Post on 07-Mar-2018
transcript
8/22/12
1
NCC Review Cardiac
Tracey Buckley MSN,RNC, NNP-BC Cape Fear Valley Health System
Topics
• Transition to Extrauterine Life • Cyanosis • Congenital Heart Disease (CHD) • Clinical Manifestations of CHD • Therapeutic agents in cardiac
disease
Intrauterine Blood Flow
• Key Points • Umbilical Cord = 1 vein and 2 arteries • Umbilical Vein (UV) - O2 blood from
placenta to fetus • Umbilical Arteries (UA) - O2 blood from
fetus to placenta • Right ventricle - main pumping chamber • Systemic vascular resistance (SVR) - LOW • Pulmonary vascular resistance (PVR) - HIGH
8/22/12
2
Fetal Shunts
• Ductus venosus – allows for blood to bypass the liver and enter the IVC
• Foramen Ovale – allows blood to bypass the pulmonary system
• Ductus arteriosus – allows blood to bypass the pulmonary system
RA
RV
LA
LV
BODY LUNGS
PLACENTA
IVC/SVC PV’s
PA’s
DA
DA
Picture by T. Buckley NNP_BC
Fetal Circulation
Blood Gas Parameters of Umbilical Vessels
Vessel pH pCO2 pO2 % O2 UA 7.35 48 15 30%
UV 7.38 43 27 68%
Normal blood gas parameters in term Newborn (ABG)
pH pCO2 pO2 HCO3 >7.30 40-50 50-70 20-24
8/22/12
3
How does the fetus survive ???
• Fetus tolerates lower pO2 because • Fetal hemoglobin (Hgb F) has a higher affinity
for oxygen • Increased Hgb in fetus = increased oxygen
carrying capacity • Increased ability to utilize glucose by
anaerobic metabolism
RA
RV
LA
LV
BODY LUNGS
PLACENTA
IVC/SVC PV’s
PA’s
DA
DA
Picture by T. Buckley NNP_BC
Hemodynamic Changes at Birth
AfterDelivery
Normal Circulation after birth
Courtesy of Microsoft Office. http://office.microsoft.com/en-us/images/
8/22/12
4
Hemodynamic Changes at Birth
• After delivery • Gas exchange occurs in lungs (not
placenta) • Lungs expand with air PVR
pulmonary blood flow LA pressure (now > RA pressure) FO closes
• SVR increases • Ductus venosus closes (no more blood
flow) • PDA closes
Cardiac Output
• Cardiac Output = Heart Rate x Stroke Volume • Factors affecting cardiac output
• Preload • Afterload • Contractility • Heart Rate
• Stroke Volume: Amount of blood ejected from the LV with each heartbeat
Incidence of CHD
• 8 in 1000 live births • 2 in 1000 presenting <1 year of age
• 2-5% recurrence if a previous child has CHD • 6-7% if mother has CHD • 1.5-3% if father has CHD
8/22/12
5
Incidence of specific defects
• VSD 16% • Pulmonary stenosis with intact ventricular septum
7.5-12% • TOF 8-10% • ASD 10% • TGA 5-10% • PDA 4-10% (full-term infants) • Coarctation of Aorta 5-8% • HLHS 1.5%
Incidence of specific defects
• VSD – most common CHD • TOF – most common CHD beyond infancy • TGA – most common CHD in 1st week of life • HLHS – 2nd most common CHD in 1st week of
life and MOST common cause of mortality in 1st week of life
It is only after the maternal circulation is eliminated and the cardiovascular system of the infant becomes independent that the input of the anatomical and hemodynamic abnormalities become apparent
8/22/12
6
Clinical Manifestations of CHD
• Cyanosis***** • Respiratory Distress****** • Congestive Heart Failure and diminished cardiac output • Abnormal rhythm • murmurs
Central Cyanosis
• Definition: the absolute amount of reduced hemoglobin
• Observed when Hgb is reduced by 3-5g/dl • Anemia decreases clinical appearance • Polycythemia increases clinical appearance
Six components of oxygen delivery
• CNS • Musculoskeletal • Airways • Gas exchange interference in the lungs • Hemoglobin • CV System
8/22/12
7
Central Cyanosis versus Peripheral Cyanosis
Peripheral cyanosis • Due to poor blood flow to the skin
(acrocyanosis) Central cyanosis
• Generally due to R to L shunting • Desaturated venous blood mixes with saturated blood • Decreased blood to the lungs
Left to Right Shunts
• SVR and PVR • Blood takes the path of least resistance • Blood shunts from the oxygenated side to the deoxygenated side (returns to lungs) • Via ASD, VSD, PDA
RA
RV
LA
LV
BODY LUNGS
IVC/SVC PV’s
PA’s
Left to Right Shunts
PVR SVR
ASD/PFO
VSD
8/22/12
8
Right to Left Shunts
• Blood shunts from the deoxygenated side to the oxygenated side (skips the lungs)
• Examples • Pulmonary atresia: from RV thru PDA to
aorta • Tricuspid atresia: from RA thru ASD to LA • Hypoplastic right heart: from RA thru ASD
to LA • Usually PATHOLOGIC!!!
RA
RV
LA
LV
BODY LUNGS
IVC/SVC PV’s
PA’s
Right to Left Shunts
PVR SVR
Arterial Sampling Sites
• Pre-ductal • R radial
• Post-ductal • L radial • Umbilical • Lower extremities
8/22/12
9
Cardiac versus Pulmonary Cyanosis Hyperoxia Test
1 ABG from right arm in room air 2 100% hood for 5-10 minutes 3 Repeat ABG 4 PaO2 >150mmHg = Respiratory 5 PaO2 unchanged = CHD
Clinical Pearls • GET A CENTRAL HEMATOCRIT
• r/o polycythemia as a cause of cyanosis • ↓ cyanosis with crying = respiratory disease • ↑ cyansis with crying = CHD • Be sure you hear a split S2 on cardiac exam • Respirations
• Hyperpnea = hypoxia • Tachypnea = pulmonary edema
Classification of Cardiac Defects • Lesions which increase pulmonary blood flow
• Lesions which decrease pulmonary blood flow
• Lesions which decrease systemic blood flow
8/22/12
10
Cyanotic versus Acyanotic Cardiac Defects
• Cyanotic • Results in decreased oxygen in blood • Right to left shunt
• Acyanotic • Defect that does not lower blood oxygenation • Left to right shunts
Physical Exam
• Heart sounds • Murmurs • Pulse Pressure • Blood Pressure
Heart Sounds
RA
RV
LA
LV
BODY LUNGS
IVC/SVC PV’s
PA’s
S1 Tricuspid/Mitral Valves
Closes
S2 Pulmonic/Aortic
Valves close
8/22/12
11
Murmurs
Clipart courtesy of Microsoft Office. Labels by T. Buckley NNP-BC
ULSB
URSB
ICS 1st
4th
2nd
3rd
5th
LLSB Nipple Line APEX
Pulse Pressure
• Difference between the SBP and DBP • Widened pulse pressure
• Most common: PDA, truncus arteriosus • Narrow Pulse Pressure
• Most Common: Pericardial tamponade, AS
Blood Pressure
• Varies with gestational age • Mean ~ gestational age
• Cuff selection is very important • Small cuffs give falsely high values
• Hypertensive Infant • Term – SBP >95 • Preterm – SBP>80
• Most common cardiac cause of hypertension - Coarctation
8/22/12
12
Shock
• Acute failure of circulatory function • Characterized by inadequate tissue and organ
perfusion • Early compensated shock
• Blood flow preserved to heart, lung, brain, and kidneys
• Late Decompensated shock • Tissue ischemia and metabolic acidosis
• S/S: UOP, HR, BP
CHF • Inability if the heart to meet the metabolic requirements
of the body • Etiology of CHF:
• Volume overload • Pressure overload • Cardiomyopathy • Dysrhythmias
Radiographic Findings of CHD
• Boot shaped heart TOF • Egg on a string d-TGA • Snowman TAPVR
8/22/12
13
Congenital Heart Disease
• Cyanotic Heart Disease • Left to Right Shunts • Left and right sided obstructive lesions • Valvular Disease • Other abnormalities
Cyanotic Heart Lesions
• TGA • TOF • PA (with intact ventricular septum) • Truncus Arteriosus • Tricuspid Atresia • Ebstein’s Anomaly • Single Ventricle • TAPVR • Double Outlet Right Ventricle
Left to Right Shunts
• VSD • ASD • PDA • Complete AV canal • Partial APVR
8/22/12
14
Left and Right Sided Obstructive Lesions
• Coarctation of the Aorta (CoA)
Valvular Diseases
• Aortic Valve Regurgitation (AR) • Mitral Valve Regurgitation (MR) • Tricuspid Valve Regurgitation (TR)
Other Diseases
• Hypoplastic Left heart syndrome (HLHS) • Cardiomyopathy • Eisenmenger’s Complex • Cor Pulmonale • Pericardial Effusion
8/22/12
15
Prostaglandins • Maintains patency of the ductus arteriosus in
utero • Administered to maintain blood flow through the
DA • TA, PA, severe PS, AS, coarctation or
interrupted aortic arch • Dosage: 0.05 – 0.10 mcg/kg/min IV • Adverse effects
• APNEA • Vasodilation, hypotension,Thrombocytopenia
Cardiac Tamponade • Blood, serous fluid, or air, under tension, fills the
pericardial sack, • Causes life-threatening compromise of
venous return and decreased stroke volume • Classic signs (Beck’s Triad):
• Hypotension • Pulsus paradoxus (acute drop in SBP)
• Jugular venous distention • Muffled heart sounds
• Often associated with Central Lines in neonates
Basic Principles of EKG
P wave: Atrial depolarization
QRS complex : ventricular depolarization
T wave: ventricular repolarization
U wave: late phase of repolarization
8/22/12
16
ECG Waves
Courtesy of: Anthony Atkielski, public domain.
Cardiac Conduction
Patrick J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist.http://creativecommons.org/licenses/by/2.5/
ECG Interpretation
• 1. Measurements • 2. Rhythm analysis • 3. Conduction analysis • 4. Waveform description • 5. ECG interpretation • 6. Comparison with previous ECG (if
available)
8/22/12
17
Practice Questions
References • Fetal Circulation flash videos.
http://www.indiana.edu/~anat550. Permission granted by Valerie O’Loughlin, Associate Professor, Indiana State University.
• Verklan, M. & Walden. M. (2010). Core curriculum for neonatal intensive care nursing. Saunders/Elsevier.
• Brodsky, D. & Martin, C. (2003). Neonatology review. Hanley & Belfus.
• Merenstein, G & Gardner, S. (2002). Mosby. • Ribcage clipart & Heart Clipart. Courtesy of Microsoft
Office (public). http://office.microsoft.com/en-us/images.
References • Image: Heart anterior view coronal section. Patrick
J. Lynch, medical illustrator; C. Carl Jaffe, MD, cardiologist. Permission: Creative Commons Attribution 2.5 License 2007. (http://creativecommons.org/licenses/by/2.5/ ). http://en.wikipedia.org/wiki/File:RLS_12blauLeg.
• Schematic diagram of normal sinus rhythm for a human heart as seen on ECG. (2007). Agateller (Anthony Atkielski). Permission: Public Domain. http://en.wikipedia.org/wiki/File:SinusRhythmLabels.svg