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Accumulation of fluid within the pericardial sac results in elevation of intrapericardial pressure with consequent cardiac compression or tamponade. Cardiac tamponade is a life-threatening condition which requires urgent evacuation of pericardial effusion (PE). Current pericardial evacuation techniques and approaches are varied. Echocardiography provides valuable insights into identifying patients who are suitable candidates and further facilitates pericardiocentesis by improving guidance techniques. Several previous publications have provided excellent reviews of the pathophysiology of cardiac tamponade. We review the clinical presentation and role of echocardiography for diagnosis of tamponade. We focus on medical and surgical approaches for the removal of PE. Moreover, as the clinical and hemodynamic consequences of PE depend on the volume and the rate of accumulation of PE, we review the various scenarios of "small" PE resulting in cardiac tamponade.

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BACKGROUND: Echocardiographic imaging using a handheld transducer in conjunction with treadmill exercise testing is commonly used for the diagnosis of coronary artery disease. Motion of the hand and the transducer during peak exercise preclude optimal imaging. To circumvent the limitations of handheld transducers, we developed a low profile transducer (CONTISON) which can be attached to the chest wall for continuous cardiac imaging. METHODS AND RESULTS: This feasibility study was performed in 10 normal male subjects (28 to 36 years). The ultrasound transducer was placed in the third or fourth intercostal space at the left sternal border to permit imaging of the left ventricle in its short axis. The transducer was interfaced with a commercially available ultrasound machine. The left ventricle was imaged at rest and while subjects exercised according to a standard Bruce protocol. All segments of the left ventricular short axis were seen at rest and peak exercise. Increased left ventricular wall thickening and wall motion were seen at peak exercise. There were no complications from the procedure. CONCLUSION: We demonstrated the feasibility of hands-free left ventricular imaging during treadmill exercise using the CONTISON transducer. Further evaluation of the technique to detect stress-induced wall motion abnormalities, as a means of diagnosing myocardial ischemia, appears warranted. (ECHOCARDIOGRAPHY 2010;27:563-566).

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Hibernating myocardium is viable myocardium that recovers after revascularization. The observation of loss of contractile proteins (myofibrils) and accumulation of glycogen in hibernating cardiomyocytes provide the basis for diagnosing hibernating myocardium. In this pilot study, acoustic microscopy was used to identify the cellular structure of normal vs. hibernating myocardium. Sections cut at 5-microm of archival paraffin blocks on glass slides were used for this study. Acoustic microscopy of normal cardiomyocytes showed intracellular linear echoes suggestive of myofibrils, and cardiomyocytes of hibernating myocardium revealed absence of myofibrils and dense intracellular echoes that corresponded to glycogen accumulation on optical microscopy. This modality of visualization allows a definitive diagnosis of hibernating myocardium.

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BACKGROUND: Pericardiocentesis can be monitored with a hand-held transducer. The purpose of this study was to assess the feasibility of monitoring pericardiocentesis using a novel ultrasound transducer, which can be attached to the chest wall, developed in our laboratory (CONTISON). METHODS: We studied nine patients with large pericardial effusions. The 2.5-MHz transducer is spherical in its distal part and mounted in an external housing to permit steering in 360 degrees. The external housing is attached to the chest wall using an adhesive patch. The CONTISON transducer was placed at the cardiac apex and an apical four-chamber view obtained. Pericardiocentesis was performed from the subcostal position. The pericardial effusion was continuously imaged. Mitral inflow velocity signals were recorded before and after pericardiocentesis. When fluid was first obtained, 50 mL of fluid were discarded after which 5 mL of agitated saline was injected through the needle. RESULTS: In the first patient the pericardiocentesis needle was seen in the left ventricular cavity. Saline injection produced a contrast effect in the left ventricle. The needle was gradually withdrawn until contrast was seen in the pericardial sac. A total of 1100 mL was removed without further complications. The second patient had clear fluid followed by blood stained aspirate. The echocardiogram revealed gradual appearance of granular echoes within the pericardial sac, suggestive of intrapericardial clot that was subsequently surgically evacuated. In the remaining seven patients, agitated saline produced a contrast effect in the pericardial sac indicative of proper needle position. Mitral flow velocity paradoxus was noted in five patients, and it resolved after pericardiocentesis in four patients. No adjustment of the transducer was required. CONCLUSION: The CONTISON transducer permitted continuous monitoring of pericardiocentesis. This technique could potentially facilitate pericardiocentesis.

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A novel ultrasound transducer developed in our laboratory (CONTISON) was used for monitoring catheter balloon commissurotomy (CBC). The transducer was placed at the cardiac apex to obtain an apical four-chamber view and attached to the chest wall using an adhesive ring. During the procedure, the tip of the needle was imaged first in the right atrium and was seen to traverse the interatrial septum and enter the left atrium. Mitral valve gradients were measured before and after CBC.

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BACKGROUND: The feasibility of hands-free transthoracic continuous ultrasonic cardiac imaging has not been demonstrated previously. We developed a 2.5-MHZ spherical transducer mounted in an external housing to permit steering in 360 degrees (CONTISON). The external housing was attached to the chest wall using an adhesive patch. METHODS AND RESULTS: The transducer was placed in the third or fourth interspace at the left sternal border to permit imaging of the left ventricle (LV) in its short axis and attached to the chest wall. The transducer then was attached to an ultrasound machine. Ten normal subjects and 20 patients with previous myocardial infarction were studied. The following maneuvers were performed at the beginning of the study: (1) The patient was rotated from the supine position (0 degrees ) in 20 degrees increments to the left lateral decubitus position (90 degrees ). The echocardiogram was displayed continuously and was recorded on videotape (parasternal short-axis view) at 0 degrees, 20 degrees, 40 degrees, 60 degrees, 80 degrees, and 90 degrees. (2) The patient was returned to the supine position and an echocardiogram was obtained. The patient was then seated up 20 degrees, 40 degrees, 60 degrees, 80 degrees, and 90 degrees by using the controls on the bed. (3) The patient then was returned to the supine position and the echocardiogram was displayed continuously on the monitor. The echocardiogram was recorded every 15 minutes for a period of 4 hours. All segments of the LV were visualized in the supine position and during lateral rotation (0 degrees -90 degrees ). Thus, body position did not affect the image. All segments of the LV were visualized during sitting up (0 degrees -90 degrees ), and all segments were visualized during the 4 hours of imaging. The patients were able to move around without distortion of the image. CONCLUSION: The CONTISON transducer permitted continuous imaging of LV wall motion. Body position did not affect interpretation of wall motion. This device has potential applicability in monitoring LV function in the intensive care setting.

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OBJECTIVE: To determine the effect of nitroglycerin on coronary blood flow velocity during controlled hypotensive anesthesia in humans. DESIGN: Internally controlled prospective study. SETTING: Single university hospital. PARTICIPANTS: Twenty American Society of Anesthesiologists class I and II patients undergoing general anesthesia for surgical resection of a malignancy. INTERVENTIONS: General anesthesia was induced with thiopental, fentanyl, and succinylcholine and maintained with isoflurane and vecuronium. Transesophageal echocardiography was used to evaluate left ventricular wall motion and blood flow velocity in the left anterior descending coronary artery. Intravenous nitroglycerin was used to reduce systolic arterial pressure to 60 to 70 mmHg. Intravenous albumin 5% was administered to maintain pulmonary capillary wedge pressure >5 mmHg. MEASUREMENTS AND MAIN RESULTS: The left anterior descending coronary artery was visualized clearly in 16 of 20 patients. At a mean nitroglycerin dose of 16+/-14 microg/kg/min, peak diastolic left anterior descending flow velocity increased significantly from 32.5+/-10.3 cm/sec to 44.7+/-14.6 cm/sec (p = 0.0103). None of the patients developed any ST-segment changes. CONCLUSIONS: During nitroglycerin-induced hypotensive anesthesia, coronary blood flow as assessed by peak diastolic left anterior descending flow velocity is preserved or increased in most patients. Increases in left anterior descending flow velocity are predictably achieved only at nitroglycerin doses >5 microg/kg/min. Intraoperative transesophageal echocardiography is useful in monitoring coronary flow velocity responses to controlled hypotensive anesthesia.

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The ability to differentiate active from chronic valvular vegetations (VEGs) by digital image processing and by visual observation was evaluated in 18 patients with a clinical diagnosis of infective endocarditis (IE). Two-dimensional echocardiographic (2-DE) examinations were performed on all patients at diagnosis and after a mean period of 52 days. Two comparable images (active and chronic) from the same patient and in the same phase of the cardiac cycle were digitized, magnified, and displayed on a high resolution monitor. The mean pixel intensity (MPI) was 72+/-14 in the active stage and 143 +/-23 in the chronic stage (P<0.0001). The VEG size was 0.64+/- 0.15 cm(2) in the active stage and decreased to 0.46+/-0.17 cm(2) in the chronic stage (P<0.001). Two experienced echocardiographers, who were blinded to the age of the VEGs, identified each echocardiographic image as active or chronic based on visual observation of density of the VEGs. The VEGs were correctly identified as active or chronic in 17 out of the 18 patients. In summary, although digital image processing of 2-DE may be useful, the density of VEGs assessed by visual inspection will help differentiate between active and chronic VEGs of IE. The standardization procedure at the time of the initial study and use of identical gain settings in subsequent studies are key factors in making this distinction.

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Measurement of flow velocity in the left anterior descending coronary artery by transesophageal echocardiography in subjects without risk factors for coronary artery disease (group 1) and in subjects with normal coronary arteries but conditions associated with endothelial dysfunction (group 2) revealed that there was a significantly impaired coronary flow velocity response to the cold pressor test in group 2 subjects. Thus, transesophageal echocardiography provides a minimally invasive tool for the functional assessment of endothelium and can be valuable in evaluating endothelial dysfunction and recovery in a variety of disease states.

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Several investigators have demonstrated the feasibility of imaging at the cellular level using acoustical microscopy. It has also been proposed that acoustical microscopy technology might be adopted for in vivo applications. Before such applications are implemented, it is important to demonstrate that any major deleterious effects are highly unlikely. To this end, we have repeatedly scanned NIH/3T3 mouse fibroblasts in culture using an Olympus UH3 acoustical microscope operating at 600 MHz. No adverse effects were observed even after exposures for 1 h. Spatial peak temporal averaged intensities were estimated to be below 300 mW/cm2.

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Transesophageal echocardiography was used to image bypass grafts and measure flow reserve in these conduits. Imaging and measurement of flow reserve were feasible in most patients.

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Coronary artery aneurysms are rare and may be difficult to detect clinically. Multiplane transesophageal echocardiography provides numerous imaging planes that may improve the assessment of coronary aneurysms and act as an adjunct to standard angiography. Five patients with angiographically detected coronary aneurysms were studied with multiplane transesophageal echocardiography and Doppler flow imaging. Transesophageal echocardiography was successful in identifying the size and characteristics of the coronary aneurysms. Doppler ultrasound identified markedly increased flow velocity in a patient with a coronary arteriovenous fistula and decreased coronary flow velocity in two patients with aneurysmal coronary arteries and intracoronary thrombus. Multiplane transesophageal echocardiography is a useful, noninvasive method of assessing coronary artery aneurysms and may act as an adjunct to angiography in identifying fistula anastomosis.

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Through the careful and judicious use of the time gain controls in conventional echocardiographic instrumentation, we have found that it is possible to obtain quantitative estimates of the attenuation of ultrasound beams even in vivo. These estimates are based on the quantitative comparison of the amplitude of the echo waveforms at different depths. Here, we report on such attenuation measurements using both a tissue phantom and the interventricular septum of the myocardium in vivo. The in vitro estimates of attenuation with this method are in agreement with independent laboratory measurements of the same parameter. In vivo measurements on the myocardium indicate oscillations in the magnitude of the attenuation over the heart cycle and suggest methods for the quantitative assessment of a variety of pathologic conditions in the myocardium noninvasively using conventional ultrasound scanners.

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Fibrous tissue on conventional ultrasound images appears as an echo-bright area. We have observed that on high-frequency ultrasonography images of thin sections of myocardium, fibrous tissue may appear as either a dark or light area. This study was designed to test the hypothesis that echo characteristics of fibrous tissue on high-frequency ultrasonography are determined by collagen fiber morphologic characteristics. We examined 16 tissue specimens from human beings and rats containing different forms of fibrosis. The specimens were sectioned at 5 microns, placed on a glass slide, and imaged with a 600 MHz transducer. On ultrasound images, collagen appeared either as a dark amorphous area or a light area that had a fibrillar pattern. The same specimens were then stained with picrosirius red and examined with polarized light. When viewed with polarized light microscopy, thick collagen fibers appear red or orange and thin fibers appear green or yellow. Polarized light microscopy revealed that dark areas on ultrasound images corresponded to thick collagen fibers that were predominantly longitudinally sectioned. In contrast, light areas corresponded to regions of thin, loosely packed fibers, or to thick collagen fibers that were obliquely sectioned. Collagen has different appearances on high-frequency ultrasound images depending on collagen fiber morphologic characteristics. If such variation in echo intensity also occurs with lower frequency transducers used in clinical echocardiography, the differentiation between normal myocardium and immature scar may be difficult.

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Unless thrombolytic or surgical therapy is rapidly available, massive pulmonary embolism in both pulmonary arteries invariably results in instantaneous death. A patient is presented with congenital atrial septal defect and right ventricular thrombus who developed extensive bilateral pulmonary embolism with an apparently prolonged survival. The ante- and postmortem findings represent the unusual and interesting aspects of this particular case.

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Doppler velocimetry with the use of transesophageal echocardiography can record flow in the proximal left anterior descending artery (LAD). To assess whether this limited sampling ability influences the recording of velocity and the calculation of coronary flow reserve (CFR), 32 patients with LAD stenosis (4 ostial stenoses, 18 proximal stenoses, 10 mid-LAD stenoses) and 33 patients with arteriographically normal LADs were studied. Basal flow and dipyridamole-induced hyperemic flow rates were recorded. The mean basal flow velocity in ostial stenoses was greater than in other groups, and the mean basal flow velocity in proximal stenoses was less than that in mid-LAD stenoses and in the normal group. Maximal hyperemic velocity did not differ between the groups. CFR in all stenoses groups was less than that in the normal group. Ostial CFR was less than in all other groups, and proximal CFR was less than that in either the mid-LAD or the normal LAD groups. With this technique, coronary flow velocimetry and estimation of CFR is affected by the location of stenosis.

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OBJECTIVES: This study sought to examine the vasodilatory response of the renal circulation to endothelial stimulation in patients with chronic heart failure. BACKGROUND: Renal blood flow is often reduced in patients with chronic congestive heart failure and may lead to deterioration of renal function. Stimulation of renal endothelium has been shown to cause renal vasodilation in animals and in isolated human renal artery. The vasoregulatory role of the renal endothelium in patients with heart failure has not been evaluated. METHODS: Renal vasodilatory effect of endothelial stimulation with acetylcholine was assessed and compared with that of endothelial independent vasodilation with nitroglycerin. Both drugs were infused into the main renal artery. Renal artery cross-sectional area was measured with intravascular ultrasound and renal blood flow velocity with the aid of an intravascular Doppler technique. RESULTS: Both drugs caused a significant and comparable increase in renal artery cross-sectional area (maximal increase [mean +/- SE] 14 +/- 5% with acetylcholine, 15 +/- 5% with nitroglycerin; both changes < 0.05 vs. baseline). Acetylcholine also caused a significant reduction in renal vascular resistance (maximal reduction 55+/- 6%) and increase in renal blood flow (maximal increase 136 +/- 54%). In contrast, nitroglycerin administration showed no significant effect on renal vascular resistance and blood flow. CONCLUSIONS: Stimulation of endothelium-derived nitric oxide with acetylcholine results in a significant vasodilatory effect on both conductance and resistance renal blood vessels and leads to a marked reduction in renal vascular resistance and enhancement of renal blood blow. Nitroglycerin, an exogenous nitric oxide donor, caused a selective vasodilatory effect on renal conductance but not on resistance blood vessels and failed to increase renal blood flow. These data suggest the possibility that stimulation of endogenous nitric oxide production in the kidney could be used as a therapeutic target for enhancement of renal flow in patients with heart failure.

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To assess the effect of regular and high-dose dipyridamole on coronary flow velocity in the left anterior descending artery (LAD), and to determine whether assessment of coronary flow velocity reserve (CFVR) is more sensitive for detection of ischemia than standard echocardiographic criteria, 47 patients were studied prospectively: 16 patients with stenosis of the LAD, 18 patients with angiographically normal LADs, and 13 patients with minimal disease. Patients underwent transesophageal echocardiographic study of wall motion and LAD flow velocity at baseline and at hyperemia, and for angina and electrocardiographic changes. The mean CFVR values after 0.56 mg/kg after 0.84 mg/kg of dipyridamole were similar: 2.52 +/- 0.87 versus 2.62 +/- 0.90. A CFVR <2.3 (normals mean -2 SDs) was more sensitive (88% at both doses) for the detection of underlying coronary obstruction than was wall motion monitoring (44% and 75%, respectively). The combination of CFVR <2.3 and wall monitoring was more sensitive than index alone (94% at both 0.56 and 0.84 mg/kg). The rate-pressure product was not significantly different at the two doses of dipyridamole. When flow response is the end point of stress testing, as with transesophageal monitoring, the 0.56 mg/kg dose of dipyrid mole is adequate, but when ischemia is the end point (as with wall motion monitoring by 2-dimensional echocardiography), the dose of 0.84 mg/kg is more sensitive.

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