Tsui-Lieh Hsu

Different Effects of Fosinopril and Atenolol on Wave Reflections in Hypertensive Patients

We conducted this study to compare the effects of fosinopril versus atenolol on peripheral blood pressure, central arterial wave reflection, and left ventricular mass in a group of patients with essential hypertension. We conducted a double-blind, randomized trial of fosinopril and atenolol in 79 hypertensive patients (52 men, 27 women; mean age, 45.8 +/- 8.5 years; range, 30 to 68 years). Carotid pressure waveforms were recorded noninvasively by applanation tonometry with a Millar micromanometer-tipped probe. The extent of wave reflection was estimated by the augmentation index defined as the ratio of the amplitude of pressure wave above its systolic shoulder to the pulse pressure. The augmentation index, left ventricular mass index by two-dimensional echocardiography, and 24-hour ambulatory blood pressures were determined before and after 8 weeks of daily treatment with fosinopril (10 to 20 mg) or atenolol (50 to 100 mg) with or without diuretics and compared with those values in 79 normotensive control subjects. After 8 weeks of treatment, both drugs lowered 24-hour ambulatory peripheral systolic and diastolic pressures into the normal range to a similar extent (fosinopril, -18/-13 mm Hg; atenolol, -23/-17 mm Hg, both P = NS). On the other hand, whereas the elevated augmentation index in hypertensive patients compared with normotensive subjects (16 +/- 11% versus 10 +/- 8%) was completely normalized by fosinopril (-9.3 +/- 9.8%, P < or = .002), it was lowered by atenolol (-4.8 +/- 8.9%, P < .002) but to a significantly smaller extent (fosinopril versus atenolol effect, P = .04).(ABSTRACT TRUNCATED AT 250 WORDS)

Dynamic three-dimensional echocardiographic assessment of intracardiac blood flow jets

Transthoracic dynamic 3-dimensional reconstruction of the heart with tissue depiction has been proved to be feasible when using various methods of data acquisition. The same method can theoretically be applied to color Doppler flows to generate dynamic 3-dimensional images of intracardiac blood flow jets. To explore the feasibility of this approach, we studied 41 patients with various valvular disorders or intracardiac shunts. We acquired sequential 2-dimensional images along with color Doppler information using rotational scanning from a transthoracic or a subcostal window. Images were digitized and processed for 3-dimensional reconstruction using dedicated software. After adequate segmentation, the flow jets were displayed in 3 dimensions in a gray scale format. With use of this approach, 3-dimensional reconstruction of color Doppler flows was possible in all but 1 patient. Still frames allowed immediate appreciation of the shape of the jets, their location in the cardiac chambers, and their size related to that cavity. Dynamic display was even more striking by showing the flow in real time. Dynamic 3-dimensional images enabled visualization of flow jets in projections not available in conventional color flow Doppler, looking directly at the views of shunt and regurgitant flows, and also permitted 3-dimensional delineation of flow convergence zones. We conclude that dynamic visualization of various intracardiac flows in 3 dimensions using transthoracic echocardiography is possible. It provides a better understanding of the shape and size of the jets, and can potentially aid in flow quantification by displaying the actual shape of flow convergence regions.

Intravascular ultrasound imaging in acute aortic dissection

OBJECTIVES This study was performed to determine the potential of intravascular ultrasound in the detection and delineation of aortic dissection. BACKGROUND Intravascular ultrasound is a new technique capable of displaying real-time cross-sectional images of arterial vasculature. Its clinical use has been explored mostly in coronary and peripheral arterial circulation. METHODS Intravascular ultrasound imaging of the aorta was performed using a 20-MHz ultrasound catheter in 28 patients with suspected aortic dissection. All patients underwent contrast angiography; 7 had computed tomography; and 22 had transesophageal echocardiography. RESULTS Imaging of the aorta from the root level to its bifurcation was performed in all patients in an average of 10 min. No complications occurred. Dissection was present in 23 patients and absent in 5. In the patients without dissection, intravascular ultrasound revealed normal aortic anatomy. In all 23 patients with dissection, intravascular ultrasound demonstrated the intimal flap and true and false lumena. The longitudinal and circumferential extent of aortic dissection, contents of the false lumen, involvement of branch vessels and the presence of intramural hematoma in the aortic wall could also be identified. In cases where aortography could not define the distal extent of the dissection, intravascular ultrasound did. CONCLUSIONS Our experience in this series of patients with aortic dissection indicates that intravascular ultrasound could be valuable in the identification and categorization of aortic dissection and in the description of associated pathologic changes that may be clinically important. It can be performed rapidly and safely and could serve as an alternative or adjunct diagnostic procedure in patients with aortic dissection.

Intracardiac Echocardiographic Imaging of Cardiac Abnormalities, Ischemic Myocardial Dysfunction, and Myocardial Perfusion: Studies With a 10 MHz Ultrasound Catheter

Intracardiac echocardiography (ICE), an echocardiographic examination from within the heart itself, has been proposed as a new modality for cardiac imaging. A major shortcoming has been the limited depth of field provided by previously available devices. We used 10 MHz catheters for ICE to determine if this lower frequency would allow for greater display of cardiac anatomy. We performed ICE in seven animals; myocardial ischemia was induced in three. With the imaging catheter in the right atrium, all four cardiac chambers and valves could be imaged. Advancing the transducer into the right ventricle allowed for short-axis images of the left ventricle. Coronary perfusion territories and segmental wall motion abnormalities could be observed. We then performed ICE in six patients by advancing the catheter into the right side of the heart percutaneously. Structures of the right side of the heart, the mitral valve, aortic valve, left atrium, and portions of the left ventricle, were visualized. Congenital and acquired abnormalities could be identified. There were no complications. We conclude that ICE with 10F, 10 MHz ultrasound catheters allows for expanded imaging capabilities because of the increased depth of field. With this imaging modality, congenital and acquired abnormalities as well as myocardial ischemia can be detected.

Intracardiac Two-dimensional Echocardiography in Patients with Pericardial Effusion and Cardiac Tamponade

The utility of intracardiac two-dimensional echocardiography in the identification of pericardial effusion was assessed in five patients with pericardial effusion and cardiac tamponade. A 20 MHz, mechanically rotating ultrasound catheter was used for intracardiac imaging. In all five patients, intracardiac echocardiography yielded high resolution of images of the right atrial cavity, the right atrial wall, and the pericardial effusion. In two patients, right atrial collapse could be identified during real-time imaging. Although the entire right atrial cavity and the pericardial effusion could not be displayed in a single imaging field because of the limited depth of field associated with the 20 MHz catheter, manipulation of the catheter allowed visualization of the pericardial effusion and the parietal pericardium in each patient. The effusion was seen to surround the superior vena cava, as well, in all patients. After pericardiocentesis, the reduction in the size of the effusion and increase in the right atrial cavity size could be recognized by intracardiac echocardiography. The introduction and manipulation of the ultrasound catheter was easily performed without any complications. This experience presents one clinical application for intracardiac echocardiography and indicates its potential value in the invasive cardiac laboratory.

Single, biplane, multiplane, and three-dimensional transesophageal echocardiography. Echocardiographic-anatomic correlations.

Advances in TEE instrumentation have led to the emergence of this modality as a powerful diagnostic tool. Numerous investigations in humans have clearly defined the plethora of clinical applications of TEE in a variety of patient care scenarios. Research in progress in the area of transducer technology and computerized image processing is likely to bring 3-D TEE to the clinical front.

Intracardiac echocardiography: current developments.

Intracardiac echocardiography refers to the method of imaging cardiac structures from intracardiac locations with the use of ultrasound catheters. Advances in catheter-based interventional cardiologic procedures to treat cardiovascular lesions and the problems encountered during those procedures due to inadequate guidance provided by fluoroscopy have given the impetus to develop other guidance modalities. Experimental explorations with intracardiac ultrasound probes have indicated that detailed visualization of cardiac structures in real-time is possible by intracardiac ultrasound. Recent advances in catheter-based ultrasound technology make it feasible to safely pass small-sized catheters in humans into various intracardiac locations and acquire images of valvular structures and various chambers. Experience with 20 MHz ultrasound catheters indicates that high resolution images of normal and abnormal structures can be obtained if the catheter is manipulated close to the region of interest. The problem of the limited depth of field associated with 20 MHz catheters has led to the fabrication of catheters with lower frequency ultrasound elements. Experimental and clinical experience with 12.5 MHz ultrasound catheters points to the capability and potential of intracardiac echocardiography to not only display normal structures but also aid in the identification of valvular abnormalities, chamber dysfunction and pericardial effusions. In addition, aortic disorders such as acute dissection, coarctation and atherosclerotic disease could be delineated. Similarly, abnormalities involving the pulmonary arteries such as pulmonary embolism, organized thrombi, peripheral pulmonary arterial stenoses, and pulmonary hypertension-induced vascular changes could be recognized. Many modifications in the catheter design are being explored. With further work in the area of catheter technology and ultrasound image processing, intracardiac echocardiography is likely to become a clinical tool.

Left ventricular diastolic collapse in regional left heart cardiac tamponade: An experimental echocardiographic and hemodynamic study☆

OBJECTIVES This study was designed to describe the hemodynamic abnormalities associated with the appearance of left ventricular diastolic collapse in the setting of regional left heart cardiac tamponade. BACKGROUND Cardiac tamponade after heart surgery is frequently associated with localized pericardial effusion. Although right ventricular diastolic collapse and right atrial collapse are reliable echocardiographic findings in patients with circumferential pericardial effusion and tamponade, they are often not present in postoperative patients with localized pericardial effusion and regional left heart tamponade. Left ventricular diastolic collapse has been described in such patients, but the degree of hemodynamic alteration that exists with this finding is not known. METHODS Acute regional left heart tamponade was produced 14 times in seven spontaneously breathing anesthetized dogs by infusing fluid into an isolated compartment created in the pericardial space adjacent to the left ventricular free wall. Continuous echocardiographic imaging and hemodynamic monitoring of left ventricular, systemic arterial, right atrial, pulmonary capillary wedge and pericardial pressures were performed. Measurements at baseline were compared with those made at the onset of left ventricular diastolic collapse and at decompensated tamponade. RESULTS Left ventricular diastolic collapse was noted in all 14 episodes of regional tamponade. It occurred when pressure in the left pericardial compartment exceeded left ventricular diastolic pressure by 3.0 +/- 1.9 mm Hg. At the onset of left ventricular diastolic collapse, cardiac output and mean arterial pressure were significantly reduced from the control value (p < 0.05). Systolic hypotension was noted only twice at this stage, respiratory variation in systolic pressure > 10 mm Hg only once. The appearance of this sign was also associated with elevated left heart filling pressures. CONCLUSIONS Left ventricular diastolic collapse is a reliable sign of regional left ventricular tamponade and is associated with a reduction in cardiac output. This echocardiographic finding usually occurs before the development of arterial hypotension and pulsus paradoxus. Thus, left ventricular diastolic collapse is potentially more reliable than hypotension or pulsus paradoxus in the diagnosis of regional left ventricular tamponade.

Panoramic transesophageal echocardiography. Clinical application of real-time, wide-angle, transesophageal two-dimensional echocardiography and color flow imaging.

Panoramic transesophageal echocardiography is a new development in transesophageal echocardio‐graphic (TEE) technology, which yields a wide‐angle imaging field for real‐time two‐dimensional and color flow imaging. We report our early experience in patients with the use of an annular‐array TEE probe that provides a wide, 270° angle imaging field for two‐dimensional echocardiography imaging. The field of view can, however, be narrowed to 15°. The field of view for color flow imaging can be varied from 180° to 10°. Pulsed‐Doppler recordings of flow velocity are also possible. This TEE system provides a panoramic vision of cardiac and paracardiac structures from the esophagus and stomach. Besides cardiovascular structures, other thoracic and upper abdominal organs can be visualized. The wide field of view allows a better comprehension of the cardiac anatomy and its relationship with adjacent structures. The initial experience suggests that this method, besides providing the usually required diagnostic information, may have a number of additional applications. Its clinical potential and directions for future developments are reviewed. (ECHOCARDIOGRAPHY, Volume 8, November 1991)

The Value of Transesophageal Echocardiography in the Diagnosis of Cardiac Metastasis

To assess the diagnostic value of transesophageal two‐dimensional echocardiography (TEE) as compared with transthoracic echocardiography (TTE), TTE and TEE were performed in eight consecutive patients (age range from 20 to 76 years, six male and two female) with clinical evidence of malignant tumors arising from the liver (n = 1), lung (n = 3), larynx (n = 1), osteogenic sarcoma (n = 1), lymphoma (n = 1), and yolk sac tumor in the anterior mediastinum (n = 1). In one case, the gastroscope could not be inserted because of tumor compression of the esophagus. Transesophageal echocardiography provided superior imaging in the detection of intracavitary metastatic lesions. In the case of right ventricular outflow tract tumor and greater vessel involvement, TTE may provide more imaging than TEE due to a blind area in this region by the transesophageal approach. In conclusion, TEE is complementary to TTE in the diagnosis of metastatic cardiac tumor.