Page 551 - Cardiac Nursing

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LWBK340-c22_ p pp511-536.qxd 30/06/2009 11:00 AM Page 527 Aptara
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C HAPTER 22 / Acute Coronary Syndromes 527
heparin-induced thrombocytopenia, allergy, or acute cerebrovascu- sustained anticoagulant effect for once-a-day, fixed-dose SC ad-
4
lar accident or a history of life-threatening gastrointestinal bleeding. ministration. Fondaparinux does not affect thrombin that is
already present, a possible reason for the increased rate of catheter-
Nursing Implications. Obtain a baseline aPTT before start- 53
associated thrombosis with fondaparinux.
ing therapy with UFH, and again every 6 hours after any dosage
The ACC/AHA UA/NSTEMI guidelines for fondaparinux
change or significant change in clinical status. The dosage of UFH 4,94
use are the following :
is adjusted so that the aPTT is within the therapeutic range. Daily
complete blood cell count with differential should be evaluated 1. For patients undergoing early invasive strategies, fonda-
for bleeding or thrombocytopenia. Although aPTT and pro- parinux (along with enoxaparin, UFH, and bivalirudin) has
thrombin times are not monitored with LMWH, a complete established efficacy for patients undergoing an early invasive
blood cell count with differential should be evaluated for bleeding strategy. However, if fondaparinux is selected, supplemental
4
or thrombocytopenia. UFH should be administered during PCI, leading others not
to recommend its use in patients undergoing an invasive
Direct Thrombin Inhibitors strategy. 94
2. For patients selected for a conservative strategy, fondaparinux
Actions/Indications. The naturally occurring anticoagulant and LMWH are considered preferable to UFH.
hirudin (the active principal component in the salivary secretion 3. For patients in whom CABG is planned within 24 hours, UFH
of leeches) and bivalirudin, its synthetic analog, are direct throm- is preferred to fondaparinux or LMWH, because its anticoagu-
bin inhibitors. Thus, they are able to inactivate thrombin in blood lant effect can be more rapidly reversed.
clots, which is in contrast to the action of UFH, which targets 4. For patients at increased risk of bleeding, fondaparinux is rec-
only soluble thrombin. 91 ommended as the anticoagulant of choice.
The ACC/AHA UA/NSTEMI guidelines for the use of direct
thrombin inhibitors are the following 4,91 : Contraindications/Adverse Reactions. Contraindications
include hypersensitivity to fondaparinux or any of its compo-
1. For patients in whom an invasive strategy is selected, bi-
nents, severe renal impairment (creatinine clearance 30
valirudin is recommended as the anticoagulant of choice, with
mL/min), low body weight ( 50 kg), active major bleeding, bac-
enoxaparin, UFH, and fondaparinux (see the following sec-
terial endocarditis, and thrombocytopenia associated with a
tion) as acceptable alternatives. When bivalirudin is selected, a
positive in vitro test for antiplatelet antibody in the presence of
GP IIb/IIIa inhibitor may be omitted before diagnostic an-
fondaparinux. The major adverse event is bleeding at any site.
giography and PCI as long as clopidogrel (at least 300 mg) was
Risk for adverse reactions may be increased in patients with renal
administered within 6 hours.
dysfunction, whose age is greater than 75 years, and whose weight
2. For patients in whom CABG is selected following coronary an- 95
is less than 50 kg.
giography, discontinue bivalirudin 3 hours before CABG and
switch to UFH per institutional protocol. Nursing Implications. Following sheath removal, do not re-
3. For patients in whom medical therapy is selected following sume fondaparinux for at least 2 hours in patients with
95
coronary angiography and bivalirudin was administered prior to UA/NSTEMI and 3 hours in patients with STEMI. Periodically
angiography, either discontinue bivalirudin or continue admin- monitor complete blood cell count and serum creatinine, but as
istration for up to 72 hours at the discretion of the physician. with LMWH, fondaparinux does not require laboratory coagula-
tion monitoring. Monitor all puncture sites for potential bleeding
Contraindications/Adverse Reactions. The major con- and test for occult blood in the stool.
traindications are hypersensitivity to hirudins and active major
bleeding, which can occur at any site. In the ISAR-REACT 3 (In-
tracoronary Stenting and Antithrombotic Regimen: Rapid Early COMPLICATIONS OF MI
Action for Coronary Treatment 3) clinical trial, the incidence of
major bleeding was 33% lower with bivalirudin (3.1%) compared Ventricular Free Wall Rupture
with UFH (4.6%). The incidence of minor bleeding was also sig-
nificantly less with bivalirudin. However, transfusion and throm- Ventricular free wall rupture may account for up to 10% of acute
bocytopenia incidence were similar. 92 Back pain, headache, and MI-associated mortality. It occurs in near equal frequency in both
hypotension are the most common adverse reactions. 93 anterior and inferior MI, typically within the first week after in-
farction. Clinical presentations are pulseless electrical activity and
Nursing Implications. Bivalirudin is administered intra-
93
venously and has a short (25 minutes) half-life. Monitor for ma- sudden death. Attempts at resuscitation are futile. Accurately
identifying patient populations at high risk for ventricular free
jor and minor bleeding, including evaluation of hemoglobin and
wall rupture is difficult. Large Q-wave infarcts are more likely to
hematocrit and assessment of vascular access sites.
demonstrate rupture than others. The risk of this devastating
Factor Xa Inhibitor: Fondaparinux complication increases with the age of the patient. 2
Actions/Indications. Fondaparinux is a synthetic heparin Ventricular Septal Rupture
pentasaccharide that selectively binds to antithrombin III, conse-
4
81
quently inhibiting factor Xa, interrupting the blood coagulation Ventricular septal rupture occurs in 1% to 3% of acute MIs. It
cascade, and thus inhibiting thrombin formation and thrombus tends to occur from 3 to 7 days post-MI, and clinically presents
development. Compared with UFH, fondaparinux has decreased with abrupt, severe LV failure, a new loud holosystolic murmur, and
plasma-protein and endothelial-cell binding; dose-independent systemic hypoperfusion due to left-to-right shunting. Diagnosis is
clearance; and longer half-life, allowing a more predictable and made with echocardiography to visualize the ventricular septum.