Heart Disease in Pregnancy - part 8 pptx

Physical signs are often deceptively few. Clinical signs of acute right ventricu- lar failure can be subtle. Tachypnea is the most frequent followed by tachycar- dia. The jugular venous pressure may be raised and there may be increased left parasternal pulsation, a third heart sound gallop and widely split second sound. The lungs are usually clear but there may be focal crackles as surfactant is lost from non-perfused segments of lung. At this stage the arrival of further emboli will very probably be fatal, but otherwise the evidence of acute cor pulmonale has usually resolved in just a day or two. Massive PE The patient, who may have seemed quite fit up to then, has suddenly collapsed and is in shock, pale, cold, clammy and shut down or in actual circulatory arrest. In patients with maintained consciousness, tachypnea and hyperpnea are strik- ing with poor peripheral perfusion. Substernal chest pain may be confusing. The lungs are usually clear with good air entry. Rarely, PE may trigger bron- chospasm in people with asthma. The pulse is rapid and ill-sustained and blood pressure maintained only with the patient supine. There may be pulsus para- doxus as filling of the left ventricle and stroke volume fall on inspiration (see Figure 17.1). The venous pressure will be raised but this cannot be observed clinically because the patient is lying flat and also because of her heightened res- piratory efforts. A third heart sound gallop is prominent but pulmonary valve closure is soft (not accentuated as generally stated) and may be absent if the right ventricular diastolic pressure has risen to equal the diastolic pressure in the pulmonary artery. In less severe cases the second heart sound is widely split. A systolic murmur of tricuspid regurgitation may be audible but it is often silent because right ventricular pressure and flow may be insufficient to produce au- dible turbulence, and indeed all the heart sounds become soft as the circulation fails. When circulatory arrest occurs sinus rhythm is commonly maintained (persistent electrical activity). A low P CO 2 may be coupled with a low PO 2 sometimes contributed to by cen- tral right-to-left shunting if the foramen ovale is patent. This can lead to con- comitant stroke, which may dominate the clinical scene. The association of hypoxemia with hypocapnia and a respiratory alkalosis is always highly sugges- tive of pulmonary embolism but hypoxemia is not invariable. 24,25 Recurrent PE Patients with shortness of breath and features of pulmonary hypertension may have had recurrent episodes of PE or give no such history but show widespread perfusion defects on scanning. An underlying thrombophilia is likely but sometimes tests reveal au- toimmune disease with lupus or Behçet syndrome, and the pulmonary hypertension has resulted from pulmonary arteritis with thrombosis in situ rather than embolism. In rare cases pulmonary angiography or cardiac mag- netic resonance imaging (CMRI) may show multiple pulmonary artery branch stenoses. Pulmonary embolism 249 Paradoxical embolism Elevation of right atrial pressure favors paradoxical passage of emboli if the foramen ovale is patent. A devastating stroke or unexplained systemic em- bolism should lead to a search for a cardiac source and suspicion of paradoxical embolism, so concomitant PE and occult DVT should also be sought. 26,27 Echocardiography with injection of a sonicated indicator while the patient performs a Valsalva maneuver will force a right-to-left shunt, with passage of bubbles through the defect and their appearance in the left atrium. The tech- nique is more sensitive if imaging is performed from the transesophageal ap- proach. If patency of the foramen ovale is revealed after systemic embolism, device closure should be performed. Non-thrombotic PE Amniotic fluid, fat, tumor or air may embolize to the lungs. 28,29 Fat embolism may occur after major fractures. Progressive pulmonary hypertension may re- sult from multiple microtumor embolism in chorioncarcinoma. This sometimes develops years after a normal pregnancy or abortion. A pregnancy test should be performed if there is clinical suspicion. Air embolism is a complication of cen- tral venous lines and special care is necessary when the right atrial pressure is raised, in case of patency of the foramen ovale. A much smaller amount of air than is tolerated on the right side can have devastating consequences when re- leased into the systemic circulation. Embolism of amniotic fluid is usually asymptomatic and is common peripar- tum but, rarely, it causes sudden collapse during or after delivery, particularly after surgical delivery in multiparous patients but is distinguished by the dis- seminated vascular coagulopathy that usually follows. Diagnostic strategy The diagnostic strategy depends on the initial hemodynamic presentation. 30–32 Suspected PE always requires urgent confirmation or exclusion. In patients whose general condition is good and who are hemodynamically stable there is time for diagnostic imaging. Suspicion rests on clinical prob- ability (see Figure 17.2) and diagnosis will follow the results of the baseline tests and scans (Figure 17.3). Diagnostic delay must be minimized in patients needing urgent reperfusion (Figure 17.4). There is no time for imaging tests apart from immediate on-site echocardiography. Patients who are in cardiogenic shock need reperfusion treatment right away. Echocardiography also plays a central role in identifying those patients without shock but whose hemodynamic instability and poorer outlook are shown by right ventricular dilatation. Baseline tests Blood gases, ECG and chest radiograph are basic. They may be uninformative diagnostically if they are all normal but they say much about the general condi- tion of the patient and are useful in exclusion of other conditions. 250 Chapter 17 Arterial blood gases These are helpful but not specific and may be normal. A normal alveolar– arterial oxygen gradient does not exclude PE but a reduced P O 2 in an apparently fit patient is highly significant, especially when combined with a low P CO 2 . Arte- rial samples should be taken with the patient sitting up if possible. 25,33 The electrocardiogram The ECG (Table 17.4) may reveal evidence of right ventricular overload with clockwise rotation and right-sided T-wave inversion, low voltage, right axis and rSr in V1 or occasionally right bundle-branch block. 24 The chest radiograph This is usually normal but a near-normal film in the setting of severe respira- tory and circulatory compromise is highly suggestive of massive PE. The chest radiograph is useful in ruling out other lung pathology such as pneumonia or pneumothorax. It may show non-specific abnormality such as patchy basal at- electasis or pleural effusion or, rarely, one of the classic signs, a wedge-shaped Pulmonary embolism 251 D-dimer a Normal In first trimester In second trimester In third trimester Clinical probability Low a Spiral CT Negative Perfusion scan, CUS or arteriography Abnormal PE unlikely Abnormal >700 ng/mL >1000 ng/mL >1420 ng/mL <700 ng/mL <1000 ng/mL <1420 ng/mL Moderate or high Positive Negative Positive Normal Abnormal ? Infection TREAT TREAT Perfusion scan or Chest radiograph Normal Figure 17.3 Diagnostic strategy for pulmonary embolism (PE) in stable patients. CT, computed tomography; CUS, compression ultrasonography. a Reliability in pregnancy needs further confirmation. opacity caused by segmental infarction or focal oligemia (Westermark’s sign), indicating massive central embolic occlusion. 24 D-dimers These are breakdown products of fibrin clot. They indicate on-going fibrino- lysis. A normal level is a rapid test, currently much used to rule out throm- boembolism but pregnancy itself increases the plasma D-dimer concentration above the normal upper limit of 500 ng/mL. Normal ranges at different stages of pregnancy were recently established from quantitative assays in 50 normal pregnant women using a US Food and Drug Agency (FDA)-approved ELISA (enzyme-linked immunosorbent assay) method. D-dimer levels increased through pregnancy and exceeded 500 ng/mL in 50%, 75% and 100% of women in the three trimesters. The study indicated that levels above 700, 1000 and 1420 have >50% likelihood of being abnormal 252 Chapter 17 Short axis projections DiastoleSystole Figure 17.4 Transthoracic echocardiogram, short-axis projection, systole on the left, diastole on the right, showing diastolic bowing of the ventricular septum toward the left ventricle and reduced left ventricular volume in acute pulmonary embolism. Table 17.4 The ECG in pulmonary embolism T-wave inversion in leads III, aVF and right-sided chest leads Right axis and clockwise rotation, dominant S–V5 rSr in V1; complete right bundle-branch block (rare) Low voltage in limb leads Qs in leads III and aVF for each trimester (see Figure 17.3) but more studies are still needed before these figures can be relied on. Raised D-dimer levels are not specific but normal levels can be used to back up clinical assessment of the low probability to rule out PE and remove the need for imaging. Levels raised above the recently established norms in otherwise healthy pregnant women are highly suggestive of PE, 34,35 but more studies are still needed. Diagnostic imaging (Table 17.5) Echocardiography Echocardiography is under-used as the most rapid diagnostic measure in emer- gency circumstances. 36 It is also non-invasive and does not involve radiation. Right ventricular dysfunction is found in about a third of all patients with acute PE (see Figure 17.4). The degree of dilatation and severity of systolic dysfunc- tion give both therapeutic and prognostic guidance and are the single most im- portant prognostic factor for in-hospital death. 37 They are usually immediately available in the accident and emergency department (A&E) to A&E staff, cardi- ologists or obstetricians faced with a patient in shock or with recent onset of Pulmonary embolism 253 Table 17.5 Diagnostic imaging in suspected pulmonary embolism No lung scan needed if leg scan positive Chest radiograph Usually normal or non-specific Echocardiography Immediate availability Shows RV (TTE), main PA branches (TOE) Perfusion scan Positive scan with normal chest radiograph; start heparin Useful if SCT negative and clinical probability high Ventilation scan Useful if both radiograph and perfusion scan are abnormal If abnormal consider antibiotics If normal start heparin or both Spiral CT scan Positive scan with normal chest radiograph; start heparin Useful if perfusion is equivocal and chest radiograph or ventilation are normal May miss subsegmental PE CMRI Becoming more generally available; shows RV too Pulmonary angiography Essential for fragmentation or embolectomy Gold standard but invasive Involves radiation CMRI, cardiac magnetic resonance imaging; PA, pulmonary artery; PE, pulmonary embolism; RV, right ventricle; SCT, spiral computed tomography; TOE, transesophageal echocardiography; TTE, transthoracic echocardiography. puzzling symptoms, and their usefulness will increase further as hand-held machines come into more general use. Although detection of right ventricular dysfunction lacks specificity, this is of much less importance in the largely healthy pregnant population than in the older suspect population with a higher incidence of co-morbidity. Rarely, echocardiography will reveal a clinically unsuspected cardiomyopathy, parti- cularly peripartum cardiomyopathy with its high incidence of intraventricular thrombi that may present with pulmonary (or systemic) embolism. Otherwise unexplained right ventricular dilatation, poor function and tricus- pid regurgitation are frequently a surprise in patients with negative clinical findings who may have complained only of some shortness of breath, transient dizziness or faintness, and who do not appear to be in distress. Bowing of the ventricular septum towards the left ventricle in diastole indicates right ventric- ular volume overload. 38,39 Rarely, worm-like emboli swim in the right atrium to poke in and out of the tricuspid valve or extend into the ventricle or pulmonary artery. 40 The central pulmonary arteries are not seen in transthoracic views for which transesophageal imaging is needed. Transesophageal echocardiography does not have the brilliant immediacy of transthoracic echocardiography but needs no preparation or cooperation from radiological colleagues to delay it. It shows the main pulmonary artery, the right and the proximal left pulmonary artery, and any thrombi or filling defects. 41 Compression venous Doppler ultrasonography Loss of venous compressibility indicates thrombosis. Augmentation of flow is absent or reduced during compression. This is the primary diagnostic test for DVT because it is non-invasive and totally safe for the fetus. The test is highly sensitive and specific for proximal DVT with thrombosis of femoral veins, but is not reliable for isolated iliac thrombosis (more prevalent during preg- nancy) and ultrasound diagnosis of isolated calf vein thrombosis needs special expertise. 13,42 About half of all patients with PE have no imaging evidence of DVT. Although a normal ultrasound examination therefore does not rule it out, its identifica- tion indirectly establishes the diagnosis of PE but false-positive results may be obtained in the third trimester as a result of compression of the iliofemoral veins by the uterus. Real-time ultrasonography The common femoral vein and popliteal vein can be visualized and intraluminal clots detected, although their echogenicity varies according to their age. Real- time imaging uses standard equipment, is easy, and can be repeated and com- bined with compression. It cannot detect isolated iliac vein thrombosis. Contrast phlebography This is reserved for investigation of equivocal results of ultrasound examination in patients with high clinical probability of DVT but with no evidence of PE. It is 254 Chapter 17 rarely indicated in pregnancy but the alternative may possibly be unnecessary heparin treatment. Ventilation–perfusion scans Perfusion lung scans These are indicated as the primary test for PE. They are performed by injecting technetium-99m ( 99m Tc) coupled to microaggregates of human albumin and scanning the distribution of radioactivity with a gamma camera. The radiation dose to the fetus is minimal. A normal scan rules out PE. Unfortunately an ab- normal scan cannot confirm the diagnosis, although non-specific abnormalities are less frequent in pregnant patients than in an older age group. Large perfu- sion defects with a normal chest radiograph are likely to be the result of PE and make a ventilation scan unnecessary. The original classification stemming from the PIOPED trial has been revised 44 and was followed by the attempt in the PISAPED trial with the aim of eliminating equivocal results. 45 Ventilation scans These employ inhaled xenon-133 ( 133 Xe) or krypton-81m ( 81m Kr). An abnor- mal perfusion scan followed by a normal ventilation scan is diagnostic of PE and reported as ‘high probability of PE’. Matched abnormalities in perfusion and ventilation scans with an abnormal chest radiograph are likely to be caused by infection. One reason for abnormalities on the ventilation scan, especially when a scan is delayed, is the patchy atelectasis of embolized segments of lung that often follows in the next few days. The radiation dose is similar to that with a perfusion scan. Doubt has been expressed as to whether the ventilation scan is any more use- ful than a chest radiograph in interpreting the perfusion scan. Spiral computed tomography With the development of more accurate scanners, spiral CT has increased in popularity as the primary imaging test for PE. 46,47 This preference is because ventilation–perfusion scans still produce so many equivocal results in older pa- tients with co-morbidity, among whom reports of ‘intermediate risk of PE’ are frequent and frustrating. They are especially likely when the chest radiograph is abnormal. These limitations of ventilation–perfusion scans are much less of a problem in the younger and otherwise healthy pregnant population. Spiral CT produces a definite positive or negative result but is less accurate in revealing segmental PE than central or lobar emboli. A normal study therefore cannot rule out isolated peripheral subsegmental PE or be the basis for with- holding anticoagulant treatment. The technique has the disadvantages of both exposure to radiation and a fetal dose of iodinated contrast, although the fetal radiation dose with spiral CT is lower than with ventilation–perfusion scanning and neonatal hypothyroidism has not been reported. Pulmonary embolism 255 Magnetic resonance imaging MRI with gadolinium enhancement now has similar accuracy to pulmonary angiography and CMRI also allows assessment of ventricular function. It avoids radiation and the use of radiographic contrast and imposes no risk, but is not usually immediately, or as yet generally, available. 48 Both spiral CT and MRI can be extended to look for DVT but there is no point if imaging for PE has been positive. Neither CT nor MRI are needed if leg vein ultrasonography is positive. Pulmonary angiography Pulmonary angiography is safe during pregnancy with suitable abdominal screening, but is rarely indicated except as part of the interventional treatment of immediately life-threatening massive embolism. It is regarded as the gold standard but carries a mortality rate of about 0.5%, is technically demanding and often hard to interpret despite good image quality, for both of which the skills of a radiologist may be needed especially for out-of-hours emergency work. Safety and accuracy have been greatly increased by the use of selective injections, digital subtraction and magnification. 48–50 Anticoagulants may be withheld if pulmonary angiography is normal. 50,51 Management Patients in cardiogenic shock or hemodynamically unstable Massive and subacute massive PE The management of a patient with a high clinical probability of PE and who is in shock is aimed at restoring circulation and saving life (Table 17.6). The diagnosis needs to be confirmed and action taken with no time lost (Figure 17.5). If the di- agnosis is confirmed by right ventricular dilatation shown on transthoracic echocardiography, percutaneous catheter fragmentation and thrombolysis (Figure 17.6) should be carried out immediately and without delay for other investigations. 18,31,52–54 It is usually successful if the embolism was truly acute. It 256 Chapter 17 Table 17.6 Massive pulmonary embolism (emergency treatment to save life) Cardiopulmonary resuscitation (CPR) if circulatory arrest Elevate legs Oxygen Central intravenous line Start heparin Consider dobutamine infusion Consider inhaled nitric oxide Thrombolytic drug Per catheter clot fragmentation and/or extraction will fail if the circulation has collapsed after apparent sudden onset, although all or most of the material has been gradually accreted through recurrent episodes. A pigtail catheter should be introduced by the brachial route or central vein with the patient tilted head down. Fragmentation can be accomplished very swiftly and, if it is successful, blood pressure and consciousness are restored within minutes. The extreme emergency is over. The catheter is inserted via a brachial or central route so as to avoid dislodging any thrombus in the pelvis or vena cava, and to save the fetus from radiation if the patient is undelivered. Pro- vided that the obstruction is caused by freshly arrived embolic material that is still lying centrally, it can usually be moved on with dramatic improvement. Formal angiography is not required but contrast is needed to guide the proce- dure and should be used as sparingly as possible. If attempts to fragment central emboli and move them on are unsuc- cessful, per catheter embolectomy should be tried and, if all else fails, surgical embolectomy. Pulmonary embolism 257 Stable Baseline tests D-dimer* Echocardiography Normal RV Normal RV Perfusion scan + positive or Peripheral TREAT PE EXCLUDED Follow management strategy for stable patients Catheter fragmentation Successful Thrombolysis Surgical embolectomy Cardiogenic shock Echocardiography Dilated RV Dilated RV Central Spiral CT Unsuccessful Figure 17.5 Management strategy in patients with pulmonary embolism (PE) again stressing the key role played by echocardiography. RV, right ventricle. a Reliability in pregnancy needs further confirmation. Other measures are adjuvant. The legs should be elevated and oxygen given. If consciousness has been lost chest compression will help to empty the right ventricle and be directly therapeutic if it dislodges thrombi and assists in moving them on. If the circulation is compromised and the right ventricle dilated, but the patient is conscious and not in shock, there is time for perfusion or spiral CT to assess the size and distribution of the clot burden. A central line is inserted and unfractionated heparin is started. It is usual to give inotropes and vasopressors but, unless an effective circulation returns rap- idly, an attempt should be made to fragment the emboli per catheter. Dobuta- mine is usually given even though endogenous neuroendocrine activation is likely to be providing maximum stimulation already. Dobutamine provides positive inotropic effect with pulmonary vasodilatation through its beta- adrenergic action. Inhaled nitric oxide may release pulmonary vasoconstriction and help to reduce right ventricular afterload. Fluid loading is probably unhelpful and no more than 500 mL fluid should be given, more only if it appears to have been beneficial (as ventricular interdepend- ence may cause further compromise of left ventricular filling). This can most rap- idly be appreciated by following the effect of the infusion echocardiographically. Thrombolytic treatment with recombinant plasminogen activator (rtPA) should be given only if the circulation remains compromised. This does not 258 Chapter 17 Figure 17.6 The right digital subtraction pulmonary arteriogram from a patient with massive pulmonary embolism (a) before and (b) after restoration of flow to the lower lobe by mechanical fragmentation. The pigtail catheter is clearly visible. [...]... measures should be instituted when managing all gravid women with heart disease (Table 19.2), including pain control, strict input and output, continuous ECG monitoring, oxygen supplementation and intravenous filters if a shunt is present In addition, attention to patient positioning in the semi-recumbent/left lateral tilt, fetal monitoring, thrombosis and (in high-risk patients) infective endocarditis... documented reading However, in pregnancy there are specific concerns relating to the position of the patient The blood pressure is lower in the second half of pregnancy in patients lying supine This is because the gravid uterus obstructs Hypertensive disorders of pregnancy 267 Table 18. 2 Abnormalities that may be found on investigation indicating pre-eclampsia Maternal Elevated urea and creatininea, b Elevated... 112:722 8 42 Kearn C, Julian JA, Newman E, Ginsberg JS, for the McMaster Diagnostic Imaging Practice Guidelines Initiative Non-invasive diagnosis of deep vein thrombosis Ann Intern Med 19 98; 1 28: 663–77 43 Chan WS, Ray JG, Murray S, Coady GE, Coates G, Ginsberg JS Suspected pulmonary embolism in pregnancy: clinical presentation, result of lung scanning and subsequent maternal and pediatric outcomes Arch Intern... hypertension Lancet 1 983 ;1:431–4 38 Butters L, Kennedy S, Rubin PC Atenolol in essential hypertension during pregnancy BMJ 1990;301: 587 –9 39 Constantine G, Beevers DG, Reynolds AL et al Nifedipine as a second line antihypertensive drug in pregnancy Br J Obstet Gynaecol 1 987 ;94:1136–42 Hypertensive disorders of pregnancy 279 40 Serra-Serra V, Kyle PM, Chandran R et al The effect of nifedipine and methyldopa... prevents pregnancy- induced hypertension and pre-eclampsia in angiotensin-sensitive primigravidae Lancet 1 986 ;1:1–3 21 CLASP: a randomised trial of low-dose aspirin for the prevention and treatment of pre-eclampsia among 9364 pregnant women CLASP (Collaborative Low-dose Aspirin Study in Pregnancy) Collaborative Group Lancet 1994;343:619–29 22 Duley L, Henderson-Smart D, Knight M, King J Antiplatelet... Renal disease Renovascular hypertension has no specific problems in pregnancy but this is not true of renal parenchymal disease Hypertension and renal impairment 276 Chapter 18 interact in a way that is not well understood to increase the risks of superimposed pre-eclampsia and acute and chronic fetal distress, e.g in renal disease the presence of hypertension increases the incidence of intrauterine growth... proteinuria, it is termed pregnancy- induced hypertension’.7 Pre-eclampsia is defined as new onset hypertension with proteinuria (>300 mg/24 h or ++ on urine dipstick) in the absence of a urinary tract infection after 20 weeks’ gestation .8 If a patient with pre-existing hypertension develops proteinuria (>300 mg/24 h or ++), this is termed superimposed pre-eclampsia (Table 18. 3) Eclampsia is defined as... Scand 19 98; 77:170–3 3 Report on Confidential Enquiries into Maternal Deaths in the United Kingdom 1994–96 London: HMSO, 19 98 4 Danilenko-Dixon DR, Heit JA, Silverstein MD et al Risk factors for deep vein thrombosis and pulmonary embolism during pregnancy or post partum: a population based, case–control study Am J Obstet Gynecol 2001; 184 :104–10 5 Toglia MR, Weg JG Venous thromboembolism during pregnancy. .. measured by cardiotocography) a Tests commonly used in the UK bUrea and creatinine both fall during pregnancy as a result of hemodilution; values should be compared with ‘normal’ ranges for pregnancy Table 18. 3 Classification of hypertensive disorders in pregnancy Chronic hypertension Pregnancy- induced hypertension (gestational hypertension) Pre-eclampsia Pre-eclampsia superimposed on chronic hypertension... Hypertensive disorders of pregnancy 269 antioxidants, such as vitamins C and E, has been shown in a study of 283 highrisk women to reduce incidence of pre-eclampsia from 26% to 8% .26 A large multicenter, placebo-controlled, randomized trial is being undertaken in the UK and is expected to report results in 2006 A Cochrane meta-analysis of antihypertensive treatment before conception or during pregnancy concluded . products of fibrin clot. They indicate on-going fibrino- lysis. A normal level is a rapid test, currently much used to rule out throm- boembolism but pregnancy itself increases the plasma D-dimer concentration above. Physical methods of prophylaxis include pos- ture (sleeping semi-prone rather than supine in later pregnancy) and compres- sion stockings. LMWH should be given to high-risk patients. Prevention of. Diagnostic Imaging Practice Guidelines Initiative. Non-invasive diagnosis of deep vein thrombosis. Ann Intern Med 19 98; 1 28: 663–77. 43 Chan WS, Ray JG, Murray S, Coady GE, Coates G, Ginsberg JS.