Evaluation of non-ST segment elevation acute chest pain syndromes with a novel low-profile continuous imaging ultrasound transducer.

BACKGROUND: This investigation was designed to test the hypothesis that continuous cardiac imaging using an ultrasound transducer developed in our laboratory (ContiScan) is superior to electrocardiogram (ECG) monitoring in the diagnosis of coronary artery disease (CAD) in patients with acute non-ST segment elevation chest pain syndromes. METHODS: Seventy patients with intermediate to high probability of CAD who presented with typical anginal chest pain and no evidence of ST segment elevation on the ECG were studied. The 2.5-MHz transducer is spherical in its distal part mounted in an external housing to permit steering in 360 degrees. The transducer was placed at the left sternal border to image the left ventricular short-axis view and recorded on video tape at baseline, during and after episodes of chest pain. Two ECG leads were continuously monitored. The presence of CAD was confirmed by coronary arteriography or nuclear or echocardiographic stress testing. RESULTS: Twenty-four patients had regional wall motion abnormalities (RWMA) on their initial echo which were unchanged during the period of monitoring. All had evidence of CAD. Twenty-eight patients had transient RWMA. All had evidence of CAD. Eighteen patients had normal wall motion throughout the monitoring period, 14 of these had no evidence of CAD, and four had evidence of CAD. These four patients did not have chest pain during monitoring. The sensitivity, specificity, and accuracy of echocardiographic monitoring for diagnosing non-ST elevation myocardial infarction was 88%, 100%, and 91% respectively. The sensitivity, specificity, and accuracy of the ECG for diagnosis of CAD were 31%, 100%, and 52%, respectively. Echocardiography was superior to ECG (P < 0.001). CONCLUSIONS: The data indicate that continuous cardiac imaging is superior to ECG monitoring for the diagnosis of CAD in patients presenting with acute non-ST segment elevation chest pain syndromes. This technique could be a useful adjunct to ECG monitoring for myocardial ischemia in the acute care setting.

Implications of acute left ventricular remodeling during squatting stress echocardiography.

BACKGROUND: We previously demonstrated that squatting induces left ventricular (LV) wall motion abnormalities (WMA) in areas subtended by stenotic coronary arteries. In addition, it was observed that some subjects developed acute changes in LV shape (acute left ventricular remodeling [ALVRM]) during squatting. OBJECTIVE: This study tested the hypothesis that patients with ALVRM during squatting echocardiography have higher incidences of severe coronary artery disease (CAD). METHODS: Echocardiography was performed in all standard views during standing and squatting. End-systolic frames in the apical four-chamber view were analyzed. RESULTS: The subjects were divided into three groups. Group 1 consisted of 12 subjects who developed squatting-induced ALVRM with apical and distal posterior septal akinesis, dilation of the apex and marked LV shape change at end-systole. Group 2 consisted of 20 subjects with distal posterior septal and apical akinesis without ALVRM, during squatting. Group 3 consisted of 64 subjects who developed WMA in areas other than the apex (n = 49), or normal wall motion (n = 15) during squatting. Coronary angiography in group 1 revealed that 6 subjects had left main coronary artery stenosis (LMCAS ≥ 50%), two had severe three vessel disease (≥ 90% stenosis), and one had 100% left anterior descending coronary artery occlusion. Severe CAD was defined for purpose of this study as the presence of LMCAS, or severe three vessel disease (≥ 90% stenosis). Six subjects in group 2 had LMCAS and none had severe three vessel disease (P < 0.05 vs. group 1 for LMCAS and/or three vessel disease). In group 3, eight had LMCAS and none had severe three vessel disease (P < 0.0001 vs. group 1). CONCLUSION: Patients with ALVRM have severe CAD. Therefore, patients who develop ALVRM during squatting require urgent evaluation for revascularization therapy.

Comparison of squatting stress echocardiography and dobutamine stress echocardiography for the diagnosis of coronary artery disease.

BACKGROUND: Dobutamine stress echocardiography (DSE) is commonly used for the diagnosis for coronary artery disease (CAD). We previously demonstrated that squatting induces wall motion abnormalities (WMA) in areas subtended by stenotic coronary arteries. OBJECTIVE: This study was designed to test the hypothesis that dobutamine and squatting stress echocardiography are equally useful for the diagnosis of CAD. METHODS: We studied 39 patients who were scheduled to have coronary angiography for the evaluation of chest pain. Each patient had squatting stress echocardiography followed by DSE. For squatting stress echocardiography the echocardiogram in standard views was recorded in the standing position. The procedure was repeated during squatting for 2 minutes. Dobutamine echocardiography was performed using standard protocol. The squatting and dobutamine stress echocardiograms were interpreted by an observer blinded to the results of coronary angiography. RESULTS: During squatting, new or worsening WMA developed in 20 patients. Six patients developed WMA in the left anterior descending artery territory, three in circumflex territory, three in the right coronary artery territory, and eight in multiple coronary territories. The sensitivity, specificity, and accuracy of squatting echocardiography for diagnosis of CAD were 95%, 94%, and 94%, respectively. For DSE, the sensitivity, specificity, and accuracy for the diagnosis of CAD were 85%, 94%, and 90%, respectively. There was no significant difference between squatting and dobutamine stress echocardiography for the diagnosis of CAD (P = 0.702). CONCLUSION: These data indicate that squatting and dobutamine echocardiography are equally useful in the diagnosis of CAD. In selected patients, squatting echocardiography may be used in place of dobutamine echocardiography for the diagnosis of CAD.

Usefulness of transthoracic echocardiography in demonstrating coronary blood flow after coronary artery bypass grafting.

In this pilot study, we used transthoracic echocardiography to measure coronary sinus blood flow in 15 patients before and after coronary artery bypass grafting. Coronary sinus blood flow before and after revascularization was 274 +/- 95 and 451 +/- 102 ml/min, respectively (p <0.001). This finding is consistent with those previously demonstrated by invasive techniques.

Continuous recording of pulmonary artery diastolic pressure and cardiac output using a novel ultrasound transducer.

BACKGROUND: The feasibility of hands-free transthoracic continuous determination of pulmonary artery (PA) diastolic pressure (PAD) and cardiac output (CO) by Doppler ultrasound has not been previously demonstrated. 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: Fifty patients in the coronary care department who had PA catheters had Doppler ultrasound studies. The 2.5-MHz spherical transducer was placed at the left sternal border to permit imaging of the pulmonic valve and was attached to a commercial ultrasound machine. The PA was imaged and its diameter measured. The pulmonary flow velocity signal was recorded and the time velocity integral obtained. The CO was calculated as: CO = time velocity integral of the PA systolic flow velocity signal x pi diameter(2) divided by 4 x heart rate. The pulmonary regurgitation signal was then recorded and the end-diastolic velocity of the regurgitant signal was measured. Right atrial pressure was assessed from the jugular venous pressure or from the size and pulsatility of the inferior vena cava. The PADP was calculated as: PADP = 4 end-diastolic velocity of the regurgitant signal(2) + right atrial pressure. The CO, PADP, and pulmonary wedge pressure were recorded from the PA catheter immediately after the ultrasound studies. Serial data were obtained every half hour or 1 hour up to a maximum of 5 hours. Adequate Doppler signals were obtained in 43 patients. RESULTS: There was a good correlation between the PADP by Doppler versus PA catheter (r = 0.90, standard error of the estimate = 3.3 mm Hg); PADP by Doppler versus PA wedge pressure (r = 0.88, standard error of the estimate = 3.7 mm Hg); and CO by Doppler versus PA catheter (r = 0.92, standard error of the estimate = 0.7 L/min). CONCLUSION: The 2.5-MHz spherical transducer permitted accurate assessment of CO and PAD. This transducer could be of potential value in monitoring patients in the intensive care setting.

Detection of Barrett's epithelium by acoustic microscopy.

Barrett's esophagus is associated with increased risk of adenocarcinoma of the gastroesophageal junctional region. The presence of goblet cells (intestinal metaplasia) in columnar cell-lined esophageal mucosa defines Barrett's change. The diagnosis of Barrett's esophagus is based on the presence of intestinal metaplasia in a biopsy from an endoscopically visualized abnormal columnar epithelium. In this pilot study, acoustic microscopy was used to identify the mucosal structure of 10 distal esophageal biopsies. Sections cut at 5 microm of archival paraffin blocks on glass slides were used for this study. Acoustic microscopy permitted the identification of low- and high-power images of epithelial architecture and cellular detail, including Barrett's epithelium. This modality of visualization has the potential to detect lesions such as Barrett's metaplasia, low- and high-grade dysplasia and early carcinoma. If it can be applied to in vivo endoscopy, acoustic microscopy has the potential to increase the accuracy of the diagnosis of Barrett's esophagus, dysplasia and malignancy by providing a method of accurately directing biopsies at endoscopy.

Transesophageal Echocardiographic Assessment of Lesions of the Right Ventricular Outflow Tract and Pulmonic Valve.

To establish the role of biplane transesophageal echocardiography (TEE) in the assessment of congenital and acquired lesions involving the right ventricular outflow tract (RVOT) and pulmonic valve (PV), 28 consecutive RVOT and PV lesions in 22 consecutive patients were studied by two-dimensional and color Doppler transthoracic echocardiograms (n = 22), horizontal (n = 22) and vertical (n = 22) plane TEEs, cardiac catheterization (n = 15), cardiac surgery (n = 6), and magnetic resonance imaging (n = 1). Sixteen patients had congenital lesions, and six had acquired lesions. Longitudinal TEE clearly imaged 25 of 28 abnormalities, transverse TEE clearly imaged 12 of 28, and transthoracic echocardiography clearly imaged 9 of 28. Two-dimensional TEE scanning revealed the lesion or site of stenosis. Color Doppler revealed conspicuous mosaic jets in relation to a structural abnormality in most cases. Longitudinal TEE was more sensitive in the detection of small vegetations of the PV, in the depiction of PV doming in cases of valvar pulmonic stenosis, and in the display of the RVOT and PV so that the longitudinal extent of involvement of larger masses could be appreciated. However, longitudinal TEE was not able to assess the gradient of a stenosis at the RVOT or PV level in any case. Biplane TEE is helpful in the anatomic assessment of congenital and acquired lesions of the RVOT and PV in adults. (ECHOCARDIOGRAPHY, Volume 13, January 1996)