Maternal Cardiac Disease Flashcards
Define gHTN
BP >/= 140/90 >/= 20 weeks on 2 occasions at least 4 hours apart
AND
-No history of hypertension
-No history of proteinuria
-No severe features of preeclampsia
Define preeclampsia and what features are severe
BP >/= 140/90 >/= 20 weeks at least 4 hours apart
AND
-Proteinuria (P/C >/= 0.3 or >/=300mg/24hr)
—— severe features—–
-Thrombocytopenia, < 100k
-Renal insufficiency, Cr >1.1mg/dL or 2x baseline
-Impaired liver function, 2x upper limit normal AST or ALT
-Pulmonary edema
-Cerebral or visual symptoms
-Refractory RUQ/epigastric pain
Incidence of hypertensive disease of pregnancy
4% pregnancies in US
Those recommended to use prophylactic LDA and dosing
- 1 or more high risk factors (=8% risk of pree)
OR
-2 or more moderate risk factors
81mg daily >/=12 -28 weeks-, ideally before 16 weeks
High risk factors for LDA therapy
- History of preeclampsia
- Multifetal gestation
- Renal disease
- Chronic hypertension
- Pregestational diabetes
- Autoimmune disease (SLE, APS)
Moderate risk factors for LDA therapy
- Age >35
- Nulliparity
- BMI >30 kg/m2
- Black race
- Mother or sister with preeclampsia
- Low income
- IVF pregnancy
- History – SGA, adverse pregnancy outcome, pregnancy interval >10years
LDA reduces the rate of
- Preeclampsia ~50%
- Fetal growth restriction~60%
- Medically indicated preterm birth before 35 weeks
Contraindications to expectant management of preeclampsia
- uncontrolled severe range BP
- refractory headache
- refractory RUQ/epigastric pain
- visual disturbances
- pulmonary edema
- HELLP
- eclampsia
- Renal dysfunction
- MI
- Stroke
- placental abruption
- abnormal fetal testing
- fetal death or lethal anomaly
- REDF
Long term health risks of preeclampsia
-2-3x risk of developing CVD (CAD, MI, HF and stroke)
-Offspring effects (DM, HTN, neurodevelopmental)
Time frame for BP check after preeclampsia discharge
within 72hrs
Risk of gHTN developing preeclampsia
50%
HELLP diagnsosi
- Hemolysis - LDH >600 IU/L
- LFT dysfunction - AST/ALT 2x upper limit of normal
- Thrombocytopenia - <100k
15% without HTN or proteinuria
Typical main symptoms with HELLP
RUQ pain, generalized malaise, nausea, vomiting
Define eclampsia
new onset, tonic-clonic/focal/multifocal seizures in the absence of other causative conditions (epilepsy, cerebral ischemia/infarct, ICH, drug use)
Cause of maternal mortality with eclampsia
maternal hypoxia, trauma, aspiration pneumonia
Is there residual neuro damage after eclampsia
Rarely – some women have short and long term memory and/or cognitive impairment
Are there usual premonitory signs of eclampsia
Yes – headache, blurred vision, photophobia, altered mental status
Some cases without htn or proteinuria or any premonitory signs
Cause of headache in htn disorder/eclampsia
elevated cerebral perfusion pressure, cerebral edema, hypertensive encephalopathy
Define PRES
Posterior reversible encephalopathy syndrome
abnormal nervous system manifestations vision loss or deficit, seizure, headache, altered sensorium or confusion
How is diagnosis of PRES made
vasogenic edema and hyperintensities in the posterior aspect of the brain on MRI
Treatment of PRES
same as preeclampsia
Which LFT is usually more elevated first in preeclampsia and why
AST due to periportal necrosis
In general, evaluation of coagulation factors in preeclampsia is indicated when
Thrombocytopenia, significant liver dysfunction, placental abruption
Cause of proteinuria in preeclampsia
increased tubular permeability to proteins
What happens to urinary Ca in preeclampsia
Decreases because there is increased tubular resporption
What causes renal sodium and water retention in preeclampsia
the intravascular depletion, vasoconstriction leads to decreased renal perfusion
What are some fetal consequences of preeclampsia and mechanism
Impaired uteroplacental blood flow – fetal growth restriction, non-reassuring fetal status, oligohydramnios, abruption, preterm delivery, hypoxia-acidosis, neurologic injury, death
Mechanism of LDA in pree prevention
Inhibition of thromboxane A2
Magnesium decreases risk of seizure how much…decrease or increase anything else?
Decrease eclampsia by ~50%
Reduced risk of placental abruption
Maternal side effects in 25%
5% increased rate of CD
Rate of eclampsia in preeclampsia with severe features
4 in 200 without magnesium
1 in 200 with magnesium
Number needed to treat with Mag to prevent eclampsia
Pree with severe features - 129
Pree with severe features and symptomatic - 36
Contraindications to Mag
Myasthenia gravis
Hypocalcemia
Severe renal failure
Cardiac ischemia
Heart block
Myocarditis
Mag therapeutic/toxic levels
5-9 mg/dL therapeutic
> 9 loss of DTR
>12 respiratory compromise
>30 cardiac arrest
toxicities due to its action as a smooth muscle relaxant
Magnesium dosing
4g bolus over 20-30 minutes
1-2g/hr
IM dosing of magnesium
10g loading (5mg each buttock)
then 5g every 4 hours
Mg dosing in renal dysfunction
Cr 1-1.5, oliguria (<30mL/hr x4 hrs) = normal load, followed by 1g/hr
Cr >1.5 =
When to check mag levels
Renal dysfunction (every 4 hours, if >9.6 then stop infusion and check q2hrs, restart at lower infusion rate when <8.4))
Suspected Mg toxicity
Treatment of Mg toxicity
Calcium gluconate 10% solution – 10mL IV over 3 minutes
Consider Lasix
Why treat severe HTN
to prevent ischemic/hemorrhagic stroke, renal injury/failure, myocardial ischemia, CHF
When to treat HTN
Severe BP sustained for 15 minutes or more
Treat within 30-60 minutes
Labetalol max dose for PO regimen
2400mg/day
Labetalol max dose for acute IV regimen
300mg
Practice Labetalol/Nifedipine/Hydralazine acute treatment algorithms
Likelihood of CD in preterm preeclampsia
<28 weeks 97%
28-32 weeks 65%
Risks of general versus regional anesthesia
general = aspiration, failed intubation, stroke secondary to increased systemic and intracranial pressure during intubation/extubation
Effect of Mg on anesthesia
Prolongs duration of nondepolarizing muscle relaxants
Why no stop Mg for cesarean
1/2 life is 5hrs, so cessation only minimally reduces Mg concentration at time of delivery while possibly increased seizure risk
Steps to take during eclampsia
- call help
- ensure maternal safety
- lateral decubitus position
- administer oxygen
- monitor vitals and o2 saturation
- magnesium to prevent additional seizures
Treatment of recurrent eclamptic seizure
an additional 2-4 g of mag administered over 5 minutes
Treatment of refractory eclampsia (seizing 20 mins after bolus, more than 2 recurrences)
Amobarbital - 250mg IV in 3 minutes
Phenytoin - 1250mg IV at rate of 50mg/minute
Intubation, ICU admission, head imaging
HELLP labs that suggest increased mortality risk
LFT’s > 2000
LDH > 3000
In HELLP the lowest observed platelet counts tend to be seen
23hours after delivery
What is the underlying pathophysiology of cardiovascular changes in pree
vasoconstriction – imbalance between normal vasodilatory and vasoconstrictive substances
hemoconcentration - due to intravascular volume depletion
Cause of thrombocytopenia in pree
microangiopathic hemolysis possibly
Profound renal insufficiency in pree can lead to what renal condition
acute tubular necrosis
Differential diagnosis in HELLP
TTP/HUS
AFLP
Lupus
APLS
Labs to differentiate between HELLP, HUS/TTP, AFLP
Ammonia - elevated AFLP
Anemia - severe TTP/HUS
ATIII - decreased AFLP, may be elevated HELLP
AST - normal in TTP/HUS
Fibrinogen - decreased AFLP
Glucose - decreased AFLP
LDH - elevated in all
ATN postpartum….signs/sx
Worsening renal dysfunction, not associated with a aHUS picture (hemolysis, thrombocytopenia)
Risk of recurrent eclamptic seizure while on magnesium
10%
When is head imaging indicated in cases of eclampsia
Recurrent or refractory seizures
Focal neurological signs are persistent
Coma
Uncertain diagnosis
Why is the IM route for magnesium not preferred
Painful
Gluteal abscess
Monitoring for magnesium toxicity is achieved how
DTR’s
Respiratory status
Mental status
Urine output
How does Ca gluconate work as an antidote for Mg toxicity
Calcium competitively inhibits magnesium at the neuromuscular junction
At what BP is hypertensive encephalopathy generally achieved
> 220/120
However, women with typical normotensive values may develop at lower threshold as compared to someone with history of cHTN
Other systemic signs of HTN enecphalopathy
Retinal ischemia - vision changes
Cardiac ischemia - MI or angina
Renal ischemia - ATN or renal dysf
Drug of choice in hypertensive crisis
sodium nitroprusside
alternatives - nitroglycerin, nifedipine, nicardipine, hydralazine
Aim of initial therpay for htn emergency
Reduce MAP by 25% in first hour, goal 155-160/100-110
Why is BP lowering done slower in htn emergency
Esp in cHTN the cerebral autoregulation may be shifted. Lowering too quickly could clear to cerebral ischemia, stroke, coma in additional to reduced flow to other organs (coronary, placenta, renal)
MOA of sodium nitroprusside
Interferes with calcium influx and activation of intracellular calcium – leads to arterial and venous relaxation
How is sodium nitroprusside administered
IV infusion
short half life – works quickly, stops working quickly when IV stopped (3-5 mins)
Risks of nitroprusside
Hypotension - quickly reversed with cessation
Thiocyanate metabolite excreted in urine – can accumulate if renal or liver dysfunction, large doses, prolonged administration (48 hrs)
Cyanide toxicity symptoms
Anorexia
Disorientation
Headache
Fatigue
Restless
Tinnitus
Delirium/hallucinations
Nausea/vomiting
Metabolic acidosis
Treatment if cyanide toxicity
sodium nitrite
sodium thiosulfate
Nitroglycerin use with hypertensive encephalopathy?
contraindicated, it increased cerebral blood flow and intracranial pressure
MOA of magnesium
Elevated concentrations of Mg act on cell membranes to slow or block neuromuscular and cardiac conducting system transmission
decrease smooth muscle contractility
depress CNS irritability
Adverse effects of Mg MOA
Also decrease smooth muscle contractibility of uterus and heart
respiratory depression
Why not do intermittent bolus of Mg?
Leads to transient elevations in Mg level
Agents that can be used to terminate a seizure if already on magnesium
Valium - 5 or 10mg
Lorazepam - 4mg
General anesthesia
Hydralazine MOA
Dilation of arterioles
Labetalol MOA
alpha and beta-adrenergic blockade
Nifedipine MOA
Calcium channel blocker
Hydralazine effect on heart and uterus
Vasodilation leads to increased CO and increased uterine perfusion
Side effects of hydralazine
Headache and epigastric pain
CHAP trial demonstrates what findings for treatment of cHTN
BP <140/90 associated with decreased risk of preeclampsia w/ severe features, medically indicated birth <35 weeks, placental abruption/fetal/neonatal death
No change in SGA
