Alyson N. Owen

Transesophageal echocardiographic evaluation in mechanically assisted circulation.

Transesophageal echocardiography (TEE) has assumed an increasing importance in cardiothoracic surgery, but its use in patients with mechanically assisted circulation is unclear. We performed TEE in 11 patients: total artificial heart (TAH) 2, right ventricular assist device (RVAD) 2, left ventricular assist device (LVAD) 6, biventricular assist device (BVAD) 1. TEE was helpful in three areas. (1) selection of the assist device (AD): evaluation of left and right ventricular function allows differentiation of left, right or biventricular failure. (2) management of patient and optimization of pump performance: in all patients, correct cannula position and pump flow could be identified. Right ventricular failure in the presence of LVAD was found to cause hemodynamic instability in 4 patients. In 1 patient with repeated RV dilation and hypotension despite RVAD, TEE allowed optimal pump settings to be determined. (3) weaning from AD: Recovery of ventricular function can be assessed prior to weaning and repeatedly monitored during weaning. TEE in TAH is limited to problems such as identification of atrial thrombus or inflow valve dysfunction. We conclude that TEE is useful in the setting of mechanically assisted circulation for AD selection, improvement of patient management, optimization of pump performance and during weaning from AD.

Rapid Development of a Papillary Fibroelastoma with Associated Thrombus: The Role of Transthoracic and Transesophageal Echocardiography

Transthoracic echocardiography (TTE) and transesophageal echocardiography (TEE) are frequently utilized in patients with suspected cerebral vascular ischemia. We describe a patient with suspected cerebral vascular ischemic event whom was found to have a mobile valvular mass by TTE and TEE. The lesion was unusual due to its rapid development over a period 6 months, which was documented on serial echocardiography. The mass was excised surgically and pathology showed a papillary fibroelastoma with extensive thrombus. The differential diagnosis of a cardiac valvular mass and the treatment of cardiac fibroelastomas are reviewed. In this case, both TTE and TEE were valuable in diagnosis and facilitating surgical management of a cardiac fibroelastoma.

Left Atrial Volume: Comparison of 2D and 3D Transthoracic Echocardiography with ECG-gated CT Angiography

RATIONALE AND OBJECTIVES Left atrial volume (LAV) measurement by conventional two-dimensional (2D) transthoracic echocardiography (TTE) may be limited by the geometric model, by suboptimal definition of left atrial endocardium, or by chamber foreshortening. Three-dimensional (3D) TTE is posited to eliminate chamber foreshortening, and LAV measurement by 3D TTE should be more reflective of true LAV. The aim of this study was to compare conventional 2D TTE and newer 3D TTE for measurements of LAV to multidetector computed tomographic (MDCT) measurements using automated chamber reconstruction (ACR). MATERIALS AND METHODS Twenty-two subjects consented to undergo 2D TTE and 3D TTE immediately prior to or following coronary computed tomographic angiography. LAV was calculated from 2D TTE using the area-length method (ALM) and from 3D TTE with the ALM as well as with a 3D model. Electrocardiographically gated coronary computed tomographic angiography was performed in helical mode. LAV was measured using the ALM as well as ACR. RESULTS LAV was significantly smaller by 2D TTE (80 ± 21 mL) and 3D-TTE (90 ± 24 mL with the ALM, 61 ± 16 mL with the 3D model) compared to MDCT ACR (120 ± 30 mL) (P < .01). Correlation between MDCT ALM and MDCT ACR was excellent (mean Δ = -1.4 ± 14 mL, r = 0.91). Correlation with MDCT ACR was no better for 3D TTE (r = 0.80) than for 2D TTE (r = 0.80). CONCLUSIONS LAV is underestimated by both 2D TTE and 3D TTE relative to coronary computed tomographic angiography. Excellent agreement between the ALM and ACR with MDCT imaging suggests that the geometric model plays a negligible role in the underestimation of LAV. Underestimation of LAV by echocardiography is likely related to suboptimal definition of left atrial contour.

Measurement of aortic flow velocity during transesophageal echocardiography in the transgastric five-chamber view

Continuous-wave Doppler echocardiography of aortic flow velocity has a variety of clinical and research applications. Recently, continuous-wave Doppler echocardiography has been added to transesophageal echocardiographic systems. However, alignment of the Doppler beam with aortic flow is not possible with standard single and biplane views. A modified transesophageal echocardiographic view; the transgastric five-chamber (TG5C) view, allows for measurement of aortic flow velocity but its feasibility and accuracy in an unselected consecutive population have not yet been described. The feasibility of obtaining the TG5C view and measuring aortic flow velocity was assessed in 58 consecutive transesophageal echocardiographic investigations. The TG5C view was obtained in 97% and adequate Doppler flow velocity signals were obtained in 91% of patients. The accuracy of measurements was assessed in 24 patients in whom flow signals from both the TG5C and standard transthoracic views could be obtained. The correlation between TG5C and transthoracic views was excellent, with r values of 0.968 and 0.952 for peak aortic flow velocity and mean aortic flow velocity, respectively. Accurate aortic flow velocity measurements can be obtained in most patients during transesophageal echocardiography with the TG5C view. This view has great utility in a variety of situations in which adequate transthoracic imaging is not possible, especially the operating room and intensive care unit.

Characterization and normal measurements of the left ventricular outflow tract by ECG-gated cardiac CT: implications for disorders of the outflow tract and aortic valve.

RATIONALE AND OBJECTIVES Studies suggest that electrocardiographically gated coronary computed tomographic angiography provides a clear definition of the left ventricular outflow tract (LVOT), and normal LVOT morphology may not be round, as assumed when the continuity equation is applied during echocardiography. The aims of this study were to demonstrate the morphology of the LVOT on coronary computed tomographic angiography and to establish normal values for LVOT measurements. MATERIALS AND METHODS Two independent readers retrospectively measured anterior-posterior (AP) and transverse diameters of the LVOT and performed LVOT planimetry on coronary computed tomographic angiographic studies of 106 consecutive patients with normal aortic valves. RESULTS Excellent interobserver agreement was observed for all measurements (r = 0.78-0.94). The LVOT was ovoid, with a larger transverse diameter than AP diameter during diastole and systole (P < .001). However, the ratio of AP diameter to transverse diameter was closer to 1.0 during systole (P < .001). Mean indexed LVOT area was minimally larger in systole than in diastole (P = .01-.04) and was larger in men than in women during diastole (P ≤ .001) and systole (P ≤ .01). Mean LVOT area indexed to body surface area was 2.3 ± 0.5 cm(2)/m(2) in women and 2.6 ± 0.7 cm(2)/m(2) in men. LVOT area demonstrated significant correlation with aortic root diameter. CONCLUSIONS The normal LVOT is ovoid in shape. LVOT is more circular during systole, but the AP diameter remains smaller than the transverse diameter throughout the cardiac cycle. The oval shape of the LVOT has important implications when LVOT area is calculated from LVOT diameters. Normal LVOT area values established in this study should facilitate diagnosis of the fixed component of LVOT obstruction.

Mycotic aneurysm of the descending thoracic aorta: The role of transesophageal echocardiography

Mycotic aneurysms of the aorta are prone to rupture. Thus rapid and accurate diagnosis is essential so that surgical repair can be undertaken. We report a case of mycotic aortic aneurysm caused by mitral valve endocarditis. The aneurysm situated at the junction of the thoracoabdominal aorta was readily detected by transesophageal echocardiography. Computed tomography and aortography were complementary to transesophageal echocardiography in establishing the diagnosis. The patient underwent successful repair and acute inflammation of the aneurysm was present at histologic examination.

The effects of dobutamine therapy in critically ill patients measured by transoesophageal echocardiography and intracardiac monitoring

Fourteen patients with severe hypotension and adult respiratory distress syndrome after trauma (n= 7), general surgery (n = 6) or burns (n = 1) were studied. After volume loading with 6 ml.kg‐1 hydroxyethyl starch over 30 min (time I), dobutamine was infused intravenously at 5 μg.kg‐1.min‐1 (time II) and 10 μg.kg‐1 .min‐1 (time III). A 5 MHz transoesophageal echocardiographic probe was used to image a standard transgastric short axis view of the left ventricle. Haemodynamic data were obtained from thermodilution studies using pulmonary flotation catheterisation. Echocardiographic measurements (off‐line from videotape) and qualitative visual assessment of left ventricular function (visual assessment, on‐line) were performed. All measurements were made after fluid replacement, and during infusion of the two dobutamine doses. An improvement in mean systemic arterial blood pressure and mean stroke volume occurred from time I to the end of dobutamine infusion (p < 0.05). All patients, after volume infusion, were normovolaemic according to transoesophageal echocardiography and there was a good correlation between end‐diastolic area and stroke volume (r = 0.73). During dobutamine infusion, echocardiographic measurements showed no significant dose‐related increase in mean (SD) percentage left ventricular short axis area change from baseline after hydroxyethyl starch (time I: 60 (2); time II: 63 (2); time III: 64 (2)). However, a significant increase in short axis area change was seen in nine of the 14 patients (67%). Analysis of the end‐diastolic area/short axis area change relationship revealed a heterogeneous response to dobutamine. Dobutamine infusion resulted in an improvement in haemodynamics in the majority of patients with sepsis‐related adult respiratory distress syndrome, and transoesophageal echocardiography provided important additional information on ventricular performance.

Haemodynamic evaluation during small volume resuscitation in patients with acute respiratory failure.

In addition to the invasive haemodynamic monitoring procedures, an on-line assessment of cardiac performance by means of transoesophageal echocardiography might have a certain role in small volume resuscitation of patients with acute respiratory failure or Adult Respiratory Distress Syndrome (ARDS). The goal of this investigation was therefore to determine the effects of a hypertonic hyperoncotic solution, hypertonic hydoxyethl-starch (HHES), (HHES = HES [200.000/0.6-0.66; 60 g l-1; Leopold, Graz; Austria] combined with NaCl [75 g l-1) on haemodynamics and cardiac performance using the transoesophageal echocardiography. After institutional approval we investigated 23 patients suffering from septic ARDS after trauma or major surgery during four periods of resuscitation. Phase I = control values after infusion of 20 ml kg-1 crystalloid solution, phase II = 50% hypertonic hydroxyethyl-starch solution (2 ml kg-1), phase III = at the end of HHES (4 ml kg-1), IV = 30 min after the end of HHES. Before HHES-infusion, all patients showed arterial hypotension with mean arterial pressures of 64 +/- 2 mmHg. The infusion of 2 ml kg-1 HHES resulted in a significant increase of systemic and pulmonary arterial pressures over the study period. A significant improvement in cardiac output was associated with increasing stroke volumes, oxygen delivery and oxygen consumption (see Tables 1 and 2). Small volume resuscitation also resulted in significant increases of endsystolic and endiastolic left ventricular areas and the corresponding calculated wall stress (Figs 1-3). We conclude from our preliminary data that when using HHES, only modest fluid resuscitation was sufficient to restore adequate preload and oxygen delivery in patients with sepsis-related acute respiratory failure.