Cardiolgy ♥️ Flashcards
Heart lesion with reverse differential cyanosis
D - TGA with PDA and PPHN, interrupted aortic arch or coarctation of aorta
Mechanism of action of milrinone
- Phosphodiesterase 3 inhibitor—increased cAMP
* * Decreased breakdown of cyclic AMP->perpetuating Ca influx —> improve systemic blood flow - Improved ventricular function Inotropic, inodilator (promotes cardiac contractility) lusitropic (promotes relaxation)
- Decreases SVR
Indications: RV dysfunction, improving function in cardiac patients coming off bypass (especially if need decreased SVR)
HLHS
7-9% of congenital ♥️ defects
RV + tricuspid valve represent systemic ventricle + AV valve
Describe normal neonatal ECG findings
Normal QRS measured in V5 20-80msec
QRS axis ranges from +55 to 200+ in terms and +65-+174 in preterm
Predominant myocardial substrate prenatally and postnatally
Prenatally glucose and lactate
Postnatally fatty acids
The factor that causes the most significant change in blood flow with minor alteration is
Radius/diameter
R proportional 8x viscosity x L/pi x rx4
Responsible for pulmonary vascular changes at delivery
NO
Arachidonic acid metabolites
Patients with Pompes have which ECG finding?
Short PR interval and biventricular hypertrophy given hypertrophic cardiomyopathy
Noonan Syndrome findings
Hypertelorism Downward eye slanting Low set ears Short stature Pulmonic stenosis (60%) Web neck
**Noonan’s syndrome is the MCC of hypertrophic cardiomyopathy in neonates and children < 4yo
Hypertrophic cardiomyopathy
Rapid heart rate with atrial contractions precede ventricular contractions, atrial rate 180-240 which seems to speed up and slow down. What is diagnosis?
Ectopic atrial tachycardia
The most common non renal association with hypertension in preterm is?
BPD
Approach to management of HLHS is?
Norwood palliation
Treatment of fetal SVT vs AVnRT (atrioventricular nodal reentry tachycardia)
SVT is Digoxin
AVNRT is amiodarone
How does hydrocortisone express myocardial action in hypotensive patients?
Inhibits expression of nitric oxide synthase and vasodilators prostaglandin action
Upregulation of CV adrenergic receptors (vasoconstriction, inc Co, inc BP)
Upregulation of angiotensin II receptors to increase vascular resistance
Inhibits catecholamine metabolism and release of vasoactive factors
Inc in intracellular Ca concentration (enhances cardiac responsiveness to catecholamines)
Which genetic polymorphism is associated with abnormal neuro development at 1 year post cardiac surgery?
Genetic polymorphisms in apolipoprotein E
Which population of NICU patients should avoid ACE inhibitors
Preterm
Renal failure
Hypokalemia
Describe findings in HLHS and subtypes
Severe MV and AV stenosis/atresia
Hypoplastic LV
Aortic arch hypoplasia
30% mitral and aortic atresia
25% mitral stenosis and aortic atresia (high risk 2/2 presence of coronary-cameras fistulas in 50%)
45% mitral and aortic stenosis
Dopamine acts on which receptors at which doses?
Alpha 1: vasoconstriction (6-10)
Beta 1 and 2 chronotropy (HR) and contractility (2-6)
Dopaminergic at low dose (2-4) renal vasodilation and splanchnic vessels
At high dose 10-20, increases PVR via alpha 1
Hyperpercapnic-induced vasodilation in CBF is mediated by:
Hydrogen ion concentration requiring basal nitric oxide
Norepinephrine works where?
- endogenous catecholamine
- increases SVR and CO by alpha 1,2 and beta 1 receptors
- constricts systemic vascular»_space; pulmonary vascular
Mechanism of action of dobutamine
Acts directly in alpha and beta receptors without release of Norepi
Hydrocortisone side effects
Hyperglycemia
Osteopenia
Inhibits immune function and somatic growth
Associated with SIP if concurrent indomethacin
Aid in hypotension by decreasing breakdown of catecholamines, inc Ca in myocardial cells and upregulating adrenergic receptors
Which mutations have been found in HLHS?
HAND1 and NOTCH1
Recurrence HLHS sibling 8%
Recurrence of any congenital is 22%
What abnormalities are seen in Ebstein anomaly?
Apical displacement of septal and posterior leaflet of TV (atrial I zing the RV)
WPW (60%)
Right bundle branch block (70-80%)
Most commonly affected gene in long QT syndrome
KCNQ1- potassium channel gene
Abnormalities Associated with this gene also correlate with A fib later in life
What is the difference in functional vs fractional saturation of hgb?
Functional measures oxyHb and reduced Hb alone
Fractional saturation measures oxyHb ans. reduced Hb. And approximates carboxyHb and methHb.
Functional Hb 1.6-2 points higher than fractional saturation.
Most Common CHD in maternal diabetes
VSD
Double outlet RV
Truncus Arteriosus
What is therapy of hypertrophic cardiomyopathy in IDM neonates?
B blockers
Maintenance fluid
Contraindicated-inotropic support bc can make condition worse
What is the prognosis of HCM in neonate born with maternal diabetes?
excellent with resolution of ventricular hypertrophy at 1 mo of age
Mainly diastolic dysfunction
How is BP affected in preterms? Ie relative to SVR
Preterms may have low systemic blood flow because of structure of preterm myocardium is less able to overcome increased SVR after birth
How is preterm blood pressure influenced by chorioamnionitis
Chorio is associated with hypotension —> caused by release of inflammatory mediators (IL -1 and TNF)
When does cyanosis occur in neonates?
With drop of 3-5g/dL of Hgb of reduced Hgb
Cyanosis is more visible in polycythemic than in anemic babies
Cyanosis notable at this %saturation Hb: Reduced Hgb/total Hgb
Vasopressin mechanisms of action
Minimal chronotropic effects
Vasoconstriction during hypoxemia and acidosis
Which is the most common cause of HCM in neonates and children <4years?
Noonan syndrome
Describe Heart embryology and GA at formation
Arises from mesoderm
Right sided or dextro looping at 21 days
Septation at 3-4 weeks
Functional at 8 weeks
In utero, what percentage does the RV and LV supply to fetus?
66% RV
34% LV
7-15% of total blood volume goes to fetal lungs
Name the order from highest to lowest O2:
Umbilical artery, vein, uterine artery and vein
Uterine artery, uterine vein, umbilical vein, umbilical artery
How does the fetus compensate for hypoxemic environment?
Increase in erythropoietin
Fetal hemoglobin
Decreased O2 consumption
How can you increase stroke volume?
Increase EDV by inc preload or inc ventricular compliance
Decrease ESV by inc contractility and dec afterload
How best does the neonate regulate CO
HR
Preload
What target conditions does critical congenital heart screening identify?
HLHS Pulmonary Atresia with intact septum Tetralogy of Fallot TAPVR TGA Tricuspid Atresia Truncus Arteriosus
Describe the surgical repair for HLHS
Norwood
Stage 1
Atrial septectomy (creating pop off for LA) — preventing pulmonary venous congestion
Proximal portion of MPA —-> ascending aorta (to provide systemic circulation)
Systemic - pulmonary artery shunt to provide systemic blood flow (BT shunt - subclavian to pulmonary artery to ensure adequate pulmonary blood flow)
Stage 2 - BiDirectional Glenn
Decrease volume overload on RV
Remove BT - connects SVC directly to pulmonary artery (increasing pulmonary blood flow without increasing RV volume load)
Stage 3 - modified Fontan Reroutes IVC (to now meet SVC) to PA to create separate systemic and pulmonary circulation
This occurs in multi step process to allow pulmonary pressures to decrease
GLENN (G for Glenn) goes FIRST (F for Fontan)
Tetralogy of Fallot
RVH
PS
Overiding Aorta (allowing blood to leave both LV and RV)
VSD
- Right sided obstructive lesion
Variation in which enzyme has been associated with TOF?
ALDH1A2 (enzyme imp in retinoic acid production)
Genes associated with TGA
NODAL and FOXH1
Workup of dilated cardiomyopathy
Echo for ALCAPA
Viral PCR
Genetic/metabolic
In hypoxic condition the major pathway for energy production in neonatal heart is?
Lactate dehydrogenase (facilitates reduction of pyruvate to lactate reflecting anaerobic glycolysis)
Differentiate mechanism of action of Epi at low dose and high dose
Low dose 0.01-0.1mcg/kg/min Stimulates beta receptors enhancing myocardial contractility and peripheral vasodilation
High dose >0.1mvg/kg/min stimulates alpha receptors causing peripheral vasoconstriction and increase SVR
Remember it is a non selective alpha agonist and activates both B1 and B2 adrenergic receptors
How does fetal heart facilitate glucose uptake??
Glucose transporters
GLUT1 and GLUT4
GLUT1 plays primary role in bringing glucose into the cardiac monocyte
Prenatally
GLUT1»_space;GLUT4
Postnatally
GLUT4 > GLUT1
Treatment of SVT with WPW
Propanolol
Timing of CHD Presentation
TGA —-> 1-2 days
HLHS —-> 3-7 days
Coarctation Ao —> ~14 days
VSD —> ~4-6 weeks
3.2 kg baby with tachypnea + poor perfusion. Pre/post sats 82%. O2 via hood worsens condition. Placed on ventilator (TV 20ml, PEEP 6, iT 0.35, FiO2 70%)
CBG - 7.24/38/46/18/-8.
Saturations are still low (~75%)
What is the next step in management?
Decrease TV
Decrease rate
Decrease FiO2
In HLHS - oxygen worsens the condition due to steal of blood from PDA
Newborn Baby within 1st week of worsening with O2 - T/C HLHS
Qp/Qs calculation
>1
Ao sat-SVC sat/RV sat-PV sat
> 1 L to right shunt (inc PBF)
<1 R to L shunt (PPHN)
Remember inverse (systemic/pulmonary)
Which type of heart failure does PDA lead to?
Left to right shunt
Therefore, left sided heart failure
Characteristics of Fetal Circulation
Oxygenated blood —> placenta
—> IVC —> RA (SVC brings deoxygenated blood so mixing occurs) —> RV —> PA —> PDA —> descending Ao
Oxygenated blood —> placenta
—> IVC —> Ductus Venosus —> LA (PFO) —> ascending Ao
** LA, LV, ascending Ao have the highest PO2
Name Contracting and Dilating Mediators
For example - PDA closure occurs with increasing contracting mediators and decreasing dilating mediators
Constrictors PGF2α Αcetylcholamine Bradykinin Oxygen
Dilators PGE1 PGI2 (prostacyclin) Hypoxemia Acidosis
EKG Measurements
HR - big boxes - 300 —> 150–> 75
1 big box = 0.2 seconds or 200 milliseconds
1 small box = 0.04 seconds = 1 millivolt
Describe the expected pressure measurements with umbilical catheter in IVC, Aorta, LA
IVC - 1-3 mmHg
Ao - should approach systemic means
LA - mean pressure of 8mmHg
Calculate Mean Blood Pressure
Mean BP=
Diastolic + 1/3 (SBP - DBP)
** Remember to average blood pressures if given more than one)
Indirect Measure of cerebral perfusion
SVC blood flow + Doppler
SVC flow reflects upper body venous return and is less influenced by shunts
May reflect cerebral perfusion
Describe echo findings of dilated cardiomyopathy in terms of
- shortening fraction
- ejection fraction
- left ventricular dimension Z score
Shortening fraction <25%
EF<40%
LV dimension Z score greater than 2
Which mediator is decreased in expression in pulmonary casualties in idiopathic pphn?
Endothelial nitric oxide synthase and downstream target soluble guanylate cyclase
Remember endothelin 1 plays goal in maintaining high vascular tone in utero
T or F
Blood pressure has a strong relationship with cardiac left ventricle output
False
BP is a function of both blood flow and SVR.
Weak relationship between LV output and mean BP
Physical exam findings in HLHS
Hyperdynamic precordial activity reflects right ventricular volume and pressure overload
Decrease in amplitude of peripheral pulses only after ductal constriction
Single S2 if aortic atresia present
Murmur for TR
Primary site of fatty acid oxidation regulation by fetal and neonatal cardiac myocytes is
Carnitine palmitoyltransferase
Wandering atrial pacemaker is most associated with:
High vagal tone
The BT shunt involves shunting from which vessels?
Subclavian artery to ipsilateral pulmonary artery
Ductal patency in utero depends on which 3 substances
PGE2
Prostacyclin
Thromboxane 2
Describe 4 mechanisms how fetus tolerates lower pO2
- Fetal hemoglobin
- Increased O2 carrying capacity bc of elevated Hgb in fetus 2/2 hypoxemic erythropoeitin production
- Decreased O2 consumption
- Increased ability to utilize glucose by anaerobic metabolism
Describe 3 Mechanisms by which fetus compensated for worsening hypoxemia
Blood flow preferentially goes to heart brain and adrenals
Dilation of DV so more oxygenated blood goes to left side of heart
Fetus goes into hybernation mode
What is the % of fetal blood flow in 2nd trimester?
In 3rd trimester?
7-15% (2nd trimester)
35% (fetal growth)
How does the fetus adjust to
the relatively low intra utérine oxygen environment ?
Epo
Fetal Hb (high affinity for oxygen which allows for increased oxygen uptake even in hypoxia environments)
Decreased oxygen consumption
How does fetal
Heart increase cardiac output ?
CO = SV x HR
fetal tachycardia—> increases cardiac output
Describe a pt with Qp/Qs>1
Tachypnea, FTT, CHF
Baby with cyanosis, acidosis and tachypnea. What’s the Qp/Qs?
Qp/Qs<1
In a patient with cardiac tamponade how does the blood pressure change?
Pulsus paradoxus is a decrease in systolic blood pressure during spontaneous inspiration
Pulsus paradoxus is a common finding in cardiac tamponade in a spontaneously breathing patient.
Because systolic blood pressure normally increases during inspiration while receiving positive pressure ventilation, reversed pulsus paradoxus is observed in patients with cardiac tamponade who are receiving mechanical ventilation.
List disorders associate with single S2
S2 is closure of aortic and pulmonary valve
Single S2 heard with:
- Pulmonary hypertension (both close at same time)
- 1 semilunar valve (PA, aortic atresia, truncus, TOF/absent PV)
- P2 not heard (TGA, TOF, severe PS)
Single S2 with bounding pulses. Dx?
Truncus arteriousus
Single S2 because one arterial vessel exiting heart
Bounding arterial pulses because of diastolic runoff into PA
Which enzyme do catecholamines (ie dopamine) regulate for renal solute transport and Na absoption?
Basolateral Na/K ATPse (increased Na absorption)
Hypertrophic cardiomyopathy is seen with which genetic conditions?
Noonan
Beckwith Weideman
Costello Syndrome (fasciocutaneoskeletal syndrome)
Eagle Barrett (prune belly)
Side effects of dopamine use
Decreased thyroyropin
Deceased prolactin
Decreased thyroxine
Increases PVR
Long term dopa use (> 12 h) does what to the heart?
Depleted norepinephrine stores
Right and left differentiation begins during which stage of embryonic development?
Gastrulation
What suggests R > L shunting?
> 15 torr difference in pre/post ductal paO2
>10% difference in O2 saturations
