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Aortic Stenosis in Pregnancy. Brendan Astley MD & Norman Bolden MD. Nov 2006. PMH- “Heart condition” since age 12 (no further follow-up) SOB and CP at rest and exertion worse over last two years PSH- none Medications- PNV Allergies- NKDA FH- unknown SH- no tobacco, EtOH or drug use.
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Aortic Stenosis in Pregnancy Brendan Astley MD & Norman Bolden MD Nov 2006
PMH- “Heart condition” since age 12 (no further follow-up) SOB and CP at rest and exertion worse over last two years PSH- none Medications- PNV Allergies- NKDA FH- unknown SH- no tobacco, EtOH or drug use 18 year old G1P0 Spanish speaking female
Physical Exam • Vitals BP 104/62 HR 79 temp 36.6 RR 18 sat 100% • Height 4’10” Weight 99lbs. now 119lbs. • Heart– IV/VI systolic murmur… cresendo-decresendo murmur with no diastolic component, heard best at R upper sternal border, radiation to carotids bilaterally, no JVD, no 3rd or 4th heart sound • Airway– nml, Mal I • Lungs– CTA Bil., no w/r/r • Abd– NT gravid uterus, soft • Ext– no edema good pulses distally
Labs: B positive BNP 5.5 WBC 8.71, Hg 12.5, Hct 36.8, Plts 256 Na 136, K 3.9, Cl 108, CO2 21, BUN 5, Cr 0.5, Glu 71 Ca 8.5 TSH 0.9, RPR, NR, HIV, VZ immune, RI, GC/ chlam, hep B all negative Plan: Admit to antepartum unit (social admission) to facilitate consultations by Maternal/Fetal Medicine, Cardiology, NICU and Anesthesiology.
Cardiology • Murmur appreciated and echo performed: on 9/15 showing AS <.6cm2, probable bicuspid valve and EF 65%. • Pt followed for change in symptoms…. • Mid Oct. at about 35 wks. Gestation she complains of increased CP and SOB especially with exertion but also at rest. • .1%-1.4% pregnancies with clinically significant cardiac problems • Mortality from these .5%-2.7%
Cardio cont’d • Echo shows peak gradient of 62mmHg and .58cm2 orifice by the continuity equation. • Velocity waveform is asymmetric which usually equates with less than severe stenosis. • CXR- WNL, no cardiopulmonary disease • CXR abnormalities may include enlarged aorta, cardiomyopathy and possibly pulm. edema
Expected EKG changes with AS Left ventricular hypertrophy (LVH) • There are many different criteria for LVH. • Sokolow + Lyon (Am Heart J, 1949;37:161) • S V1+ R V5 or V6 > 35 mm • Cornell criteria (Circulation, 1987;3: 565-72) • SV3 + R avl > 28 mm in men • SV3 + R avl > 20 mm in women • Framingham criteria (Circulation,1990; 81:815-820) • R avl > 11mm, R V4-6 > 25mm • S V1-3 > 25 mm, S V1 or V2 + • R V5 or V6 > 35 mm, R I + S III > 25 mm • Romhilt + Estes (Am Heart J, 1986:75:752-58) • Point score system • Left atrial abnormality (dilatation or hypertrophy) • M shaped P wave in lead II • prominent terminal negative component to P wave in lead V1
? Suggestions for Anesthetic Plan • Anesthesia for Vaginal Delivery • Monitors for Vaginal delivery • Anesthesia for C/S • Monitors for C/S. • Maternal-Fetal Medicine, Cardiology , NICU, and Anesthesia develop working plan. • ***If possible, avoid C/S. If vaginal delivery, must avoid valsalva.
Anesthesia for Vaginal Delivery • Neuroaxial anesthesia… • Continuous Spinal • Single shot spinal not reasonable for prolonged labor • Reliable block • Intrathecal narcotics avoid the sympathectic block with ensuing hypotension • Intrathecal narcotics not effective for second stage of labor. • Small doses of intrathecal LAs added to narcotics improve analgesia while limiting hemodynamic consequences. • Chance for spinal headache
Anesthesia for Vaginal Delivery • Neuroaxial anesthesia… • Epidural • Pros…titratable to produce minimal hemodynamic changes, adequate anesthesia possible for vaginal or C-section, if performed properly no spinal headaches • Cons…higher failure rate compared with spinal
Anesthesia for Vaginal Delivery • IV Narcotic analgesia (PCA) • Pros…would offer patient some analgesia (most still report 8-10/10 pain despite Fentanyl PCA) • Cons… Respiratory Depression (mother and fetus), Sedation (mother and fetus), N/V, decreased beat to beat variability on fetal heart rate tracing. • Cons….Would not effectively control the pain from second stage of labor and therefore would not attenuate the increase in HR associated with delivery.
Stages of Labor • 1st stage – 2 phases: • latent phase encompasses the onset of pain to the first noticed change in cervical dilation • Maximal dilation phase…begins around 3 cm • 2nd stage – Maximal cervical dilation 10cm until delivery of fetus • 3rd stage – After delivery of fetus until delivery of placenta
Board Questions?? • During the first stage of labor, the pain of uterine contractions is transmitted via spinal cord segments.. • A…T6 to L1 • B…T6 to L5 • C…T10 to L1 • D…T10 to S1 • E…T10 to S5 • Answer is….C
Anesthesia for C-section • General anesthesia… • Pros…good airway control, minimal hemodynamic changes compared to epidural/spinal boluses to start case, can treat hemodynamic changes rapidly with close monitoring • Cons…possible difficult airway, aspiration risks, tachycardia and/or hypertension on induction or emergence, caution with volatile agents and hypotension or myocardial depression
Hospital Course • Induced to L & D at 35 weeks. • Arterial line placed • Swan-Ganz catheter placed • Early epidural also placed by anesthesia • Continuous Telemetry monitoring • Pitocin was started on the night of 11/7 and by morning she was well dilated and contracting regularly
11/7 1950hrs: PCWP 10-11, CVP 5-7, good UOP 2330hr: PCWP 10-13 11/8 0100: PCWP 7-9…complains of CP 0300:CVP 15-16, trop .15 0500: PCWP 11-15, CO 5L/min 0800: trop <.1 (nml) Wedge maintained in above normal range Delivery at 1130am PCWP/CVP readings
Hospital Course cont’d • No symptoms of AS during induction course. • Ready for delivery in AM with forceps • No valsalva by mother and epidural working well with slow dosing. • PCWP and urine output maintained throughout delivery with fluids and gentle epidural dosing.
Hospital Course cont’d • After forceps delivery pt transferred to Step-Down on esmolol drip due tachycardia. • Drip stopped in CCU 11/8 and gentle diuresis started with Lasix. • Stable vital signs throughout hospital stay. • Day #3 post-forceps delivery patient transferred home with 6 week follow-up with cardiology for possible valve replacement.
Physiologic Changes during pregnancy • Beginning to change at 5 weeks…10 fold increase in uterine blood flow at term • Cardiovascular : Blood volume 35%, CO 40-50%, SV 30%, HR 15-20% • Cardiovascular : SVR 15%, sys and diastolic BP 10mmHg • Pulmonary Changes: O2 consumption 20%, RR 15%, MV 50%, TV 40%, alv vent. 70% ERV 20%, FRC 20%
Aortic Stenosis • In the past Rheumatic Valvular degeneration was the primary cause • Congenitally bicuspid valves become calcified and cause stenosis most commonly now…(1-2% of population) • Senile degeneration can also occur • 30% of patients older than 85 have significant changes • Risk for sudden death with AS increases when grad. >50mmHg and orifice less than .8cm2
AS 2D echo • Two-dimensional echocardiogram from a patient with aortic stenosis due to a bicuspid aortic valve (congenital). a. Parasternal long-axis view shows systolic doming (bowing) of the anterior and posterior cusps of the aortic valve (arrowheads). b. Parasternal short-axis view at the level of the aorta shows only two cusps (arrowheads). Ao, aorta; LVOT, left ventricular outflow tract; RVOT, right ventricular outflow tract; RA, right atrium; LA, left atrium; RV, right ventricle. • J.M. Felner M.D., R.P. Martin M.D., The Echocardiogram, The Hurst's The Heart, 8th ed., p 406. (modified)
Symptoms • Rheumatic AS patients may remain asymptomatic for 40 years • Bicuspid valve patients will develop symptoms between 15-65 years of age • Calcifications of the valve usually occur after age 30 • THE TRIAD….
The triad… • Any one of these symptoms being present is ominous and the patient’s life expectancy is less than 5 years… • ANGINA • SYNCOPE • CHF
Angina • This is the initial symptom in 50-70% of patients. Most commonly occurring with exertion • May be present without CAD b/c of… • Increased myocardial O2 consumption, with increased myocardial thickness and increased afterload • Also increased LVEDP impairing flow to subendocardial layers
Syncope • First symptom in 15-30% of patients • Once this occurs the average life expectancy is 3-4 years • Origin of syncope is controversial, however it may be related to uncompensated decrease in SVR with exercise
CHF • Due to diastolic dysfunction (increased LV thickness) or systolic dysfunction (increased afterload or decreased myocardial contractility) • Once LV failure occurs the average life expectancy is 1-2 years • All AS patients are at increased risk of sudden death, as previously stated and…. • Only 18% of patients are alive 5 years after the peak systolic gradient is >50mmHg or the orifice <0.7cm2
Pathophysiology • Stage 1: asymptomatic—mild stenosis • Normal stroke volume maintained as gradient between LV and aorta increases • Higher gradient results in concentric LV hypertrophy
Pathophysiology • Stage 2: moderate stenosis—symptomatic • Dilation as well as hypertrophy occur in this stage • Decreased EF may be noted (due to decreased contractility) • Increased LVEDP and LVEDV leads to increased myocardial work and O2 consumption….at risk myocardium
Pathophysiology • Stage 3: critical AS • Valve area is less than .5cm2/m2 and EF decreases further with further increases in LVEDP • Pulmonary edema when LA >25-30 mmHg • RV failure will develop if sudden death does not occur first
Calculation of Stenosis • Gorlin equation: AV area (cm2)= CO (L/min)/ Mean pressure gradient1/2 This is the simplified version of the Gorlin equation (Hakki equation)
Continuity equations • AV area=LVOT velocity/AV velocity x LVOT area ---LVOT calculation can have errors because it’s an area squared. • AV area= CO/(HR x systolic ejection period x 44.3 x gradient in mmHG1/2) ---Gorlin equation weak under low CO states • Hakki equation—based on the fact that HR x sys ejection period x 44.3= 1000; therefore AV Area= CO/ sq root of gradient (mmHg)
PA Cath • Because of increased LVEDP stretching the mitral annulus a prominent v wave can be observed with disease progression. LA hypertrophy develops and the A wave becomes prominent • Example to follow on next slide…
Arterial line • Pulsus parvus (narrow pulse pressure) • Pulsus tardus (delayed upstroke) • These features make the wave appear overdampened
Hemodynamic profile • AS– increase LV preload and SVR • Decrease HR • Keep contractile force and PVR constant • Preload – because of Decreased LV compliance as well as Increased LVEDP preload augmentation is needed • (caution with nitro)
Hemodynamics continued • Heart rate– no extremes of HR • Increase HR = decreased coronary perfusion • Sinus rhythm important for added EF • Contractility • avoid B-blockers they can increase LVEDP and decrease CO
Hemodynamics continued • SVR– most of afterload is due to stenotic lesion, therefore it’s fixed. • If SBP is decreased the patient can develop subendocardial ischemia • Early alpha-adrengic agonists needed as treatment • PVR– this stays normal until very late in the disease process
Toronto study • 1986-2000 of 49 pregnancies in women with AS • Mild AS (>1.5cm2 or grad<36mmHg) • Mod AS (1.0-1.5cm2 or grad 36-63mmHg) • Severe AS (<1.0cm2 or grad >63mmHg) • All women had functional NYHA class I or II disease when enrolled • 59% of patients, 29/49 had severe AS • Silversides C.K., Colman J.M., Sermer M., Farine D., Sui S. C., Early and intermediate-term outcomes of pregnancy with congential aortic stenosis. American Journal of Cardiology 2003;91:11
NYHA functional classification • Class I – Asymptomatic • Class II – Symptoms with greater than normal activity • Class III – Symptoms with normal activity • Class IV – Symptoms at rest
Toronto study continued • 10% of severe AS patients (3/29) had early cardiac complications (pulmonary edema or atrial arrhythmias)…no complications in mild/mod groups • One pt. had AVA .5cm2, peak gradient 112mmHg, she developed pulmonary edema at 12 weeks had emergent aortic valvuloplasty then had a Ross procedure 4 years after delivery • The second pt. had gradient of 104mmHg; she had postpartum hemorrhage, hypotension and subsequent pulmonary edema. Resection of her subaortic membrane was performed 17 months after delivery. • The third pt had a bicuspid valve AVA .7cm2, gradient of 64mmHg, she had atrial arrhythmias during antepartum period. She underwent a Ross procedure 18 months postpartum.