Sherif B. Labib

Cardiac papillary fibroelastoma

Papillary fibroelastomas are rare cardiac tumors, but they are the most common primary tumor of the heart valves. These lesions occur on any of the valves or endothelial surfaces of the heart and may be detected by echocardiography, cardiac catheterization, during open heart operation for other conditions, or at autopsy. Because of their potential for cerebral and coronary embolization, even small papillary fibroelastomas should be excised.

Obstruction of right ventricular outflow tract caused by intracavitary metastatic disease: Analysis of 14 cases

Obstruction of the right ventricular outflow tract from metastatic disease is rare. Eleven previous case reports and three new cases are presented. Two tumor types (pancreas and breast), not previously associated with right ventricular outflow tract obstruction, are included. Congestive symptoms, systolic murmur and right axis deviation or right bundle branch conduction abnormality were universal features. Echocardiography is valuable in the delineation of metastatic cardiac involvement and the detection of intracardiac gradients. Adverse hemodynamic consequences developed in 3 of 10 patients who underwent right heart catheterization in which two died. This procedure should be performed only when absolutely necessary. Metastatic obstruction of the right ventricular outflow tract should be considered in the absence of widespread malignancy because the heart was the sole site of metastasis in 5 of 10 autopsy patients. Two patients with solitary cardiac metastasis benefited from resection of the obstructing tumor, underscoring the importance of early identification of this subgroup.

Aortic dissection and aortic aneurysm surgery.

During the last year, the role of noninvasive studies for aortic dissection--magnetic resonance imaging, computed tomography scanning, and transesophageal echocardiography--has become better defined. Both magnetic resonance imaging and transesophageal echocardiography are highly accurate in detecting aortic dissection. On transesophageal echocardiographic imaging of the ascending aorta, artifacts may be present that mimic an intimal flap (septum). These linear echo densities have characteristic features which distinguish them from a true intimal flap (septum). Their recognition is critical in avoiding false positive transesophageal echocardiography findings. The general consensus on operations for ascending aorta and aortic arch dissection is that patients should be operated upon immediately. Controversy still remains, however, as to whether the aortic arch needs replacement at the time of the ascending and proximal aortic arch repair. Most authors agree that deep hypothermia with circulatory arrest is the preferable technique for acute aortic dissection repair and for surgery on the aortic arch in adults. Retrograde perfusion of the jugular veins is an added advantage. For acute aortic dissection involving the descending thoracic or thoracoabdominal aorta, evidence continues to accumulate that initial medical therapy with beta-blockers and antihypertensives is the preferable mode of treatment unless complications requiring surgery arise. Percutaneous techniques are increasingly being described, including fenestration of the aortic dissection septum, stenting of the aorta or aortic branches, and insertion of intraluminal aortic tube grafts. The safety of surgery on the thoracoabdominal aorta and on the descending thoracic aorta, including the prevention of complications, is reviewed.

Paradoxical Embolism in the Left Main Coronary Artery: Diagnosis by Transesophageal Echocardiography

We describe a patient with a paradoxical coronary embolism diagnosed by transesophageal echocardiography. The patient developed a stroke followed by a myocardial infarction. Coronary angiography showed an obstruction of the left main coronary artery. Transesophageal echocardiography showed the mechanism of the neurologic and cardiac events to be a paradoxical embolism. Emergency surgical retrieval of the thrombus lodged in the left main coronary ostium and of a separate thrombus traversing a patent foramen ovale was performed. To our knowledge, direct visualization of the paradoxical coronary embolism by echocardiography has not been reported previously. We discuss mechanisms responsible for paradoxical coronary embolism and review the literature pertaining to this condition.

Anthropometric normalization of left ventricular size in chronic mitral regurgitation.

A considerable body of clinical and experimental evidence supports the notion that a major cardiac adjustment to mitral regurgitation (MR) is enlargement of the left ventricle.1–7 However, definitions of left ventricular (LV) enlargement ostensibly require a consideration of body size. Body surface area (BSA) has long been used to normalize LV internal dimensions,3,4 but recent studies of chronic MR have utilized data without consideration of body size.5,6 Thus, there is a lack of agreement as to whether LV size should or should not be normalized for BSA, or for some other anthropometric index.8,9 In an attempt to clarify this issue, we identified 48 patients with clinical and echocardiographic color Doppler evidence of chronic MR. Anticipating a high prevalence of LV enlargement, we compared the conclusions drawn from non-normalized measurements with those normalized for BSA, the square root of BSA, and on the basis of height. In this manner, we evaluated the relative merits of the 3 normalization techniques. • • • Using a database for 1997 to 1998, patients with severe MR were identified. The echo Doppler studies were reviewed by at least 2 of the investigators and the diagnosis of severe MR was confirmed (see the following). All patients had mitral valve disease with prolapse or partially flail leaflets. Those with mitral stenosis and/or associated aortic valve disease were excluded, as were those with LV wall motion abnormalities indicating coronary heart disease. Finally, a medical record review confirmed that all patients had previous clinical, radiographic, and/or echocardiographic evidence of MR for 1 year. Thus, only patients with chronic MR were included in the study. There were 31 men and 17 women; average age was 67 12 years. Two-dimensional, M-mode, and Doppler echocardiography were performed using commercially available equipment (Hewlett-Packard Medical Products, Andover, Massachusetts). LV internal minor-axis diameter was measured, just distal to the tips of the mitral leaflets (e.g., at the mid-cordal level).10 The ejection fraction was estimated from measurements of the LV diameter at end-diastole and end-systole, using a modification of the Quinones method.11,12 The severity of MR was estimated from the relative area of the regurgitant jet (Doppler echocardiography). Severe MR was defined as a color jet reaching the posterior wall of the left atrium with a high aliasing velocity area 40% of the left atrial area.13 The upper limit of normal of the LV end-diastolic diameter (EDD) was taken as 56 mm.14 Patients were separated into those with enlarged ventricles (group A) and those whose EDD was normal (group B); subgroups of those in normal sinus rhythm and with atrial fibrillation were identified (Table 1). We then normalized the LV EDD for BSA; the upper limit of normal was taken as 32 mm/m. We also normalized the EDD by the square root of BSA; the upper limit of normal was taken as 40 mm/m. Finally, we also used the regression model developed by Vasan et al9 to categorize the degree of chamber enlargement. This latter method, based on genderand height-specific limits provides categories ranging from zero (normal), to 1 (borderline), and 2 to 4 (enlarged). We then examined the conclusions drawn from these 4 methods.8,9,14 Data in Table 1 are mean SD. Significant differences (p 0.05) were assessed with an unpaired t test. The average data from our 48 patients are listed in Table 1. By definition, the average value for LV EDD was larger in group A than that in group B. Analysis of the data in these 2 groups indicates a significantly greater left atrial enlargement in group A than group B, but age, gender, ejection fraction, and E-wave velocity did not differ in the 2 groups. The E-wave velocity was 130 cm/s in 28 of the 36 patients in group A and in 10 of the 12 patients in group B. Evidence of a partial flail leaflet and/or ruptured chordae was present in 16 of the 36 patients in group A (44%) and 6 of the 12 group B patients (50%). BSA was greater in group A than group B, but the average values for height and body mass index (BMI) (kilograms per meter) did not differ in the 2 groups. BMI was 25 kg/m in 31 of the 48 patients (64%). Data from the individual patients are shown in Figure 1. The LV EDD was 56 mm in 36 patients; by this definition, 75% of the patients exhibited LV enlargement. In contrast, EDD expressed relative to BSA exceeded the upper limits of normal (32 mm/m) in only 23 patients (44%). When the EDD was normalized by the square root of BSA, the value exFrom the Echocardiography Laboratory, Department of Cardiovascular Medicine, Lahey Clinic, Burlington, Massachusetts. Dr. Gaasch’s address is: Lahey Clinic, 41 Mall Road, Burlington, Massachusetts 01805. E-mail: William.H.Gaasch@Lahey.org. Manuscript received August 27, 2002; revised manuscript received and accepted November 14, 2002.

Echocardiography in low pressure cardiac tamponade

Right ventricular (RV) diastolic collapse and right atrial (RA) collapse are 2 useful 2-dimensional echocardiographic signs of cardiac tamponade.1–4 According to investigation of the hemodynamics of tamponade in animals under conditions of varying intravascular volume, the presence of RV diastolic collapse and RA collapse implies that the effusion has importantly compromised cardiac filling and output, and that these signs occur in tamponade even when intravascular volume is contracted.3 Most clinical studies documenting the value of the echocardiographic signs of tamponade have been performed in cases of straightforward tamponade where other hemodynamic or clinical signs were also present. The importance of RV diastolic collapse and RA collapse in the detection of complicated tamponade in patients, such as that seen in a setting of hypovolemia, is not known. Recognition of tamponade is often difficult when it occurs in a state of intravascular volume depletion.5,6 In this report we present a case of low pressure cardiac tamponade where the diagnosis of tamponade was made by the presence of RV diastolic collapse and RA collapse, despite normal right-sided pressures.

Differential Effects of Dobutamine Versus Treadmill Exercise on Left Ventricular Volume and Wall Stress

BACKGROUND Dobutamine and exercise echocardiography are well-validated modalities used for the evaluation of patients with suspected myocardial ischemia. Patients undergoing dobutamine stress echocardiography (DSE), however, experience less angina, ST-segment depressions, and wall motion abnormalities. Other than the effect on heart rate, the physiologic and volumetric differences between pharmacologic and exercise-induced stress that affect myocardial oxygen demand are not well defined. The aim of this study was to test the hypothesis that in the absence of ischemia, dobutamine reduces left ventricular (LV) volume, wall tension (WTN), and peak systolic stress (PSS) compared with exercise. METHODS Seventy patients without ischemia were prospectively enrolled (35 underwent exercise echocardiography and 35 DSE), and various hemodynamic parameters were measured and LV volumes calculated (using the Simpson and Teichholz formulas). Systolic WTN and PSS were determined at rest and stress. RESULTS LV end-diastolic volume index fell significantly more with dobutamine than with exercise (-34% vs -9%, P < .0001), as did mean end-systolic volume index (-55% vs -37%, P = .07). Systolic blood pressure increased more with exercise (41 ± 22 vs 1 ± 33 mm Hg, P < .0001), as did cardiac index (2.5 ± 0.7 vs 1.0 ± 0.8 L/min/m(2), P < .0001). Systolic WTN increased with exercise by 24% (P < .0001) but decreased with dobutamine by 18% (P < .0001). PSS increased with exercise by 21% (P < .0001) but decreased with dobutamine by 23% (P < .0001). CONCLUSIONS The degree of stress achieved with DSE appears to be considerably different than with exercise. DSE produces greater reductions in LV end-diastolic and end-systolic volumes than exercise and decreases rather than increases in WTN and PSS. The lower WTN and PSS were related to both a decrease in LV volume and lower systolic blood pressure with dobutamine. These observations support recommendations favoring exercise stress testing in patients able to exercise and reinforce the notion that high-risk echocardiographic features of ischemia such as stress-induced LV dilatation may be less striking or absent with DSE.

Impedance to retrograde and forward flow in chronic mitral regurgitation and the physiology of a double outlet ventricle.

Objective Mitral regurgitation (MR) is generally characterised as exhibiting a ‘low impedance leak into the left atrium’. This notion is widely accepted without measured impedance data. The aim of this study was to define the impedance to retrograde and forward blood flow and to examine hydraulic (pressure-volume) and mechanical (stress-shortening) function in chronic severe MR. Methods A mathematical model of a double outlet ventricle was developed and the ratio of retrograde to forward impedance was plotted over a wide range of regurgitant fraction (RF). The model predicts that an impedance ratio >1 indicates that the impedance to retrograde flow exceeds that of forward flow. Left ventricular (LV) systolic pressure/flow rate was used as an index of impedance (mm Hg/mL/s). Data from 10 patients with severe MR were used to assess the clinical applicability of the model. All patients had degenerative valve disease with partial flail leaflet, an RF >50% and an ejection fraction (EF) >0.60. There were seven males and three females, aged 59±10. LV volumes as well as retrograde and forward flow rates were determined with echocardiographic and Doppler techniques. Results The model indicates that the impedance ratio is >1 when the RF ranges from zero to 57%. Clinical data: end-diastolic volume=184±47 mL; EF=0.63±3%; RF=53±4%. Values for retrograde and forward impedance were 0.77±0.17 and 0.63±0.12 (p=0.003); the impedance ratio was 1.22±0.19. Total impedance to LV emptying was low (0.35±0.06). The ratio of systolic wall stress to EF (580±81 g/cm2) was normal. Data are mean±SD. Conclusions The model, supported by clinical data, indicates that the impedance to retrograde flow exceeds the impedance to forward flow in chronic severe MR. These findings refute the notion of a low impedance leak into the left atrium. The double outlet of an enlarged ventricle provides a mechanism for low total impedance to ejection in the presence of a normal stress-shortening relation.

Identifying patients for safe early hospital discharge following st elevation myocardial infarction.

To examine whether the CADILLAC risk score is an effective method of patient stratification for early discharge following ST elevation myocardial infarction (STEMI).

CONGENITAL DOUBLE-CHAMBERED LEFT VENTRICLE PRESENTING AS MONOMORPHIC VENTRICULAR TACHYCARDIA

Left-sided double ventricle or double-chambered left ventricle (DCLV) is a rare congenital defect that generally remains asymptomatic without complications but can present with life-threatening arrhythmias. The differentiation between this rare congenital abnormality and acquired conditions such as postinfarction or posttraumatic pseudoaneurysm can pose a diagnostic challenge. The distinction is important because the presence of pseudoaneurysm typically requires surgical management. We report the case of a man who presented with monomorphic ventricular tachycardia and was ultimately diagnosed with DCLV. We also review previously reported cases in which patients were incidentally discovered to haveDCLVand various imaging studies used to diagnose this condition.