First-in-man experience with a new 7F vascular closure device (EXOSEAL™): the 7F ECLIPSE study

OBJECTIVE

This feasibility study examined safety and effectiveness of the new EXOSEAL™ Vascular Closure Device (VCD) designed to promote hemostasis and early ambulation after percutaneous procedures.

BACKGROUND

Most VCDs currently approved by the United States FDA have been associated with significantly shorter time-to-hemostasis (TTH) and time-to-ambulation (TTA) compared to standard manual or mechanical compression, but their ease of use, patient comfort during deployment, and safety profiles are variable.

METHODS

Patients underwent diagnostic or interventional procedures using 7F introducer sheaths. Primary safety endpoint was the 30-day combined rate of access-related complications and primary effectiveness endpoints were TTH and TTA.

RESULTS

Sixty patients were enrolled prospectively (mean age 63.3 ± 11.3 year, 17% diabetics). Device and procedural success was achieved in 92% and 93%, respectively. Mean TTH and TTA was 3.2 ± 3.0 minutes and 3.0 ± 6.2 hours, respectively. No deaths or serious access-related adverse events occurred. A ≥6 cm access-site hematoma was the only adverse event, observed in 3 patients.

CONCLUSIONS

Use of the 7F EXOSEAL™ VCD was associated with short TTH and TTA, as well as low rates of procedural and 30-day access-related complications.

[45-year-old woman with muscle weakness and hypopotassemia]

We report a 45-year-old female patient with muscle weakness. We diagnosed renal tubular acidosis type I by laboratory findings of hypopotassemia, hypopotassuria, metabolic acidosis and basic urine. The muscle weakness improved rapidly by substitution of potassium and an alcalescent substance. Searching for associated autoimmune diseases we diagnosed primary biliary cirrhosis and initiated a therapy with ursodeoxycholic acid.

Analysis of myocardial perfusion or myocardial function for detection of regional myocardial abnormalities. An echocardiographic multicenter comparison study using myocardial contrast echocardiography and 2D echocardiography

BACKGROUND

Echocardiography based myocardial perfusion imaging and regional wall motion analysis are used for evaluation of coronary artery disease and regional myocardial abnormalities.

AIM

This study sought to compare myocardial contrast echocardiography (MCE) and 2D echocardiography with regard to interobserver variability and detection of regional myocardial abnormalities.

METHODS

In 70 patients evenly distributed between three ejection fraction groups based on biplane cineventriculography ( > 55%, 35-55%, < 35%), unenhanced and contrast enhanced 2D echocardiography and myocardial contrast echocardiography (MCE; SonoVue; Bracco) were performed. Regional wall motion and myocardial perfusion were assessed referring to a 16 segment model. Interobserver agreement (IOA) among 2 readers was determined within each imaging modality. To define a standard of truth for the presence of segmental myocardial disease an independent expert-panel decision was obtained based on clinical data, ECG, coronary angiography and blinded information from the imaging modalities.

RESULTS

Regional wall motion assessment was possible in 98.1% of segments using contrast enhanced 2D echocardiography and in 87.2% using unenhanced 2D echocardiography (p < 0.001), while perfusion assessment was possible in 90.1% of segments (p < 0.001). IOA on presence of any regional wall motion abnormality expressed as Kappa coefficient was 0.71 (95% CI 0.53-0.89) for contrast enhanced echocardiography and 0.37 (95% CI 0.14-0.59) for unenhanced echocardiography. IOA on presence of any perfusion abnormality was 0.53 (95% CI 0.34-0.73). For MCE there was high IOA for the apical segments (kappa = 0.57) and lower IOA for the basal segments (kappa=0.14), while no such gradient was found for the IOA on wall motion abnormalities. Mean accuracy to detect expert-panel defined myocardial abnormalities was 80.6% for unenhanced echocardiography, 85.0% for contrast enhanced 2D echocardiography and 80.6% for MCE.

CONCLUSIONS

MCE is inferior to contrast enhanced 2D echocardiography with regard to visibility of all LV segments and appears slightly inferior with regards to IOA, while both are superior to unenhanced 2D echocardiography. The methods demonstrated high accuracy in detection of panel defined regional myocardial abnormalities.

Adenosine myocardial contrast echo in intermediate severity coronary stenoses: a prospective two-center study

BACKGROUND

We sought to evaluate the role of adenosine myocardial contrast echocardiography (MCE) for the determination of functional relevance of coronary stenoses with intermediate angiographic severity and compared the results to single photon imaging (SPECT). We hypothezised that sole assessment of myocardial blood volume changes during adenosine on MCE would indicate functional stensosis relevance when accompanied by increased myocardial oxygen consumption (MVO2).

METHODS

Fifty-seven patients with >or=1 coronary stenosis underwent adenosine MCE (ultraharmonic imaging) and exercise SPECT. On MCE, myocardial blood volume was assessed and constant or increased myocardial opacification during adenosine coupled with increased MVO2 was defined as normal and decreased opacification as abnormal.

RESULTS

Rate-pressure product significantly increased during adenosine in all patients due to reflex tachycardia following mild hypotension, indicative of increased MVO2. Concordance between MCE and SPECT for the detection of reversible myocardial perfusion defects was 89% (kappa = 0.83). Comparison of regions between rest and during adenosine as opposed to comparison to remote regions of the same stage was important for accurate assessment because concordance betweenn MCE and SPECT was less on separate assessment at rest (73%, kappa = 0.40) compared to stress (91%, kappa = 0.81, P < 0.05) mainly due to territories scored normal on SPECT and abnormal on MCE.

CONCLUSIONS

Assessment of myocardial blood volume changes during adenosine using MCE can be used for the determination of the functional relevance of coronary stenoses of intermediate angiographic severity if MVO2 is increased during adenosine.

Correlation between ECG and myocardial perfusion after mechanical reperfusion of acute myocardial infarction

The identification of viable myocardium after myocardial infarction (MI) carries major prognostic impact. Due to myocardial stunning early after successful mechanical reperfusion of acute myocardial infarction, analysis of myocardial perfusion but not of contractile function can be used to differentiate between necrotic and viable myocardium. Although being widely regarded as an indicator of infarct transmurality, the relation between post-infarct Q-wave formation and the amount of viable myocardium has not been studied. We hypothesized that there was a correlation between the extent of Q-wave formation and the extent of perfusion abnormalities on myocardial contrast echocardiography early after successful mechanical reperfusion of first acute myocardial infarction and that the extent of post-infarct Q-wave formation might therefore be used as a simple estimate of the amount of viable myocardium.

METHODS AND RESULTS

47 patients with first MI and treated by direct PCI were enrolled. Patients were divided into 3 groups according the presence and number of abnormal Q waves (group A-no abnormal Q wave; group B-< or =2 abnormal Q waves, group C-> or =3 abnormal Q waves). Left ventricular pump function was defined by ejection fraction (EF) on ventriculography and wall motion score index (WMSI) on echocardiography. Myocardial perfusion was defined by perfusion score index (PSI) on myocardial contrast echocardiography. Patients in group A had significantly better LV function than patients in other groups [EF 57+/-5 vs. 48+/-11% (group B) and 47+/-10% (group C); p<0.05], also WMSI was the best in this group [1.34+/-0.22 vs. 1.67+/-0.39 (group B) and 1.68+/-0.31 (group C); p<0.01]. Myocardial perfusion assessed by PSI was best in group A (1.2+/-0.3, p<0.05). With respect to PSI, there was a significant difference between group B and C (1.41+/-0.21 vs. 1.56+/-0.29; p<0.05), even though EF and WMSI did not differ in these groups. The amount of perfused segments with severe wall motion abnormality was higher in group B compared to group C (47% vs. 25%; p<0.05).

CONCLUSION

In patients after successful mechanical reperfusion of first MI, the extent of Q-wave formation on ECG may be regarded as a corollary of the amount of myocardial microvascular damage and may, therefore, be used to estimate the amount of viable myocardium post-infarct.

Analysis of Regional Left Ventricular Function by Cineventriculography, Cardiac Magnetic Resonance Imaging, and Unenhanced and Contrast-Enhanced Echocardiography

OBJECTIVES

To define the use of cineventriculography, cardiac magnetic resonance imaging (cMRI), and unenhanced and contrast-enhanced echocardiography for detection of left ventricular (LV) regional wall motion abnormalities (RWMA).

BACKGROUND

Detection of RWMA is integral to the evaluation of LV function.

METHODS

In 100 patients, cineventriculography and unenhanced and contrast-enhanced echocardiography were performed. Fifty-six of the patients underwent additional cMRI. RWMA were assessed referring to a 16-segment model for cMRI, unenhanced and contrast echocardiography. Cineventriculography was evaluated on a 7-segment model. Hypokinesia in one or more segments defined presence of RWMA. Interobserver agreement among three readers was determined within each imaging modality. Intermethod agreement between imaging modalities was analyzed. A standard of truth for the presence of RWMA was obtained by an independent expert panel decision (EPD) based on clinical data, electrocardiogram, coronary angiography, and blinded information from the imaging modalities.

RESULTS

Sixty-seven patients were found to have an RWMA by EPD. Interobserver agreement expressed as kappa coefficient was 0.41 (range 0.37 to 0.44) for unenhanced echocardiography, 0.43 (range 0.29 to 0.79) for cMRT, 0.56 (range 0.44 to 0.70) for cineventriculography, and 0.77 (range 0.71 to 0.88) for contrast echocardiography. Contrast enhancement compared to unenhanced echocardiography improved agreement of echocardiography related to cMRI (kappa 0.46 vs. 0.29) and related to cineventriculography (kappa 0.59 vs. 0.28). Accuracy to detect EPD-defined RWMA was highest for contrast echocardiography, followed by cMRI, unenhanced echocardiography, and cineventriculography.

CONCLUSIONS

Analysis of RWMA is characterized by considerable interobserver variability even using high-quality imaging modalities. Interobserver agreement on RWMA and accuracy to detect panel-defined RWMA is good using contrast echocardiography.

Assessment of infarcted myocardium with real time myocardial contrast echocardiography: comparison with technetium-99m sestamibi single photon emission computed tomography

BACKGROUND

Little is known about the relation between the extent of microvascular damage and infarct size in patients after successful mechanical reperfusion of acute myocardial infarction.

OBJECTIVE

To compare the spatial extent of reduced myocardial signal between real time myocardial contrast echocardiography (MCE) and single photon emission computed tomography (SPECT) after successful mechanical reperfusion of acute myocardial infarction and to test the hypothesis that MCE can be used for clinical infarct size assessment.

METHODS

10 days after successful mechanical reperfusion of acute myocardial infarction, 117 patients underwent MCE (power pulse inversion technique, slow contrast bolus injection) and SPECT (technetium-99m sestamibi). Location and number of segments with normal myocardial signal intensity and with mild and severe reduction were registered and the concordance between the techniques was calculated.

RESULTS

Segmental concordance between MCE and SPECT was 83% (kappa = 0.64). On average, the difference in the number of segments with reduced myocardial signal intensity between MCE and SPECT did not exceed one segment (p < 0.001). Sensitivity and specificity of MCE for the detection of an abnormal segment on SPECT were 87% and 91%, respectively. Intraobserver and interobserver agreement were 94% (kappa = 0.84) and 92% (kappa = 0.83), respectively.

CONCLUSIONS

Real time MCE is a promising technique for infarct size assessment after successful mechanical reperfusion of acute myocardial infarction.

Assessment of systolic left ventricular function: a multi-centre comparison of cineventriculography, cardiac magnetic resonance imaging, unenhanced and contrast-enhanced echocardiography

AIMS

To assess the agreement of left ventricular ejection fraction (LVEF) determinations from unenhanced echocardiography, contrast-enhanced echocardiography, magnetic resonance imaging (MRI), and cineventriculography as well as the inter-observer agreement for each method.

METHODS AND RESULTS

In 120 patients, with evenly distributed EF-groups (> 55, 35-55, < 35%), cineventriculography, unenhanced echocardiography with second harmonic imaging, and contrast echocardiography at low mechanical index with iv administration of SonoVue were performed. In addition, cardiac MRI at 1.5 T using a steady-state free precession sequence was performed in a subset of 55 patients. On-site, and two blinded off-site assessments were performed for unenhanced and contrast echocardiography, cineventriculography, and MRI according to pre-defined standards. Intra-class correlation coefficients (ICCs) were determined to assess inter-observer reliability between all three readers (i.e. one on-site and two off-site). EF was 56.2 +/- 18.3% by cineventriculography, 54.1 +/- 12.9% by MRI, 50.9 +/- 15.3% by unenhanced echocardiography, and 54.6 +/- 16.8% by contrast echocardiography. Correlation on EF between cineventriculography and echocardiography increased from 0.72 with unenhanced echocardiography to 0.83 with contrast echocardiography (P < 0.05). Similarly, correlation on EF between MRI and echocardiography increased from 0.60 with unenhanced echocardiography to 0.77 with contrast echocardiography (P < 0.05). The inter-observer reliability ICC was 0.91 (95% CI 0.88-0.94) in contrast echocardiography, followed by cardiac MRI (0.86; 95% CI 0.80-0.92), cineventriculography (0.80; 95% CI 0.74-0.85), and unenhanced echocardiography (0.79; 95% CI 0.74-0.85).

CONCLUSIONS

Unenhanced echocardiography resulted in slight underestimation of EF and only moderate correlation compared with cineventriculography and MRI. Contrast echocardiography resulted in more accurate EF and significantly improved correlation with cineventriculography and MRI. Contrast echocardiography significantly improved inter-observer agreement on EF compared with unenhanced echocardiography. Inter-observer reliability on EF using contrast echocardiography reaches a level comparable to MRI and is better than those obtained by cineventriculography.

Cardiac malignant tumor as a rare cause of acute myocardial infarction

Acute myocardial infarction is predominantly caused by coronary artery atherosclerotic plaque rupture and subsequent occlusive thrombus formation. The recognition of less common causes of acute myocardial infarction is important because they may require a different treatment strategy. We report a patient with acute myocardial infarction without any angiographic evidence of coronary atherosclerosis and a left atrial mass detected on echocardiography. Therefore, coronary embolism from intracardiac thrombus or tumor was suspected. No additional manifestations of a potential tumor were found on thoracic, abdominal and cranial computed tomography. During subsequent cardiac surgery, a large tumor could be in toto resected and was diagnosed as a highly malignant leiomyosarcoma on histopathological evaluation.

Incremental value of cardiac imaging in patients presenting to the emergency department with chest pain and without ST-segment elevation: a multicenter study

BACKGROUND

We hypothesized that imaging of regional myocardial function (RF) and perfusion (PER) will add incremental value for both diagnosis and short-term prognosis to routine demographic, clinical, and electrocardiographic findings in patients presenting to the emergency department (ED) with chest pain and without ST-segment elevation on the electrocardiogram.

METHODS

We compared contrast echocardiography (CE) with gated single-photon emission computed tomography (SPECT) for this purpose. Both CE and SPECT readings included separate and composite assessments of both RF and PER. Adverse events in the first 48 hours after ED presentation included acute myocardial infarction, emergent revascularization, and cardiac-related death.

RESULTS

Concordance between CE and SPECT was 77% (73% to 82%) for all territories, with a higher concordance for the anterior wall of 84% (78% to 89%). Of the 203 patients recruited for the study, 38 (19%) had a cardiac event within 48 hours of ED presentation: 21 had acute myocardial infarction, 16 underwent an urgent revascularization procedure, and 1 died. In multivariate logistic regression models, the number of abnormal segments on CE and SPECT were significant predictors (P <.05) of cardiac events. The composite scores on CE provided 17% incremental information (P =.009, n = 203) and gated SPECT provided 23.5% additional information (P =.020, n = 163) for predicting cardiac events compared with routine demographic, clinical, and electrocardiographic variables. RF and composite evaluation was superior on SPECT compared with CE, whereas PER alone was not.

CONCLUSIONS

Cardiac imaging of RF and PER at the time of ED presentation offers substantially greater diagnostic and prognostic information for early cardiac events in patients presenting to the ED with chest pain and no ST elevation than does the routine demographic, clinical, and electrocardiographic assessment.

[Detection of myocardial viability with venous contrast echocardiography immediately after reperfusion therapy in patients with acute myocardial infarction]

INTRODUCTION

After reperfusion therapy of acute myocardial infarction not only the patency of infarct related artery (IRA) but uncompromised myocardial perfusion are essential for recovery of myocardial contractile function.

AIM

The authors sought to evaluate the relation between the status of myocardial microvasculature early after successful mechanical reperfusion therapy of AMI and contractile function at rest two weeks later.

METHODS

Sixty-three patients with first acute myocardial infarction underwent venous myocardial contrast echocardiography (VMCE) 3 hours after successful percutaneous coronary intervention. The myocardial contrast intensity of akinetic segments was evaluated according to a semiquantitative score (1 = normal; 2 = moderate contrast defect; 3 = serious contrast defect; 4 = no contrast at all). Two weeks later the resting contractile function of previously akinetic segments (n = 218) was re-evaluated.

RESULTS

The semiquantitative contrast score was significantly different between differential functional groups observed after two weeks: normokinesia (1.21 +/- 0.47); hypokinesia (1.65 +/- 0.77); akinesia (2.75 +/- 0.85). Sensitivity and the specificity of semiquantitative venous myocardial contrast echocardiography for early prediction of functional recovery is 90% and 69%, respectively (chi 2 = 76.2; p < 0.001). The global wall motion score index improved in contrast positive patients (more than 50% of initial akinetic segments show score 1 or 2) (1.607 +/- 0.30 vs. 1.295 +/- 0.25; p < 0.001), but did not change in the contrast negative patients (1.702 +/- 0.38 vs. 1.603 +/- 0.33; p = NS).

CONCLUSION

Functional recovery after AMI can be predicted with VMCE immediately after successful reopening of IRA. The post-PTCA contrast intensity of an infarcted segment is closely related to its subsequent functional status.

Myocardial blood volume and the amount of viable myocardium early after mechanical reperfusion of acute myocardial infarction: prospective study using venous contrast echocardiography

BACKGROUND

Myocardial capillary perfusion is a prerequisite of myocellular viability after reperfusion of acute myocardial infarction. It was hypothesised that the magnitude of myocardial capillary perfusion, assessed by transmural signal intensity in venous contrast echocardiography as a corollary of the blood volume of myocardial capillaries, and the amount of viable myocardium, represented by differential levels of contractile function two weeks after reperfusion, are correlated.

OBJECTIVES

To evaluate the role of venous contrast echocardiography for the identification of viable myocardium in patients with acute myocardial infarction early after successful mechanical reperfusion.

METHODS

60 patients with a first acute myocardial infarction underwent venous contrast echocardiography several hours after successful mechanical reperfusion (median time interval 190 min.). The relative transmural videointensity (median (25th, 75th percentiles)) of akinetic segments was determined. After two weeks, contractile function was re-evaluated at rest and during dobutamine infusion if segments without functional recovery were present.

RESULTS

Relative videointensity early after reperfusion differed significantly between functional groups after two weeks: normokinesia (88% (77%, 100%)), hypokinesia (74% (54%, 99%)), and akinesia with (61% (48%, 76%)) and without contractile reserve (31% (22%, 46%)). Relative videointensity and contractile function were significantly correlated (r = -0.67). The diagnostic accuracy of relative videointensity > 50% for prediction of contractility of initially akinetic segments at rest or during dobutamine was 82% (chi2 = 76.2, p < 0.001).

CONCLUSIONS

Early after successful mechanical reperfusion of acute myocardial infarction, the magnitude of capillary perfusion in the perfusion territory of an infarct related artery is correlated with the amount of viable myocardium. Quantitative venous contrast echocardiography can be used for accurate identification of viable myocardium.

Fulminant thrombosis of mechanical mitral valve prosthesis

In patients with prosthetic heart valves non-cardiac surgery may require temporary discontinuation of oral anticoagulation. Although the risk of valve related thromboembolic complications may generally be only slightly increased during the short perioperative period, in the presence of certain risk factors, replacement of oral anticoagulation with heparin is recommended. In the presented patient, unusually fulminant and finally fatal thrombosis of a mechanical mitral valve prosthesis developed within only 48 hours after non-cardiac surgery despite heparin treatment. The thrombosis was triggered by clinical conditions favouring a hypercoagulable state. This report dramatically shows that despite improvements in prosthetic heart valve design and in the management of anticoagulation, thrombosis remains one of the most dangerous complications after valve replacement with a mechanical prosthesis.

Quantification of the physiological relevance of a coronary stenosis using myocardial contrast echocardiography

MCE can be used in the catheterization laboratory or in the operating room to provide rapid assessments of the functional significance of a coronary stenosis from direct arterial injections of microbubbles. In the past few years, the development of more stable microbubble contrast agents, and a better understanding of the interactions between ultrasound and microbubbles have led to the development of a truly non-invasive approach to quantify MBF using venous infusions. Furthermore, additional insights into the physiology of coronary stenosis, particularly as it affects MBV, have been obtained using MCE.

[Diagnosis of myocardial vitality using contrast echocardiography--ready for routine clinical use?]

The most benefit from the evaluation of myocardial viability in coronary artery disease is expected in patients with reduced left ventricular function. There is increasing evidence that the outcome of this patient group is better after revascularization if viable myocardium was present before as compared to patients without pre-reperfusion myocardial viability. Therefore, diagnostic tools for the detection of viable myocardium are of enormous therapeutic and economic relevance. The contrast echocardiographic demonstration of myocardial microvascular integrity has been demonstrated to be a corollary of myocellular viability in the experimental and clinical setting. In animal models of reperfusion in acute myocardial infarction, it could be demonstrated that myocardial echocontrast defects, however, only accurately estimate the extent of microvascular damage and the amount of viable tissue after reactive hyperemia has abated. In patients, immediately after reperfusion of the infarct-related artery in acute myocardial infarction, myocardial areas of no reflow could be detected using contrast echocardiography. It has been shown that these myocardial segments exhibit significantly reduced recovery of regional contractile function weeks after reperfusion. In contrast, regions with myocardial microvascular integrity as defined by contrast echocardiography recover function to a significantly higher degree. Furthermore, in patients with remote myocardial infarction, myocardial opacification by contrast echocardiography indicates myocardial collateral perfusion with preserved tissue viability and a high probability of functional recovery after reperfusion. In patients with chronic coronary artery disease and reduced left ventricular ejection fraction, functional recovery could be predicted by myocardial contrast echocardiography with a very high sensitivity in several studies. The lower specificity of the technique may be due to the fact that recovery of contractile function after reperfusion may not be expected in all segments at rest (which was used as the gold standard for viability evaluation in these studies) but rather during physical or pharmacological stress. Therefore, post-reperfusion demonstration of contractile reserve might be a more adequate criterion for the assessment of diagnostic accuracy of myocardial contrast echocardiography for pre-reperfusion viability detection. So far, for the evaluation of myocardial viability, myocardial contrast echocardiography has been exclusively performed using intracoronary injection of echo contrast media; based on the evidence from various studies, this technique is ready for routine clinical application; the place of venous myocardial contrast echocardiography for this purpose, which is an extremely promising technique, however, remains to be defined.

Myocardial perfusion characteristics and hemodynamic profile of MRX-115, a venous echocardiographic contrast agent, during acute myocardial infarction

We sought to determine whether MRX-115, a new venous echocardiographic contrast agent, could accurately assess risk area during coronary occlusion and infarct size after reperfusion by using novel imaging modalities meant to selectively enhance contrast signals. In 12 open-chest dogs, venous injections of 0.5 ml of MRX-115 were performed during baseline and coronary occlusion and after reperfusion in the presence of exogenous hyperemia. Ultrasound was transmitted at 2 MHz and received at both 2 MHz (fundamental) and 4 MHz (harmonic) frequencies during continuous and intermittent (end-systolic only) imaging. The risk area during coronary occlusion was compared with technetium autoradiography, and the infarct size after reperfusion was compared with postmortem tissue staining. MRX-115 produced no alterations in hemodynamic or pulmonary gas exchange at any stage. During continuous (both fundamental and harmonic) and intermittent fundamental imaging, measurements of perfusion defects were precluded in many dogs by either poor signal enhancement or posterior wall attenuation. By comparison, these measurements were possible during intermittent harmonic imaging in all dogs except one, which had a very small infarction during reflow. Correlation analysis between perfusion defect size on intermittent harmonic imaging and either autoradiographic risk area or postmortem infarct size gave r values of 0.83 and 0.92, respectively. We conclude that MRX-115 is hemodynamically well tolerated and, when imaging is performed after venous injection, can accurately assess regions of hypoperfusion when combined with intermittent harmonic imaging. These results are promising for the use of this approach in patients with acute myocardial infarction.

Myocardial perfusion imaging in the setting of coronary artery stenosis and acute myocardial infarction using venous injection of a second-generation echocardiographic contrast agent

BACKGROUND

We hypothesized that by producing excellent myocardial opacification, venous injection of FS-069 coupled with intermittent harmonic imaging (IHI) can be used to determine the presence and severity of coronary stenoses during hyperemia, the size of the risk area during coronary occlusion, and the extent of myocardial salvage after reperfusion.

METHODS AND RESULTS

Twelve dogs were imaged both continuously and intermittently (every end systole) in the fundamental (2 MHz) and harmonic (transmit at 2 and receive at 4 MHz) modes. FS-069 (1 mL) was injected intravenously for all stages and modes of imaging. Myocardial video intensity was severalfold (P<.01) higher during IHI than all other modes of imaging. Perfusion defects were difficult to measure during continuous and intermittent fundamental imaging and during continuous harmonic imaging. In comparison, the defects were clearly demarcated during IHI. When this mode was used, the magnitude of perfusion mismatch during hyperemia in the presence of a coronary stenosis correlated closely with the magnitude of flow mismatch when radiolabeled microspheres were used (r=.94). The perfusion defect sizes during coronary occlusion and reperfusion also correlated closely with postmortem risk area (r=.89) and infarct size (r=.96), respectively.

CONCLUSIONS

Venous injection of FS-069 coupled with IHI produces excellent myocardial opacification. This approach can be used to determine the severity of coronary stenoses during hyperemia, the size of the risk area during coronary occlusion, and the extent of myocardial salvage after reperfusion. This approach, therefore, holds promise in the clinical setting.

Combined use of contrast-enhanced 2-dimensional and color Doppler echocardiography for improved left ventricular endocardial border delineation using Levovist, a new venous echocardiographic contrast agent

Transthoracic echocardiography often provides inadequate endocardial border visualization, particularly of the left ventricular apex. The aim of this study was to determine whether the transpulmonary echocardiographic contrast agent, Levovist, could improve endocardial visualization. Accordingly, 43 patients underwent 2-dimensional echocardiography before and after intravenous administration of Levovist. Definition of the left ventricular septal, apical and lateral borders was graded: 0 = no definition, 1 = partial definition, 2 = complete definition. Color Doppler was performed before and after contrast in 32/43 patients and similarly scored to determine any further benefit in apical border detection. There was significant (p < 0.001) improvement of the average end-diastolic scores of the septal, apical and lateral regions (1.4 +/- 0.5, 0.6 +/- 0.7 and 0.9 +/- 0.5 before and 1.8 +/- 0.4, 1.4 +/- 0.6 and 1.7 +/- 0.5 after Levovist). The average end-systolic score was significantly different (p < 0.001) from end-diastolic values in the apex only (0.3 +/- 0.6 before and 0.8 +/- 0.7 after Levovist). Average apical scores using color Doppler improved from 0.3 +/- 0.6 and 0.1 +/- 0.2 during end-diastole and end-systole to 1.7 +/- 0.5 and 1.2 +/- 0.6, respectively, after Levovist (p < 0.001); the average end-diastolic contrast-enhanced color Doppler score was significantly higher than the corresponding grey scale score (p < 0.001). We conclude that left ventricular endocardial border definition is significantly improved by Levovist. The use of contrast enhanced color Doppler can compensate for limited efficacy of this method in the apex.

Interactions between microbubbles and ultrasound: in vitro and in vivo observations

OBJECTIVES

We attempted to examine the interactions between ultrasound and microbubbles.

BACKGROUND

The interactions between microbubbles and ultrasound are poorly understood. We hypothesized that 1) ultrasound destroys microbubbles, and 2) this destruction can be minimized by limiting the exposure of microbubbles to ultrasound.

METHODS

We performed in vitro and in vivo experiments in which microbubbles were insonated at different frequencies, transmission powers and pulsing intervals. Video intensity decay was measured in vitro and confirmed by measurements of microbubble size and concentrations. Peak video intensity and mean microbubble myocardial transit rates were measured in vivo.

RESULTS

Imaging at lower frequencies and higher transmission powers resulted in more rapid video intensity decay (p = 0.01), and decreasing exposure of microbubbles to ultrasound minimized their destruction in vitro. Although these effects were also noted in vivo with venous injections of microbubbles, they were not seen with aortic root or direct coronary artery injections.

CONCLUSIONS

Ultrasound results in microbubble destruction that is more evident at lower frequencies and higher acoustic powers. Reducing the exposure of microbubbles to ultrasound minimizes their destruction. This effect is most marked in vivo with venous rather than aortic or direct coronary injections of microbubbles. These findings could lead to effective strategies for myocardial perfusion imaging with venous injections of microbubbles.

Myocardial contrast echocardiography in acute myocardial infarction using aortic root injections of microbubbles in conjunction with harmonic imaging: potential application in the cardiac catheterization laboratory

OBJECTIVES

The aim of this study was to evaluate myocardial contrast echocardiography using aortic root injections with harmonic imaging in experimental acute myocardial infarction to determine the potential of this approach in the cardiac catheterization laboratory.

BACKGROUND

It would be desirable to have an adjunctive procedure that could evaluate myocardial perfusion at the time of cardiac catheterization in patients with acute myocardial infarction. A single injection of contrast medium in the aortic root would provide complete information on myocardial perfusion in a cross section of the heart. High quality images would provide on-line assessment of myocardial perfusion without recourse to image processing. These data could be very valuable for determining patient management.

METHODS

Perfusion defects on myocardial contrast echocardiography were measured during coronary occlusion and reflow, using fundamental and harmonic imaging in both continuous and intermittent modes in nine open chest dogs. These defects were compared with risk area on technetium-99m autoradiography and infarct size on tissue staining.

RESULTS

Whereas harmonic imaging increased myocardial video intensity by more than twofold (p < 0.001) compared with fundamental imaging after aortic root injection of contrast medium, intermittent imaging was not superior to continuous imaging. The improved signal to noise ratio of harmonic imaging allowed on-line definition of risk area (r = 0.98) and infarct size (r = 0.93) without recourse to off-line processing. Similar results could be obtained with fundamental imaging only after off-line processing.

CONCLUSIONS

Aortic root injection of contrast medium coupled with harmonic imaging can be used to provide accurate on-line assessment of risk area and infarct size during acute myocardial infarction. These results have important implications for the catheterization laboratory.

Enhancement of mitral regurgitation and normal left atrial color Doppler flow signals with peripheral venous injection of a saccharide-based contrast agent

OBJECTIVES

The saccharide ultrasound contrast agent SHU 508 A was used to test the hypothesis that an intravenous, transpulmonary contrast method can enhance color Doppler flow signals in the left atrium in a clinically useful manner.

BACKGROUND

Color Doppler display of mitral regurgitation may be unreliable because of variable signal to noise ratios that are at times poor. Traditional contrast agents enhance color Doppler flow signals in the right heart chambers. This study describes our observation of a recently developed contrast agent, SHU 508 A, capable of pulmonary transit after peripheral venous injection.

METHODS

Control subjects (n = 10) and patients with suspected mitral regurgitation (n = 23) were studied by color Doppler flow imaging before and after 3-g intravenous doses of SHU 508 A. Reference grading of mitral regurgitation (0 to 3) was formulated from left ventricular angiography. In the four-chamber view of the left atrium, we selected for analysis the systolic frame with the maximal retrograde jet of mitral regurgitation (aliased/blue) and the diastolic frame with the maximal color coding from anterograde pulmonary venous flow (red) for planimetry and for grading the intensity of the color Doppler signal (0 to 5).

RESULTS

The score of the color Doppler signal intensity increased by > or = 2.5 after 3 g of SHU 508 A (p < 0.001). Flow detection improved, as shown by the increased jet area of mitral regurgitation (> or = 170%), after 3 g of SHU 508 A (3 +/- 3 vs. 12 +/- 8 cm2, p < 0.001) and by a > or = 200% increase in normal anterograde flow area (p < 0.001) in both the mitral regurgitation group and the control group. After contrast enhancement, the correlation between angiographic grading and the relation of jet area to the left atrial area increased from r = 0.79 to r = 0.91.

CONCLUSIONS

Contrast-mediated increased echogenicity of the left atrial blood pool improves the signal to noise ratio of Doppler images of mitral regurgitation and anterograde atrial flow. The technique is safe and simple and seems to minimize variability due to instrument design and anatomic signal attenuation.