Left Ventricular Diverticulum With Hypertrophy of the Left Ventricular Apex Chojiro Yamashita, MD, Hiroomi Nakamura, MD, Satoshi Tobe, MD, Toshihiro Koterazawa, MD, and Sinnichirou Yamamoto, MD Miki City Hospital and Department of Surgery, Division 11, Kobe University School of Medicine, Kobe, Japan
A surgical case of diverticulum in the left ventricular apex is presented. A two-dimensional echocardiogram and magnetic resonance image showed a calcified tumor buried in the marked hypertrophied apex of the left ventricle. Enucleation of the oval and hard tumor (4 x 2.5 X 2.5 cm) was performed through the apex, and the defect was anastomosed by buttress sutures. Histologic
examination demonstrated that the tumor cavity was filled with a thrombus encapsulated by thickened and calcified endocardium that extended to the left vehtricu- lar cavity. In this report, the etiology of the diverticulum with a hypertrophied myocardium is discussed.
(Ann Thorac Surg 1992;54:761-3)
eft ventricular diverticulum in adults is a very rare L malformation. The majority of cases arise from the apex of the left ventricle and are usually found in chil- dren. In all cases, the muscular appendage extends out- side the normal bounds of the heart and pericardium, and often extends through the diaphragm. In our case, the diverticulum was filled with a thrombus and buried in the hypertrophic myocardium of the left ventricular apex. We assume that our case was not a congenital anomaly but was caused by myocardial infarction due to apical hyper- trophic cardiomyopathy.
A 58-year-old man was admitted to our hospital due to general fatigue and arrhythmia. Four years earlier, a ventricular premature beat and supraventricular capture were observed by a visiting doctor. Physical examination revealed normal vital signs except an irregular pulse. Cardiac and pulmonary auscultation revealed no cardiac murmur and vesicular breathing sounds. On chest roent- genogram, the cardiothoracic ratio was 0.43 and a rounded shadow 3 cm in diameter with calcification was found near the apex of the heart. An electrocardiogram showed atrial fibrillation and severe left ventricular hy- pertrophy with S-T segment depression in the lateral precordial lead. A two-dimensional echocardiogram re- vealed a low echoic lesion 2 cm in diameter in the apex and spade-like hypertrophy of the left ventricle. Magnetic resonance imaging demonstrated a spade-like hyper- trophic myocardium and calcified tumor buried in the hypertrophic apex (Fig 1). A left ventricular angiogram showed a normal left ventricle and wall motion. Coronary angiography showed normal coronary arteries. The white blood cell count was 10.5 x 109/L with 16% eosinophils. Other laboratory examinations were within the normal
Accepted for publication Dec 30, 1991.
Address reprint requests to Dr Yamashita, Department of Surgery, Divi- sion 11, Kobe University School of Medicine, 7-5-2 Kusunoki cho Chuoku, Kobe, Japan 650.
limits. With a diagnosis of cardiac echinococcosis or a fibrous diverticulum, which has the risk of rupture, we proceeded to treat him surgically.
On January 7, 1991, operation was carried out through a median sternotomy. Fibrous adhesion was seen at the apex and was dissected. Malformation of the left ventricle was not found, but a hard tumor under the epicardium at the apex was detected by palpation. The epicardium was incised and the capsule was dissected from the myocar- dium (Fig 2). On the reverse side of the tumor, the capsule became a thin root and connected to the ventricular cavity. Cutting the root showed the capsule of the tumor to be fibrous endocardium, and the tumor was filled with thrombus. The left ventricular cavity showed moderate subendocardial fibrosis at the site of apical ventriculot- omy. Near the apex, the myocardium was almost totally replaced by fibrous tissue. The defect was anastomosed with buttress sutures, reinforced by a felt strip (Fig 3) . The schema of the tumor is showed in Figure 4. The postop- erative course was uneventful. Histologic examination showed that the tumor was a thrombus encapsulated by fibrous endocardium with calcification.
Comment Left ventricular diverticulum of the heart is a rare malfor- mation. The majority arise from the apex of the left ventricle and are usually found in children. Only a few cases in adults have been reported. In the past, congenital aneurysm and diverticulum of the left ventricle were used synonymously. Treisman and associates [ 11 classified the defect as a diverticulum when its root of connection to the left ventricle was narrow and was associated with con- genital midline lesions, and as an aneurysm if the con- nection was wide and there were no other congenital defects. Recently, the definition of a diverticulum is that its wall contains three cardiac layers (endocardium, myo- cardium, and pericardium) and it contracts normally. Mady and Paulo  stated that left ventricular diverticu-
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762 CASE REPORT YAMASHITA ET AL LEFT VENTRICULAR DIVERTICULUM
Ann Thorac Surg 1992;54:761-3
Fig 2. A tumor with a calcified capsule was dissected.
information about a mass buried in the hypertrophic myocardium of the left ventricle. The mass showed no contraction, so this tumor was initially thought to be echinococcosis or a fibrous diverticulum . Shizukuda and associates  and Kida and co-workers  reported left ventricular diverticulum with hypertrophic cardiomy- opathy. Tecklenberg and colleagues  reported that an obstructing hypertrophic mass localized in the midportion of the ventricle created a pressure gradient between the apical and basal portions. They assumed that the ventric- ular apex, chronically exposed to high intracavitary pres- sure, gradually changed to a dilated muscular chamber, or diverticulum, as the midventricular obstruction worsened . In hypertrophic cardiomyopathy, angina pectoris oc- curs as the result of an imbalance between oxygen supply and demand as a consequence of the greatly increased myocardial mass. Transmural infarction may occur in the absence of narrowing of the extramural coronary arteries. B
Fig 1. (A) Magnetic resonance imaging in diastole showed diverticu- lum buried in the hypertrophic myocardium of the left ventricle (LV). ( B ) Magnetic resonance imaging in systole showed diverticulum and a spade-like hypertrophic myocardium of the left ventricle. (RV = right ventricle.)
lum has two types; one is muscular and the other is fibrous. Muscular diverticulum is usually located at the apex or the inferoposterior wall. The wall of the muscular diverticulum consists of intact musle layers and some fibrous tissue. Fibrous diverticula are usually apical or subvalvular in position, and the walls are composed of fibrous tissue, with no contractility. An aneurysm of the left ventricle develops as a result of infection, ischemia, trauma, and postoperative coronary disease and consist of a fibrous saccular lesion with paradoxical contraction of its wall.
In our case, a tumor in the apex and hypertrophy of the left ventricle were discovered by echocardiogram. Mag- netic resonance imaging provided valuable anatomical
Fig 3. The defect was anastomosed by buttress sutures, as well as being reinforced by u felt strip.
Ann Thorac Surg 1992;54:761-3
CASE REPORT YAMASHITA ET AL 763 LEFT VENTRICULAR DIVFRTICULUM
In conclusion, we hypothesize that severe myocardial hypertrophy produced subendocardial and apical infarc- tion, which eventually became diverticulum with a mural thrombus.
Fig 4. Schema of the tumor and hypertrophied myocardium.
Impaired diastolic relaxation may also produce suben- docardial ischemia as a result of prolonged maintenance of wall tension with a concomitant slower than normal decrease in the impedance to coronary blood flow [7, 81.
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