Cardiac/Vascular Nurse Exam Secrets Study Guide (24 page)

HMG coenzyme A reductase inhibitors or statins

Statins compete for inhibition of HMG coenzyme A reductase, which impacts cholesterol biosynthesis. Statins are well tolerated and effective agents for the treatment of hyperlipidemia and hypercholesterolemia. The pharmacologic effects of statins include decrease in low-density lipid levels, increase in high-density lipid levels and decrease in triglyceride levels. Higher doses of more potent statins such as atorvastatin and simvastatin are more effective in reducing triglyceride levels.

Therapeutic uses of statins include hypertriglyceridemia, hypercholesterolemia, and hyperlipidemia. Statins are recommended only when a patient fails first line therapy with diet modifications and exercise and their low-density lipid levels are above 160 mg/dL or above 130 mg/dL with more than 2 cardiovascular risk factors such as obesity, smoking or high-density lipid levels below 40 mg/dL. The goal of treatment when prescribing statins in patients with coronary heart disease or at high risk for coronary heart disease is low-density lipid levels below 100 mg/dL.

Adverse events associated with HMG coenzyme A reductase inhibitors or statins include liver dysfunction, increase liver transaminases, myopathy, rhabdomyolysis associated with myalgia and fatigue, hypersensitivity, and renal failure. Due to risk of liver dysfunction and liver transaminases, practicing clinicians should monitor patients’ alanine aminotransferase (ALT) levels. Measurements should be taken upon initiation of treatment and should be repeated every 3 months. Practicing clinicians should also monitor patients for cataract development, especially in elderly patients.

Additionally, due to increased risk for myopathy and rhabdomyolysis, practicing clinicians should inform patients to tell them if they experience any muscle or joint pain, as that may be early indication for rhabdomyolysis, which is a serious complication.

Contraindications associated with statins include liver disease and pregnancy. Statins should be administered prior to bedtime since the highest rates of cholesterol synthesis occur between the hours of midnight and 5 AM.

Fibric acid derivatives

The pharmacologic effects of fibric acid derivatives include decrease in low-density lipid levels, increase in high-density lipid, and decrease in triglyceride levels. However, the exact mechanism of action of fibric acid derivatives is unknown.

Therapeutic uses of fibric acid derivatives include treatment of hypertriglyceridemia primarily, with minimal effect on hypercholesterolemia and hyperlipidemia. Fibric acid derivatives are recommended only when a patient fails first-line therapy with diet modifications and exercise and their triglyceride levels still remain very elevated.

Adverse events associated with fibric acid derivatives include gastrointestinal upset, rash, alopecia, fatigue, headache, impotence, and anemia and myositis flu-like syndrome.

Contraindications associated with fibric acid derivatives include renal failure and liver failure. Caution needs to be taken when prescribing fibric acid derivatives with other agents, as fibric acid derivatives also have antiplatelet effects. Gemfibrozil should not be administered with statins due to increased risk of rhabdomyolysis. However, if gemfibrozil is administered with a statin, practicing clinicians need to monitor patients very closely for the any indication of rhabdomyolysis. Therefore, due to increased risk for myopathy and rhabdomyolysis, practicing clinicians should inform patients to tell them if they experience any muscle or joint pain, as that may be early indication for rhabdomyolysis.

Role of hormone replacement therapy

Hypertension
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Recent data has demonstrated that the use of antihypertensive agents reduces cardiovascular complications such as risk for stroke, myocardial infarction, and congestive heart failure. In women, undergoing treatment with hormone replacement therapy, these agents have been shown to have no effect on blood pressure or risk of stroke but estrogen may improve compliance of large blood vessels. However, hormone replacement therapy with estrogen is contraindicated in postmenopausal women with a history of cardiovascular complications such as thromboembolic disorders.

Therefore, use of hormone replacement therapy for the treatment of hypertension and other cardiovascular complications remains controversial.

Coronary heart disease
:

The use of hormone replacement therapy to prevent acute myocardial infarction or recurrent myocardial infarction remains controversial. Initial observational studies have demonstrated the benefit of hormone replacement therapy in the prevention of acute myocardial infarction or recurrent myocardial infarction. However, the Women’s Health Initiative (WHI) showed that although estrogen replacement has a beneficial effect on lipids, it may increase the risk of cardiovascular complications and, additionally, breast cancer.

Estrogen antagonists and selective estrogen receptor modulators may have similar impact, not reducing coronary heart disease as compared with estrogen or estrogen-progesterone combination. Currently, no evidence exists that demonstrates that estrogen antagonists and/or selective estrogen receptor modulators have any effect on coronary artery disease.

Percutaneous transluminal coronary angioplasty (PTCA) procedure

The goal of percutaneous transluminal coronary angioplasty is to increase blood flow to the coronary arteries by reducing plaque buildup. The procedure involves the use of a catheter introduced through the femoral, brachial, or radial artery into the diseased coronary artery. The catheter has a balloon at the end of the device to be used to tamponade plaque in the diseased vessel. Once the catheter is inserted, balloon pressure is applied to the area of plaque formation to decrease plaque size and/or stretch the vessel wall. The balloon is threaded over a wire after the wire is placed properly in the diseased vessel through angiography. A stent is often placed after ballooning opens the vessel.

Percutaneous transluminal coronary angioplasty is indicated for patients with refractory angina, unstable angina, evidence of cardiac ischemia, acute myocardial infarction, angina post coronary bypass surgery, unsuitable coronary anatomy for coronary bypass surgery, and restenosis after successful percutaneous transluminal coronary angioplasty or stent placement.

Prior to percutaneous transluminal coronary angioplasty, practicing clinicians should take the patient’s medical history, perform a physical examination, and evaluate the patient’s overall health. Patients should be screened for drug-drug interactions, allergies, vital signs such as heart rate and blood pressure and cardiovascular blood indicators such as potassium levels, prothrombin time, and hematocrit and creatinine levels. Patients should also undergo electrocardiogram and echocardiogram prior to procedure.

During the procedure, patients should only receive medications via intravenous access, except for aspirin, which is given orally prior to procedure. Pharmacologic agents used during the procedure include heparin, nitroglycerin, and/or glycoprotein IIb/IIIa receptor inhibitor such as abciximab.

Post percutaneous transluminal coronary angioplasty, practicing clinicians should perform electrocardiogram, echocardiogram, perform physical assessment, monitor peripheral blood flow and look for swelling and evaluate cardiac pain. Hospital protocols for aftercare should be followed. Prior to patient release, practicing clinicians should perform additional physical assessment and laboratory tests such as hematocrit, potassium levels, creatinine levels, and cardiac enzymes. Cardiac stress testing should be completed 2 to 6 months postprocedure.

Stent

A stent is defined as a small mesh tube that is inserted into diseased cardiac vessel that is narrowed or weakened to increase blood flow and restore cardiac function. Stents are typically implanted during an angioplasty procedure. Stents can be made of metal such as stainless steel, tantalum, cobalt alloy, platinum or nitinol, fabric, and/or also drug coated to prevent restenosis.

A stent procedure is very similar to a percutaneous transluminal coronary angioplasty. There are several types of stent procedures including balloon expandable stent procedures and self-expanding stents. With balloon expanding stents, the stent is placed over the balloon and is placed once the balloon is expanded at the plaque site within the diseased coronary vessel. Self-expanding stents are covered by a sheath that allows the stent to expand when removed.

Stent procedures are indicated for patients with refractory angina, unstable angina, evidence of cardiac ischemia, acute myocardial infarction, angina post coronary bypass surgery, unsuitable coronary anatomy for coronary bypass surgery, focal de novo lesions, stenosis of previously placed saphenous vein grafts and restenosis after successful percutaneous transluminal coronary angioplasty or stent placement.

Contraindications for a stent procedure include high-risk coronary anatomy, severe coronary artery disease, bleeding disorder and/or multiple episodes of percutaneous transluminal coronary angioplasty restenosis. If glycoprotein IIb/IIIa inhibitors are used, other contraindications include gastrointestinal bleeding, inability to take antiplatelet agents, intracranial hemorrhage, recent surgery, or trauma.

Complications associated with stent procedures include abrupt closure of diseased coronary artery, periprocedural myocardial infarction, coronary restenosis, bleeding, or hematoma at catheter introduction site, arterial embolism, pseudoaneurysm, retroperitoneal bleeding, and sudden death.

Prior to a stent procedure, practicing clinicians should take a patient’s medical history, perform a physical examination, and evaluate the patient’s overall health. Patients should be screened for drug-drug interactions, allergies, vital signs such as heart rate and blood pressure and cardiovascular blood indicators such as potassium levels, prothrombin time, hematocrit, and creatinine levels. Patients should also undergo electrocardiogram and echocardiogram prior to procedure.

During the procedure, patients should only receive medications via an intravenous route, except for aspirin, which is given orally prior to the procedure. Pharmacologic agents used during the procedure include heparin, nitroglycerin, and/or glycoprotein IIb/IIIa receptor inhibitor such as abciximab.

Post stent procedure, practicing clinicians should perform electrocardiogram, echocardiogram, perform physical assessment, monitor peripheral blood flow and look for swelling and evaluate cardiac pain. Hospital protocols for aftercare should be followed. Prior to patient release, practicing clinicians should perform additional physical assessment and laboratory tests such as hematocrit, potassium levels, creatinine levels, and cardiac enzymes. Cardiac stress testing should be completed 2 to 6 months postprocedure.

Coronary atherectomy

There are 3 currently available atherectomy procedures that include directional coronary atherectomy, rotational atherectomy, and transluminal extraction atherectomy.

Directional coronary atherectomy is a procedure that involves the use of a catheter with a balloon and cutting tool at the end of the catheter. During the procedure, the catheter is inserted into the diseased tissue, the balloon is inflated to remove or disrupt the plaque, and the cutting tool is used to remove the rest of the plaque.

Rotational atherectomy is a procedure that is also a catheter-based procedure that uses a metal cutting tool coated with diamonds, which breaks up the plaque into tiny particles to be removed.

Transluminal extraction atherectomy is a procedure involves the use of a hollow tube with a cutting tool at the end of the device. The hollow tube also has suction bottles that collect removable plaque buildup.

An atherectomy procedure, also known as a rotablator procedure, is a technique that involves a catheter with a grinding/cutting tool at the end of the device that is used to clear plaque buildup within diseased coronary arteries. An Atherectomy procedure can be done in combination with percutaneous transluminal catheter angioplasty and/or stent procedure.

The procedure involves the use of catheter introduced through the femoral, brachial, or radial artery into the diseased coronary artery. The catheter has a grinding/cutting tool at the end of the device to be used to reduce plaque buildup in the diseased vessel.

Directional coronary atherectomy is indicated for bifurcation lesions, ostial lesions and eccentric lesions. Rotational atherectomy is indicated for calcified lesions, ostial lesions, 15-to 25-mm-length lesions, and instent restenosis. Transluminal extraction atherectomy is indicated for lesions that require removal of thrombus or debris such as patients with unstable angina, acute myocardial infarction, and failed thrombolytic therapy.

Contraindications for coronary atherectomy include high-risk coronary anatomy, severe coronary artery disease, bleeding disorder, and/or multiple episodes of percutaneous transluminal coronary angioplasty restenosis.

Complications associated with coronary atherectomy include abrupt closure of the diseased coronary artery, periprocedural myocardial infarction, coronary restenosis, bleeding, or hematoma at catheter introduction site, arterial embolism, pseudoaneurysm, retroperitoneal bleeding, vascular spasm, distal embolization, vessel perforation, and sudden death.

Prior to a coronary atherectomy procedure, practicing clinicians should take patient’s medical history, perform a physical examination, and evaluate the patient’s overall health. Patients should be screened for drug-drug interactions, allergies, vital signs such as heart rate and blood pressure and cardiovascular blood indicators such as potassium levels, prothrombin time, and hematocrit and creatinine levels. Patients should also undergo an electrocardiogram and echocardiogram prior to the procedure.