Antihypertensive Drug Therapy Issues
• Discontinue medications. This may be done in patients with mild-to-moderate HTNcaused by the normal decrease in BP that occurs in pregnancy. Pharmacologic treat-ment in patients with diastolic BP <90 mm Hg or systolic BP <140 mm Hg does not improve either maternal or fetal outcome.
• Maintain medications. This may be necessary in patients with severe HTN. The drugof choice is methyl-dopa because of extensive experience and documented fetal safety. Labetalol and atenolol are acceptable alternatives. However, b-blocking agents are associated with intrauterine growth retardation (IUGR).
• “Never use” medications. Angiotensin-converting enzyme inhibitors are contraindi-cated in pregnancy, as they have been associated with fetal hypocalvaria, renal failure, oligohydramnios, and death. Diuretics should not be initiated during pregnancy owing to possible adverse fetal effects of associated plasma volume reduction.
• BP target range. Reduction of BP to normal levels in pregnancy may jeopardize utero-placental blood flow. Maintain diastolic values between 90 and 100 mm Hg.
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Chapter 9 l Hypertensive Complications
Management
Conservative outpatient management is appropriate with uncomplicated mild-to-moderatechronic HTN.
– Stop drug therapy. Attempt discontinuation of antihypertensive agents. Follow guideline outlined.
– Serial sonograms and antenatal testing is appropriate after 30 weeks’ gestation to monitor for increased risk of IUGR.
– Serial BP and urine protein assessment is indicated for early identification of superimposed preeclampsia.
– Induce labor at 39 weeks if the cervix is favorable.
Aggressive prompt delivery is indicated for chronic HTN with superimposed preeclampsia atany gestational age.
– Administer IV MgSO 4 to prevent convulsions.
– Keep diastolic BP between 90 and 100 mm Hg with IV hydralazine and/or labetalol.
– Attempt vaginal delivery with IV oxytocin infusion if mother and fetus are stable.
Complications. Progression from chronic HTN to superimposed preeclampsia, which can leadto maternal and fetal death.
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HELLP SYNDROME
A 32-year-old multigravida is at 32 weeks’ gestation. At a routine prenatal visit her BP was noted to be 160/105. Previous BP readings were normal. Preeclampsia workup was begun and revealed the following: elevated total bilirubin, lactate dehydrogenase, alanine aminotransferase, and aspartate aminotransferase, as well as platelet count of 85,000. She has no complaints of headache or visual changes.
Definition. HELLP syndrome occurs in 5–10% of preeclamptic patients and is characterized byhemolysis (H), elevated liver enzymes (EL), and low platelets (LP).
Risk Factors. HELLP syndrome occurs twice as often in multigravidas as primigravidas.
Differential Diagnosis. It can be confused with thrombotic thrombocytopenic purpura andhemolytic uremic syndrome. HTN, although frequently seen, is not always present.
Management. Prompt delivery at any gestational age is appropriate. Use of maternal cortico-steroids may enhance postpartum normalization of liver enzymes and platelet count.
Complications. Conditions that are associated with HELLP syndrome include DIC, abruptioplacenta, fetal demise, ascites, and hepatic rupture.
OB Triad
HELLP Syndrome
• Hemolysis
• ↑ liver enzymes
• ↓ platelets
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Medical Complications 10
In Pregnancy
CARDIAC DISEASE
A 30-year-old multigravida with a childhood history of rheumatic fever has echocardiography-diagnosed mitral stenosis. She is now at 20 weeks’ gestation and has no symptoms at rest but has mild shortness of breath and dyspnea with activity. On examination she has a diastolic murmur.
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Definition. General types of heart disease:
• Coronary heart disease. This condition is rarely found in women of childbearing age.Adverse consequences of hypoxic heart disease include miscarriage, fetal death, pre-term delivery, and increased perinatal morbidity and mortality.
• Rheumatic heart disease. The most common acquired lesion in pregnancy is rheu-
matic heart disease. The most common rheumatic heart disease is mitral stenosis. With severe stenosis (mitral valve area <2 cm2), the main problem is inadequate diastolic flow from the left atrium to the left ventricle. Obstruction to left ventricularfilling may lead to left atrial enlargement, pulmonary congestion, atrial fibrillation, and subacute bacterial endocarditis (SBE) with valvular vegetations causing throm-boemboli. Tachycardia and increased plasma volume, which are normal changes of pregnancy, will only exacerbate these problems. Balloon valvuloplasty may need to be performed as a last resort.
• Congenital heart disease. The most common congenital lesions are atrial (ASDs) andventricular septal defects (VSDs). The most common cyanotic congenital heart dis-ease in pregnancy is tetralogy of Fallot. ASDs and VSDs are tolerated well with preg-nancy, as are any regurgitation lesions.
Maternal Mortality Risk
• Low maternal mortality (<1% risk of death): ASD, VSD, patent ductus arteriosus(PDA), minimal mitral stenosis, porcine heart valve, and corrected tetralogy of Fallot.
• Intermediate maternal mortality (5–15% risk of death): mitral stenosis with atrialfibrillation, artificial heart valve, uncorrected tetralogy of Fallot, and Marfan syndrome with normal aortic root diameter.
• High maternal mortality (25–50% risk of death): pulmonary hypertension,Eisenmenger’s syndrome, Marfan syndrome with aortic root >40 mm diameter, and peripartum cardiomyopathy.
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USMLE Step 2 l Obstetrics
OB Triad
Peripartum Cardiomyopathy
• Late pregnancy or postpartum
• Multiparity
• Biventricular cardiac failure
Unique High-Risk Conditions
Eisenmenger syndrome
This condition is characterized by pulmonary hypertension and a bidirectional intra-cardiac shunt. The normal decrease in systemic vascular resistance (SVR) in pregnancy places the patient at risk for having the pulmonary vascular resistance (PVR) exceed the SVR. When this develops, the path of least resistance for blood from the right heart is to bypass the pulmonary circulation across the shunt. This results in the left heart pumping unoxygenated blood into the systemic circulation, resulting in a 50% mortality risk. Management is by avoiding hypotension.
Marfan syndrome
This is an autosomal dominant connective tissue disorder. In pregnancy, if the aortic root diam-eter is >40 mm, the risk of aortic dissection is high, placing the patient at a 50% mortality risk.
Peripartum cardiomyopathy
In this condition, the patient has no underlying heart disease, but develops idiopathic bi-ventricular cardiac decompensation between the last few weeks of pregnancy and the first few months postpartum. Risk factors include advanced maternal age, multiparity, hypertension, and multiple pregnancy. Mortality rate is 75% if reversal does not occur within 6 months. Management is supportive, intensive care unit (ICU) care.
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