CCRN Cardiovascular

Cardiac Output - answer-HR x SV Younger children tend to have a higher CO because their HR is faster. Cardiac Index - answer-More specific indicator of hemodynamic status than cardiac output (includes body surface area in equation). CO is normally 4-8 L/min, however CI is 2.5-4.0 L/min/m2. CI=CO/BSA MAP (mean arterial pressure) - answer-The mean pressure that takes into account the fact that the diastolic phase represents 2/3 of the cardiac cycle. MAP=2(DBP) + (SBP)/3 Patients should maintain a MAP of at least 60 mmHg to ensure adequate perfusion to the brain and kidneys. Ejection Fraction - answer-The ejection fraction should be over 50%. The is the amount of blood ejected from the left ventricle compared to the total amount available in the ventricle. An ejection fraction of 35% or less indicates a problem with contractility, outflow, or filling. The ejection fraction most closely represents left ventricular end-diastolic pressure. The LVEDP is the volume of blood under pressure left at the end of contraction. Tetralogy of Fallot - answer--Includes: VSD, overriding aorta, pulmonary stenosis, and right ventricular hypertrophy. -Condition results in low oxygenation of blood due to the mixing of oxygenatated, and deoxygnenated blood in the left ventricle via the VD, and mixing of blood from both ventricles through the aorta because of the obstruction to flow through the pulmonary valve. -End result is a right to left shunt. -Primary symptom of TET is a low blood oxygen saturation, with or without cyanosis, from birht or developing in the first year of life. -Other symptoms include a harsh systolic murmur with a thrill, difficulty in feeding, failure to gain weight, retarded growth, and physical development. Polycythemia may be present with dyspnea on exertion, along with clubbing. -Children may have tet spells--results from a transient increase in resistance to blood flow to the lungs along with increased flow of desaturated blood to the body. May be precipitated by activity and are characterized by paroxysms of hyperpnea, irritability, prolonged crying, increasing cyanosis, and decreasing intensity of heart murmur. Maye result in hypoxic brain injury and death. Older children may squat which cuts off circulation to the legs. The squatting position raises intrathoracic pressure and systemic vascular resistance, thereby improving blood flow to the brain and vital organs. Diastolic phase - answer-At birth, diastole represents half of the cardiac cycle, shortly after birth, the diastolic phase lengthens so that it represents 2/3 of the cardiac cycle. An increase in cardiac output decreases diastole. Reflex tachycardia - answer-Caused by the stretch of right atrial receptors. Known as the Bainbridge reflex. The Bainbridge reflex is believed to occur to speed up the HR if the right side because overloaded and help equalize pressures in both sides. Pulmonary Artery occlusive pressure (PAOP) - answer-Pressures in the left side of the heart and pulmonary filling pressures are represented by the PAOP. Balloon of the pulmonary artery catheter is inflacted, it eventually wedges in the pulmonary artery. The turbulence behind the balloon is blocked and it senses what is in front of it--the pulmonary vascular bed and left side of the heart. The normal value should be 5-12 mmHg. Left atrial pressure - answer-A normal LAP is 8 mmHg. A high LAP would indicate mitral valve dysfunction. High right atrial pressures would be increased by either pulmonary stenosis or tricuspid regurgitation. S4 - answer-The fourth heart sound disappears after the first 24 hours of life and if it stays indicates a decreased ventricular compliance. The heart sound is produced when an atrial contraction fills up the ventricle . If heard in a newborn, sounds like a clicking sound right before S1. Systemic vascular resistance (SVR) - answer-The mean pressure difference in the systemic vascular bed divided by blood flow. Indicates the resistance the left ventricle must pump against. Heart murmur - answer-If murmur is associated with acute valvular regurgitation, it is called S4. S4 is associated with ventricular compliance. S3 is associated with fluid status. Stroke Volume - answer-Comprised of contractility, preload, and afterload. Viscosity, blood volume, and impedance represents the components of afterload. Myocardiac sensitive toe changes, especially increased afterload. With only minute changes in afterload, the SV can fall significantly. Pulmonary catheter tracing - answer-A large A wave may be seen with increased pressure during atrial contraction. Could be caused by mitral stenosis, an ischemic left ventricle, or failure of a left ventricle. Hill's sign - answer-A popliteal BP that is 20+ mmHg higher than the brachial BP. Reflects the rapid rise in pulsation found in patients with aortic insufficiency. Pulsus alternanas - answer-Occurs in left ventricular failure when the weakened myocardium cannot maintain an even pressure with each contraction. The pulses alternate between strong and weak. Can also be seen in CHF. Adenosine - answer-Used for the suppression or elimination of sustained supraventricular tachycardia. Adverse effects may include transient arrhythmias, flushing, dyspnea, and apnea. Caffeine and thophylline diminish the effects of adenosine. Right sided heart failure - answer-Cause is often left sided heart failure. Right ventricle can't adequately pump, so filling pressures rise and the blood backs up, resulting in hepatomegaly. Thus, the CVP and RV pressures are elevated. Additional symptoms include splenomegaly, ascites, abdominal pain, S3 and S4 and weight gain. Pulmonary edema , an elevated PAD, PAOP and orthopnea are symptoms of left sided heart failure. Left heart failure EKG changes - answer-Results in wide, notched P waves. Tall, peaked P waves are indicative of right sided heart failure. Changes in ST segments indicate myocardial ischemia. Atrioventricular canal defect - answer-Condition that is often associated with an ostium primum ASD. This defect is also associated with a cleft in the anterior mitral valve leaflet, a VSD in the inlet portion of the ventricle septum, and a cleft in the septal leaflet of the tricuspid valve. Ventricular septal defect - answer-Causes pulmonary vascular resistance (PVR) to be less than the systemic vascular resistance (SVR). This imbalance causes left to right shunting. So too much blood may enter the lungs, increasing edema and possibly delaying the maturation of arterioles. A pansystolic murmur can be heard over the left sternal border. Tet spells - answer-May be treated with morphine to promote venous dilation. IV fluids can be used for volume expansion and an increase in systemic BP. If these don't work, phenylephrine or ketamine can help. Propranolol may prevent or mitigate tet spells. Pulmonary vascular resistance (PVR) - answer-The resistance against which the right ventricle must eject its volume. Calculated as a mean pressure in the pulmonary vasculature that is divided by the blood flow. Alpha-adrenergic effects of norepinephrine - answer-Peripheral arteriolar vasoconstriction. Beta adrenergic effects of norepinephrine - answer-Increased force of myocardial contraction, increased AV conduction time. S3 - answer-Occurs when increased blood flow travels across the AV valves secondary to rapid passive ventricular filling from the atria. "extra fluid"--common with CHF, mitral valve insufficiency, anemia, and left to right shunts such as ASD, VSD, and PDA. Infants with CHF and interventional procedures - answer-At high risk because contrast dye has a high sodium content. Sodium contributes to myocardial depression and creates an osmotic effect that temporarily increases intravascular volume. Infiltration of dopamine - answer-Inject Phentolamine (Regitine) 1 mg/mL. May take as much as 5 mL to treat affected area. Bidirectional Glenn procedure - answer-Used for hypoplastic left heart. Superior vena cava is anastomosed to the right pulmonary artery. Usually performed prior to 6 months of age to specifically reduce volume overload to the right ventricle. First stage is the Norwood procedure--consists of ligation of the ductus and division of the pulmonary artery. . The end result of the staged procedures is systemic circulation supplied by a single right ventricle. Cyanotic heart defects - answer-Pulmonary atresia