Shock and Acute Heart Failure Flashcards
Where does the sarcoplasmic reticulum interface with the sarcolemma membrane?
At T-tubule
What are L-type calcium channels involved in?
within T-tubule, open in resposne to membrane depolarization
The small inward calcium current activates what receptor on SR?
ryanodine receptor
What does activiation of ryanodine receptor activate?
trigger large amounts of calcium from SR, which binds to troponin C; leads to conformational change in the actin thin filament. Mosin binding sites are exposed and myocyte contraction occurs.
What occurs in diastole with calcium in cardiac contraction?
rapid reuptake of calcium and myosin binding ceases
What is the venous return curve?
Reflect circulatory volume, peripheral vascular resistance and venous and arterial compliance
What is the frank-starling relationship?
connects force and muscle fiber length; more bridge made to cycle, more contractile force will be generated, further stretch more bridge connections available
What are factors that influence cariac output?
hear rate and contractility and extrinsic(preload and afterload)
What is the equation for wall tension?
La Place: Wall stress=(pressure*radius)/wall thickness
What is a compensatory mechanism for chamber dilation?
ventricular hypertrophy
Elevated filling pressures impede what in failing hearts?
impede adequate cardiac output
What is inotropic drugs do?
used to stimulate contractility and increase dilation; ; stim icrease in intracellular calcium
What are the two types of inotropic drugs?
Beta agonists such as dobutamine, epinephrine and norepi
phosphodiesterase inhibitors which degrade cAMP; milrinone
What are techniques to measure hemodynamics?
swan-ganz catheter; based on fick principle
What is CO equal to as far as measuring oxygen consumption?
CO=O2 consumption/((arterial O2)-MVO2)
What are the symptoms of warm and wet heart failure?
increased weight, elevated JVD, peripheral edema, dyspnea/orthopnea/rales
What are the symptoms of cold and dry heart failure?
dry mucous membrane, tachy, hypotensions, cold extremities
What are the symptoms of cold and wet heart failure
most severe; hypotension, tachy cold extremities elevated JVD dyspnea/orthopnea
What is an echocardiogram?
used to determine LVEF; in heart falilure by doppler measurment of flow
What percentages ndicate the different levels of heart failure normally?
45-50 mild
35-44 moderate
less than 35 is severe
What is a swan-ganz catheter physically and where is it placed?
catheter with ballon that goes through right atrium, ventricle and into the pulmonary artery
measure PCWP directly
In what pts is swan-ganz catheter used
pts with refactory sxs or severe disease
What lab tests are often gotten for acute heart failure?
chest xray basic metabolic panel Nt-pro BNP tropoonin level ECG
What are treatments of acute heart failure?
loop diuretics-furosemide
IV admin is recommended as a bolus or continuous infusion
also thiazide diuretics
afterload reduction by nitroprusside, nitroglycerine, nesteride
inotropes
mechanical support
