aneurysm,ventricular
aneurysm,ventricular: Excerpt from Handbook of Diseases
Ventricular aneurysm is marked by an outpouching (almost always of the left ventricle) that produces ventricular wall dysfunction in 10% to 20% of patients after a myocardial infarction (MI). A ventricular aneurysm may develop within weeks after an MI, usually following anterior P-wave infarctions.
An untreated ventricular aneurysm can lead to arrhythmias, systemic embolization, or heart failure and may cause sudden death. Resection improves the prognosis in patients with heart failure or refractory ventricular arrhythmias.
Causes
When MI destroys a large muscular section of the left ventricle, necrosis reduces the ventricular wall to a thin sheath of fibrous tissue. Under intracardiac pressure, this thin layer stretches and forms a separate noncontractile sac (aneurysm).
Abnormal muscle wall movement
Accompanying ventricular aneurysm, abnormal muscle wall movement includes akinesia (lack of movement), dyskinesia (paradoxical movement), asynergia (decreased and inadequate movement), and asynchrony (uncoordinated movement).
During systolic ejection, the abnormal muscle wall movements associated with the aneurysm cause the remaining normally functioning myocardial fibers to increase the force of contraction in order to maintain stroke volume and cardiac output. At the same time, a portion of the stroke volume is lost to passive distention of the noncontractile sac.
Signs and symptoms
A ventricular aneurysm may cause arrhythmias (such as premature ventricular contractions and ventricular tachycardia), palpitations, signs and symptoms of cardiac dysfunction (weakness on exertion, fatigue, angina) and, occasionally, a visible or palpable systolic precordial bulge.
This condition may also lead to left ventricular dysfunction, with chronic heart failure (characterized by dyspnea, fatigue, edema, crackles, gallop rhythm, and neck vein distention); pulmonary edema; systemic embolization; and with left-sided heart failure, pulsus alternans.Ventricular aneurysms enlarge but rarely rupture.
Diagnosis
Persistent ventricular arrhythmias, onset of heart failure, or systemic embolization in a patient with left-sided heart failure and a history of MI strongly suggests a ventricular aneurysm. Indicative tests include the following:
Left ventriculography reveals left ventricular enlargement with an area of akinesia or dyskinesia (during cineangiography) and diminished cardiac function.
Electrocardiography may show persistent ST-T wave elevations after an MI.
Chest X-ray may demonstrate an abnormal bulge distorting the heart’s contour if the aneurysm is large; the X-ray may be normal if the aneurysm is small.
Noninvasive nuclear cardiology scan may indicate the site of infarction and suggest the area of aneurysm.
Echocardiography shows abnormal motion in the left ventricular wall.
Treatment
Depending on the size of the aneurysm and the complications, treatment may require only routine medical examination to follow the patient’s condition or aggressive measures for intractable ventricular arrhythmias, heart failure, and emboli.
Emergency treatment of ventricular arrhythmias involves an I.V. antiarrhythmic or cardioversion. Preventive treatment continues with an oral antiarrhythmic, such as procainamide, quinidine, or amiodarone.
Emergency treatment for heart failure with pulmonary edema includes oxygen, an I.V. cardiac glycoside, I.V. furosemide, I.V. morphine sulfate and, when necessary, I.V. nitroprusside and intubation. Maintenance therapy may include an oral nitrate and an angiotensin-converting enzyme inhibitor, such as captopril or enalapril.
Systemic embolization requires anticoagulation therapy or embolectomy.
Refractory ventricular tachycardia, heart failure, recurrent arterial embolization, and persistent angina with coronary artery occlusion may require surgery; the most effective procedure is aneurysmectomy with myocardial revascularization.
Special considerations
If ventricular tachycardia occurs, monitor blood pressure and heart rate. If sustained ventricular tachycardia occurs, administer I.V. lidocaine.
If cardiac arrest occurs, initiate cardiopulmonary resuscitation (CPR) and call for assistance, resuscitative equipment, and medication.
If the patient is experiencing heart failure, closely monitor vital signs, heart sounds, intake and output, fluid and electrolyte balances, and blood urea nitrogen and creatinine levels.
Because of the threat of systemic embolization, frequently check peripheral pulses and the color and temperature of extremities. Be alert for sudden changes in sensorium that indicate cerebral embolization and for any signs that suggest renal failure or a progressive MI.
If the patient is conscious and requires cardioversion, give diazepam I.V. as needed before cardioversion. Explain to him that cardioversion is a lifesaving procedure that provides brief electric shocks to the heart.
If the patient is receiving an antiarrhythmic, check appropriate laboratory tests. For instance, if he takes procainamide, check his antinuclear antibodies because this drug may induce symptoms that mimic those of lupus erythematosus.
If the patient is scheduled to undergo resection, perform the following:
Before surgery, explain expected postoperative care in the intensive care unit (including use of such things as endotracheal tube, ventilator, hemodynamic monitoring, chest tubes, and drainage bottle).
After surgery, monitor vital signs, intake and output, heart sounds, and pulmonary artery pressures. Watch for signs of infection, such as fever and purulent drainage.
Teach the patient to report light-headedness or dizziness, which may indicate arrhythmia. Encourage him to follow his prescribed drug regimen — even during the night — and to watch for adverse reactions.
Because arrhythmias can cause sudden death, refer the family to a community-based CPR training program.
Provide psychological support for the patient and his family.
Book Source Details
- Book Title: Handbook of Diseases
- Author(s): Springhouse
- Year of Publication: 2003
- Copyright Details: Handbook of Diseases, Copyright © 2003 Lippincott Williams & Wilkins.
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Copyright notice for book excerpts: Copyright © 2008 Lippincott Williams & Wilkins. All rights reserved.
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More About This Book:
Title: Handbook of Diseases
Authors: Springhouse
Publisher: Lippincott Williams & Wilkins
Copyright: 2003
ISBN: 1-58255-266-5
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