CARDIOMEGALY

If an x-ray film demonstrates cardiomegaly, the physician must find out what is causing this condition (Table 13). You have already listened to the patient and he or she does not have a murmur. This seems to exclude the common groups of causes—congenital and rheumatic heart disease. (It really does not.) The patient does not have hypertension and denies symptoms of heart failure. The ECG is normal. Now what do you do?

CARDIOMEGALY

CARDIOMEGALY, LOCAL CAUSES

This situation is all too common and I hope this chapter will remedy that situation. The basic sciences, histology and physiology are, of course, the key to an immediate differential diagnosis. Remember that the heart is divided into three basic layers: endocardium, myocardium, and pericardium; each of these can be cross-indexed with the etiologic classification using the mnemonic VINDICATE. The pathophysiologic mechanism, obstruction, provides the remaining disorders in the differential diagnosis. This is applied to the pulmonary and systemic circulations and cross-indexed with the various etiologic groups.

Beginning with the endocardium,

1. V—Vascular lesions include the ball–valve thrombosis.
2. I—Inflammatory lesions bring to mind acute and subacute bacterial endocarditis and syphilitic valvular disease.
3. N—Neoplasms suggest an atrial myxoma.
4. D—Degenerative disease signals atherosclerotic valvular disease.
5. I—Intoxication does not suggest any particular condition, because most toxins involve the myocardium.
6. C—Congenital suggests a host of valvular and septal defects and transposition of the blood vessels of the heart.
7. A—Autoimmune suggests the important rheumatic carditis and also Libman–Sack endocarditis of lupus erythematosus.
8. T—Trauma suggests all the valvular or septal defects that can occur from surgery.
9. E—Endocrine suggests the pulmonic and tricuspid valvular defects that result from carcinoid syndrome.

In the myocardium, one encounters a large number of diseases; thus, only the most common ones will be mentioned here.

1. V—Vascular should immediately suggest coronary insufficiency and myocardial infarction.
2. I—Inflammation could indicate viral myocarditis, but it would hardly be expected to remind one of diphtheria and syphilitic myocarditis because these rarely are seen.
3. N—Neoplasms of the myocardium are rare, thus the rhabdomyosarcoma needs only be mentioned here for completeness.
4. D—Degenerative and Deficiency diseases should signal beriberi and muscular dystrophy, but these are also infrequently encountered.
5. I—Intoxicating and Idiopathic disorders of the myocardium are much more common, especially alcoholism. Others include hemochromatosis, alcoholism, amyloidosis, and gout.
6. C—Congenital disorders include von Gierke disease and myocardial fibroelastosis.
7. A—Autoimmune again suggests rheumatic fever and the collagen diseases.
8. T—Trauma suggests the posttraumatic aneurysms.
9. E—Endocrine disorders include two treatable disorders: hyperthyroidism and hypothyroidism.

The pericardium is not frequently the cause of “cardiomegaly,” but tuberculosis and idiopathic pericarditis should be considered as should hemopericardium, especially in the course of a myocardial infarction.

Obstruction in the pulmonary circulation from the following:

1. V—Vascular from pulmonary infarct.
2. I—Inflammatory from chronic bronchitis and emphysema or from chronic infections such as tuberculosis and various fungi.
3. N—Neoplastic from primary or metastatic carcinoma.
4. D—Degenerative
5. I—Idiopathic or Intoxication in pulmonary fibrosis and primary pulmonary hypertension.
6. C—Congenital disorders include pulmonic stenosis and hemangiomas.
7. A—Autoimmune diseases include collagen diseases.
8. T—Trauma may cause an arteriovenous aneurysm or pneumothorax obstructing the pulmonary circulation.
9. E—Endocrine disorders do not obstruct the pulmonary vasculature.

Under systemic circulation come essential or secondary hypertension caused by coarctation of the aorta, periarteritis nodosa, or the many renal and adrenal diseases. Dissecting aneurysms of the aorta may rupture into the pericardium causing cardiomegaly.

Approach to the Diagnosis

The diagnosis of cardiomegaly can be further developed be a good history and the association of other symptoms and signs. Is there a history of hypertension, alcoholism, rheumatic fever or other systemic disease? Has the patient experienced shortness of breath, angina, fever, joint pains, and so forth? Are there findings of pedal edema, hepatomegaly, or jugular venous distention (CHF)? Are there hypertension and proteinuria (renal disease or essential hypertension)? Is there a significant heart murmur (congenital heart disease, rheumatic heart disease)?

The diagnostic workup will include a CBC, urinalysis, chemistry panel, sedimentation rate, a chest x-ray, and ECG. At this point, it is wise to consult a cardiologist. Echocardiography will be helpful in diagnosing valvular heart disease, myocardiopathy, and pericardial effusion. If CHF is suspected, a venous pressure and circulation time as will as spirometry will support the diagnosis. Echocardiography can diagnose congestive heart failure by determining the left ventricular ejection fraction (LVEF). If there is unexplained fever, an ASO titer or streptozyme test should be ordered to rule out rheumatic fever and perhaps serial blood cultures need to be done to exclude subacute bacterial endocarditis. If there is hypertension the patient may need a hypertensive workup (see page 299).

Other Useful Tests

1. Exercise tolerance test (coronary insufficiency)
2. Thallium scan (coronary insufficiency)
3. Phonocardiogram (valvular heart disease)
4. ANA analysis (collagen disease)
5. Cardiac catheterization studies (congenital heart disease, rheumatic heart disease)
6. Angiocardiogram (valvular heart disease)
7. Coronary arteriogram (coronary insufficiency)
8. Thyroid profile (myxedema)
9. 24-hour urine catecholamine (pheochromocytoma)
10. Urine thiamine afterload (beriberi)
11. Muscle biopsy (collagen disease, trichinosis)
12. CT scan (mediastinal mass)
13. MRI (dissecting aneurysm)

Book Source Details

• Book Title: Differential Diagnosis in Primary Care
• Author(s): R. Douglas Collins
• Year of Publication: 2007
• Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2007 Lippincott Williams & Wilkins.

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Copyright Details: Differential Diagnosis in Primary Care, Copyright © 2008 Williams & Wilkins.

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More About This Book: Title: Differential Diagnosis in Primary Care Authors: R. Douglas Collins Publisher: Lippincott Williams & Wilkins Copyright: 2007 ISBN: 0-7817-6812-8

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