Circulation:Overview Flashcards
Each beat of the heart pumps about __mL of blood, or _L/min
60mL, 5L/min
pressure of blood in the aorta of a young adult averages about _____
100-120 mm Hg
pressure of blood in the RA averages about _ to _ mm Hg.
0 to 5 mmHg
to maintain adequate blood flow through the coronary arteries, MAP must be at least ___ mmHg.
60 - 70 mmHg
the period of time when the heart refills (relaxing) with blood after systole (contraction)
diastole
a term describing the contraction and emptying of the atria and ventricles
systole
Myocardial contraction results from the release of large numbers of _______ ions
calcium
average CO of an adult
4-7L/min
can be determined by dividing the CO by the body surface area
cardiac index (normal range 2.7-3.2 L/min/m2)
the HR is extrensically controlled by the _______________, which adjusts rapidly when necessary to regulate cardiac output.
autonomic nervous system (ANS)
slows the heart rate
parasympathetic (vagus nerve) system
increases the heart rate
sympathetic stimulation
the amount of blood ejected by the left vetricle during each contraction
Stroke Volume (SV)
refers to the degree of myocardial fiber stretch at the end of diastole and just before contraction
preload
the pressure or resistance that the ventricles must overcome to eject blood through the semilunar valves and into the peripheral blood vessels
afterload
the peripheral component of afterload, the pressure that the heart must overcome to open the aortic valve
impedance
the force of cardiac contraction independent of preload
myocardial contractility
factors that increase myocardial contractility:
- sympathetic stimulation
- calcium release
- positive inotropic drugs
factors that decrease myocardial contractility:
hypoxia and acidemia
the force of blood exerted against the vessel walls
blood pressure
Blood Pressure
Cardiac Output x Peripheral vascular resistance
the amount of pressure/force generated by the left ventricle to distribute blood into the aorta with each contraction of the heart. it is a measure of how effectively the heart pumps and is an indicator of vascular tone
systolic BP
the amount of pressure/force against the arterial walls during the relaxation phase of the heart
diastolic BP
supplies blood to portions of the left ventricle, ventricular septum, chordae tendonae, papillary muscle, and sometimes RV
Left anterior descending (LAD) branch
supplies blood to left atrium, lateral and posterior surgaces of LV, and sometimes interventricular septum
left circumflex (LCX) branch
supplies blood to RA, RV, inferior portion of the LV. SA & AV nodes.
Right coronary artery (RCA)
Serum markers of Myocardial damage:
- troponin
- creatine kinase - MB
- myoglobin
an invasive diagnostic procedure that involves fluoroscopy and the use of contrast media. performed when an arterial obstruction, narrowing, or aneurysm is suspected.
angiography (arteriography)
Complications of Cardiac Cath:
- MI
- Stroke
- Arterial bleeding
- Thromboemolism
- Lethal dysrhythmias
- Arterial dissection
- Death
What can be given pre and post cardiac cath to help eliminate or minimize contrast-induced renal toxicity?
acetylcysteine
an alternative to injecting a medium into the coronary arteries, which introduces a flexible catheter with a miniature transducer at the distal tip to view the coronary arteries
intravasacular ultrasonography (IVUS); more reliable than angiography in indicating plaque distribution and composition, arterial dissection, and degree of stenosis of the occluded artery
How often do you monitor patients vital signs in Follow up care of a cardiac cath?
VS every 15min for 1hr, then every 30min for 2hr or until VS are stable
assesses cardiovascular abnormalities, necrotic or ischemic tissue does not absorb the radioisotope and appears as “cold spots” on the scan. Assess myocardial scarring and perfusion, to detect the location and extent of an acute or chronic MI, graft patency after bypass, evaluate antianginal therapy, thrombolytic therapies, or balloon angioplasty
Thalium imaging of the heart (myocardial nuclear perfusion imaging (MNPI)
assess cardopvascular response to an increased workload. Helps determine the functional capacity of the heart and screens for asymptomatic coronary artery disease. Detects dysrhythmias and effectiveness of antidysrhythmia drugs.
Stress test, exercise electrocardiography, exercise tolerance test
an invasive system used in critical care areas to provide quantitative information about vascular capacity, blood volume, pump effectiveness, and tissue perfusion. DIRECTLY measures pressures in the heart and great vessels
hemodynamic monitoring
how is the patency of a hemodynamic monitor maintained?
slow continuous infusion of NS, usually infused at 3-4mL/hr to prevent backup of blood and occlusion of the catheter
What information is provided by monitoring the pulmonary artery wedge pressure (PAWP)?
tip of the catheter can sense pressures transmitted from the left atrium, which reflect left ventricular end diastolic pressure (LVEDP)
increased PAWP; (trend)
Left ventricular failure, hypervolemia, mitral regurgitation, intracardiac shunt
decreased PAWP; (trend)
hypovolemia or afterload reduction
normal RA pressure
1-8mmHg
normal pulmonay artery pressure (PAP)
15-30/8-15 mmHg
normal pulmonary artery wedge pressure (PAWP)
4-12 mmHg
Increased RA pressures may occur with:
right ventricular failure
low RA pressures usually indicate:
hypovolemia
What are two very important nursing interventions to remember when performing hemodynamic monitoring? (location, balloon)
- transducer be level of the phlebostatic axis
- if balloon remains in wedge position after reading call Dr IMMEDIATELY
Direct measurements of BP are usually __ to __ mmHg greater than indirect (cuff) measurements.
10-15mmHg
