroscopy, electrode catheters are inserted into the heart. these catheters conduct electrical impulses to and from the heart that trigger abnormal heart rhythms these dysrhythmias usually disappear after removal of the electrical stimuli.
examples of positive inotrope agents include cardiac glycosides [digoxin], sympathomimetic agents [dopamine and dobutimine], and phosphodiesterase inhibitors [amrinone and milrinone]
usually the ventricle ejects only 60% of the blood it contains at the end of diastole. ejection fraction is the measure of the percent of blood ejected with each stroke volume and is used as an index of myocardial function.
peripheral resistance [afterload] involves arterial tone [vasodilation or vasoconstriciton]; while cardiac output involves heart rate and stroke volume
venous circulation is a low pressure system. it is influenced by four factors: systemic filling pressure, adequacy of the venous muscle [pump], venous peripheral resistance, and right atrial pressure.
systemic filling pressure refers th the amount of force that is available to return blood to the right side of the heart. the filling pressure is influenced by venous tone [how dilated or constricted the veins are] and blood volume;
venous vasoconstriction or increased blood volume increases filling pressure and increases venous blood return to the heart.
a chest x ray is used to view the size and position of the heart
pulmonary edema caused by decompensated heart failure may be visualized on an e ray
signs of increased contractility: radial pulse bounding and vigorous; increased pulse pressure
sings of decreased contractility: radial pulse weak and thready, splitting of S2 heart sound and decreased pulse pressure
when afterload increases [e.g., vasoconstrition, CO decreases and BP increases. this is what happens to patients with hypertension
when afterload decreases [e.g., vasodilation], CO increases and BP decreases. this is what happens in patients in septic shock
the cardiovascular effects of the sympathetic nervous system stimulaton include increased heart rate, increased contractility , and vasoconstriction.
stimulation of the parsympathetic nervous system causes decreased heart rate, decreased contractility, and vasodilation.
the ejection fraction is the stroke volume divided by end diastolic volume. a normal ejection fraction is 60%
straining during bowel movement and other valsalva maneuvers can decrease heart rate
the major function of the endocardium is to provide a protective surface for direct exposure to blood cells.
the cardiac muscle has an abundant amount of myoglobin
following the cardiac cath it is important to minimize stress on the insertion site; therefore, the patient must keep the procedural leg straight and the insertion site should be manually compressed when the patient coughs
the electrophysiology study [EPS] is an invasive procedure that evaluates the cardiac conduction system and helps classify cardiac arrhythmias
the tunica intima interfaces directly with the blood
the large arteries are able to adjust their size in response to the cardiac cycle because of an abundance of elastic fibers in the tunica media
the right heart contains the pulmonic valve, which is located at the junction of the right ventricle and the pulmonary artery. it prevents the backflow of blood from the pulmonary artery into the right ventricle
the left heart has the aortic valve, at the junction of the left ventricle and the aorta, which prevents the backflow of blood from the aorta into the left ventricle
the presence of peripheral edema may indicate too much preload to the right side of the heart. Edema associated with heart failure is generally located in the gravity dependent areas of the body, such as the feet and lower legs and sacrum
jugular venous distention may indicate a fluid distribution problem and too much preload to the right side of the heart. the venous system is a low pressure system, and it is sensitive to right atrial pressure.
cardiac catheterization is a powerful diagnostic tool that is used for a variety of reasons, such as determining the presence and extent of coronary artery disease, evaluating left ventricular function, and evaluating valvular or myocardial disorders
left heart catheterizatin is performed primarily to determine the patency of the coronary vessels, but it can also be used to observe blood flow through the chambers and valves of the heart or to deliver a thrombolytic agent directly into the coronary vessels. chamber pressures may also be measured.
the nurse prepares the insertion site, monitors vital signs, and gives medications for conscious [moderate] sedation. the patient is instructed to report the onset of chest pain during the procedure as it may be indicative or coronary artery reocclusion
left heart catheterization requires access to the arterial system. the most common insertion route is the femoral artery; however, other access sites can be used based on patient factors and the purpose of the catheterization.
the cardiac cath patient is monitored postprocedure for complications such as peripheral artery thrombosis or embolus, embolic stroke, dye allergy, or acute myocardial infarction.
one important assessment is the inspection of the flanks for signs of retroperitoneal bleeding, a complication that is difficult to diagnose and is potentially life threatening.
no coumadin is given within 48 hours of a cardiac catheterization
post catheterization keep patient supine for first hours postprocedure; head of bed flat or no higher than 30 degrees; femoral sheath removed when meets thrombin time critera [e.g., 120 seconds];
rolling the patient onto the left side moves the heart closer to the surface of the body.
precordial palpation may produce a vibration also know as thrill. this may correspond to a murmur, valvular stenosis, or increased afterlaod.
apply pressure above not directly on insertion site sufficient to stop bleeding but not to cause obsence of peripheral pulses
the nurse preparing a patient for cardiac cath must notify the cardiologist if the patient reports an allergy to shellfish
a summatin gallop, when both S3 and S4 sounds are heart, is often indicative of severe heart failure.
the presence of wet sounding crackles [rales] on auscultation of the lungs indicates pulmonary edema. severe plumonary edema is associated with frothy, pink sputum production
at rest, the right atrial pressure is near zero; however, when the atrium contracts [systole], it causes a slightly negative pressure, which has a mild sucking or vacuum effect, pulling blood into the atrium from the vena cava. this action contributes to venous blood pressure as well as cardiac output
the renin angiotensin aldosterone system [RAAS] influences arterial blood pressure through vasoconstriction and water retention
the large veins include the superior and inferior ven cavae and their immediate tributaries.
the small veins, or venules, are transition vessels located between the capillaries and the medium veins.
both branches of the autonomic nervous system [sympathetic and parasympathetic] play active roles in regulating blood pressure through adjusting peripheral resistance and cardiac output.
the sympathetic nervous system [SNS] increases CO by causeing vasconstrction, speeding up the heart rate, and increasing cardiac contractility.
decreased preload cause by decreased blood volume can be caused by hemorrhage, dehydration, diuretic use, sevry ascites, generalized edema [e.g., severe hypoalbuminemia];
AV valve stenosis [decreases ventricular filling]; venous vasodilation [blood pools peripherally; decreased blood returns to right heart]; severe tachycardia [decreases ventricular filling time]
bruits along the carotid arteries may indicate areas of occlusion. these partial blockages represent potential compromise to the cerebral vasculature and account for some signs and symptoms also attributable to decreased cardiac output
CK-MB is a cardiac specific myocardial isoemzyme that is released 4 to 12 hours after the noset of myocardial necrosis and is very specific for myocardial damage.
if a significant cardiac dysrhythmia is induced during the EPS that comes from a specific anatomic region, catheter ablation may be applied. ablation destroys irritable cardiac tissue that is triggering the dysrhythmia.
ablation is commonly performed with radio frequency energy; however, lasers, microwaves, freezing and ultrasound may also be used.
it is generally agreed that a BNP level lower than 100 pg/mL rules out heart failure
certain factors shift normal BNP levels upward, including age [increases with age], progressive kidney injury, and gender [higher in women]; therefore, results in these patients should be interpreted cautiously
factors that influence contractility are known as inotropes. factors that increase myocardial contractility have a positive inotropic effect.
examples of positive inotropes include sympathetic nervous system stimulation, increased calcium release, and the administration on inotropic drugs.
as blood pressure drops, so does perfusion to the kidneys, which triggers the release of renin, an enzyme produced by the kidneys.
renin triggers th release of angiotensin 1, which converts to angiotensin 2, a powerful vasocontrictor that primarily targets the smooth muscles of arterioles, resulting in arteriole vasoconstriction and increased arterial blood pressure.
in a patient with normal heart function, if blood pressure decreases and flow remains unchanged, peripheral resistance will increase to increase the blood pressure
septic shock, depressed sympathetic nervous system and vasodilating drugs can result in decreased afterload
blood pressure equals peripheral resistance times cardiac output
systemic filling pressure is the amount of force available to return blood to the heart
radionuclide testing can be used to evaluate myocardial perfusion and left ventricular function
a small amount of a radioisotrope is injected intravenously, and the heart is canned with a radiation detector. Ischemic or infarcted cells in the myocardium do not absorb the radioisotrope
the S3 sound, heard early in diastole, is a ventricular filling sound caused by decreased ventricular compliance and is a sign of early heart failure. it is also known as ventricular gallop.
S4 is also a ventricular filling sound but occurs late in diastole. it is heart during atrial contraction and is known as atrial gallop. it is a result of myocardial infarction, ventricular hytertrophy, and increased afterload.
preload for the left heart is assessed by evaluation the pulmonary venous system. increased preload to the left heart typically manifests as signs of too much fluid in the pulmonary circulation as fluid backs up from the left side of the heart
a splitting of S2 indicates that one ventricle is emptying earlier or later than the other, usually because of a structural [e.g., valve defect], mechanical [e.g., heart failure, or electrical [e.g., alternate pacemaker] problem
higher levels of HDLs than LDLs are desirable. the ratio should be at 5 to 1; 3 to 1 is ideal
a deficit between the apical rate and the radial rate caused by irregular heart rhythms that result in stroke volume varying from beat to beat, which results in some beats being too weak to be felt at the radial artery is called the apical radial pulse deficit
the nursing process, particularly in high acuity, depends on a thorough assessment
a patient with a perfusion disorder may complain of palpitations, often described as a skipping or thumping of the heart
increasing the heart rate is the most effective mechanism for increasing cardiac output; however this mechanism has limitations.
a severe tachycardia causes stroke volume to decease because the heart spends too little time in diastole [relaxation] and the ventricles do not have time to fill with blood
