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Biomedical subjects

Wilson Mathias

Publications and source records attributed to Wilson Mathias.

At least 19 recordsLinked to original sources

Left ventricular function after exercise training in young men.

The effects of endurance training have been extensively studied in athletes, but longitudinal studies of exercise-induced cardiac changes in normal patients are limited. To assess the effects of 6 months of moderate-intensity aerobic training (1 hour/day, 3 times/week) on normal hearts, 23 sedentary men aged 31.1 +/- 3.5 years were studied by standard and tissue Doppler echocardiography. Left ventricular (LV) systolic function was assessed by the ejection fraction and Doppler-measured stroke volume, and diastolic function was assessed by transmitral and pulmonary venous flow. Tissue Doppler systolic (Sm), early (Em), and late (Am) myocardial velocities were obtained at the septal and lateral mitral annulus. After training, there was a 14.5% increase in peak oxygen consumption (p = 0.000002) and a decrease in heart rate (60 +/- 7 to 56 +/- 8 beats/min, p = 0.01). Septal and posterior wall thickness increased (8.7 +/- 1.0 to 9.4 +/- 1.3 mm, p = 0.002, and 8.2 +/- 0.7 to 8.8 +/- 1.1 mm, p = 0.0009, respectively), with a 15% increase in LV mass index (p = 0.0002). LV diameters, stroke volumes, and ejection fractions were unchanged. Mitral inflow showed a decrease in late-wave velocity (p = 0.00004), thus increasing the early (E)/A ratio. Septal and lateral Sm (p = 0.02) and Em velocities (p <0.05) increased after training. In conclusion, the physiologic increase in LV mass in response to regular exercise in healthy young men occurs in parallel with a decrease in atrial contribution to flow. LV function estimated by tissue Doppler is improved despite the lack of changes in standard echocardiographic indexes.

Adult↗

Value of adenosine infusion for infarct size determination using real-time myocardial contrast echocardiography.

BACKGROUND: Myocardial contrast echocardiography has been used for determination of infarct size (IS) in experimental models. However, with intermittent harmonic imaging, IS seems to be underestimated immediately after reperfusion due to areas with preserved, yet dysfunctional, microvasculature. The use of exogenous vasodilators showed to be useful to unmask these infarcted areas with depressed coronary flow reserve. This study was undertaken to assess the value of adenosine for IS determination in an open-chest canine model of coronary occlusion and reperfusion, using real-time myocardial contrast echocardiography (RTMCE). METHODS: Nine dogs underwent 180 minutes of coronary occlusion followed by reperfusion. PESDA (Perfluorocarbon-Exposed Sonicated Dextrose Albumin) was used as contrast agent. IS was determined by RTMCE before and during adenosine infusion at a rate of 140 mcg.Kg(-1).min(-1). Post-mortem necrotic area was determined by triphenyl-tetrazolium chloride (TTC) staining. RESULTS: IS determined by RTMCE was 1.98 +/- 1.30 cm2 and increased to 2.58 +/- 1.53 cm2 during adenosine infusion (p = 0.004), with good correlation between measurements (r = 0.91; p < 0.01). The necrotic area determined by TTC was 2.29 +/- 1.36 cm2 and showed no significant difference with IS determined by RTMCE before or during hyperemia. A slight better correlation between RTMCE and TTC measurements was observed during adenosine (r = 0.99; p < 0.001) then before it (r = 0.92; p = 0.0013). CONCLUSION: RTMCE can accurately determine IS in immediate period after acute myocardial infarction. Adenosine infusion results in a slight better detection of actual size of myocardial damage.

Adenosine↗

Noninvasive evaluation of left circumflex coronary aneurysm by real-time three-dimensional echocardiography.

The diagnosis of coronary aneurysms has already been described using transthoracic and transesophageal echocardiography. In the present report we demonstrated the use of real-time three-dimensional echocardiography for the diagnosis of a large left circumflex coronary aneurysm. The improved spatial resolution of this new imaging technique provided valuable information for anatomic characterization of the coronary aneurysm, allowing for distinction between the lumen and lining thrombus. The findings were confirmed by magnetic resonance imaging and coronary angiography.

Computer Systems↗

Coronary flow reserve impairment predicts cardiac events in heart transplant patients with preserved left ventricular function.

BACKGROUND: The impact of allograft vasculopathy on the coronary circulation and consequently on cardiac outcome may be expressed by coronary flow reserve (CFR) impairment. Therefore, we aimed to evaluate CFR and its relation to cardiac events in heart transplant patients. METHODS: Twenty-three patients, 2 female, with left ventricular ejection fraction >45% were studied 76+/-30 months after heart transplantation. They were divided into 2 groups according to coronary angiography: Group A, 10 patients with significant coronary artery disease (stenosis> or =50%) and group B, 13 patients without significant stenosis. Twenty healthy subjects, 13 female, served as controls. Coronary flow velocity reserve (CFVR) was assessed by transesophageal echocardiography and calculated as the ratio of maximal (i.v. adenosine, 140 microg/kg/min) to baseline coronary velocities. Patients were followed for a mean of 25 months for cardiac events. RESULTS: Compared to controls, heart transplant groups showed significantly higher baseline coronary flow velocities (51+/-27, 38+/-12 and 32+/-12 cm/s, respectively) and lower maximal coronary velocities (90+/-52, 112+/-33 and 118+/-24 cm/s), resulting in a reduced CFVR (1.9+/-1.0, 3.0+/-0.5 and 3.8+/-1.2). Multivariate analysis identified heart transplantation and epicardial coronary artery disease as the only variables independently related to CFVR. Hypertension was positively related to baseline while diabetes inversely related to maximal coronary flow velocities. A CFVR <2.3 was a marker for cardiac events (4 deaths, 1 heart failure). CONCLUSION: CFVR impairment, particularly in the presence of epicardial coronary artery disease, follows heart transplantation and is associated with a worse outcome.

Adult↗

Visualization of coronary arteries using intravenous contrast agent and real-time 3-dimensional echocardiography in a patient with hypertrophic cardiomyopathy.

Real-time 3-dimensional echocardiography is a recently developed imaging technique that provides unique information on spatial geometry in real time. We described an asymptomatic patient with hypertrophic obstructive cardiomyopathy for whom 3-dimensional echocardiography was performed after intravenous injection of perfluorocarbon-filled microbubbles. It resulted in enhancement of the left ventricular endocardial border delineation and myocardial perfusion in the hypertrophic septum. A clear visualization of the entire course of the left anterior descending coronary artery and its septal perforator branches was obtained. This case illustrates the potential of real-time 3-dimensional echocardiography to improve the anatomic evaluation of coronary arteries, especially when combined with contrast agents.

Adult↗

Noninvasive detection of coronary allograft vasculopathy by myocardial contrast echocardiography.

BACKGROUND: Noninvasive detection of coronary allograft vasculopathy is still challenging. To determine the accuracy of myocardial contrast echocardiography (MCE) in detecting coronary allograft vasculopathy after heart transplantation, we studied 35 asymptomatic patients (30 men, aged 46 +/- 12.7 years) with normal left ventricular function. METHODS: Patients underwent MCE with continuous contrast (perfluorocarbon-exposed sonicated dextrose albumin) administration. Images were obtained at baseline and during peak dobutamine (up to 40 mg/kg/min) with intermittent harmonic imaging. Areas failing to increase contrast enhancement during peak stress were regarded as abnormal. Coronary artery obstructions greater than 50% at angiography were considered significant. RESULTS: Seven out of 10 patients with coronary artery disease had a positive MCE and one patient with a positive MCE had no angiographically detected disease (sensitivity = 70%, specificity = 96%, accuracy = 88.6%). Agreement between the vascular territory and perfusion defects was good for the left anterior descending coronary artery (kappa = 0.56), but not for other arteries. Although 5 patients had multivessel disease, multiple perfusion defects were detected in only one patient. CONCLUSION: MCE showed good accuracy in detecting the presence of coronary allograft vasculopathy after heart transplantation; however, it failed to identify the extent of the disease.

Adolescent↗

Non-invasive assessment of right ventricular function in the late follow-up of the Senning procedure.

Deteriorating ventricular function is a major concern after the Senning operation. A Doppler-derived non-geometric measurement, the so-called myocardial performance index, has been described for use in adults and children. We aimed to assess the utility of this index as a method for quantification of right ventricular function in patients in the late follow-up of the Senning procedure, and to correlate the right ventricular ejection fraction and the first derivative of right ventricular pressure as derived using echocardiography with the ejection fraction determined using magnetic resonance imaging. We studied 44 patients within a mean postoperative period of 15.3 years. We calculated the right ventricular myocardial performance index by pulsed wave Doppler interrogation of tricuspid inflow and aortic outflow, the ejection fraction by Simpson's rule, and the first derivative of right ventricular pressure by continuous wave Doppler from tricuspid regurgitation. Mean values of right ventricular myocardial performance index, ejection fraction, and the first derivative of right ventricular pressure were 0.50, 39 percent and 1,398 millimetres of mercury per second, respectively. A cut-off value of 0.47 for the right ventricle myocardial performance index was determined, with a sensitivity of 75 percent and a specificity of 62.5 percent. We found no correlation between ejection fraction and the first derivative of right ventricular pressure as estimated by echocardiography and the ejection fraction as shown by magnetic resonance imaging (r2 equal to 0.29 and 0.04 respectively). We concluded, first, that patients with preserved right ventricular function had values for the right ventricular myocardial performance index lower than 0.47, and second, that ejection fraction and the first derivative of right ventricular pressure as determined echocardiographically did not correlate with values derived using magnetic resonance imaging.

Adolescent↗

Contrast echocardiography can save nondiagnostic exams in mechanically ventilated patients.

Patients in an intensive care unit (ICU) under mechanical ventilation (MV) are very difficult to image by transthoracic echocardiography, diminishing the beneficial information that could be obtained by this noninvasive approach. The objective of this study is to assess whether the addition of a contrast agent to fundamental imaging (FI) can improve or change the initial diagnosis in cardiac postoperative patients under mechanical ventilation by enhancing endocardial border delineation and Doppler flow signal. Thirty mechanically ventilated post-cardiac surgery patients (20 men, mean age 61 +/- 13 years) were evaluated with FI before and after intravenous injection of contrast. Left ventricular endocardial border delineation score index (EBDSI), estimated left ventricular ejection fraction (LVEF), and color and spectral Doppler were analyzed. The use of contrast resulted in a significant increase in the number of well-delineated segments, with a salvage rate of 77% of nondiagnostic studies. EBDSI was 1.62 +/- 0.61, before contrast, increasing to 2.05 +/- 0.53 after it (P < 0.001). There was a change in the LVEF estimation in 5 exams, and a new wall motion abnormality was detected in other 4 exams, after the use of contrast. Moreover, a significant change was observed in the quantification of mitral regurgitation in 5 patients, in the aortic transvalvular peak gradient in 1 patient, and measurement of tricuspid regurgitation peak flow velocity in 8 patients. It is concluded that in cardiac postoperative patients under mechanical ventilation, intravenous injection of a contrast agent using FI resulted in a high salvage rate of studies and changed the initial diagnosis in a significant number of patients.

Albumins↗

Detection of functional recovery using low-dose dobutamine and myocardial contrast echocardiography after acute myocardial infarction treated with successful thrombolytic therapy.

OBJECTIVE: We studied the value of low-dose dobutamine stress echocardiography (LDDE) and myocardial contrast echocardiography (MCE) in early prediction of left ventricular functional recovery (LVFR) after acute myocardial infarction (AMI) treated with successful thrombolysis. DESIGN: LDDE and MCE using second-harmonic intermittent imaging were performed in first week after AMI. LVFR was defined as an absolute > or =5% increase in ejection fraction, from early to 6 months of follow-up by Technetium-99m-Sestamibi single-photon emission computed tomography. PATIENTS: Out of 50 patients studied, 19 evolved with LVFR (group 1) and 31 without LVFR (group 2). Regional dysfunction was detected in 103 (37%) infarcted-related segments in group 1 and in 173 (63%) segments in group 2. RESULTS: Sensitivity, specificity, positive, and negative predictive values and accuracy for detecting LVFR by LDDE were 94.7% (18/19), 87.1% (27/31), 81.8% (18/22), 96.4% (27/28), and 90% (45/50), respectively, and by MCE were 94.7% (18/19), 51.6% (16/31), 54.5% (18/33), 94.1% (16/17), and 68% (34/50). In group 1, functional improvement was observed in 86.9% (53/61) of segments with contractile reserve by LDDE and in 65.8% (52/79) of segments with microvascular perfusion by MCE. In group 2, functional improvement was observed in 78.3% (18/23) of segments with contractile reserve by LDDE and in 25.5% (25/98) of segments with microvascular perfusion by MCE. All segments without perfusion by MCE evolved without functional recovery. CONCLUSION: LDDE was an accurate predictor of late left ventricular function recovery after AMI, while MCE was sensitive and has a high negative predictive value demonstrating that microvascular perfusion is essential for LVFR.

Aged↗

Comparison of safety and efficacy of the early injection of atropine during dobutamine stress echocardiography with the conventional protocol.

Although dobutamine-atropine stress echocardiography (DASE) is an established method for evaluating patients who have coronary artery disease (CAD), it can increase test duration and a patient's exposure to large doses of dobutamine. New protocols, including the early injection of atropine during dobutamine stress echocardiography (EA-DSE), have been proposed to decrease test duration. This study compared the safety, efficacy, and accuracy of EA-DSE with those of DASE. We retrospectively evaluated 3,163 patients who underwent DASE and 1,664 patients who underwent EA-DSE over a period of 12 years. In EA-DSE, atropine at a dose </=2 mg was started with 20 microg/kg/min of dobutamine if heart rate was <100 beats/min. Diagnostic accuracy for detecting CAD (>50% stenosis) was assessed in patients who underwent quantitative angiography </=3 months of stress testing. The dobutamine dose used in EA-DSE was smaller than that used in DASE (31 +/- 6 vs 36 +/- 6 microg/kg/min, p <0.0001), although the atropine dose was larger (0.8 +/- 0.5 vs 0.5 +/- 0.25 mg, p <0.0001). EA-DSE resulted in a significantly shorter duration of dobutamine infusion (12.4 +/- 2.0 vs 14.6 +/- 2.5 minutes, p <0.0001), more diagnostic studies (88% vs 81%, p <0.0001), and a lower incidence of minor adverse effects than did DASE. The rate of major adverse effects was similar in the 2 protocols. Sensitivities, specificities, positive predictive values, negative predictive values, and accuracies for detecting CAD were 84%, 90%, 93%, 76%, and 86% for EA-DSE and 86%, 78%, 84%, 79%, and 82% for DASE, respectively (p = NS). Therefore, EA-DSE is a safe and effective alternative to DASE and had a similar accuracy for the detection of CAD.

Aged↗

Hand-carried ultrasound performed at bedside in cardiology inpatient setting - a comparative study with comprehensive echocardiography.

BACKGROUND: Hand-carried ultrasound (HCU) devices have been demonstrated to improve the diagnosis of cardiac diseases over physical examination, and have the potential to broaden the versatility in ultrasound application. The role of these devices in the assessment of hospitalized patients is not completely established. In this study we sought to perform a direct comparison between bedside evaluation using HCU and comprehensive echocardiography (CE), in cardiology inpatient setting. METHODS: We studied 44 consecutive patients (mean age 54 +/- 18 years, 25 men) who underwent bedside echocardiography using HCU and CE. HCU was performed by a cardiologist with level-2 training in the performance and interpretation of echocardiography, using two-dimensional imaging, color Doppler, and simple calliper measurements. CE was performed by an experienced echocardiographer (level-3 training) and considered as the gold standard. RESULTS: There were no significant differences in cardiac chamber dimensions and left ventricular ejection fraction determined by the two techniques. The agreement between HCU and CE for the detection of segmental wall motion abnormalities was 83% (Kappa = 0.58). There was good agreement for detecting significant mitral valve regurgitation (Kappa = 0.85), aortic regurgitation (kappa = 0.89), and tricuspid regurgitation (Kappa = 0.74). A complete evaluation of patients with stenotic and prosthetic dysfunctional valves, as well as pulmonary hypertension, was not possible using HCU due to its technical limitations in determining hemodynamic parameters. CONCLUSION: Bedside evaluation using HCU is helpful for assessing cardiac chamber dimensions, left ventricular global and segmental function, and significant valvular regurgitation. However, it has limitations regarding hemodynamic assessment, an important issue in the cardiology inpatient setting.

Cardiology↗

[Left atrial myxoma: three-dimensional echocardiographic assessment].

The patient was a 70-year-old female with antecedents of diabetes mellitus and hypertension, being followed up in the outpatient care clinic due to chronic anemia after corrective surgery for angiodysplasia of the proximal jejunum, in whom an image suggestive of left atrial myxoma was found on routine transthoracic echocardiography. Then multiplanar transesophageal echocardiography and 3-dimensional echocardiography were performed, showing the latter better anatomical details of the tumor. The patient underwent exeresis of the mass with anatomicopathological confirmation of the tumor. Three-dimensional echocardiography proved to be a technique that can provide additional contributions to the diagnostic investigation of structural heart diseases.

Aged↗

Value of myocardial contrast echocardiography for predicting left ventricular remodeling and segmental functional recovery after anterior wall acute myocardial infarction.

OBJECTIVE: We sought to study the value of microvascular perfusion assessed by myocardial contrast echocardiography in predicting left ventricular remodeling after anterior wall acute myocardial infarction. METHODS: In 31 patients myocardial contrast echocardiography was performed up to 48 hours after acute myocardial infarction with determination of end-diastolic and end-systolic volumes, wall-motion score index, and myocardial perfusion score index (MPSI) at rest and under dobutamine stress at 6 months. Patients were classified into remodeling group (RG) (n = 19) and non-RG (n = 12), and, according to number of segments without opacification, reflow (< or =2 segments, n = 15) and no-reflow (>2 segments, n = 16) groups. RESULTS: Wall-motion score index (1.84 +/- 0.22 vs 1.64 +/- 0.3; P =.049), MPSI (1.53 +/- 0.25 vs 1.26 +/- 0.17; P =.006), and number of segments without contrast (3.11 +/- 2.23 vs 1.08 +/- 1.38; P =.018) were higher in RG than in non-RG. End-diastolic and end-systolic volumes, and wall-motion score index, increased significantly in RG at 6 months and decreased in non-RG. MPSI increased in RG (1.53 +/- 0.25-1.66 +/- 0.21; P =.011) and was the only independent predictor of left ventricular remodeling (odds ratio = 1.8; 95% confidence interval = 1.15-2.82; P =.010). No-reflow group presented 27.8 +/- 19.9% of segments with resting functional recovery or contractile reserve, and reflow group presented 69.9 +/- 31.2% (P <.001). CONCLUSION: MPSI obtained 48 hours after acute myocardial infarction is an independent predictor of left ventricular remodeling. Patients with two or fewer segments without opacification revealed a better prognosis of resting ventricular function and contractile reserve.

Acute Disease↗