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Biomedical subjects

Robert J Siegel

Publications and source records attributed to Robert J Siegel.

At least 19 recordsLinked to original sources
PubMed2006

Noninvasive low-frequency ultrasound energy causes vasodilation in humans.

OBJECTIVES: We evaluated the potential vasodilator effects of transcutaneous low-frequency ultrasound (US) in human brachial arteries. BACKGROUND: Recent data show that transthoracic low-frequency US energy results in canine coronary artery vasodilation. METHODS: Brachial artery diameters were measured before and after low-frequency US (29 kHz, 1.4 W/cm2) exposure using US imaging with a linear-array transducer. We assessed the time course of diameter changes after US in 20 subjects. In 10 of 20 subjects, brachial artery flow-mediated vasodilation (FMD) was measured to compare the effect of US to a standard method of evaluating endothelial function. RESULTS: Significant vasodilation was seen after 2 min of US compared with baseline values. At 5 min of US, the brachial artery diameter increased by 4.1%. In addition, the arteries continued to dilate after US exposure. At 3 min after US there was a 5.4%, and at 5 min after US a 6.0% increase in vessel diameter (p < 0.001). These diameters returned to baseline dimensions about 20 min after stopping US. Ultrasound-mediated vasodilation and percentage FMD showed good correlation (r = 0.87; p < 0.001). CONCLUSIONS: This is the first study to demonstrate that noninvasive transcutaneous low-frequency US energy dilates human brachial arteries. This arterial vasodilator effect has a rapid onset (within 2 min), lasts about 20 min, and is similar in magnitude to that of FMD. The vasodilator effect of US may have diagnostic and therapeutic potential in patients with or at risk for vascular disease.

Adult↗
PubMed2006

Systematic overview and clinical applications of pacing atrial stress echocardiography.

Pacing atrial stress echocardiography (PASE) has been studied over the past 3 decades for the evaluation of myocardial ischemia. Published studies suggest that PASE may be used as an alternative to exercise or pharmacologic stress imaging. The recent introduction of improved pacing electrodes, together with use of accelerated and shortened pacing protocols and improvements in transthoracic echocardiographic imaging techniques, makes PASE an appealing stress imaging method. A critical analysis of the diagnostic accuracy of PASE shows equivalence with other imaging stress modalities. PASE has been found to be highly feasible and accurate technique that may expedite the diagnosis and risk stratification of patients with coronary artery disease. This review addresses the history, hemodynamics, protocols, accuracy, clinical utility, and cost-effectiveness of PASE as well as elucidating its place among other stress modalities.

Animals↗
PubMed2006

Non-invasive resting magnetocardiographic imaging for the rapid detection of ischemia in subjects presenting with chest pain.

BACKGROUND: Early diagnosis of ischemia is complicated by the poor sensitivity of standard tests and contraindication for stress testing in unstable angina patients. Magnetocardiography (MCG) imaging can be used for the rapid, non-invasive detection of ischemia at rest. METHODS: We studied 125 patients with presumed ischemic chest pain. All were chest pain free at the time of scanning. A 6-minute resting MCG scan (CardioMag Imaging, Inc., New York, 9-channel system) was performed. Following the MCG scan, automated software data analysis was performed, and quantitative scores were automatically calculated for each subject. The presence of ischemia was determined after testing with serial troponins, stress testing, and/or coronary angiography. RESULTS: The mean age was 59.4 +/- 13.6 years. Most patients (86.4%) had non-ischemic 12-lead ECG and normal troponin (86.2%). Fifty-five patients (44.0%) were determined to be ischemic. The MCG sensitivity, specificity, positive and negative predictive value was 76.4, 74.3, 70.0 and 80.0%, respectively, for the detection of ischemia (p < 0.0001). CONCLUSIONS: MCG is a new rapid, non-invasive imaging tool able to detect repolarization abnormalities at rest consistent with ischemia in patients presenting with chest pain syndrome and normal or non-specific 12-lead ECG and normal troponin.

Adult↗
PubMed2006

Stress echocardiography in octogenarians: transesophageal atrial pacing is accurate, safe, and well tolerated.

The feasibility and diagnostic accuracy of transesophageal pacing stress echocardiography for detection of inducible myocardial ischemia were evaluated in 161 patients 80 years of age or older (mean 84 +/- 3.9, range 80-97). The pacing time was 5.5 +/- 2.5 minutes with a total test time of 37 +/- 7 minutes. The mean achieved heart rate was 96 +/- 7% (83%-121%) of maximum predicted with an average rate pressure product of 21,560 +/- 5175 beats/min x mm Hg. There were minor adverse events in 8% of cases and no major complications occurred. Patient acceptance was high. When compared with myocardial single photon emission computed tomography, pacing stress echocardiography had a sensitivity of 89% and a specificity of 93% for the detection of myocardial ischemia, and 91% agreement (kappa = 0.80, P < .001). We demonstrate that pacing stress echocardiography is safe and accurate for detection of myocardial ischemia and, thus, a reliable substitute to exercise and pharmacologic stress testing in octogenarians.

Aged, 80 and over↗
PubMed2005

Comparison of effectiveness of hand-carried ultrasound to bedside cardiovascular physical examination.

This study compared the accuracy of cardiovascular diagnoses by medical students operating a small hand-carried ultrasound (HCU) device with that of board-certified cardiologists using standard physical examinations. Sixty-one patients (38% women; mean age 70 +/- 19 years) with clinically significant cardiac disease had HCU studies performed by 1 of 2 medical students with 18 hours of training in cardiac ultrasound and physical examinations by 1 of 5 cardiologists. Diagnostic accuracy was determined by standard echocardiography. Two-hundred thirty-nine abnormal findings were detected by standard echocardiography. The students correctly identified 75% (180 of 239) of the pathologies, whereas cardiologists found 49% (116 of 239) (p <0.001). The students' diagnostic specificity of 87% was also greater than cardiologists' specificity of 76% (p <0.001). For nonvalvular pathologies (115 findings), students' sensitivity was 61%, compared with 47% for cardiologists (p = 0.040). There were 124 clinically significant valvular lesions (111 regurgitations, 13 stenoses). Students' and cardiologists' sensitivities for recognizing lesions that cause a systolic murmur were 93% and 62% (p <0.001), respectively. Students' sensitivity for diagnosing lesions that produce a diastolic murmur was 75%; cardiologists recognized 16% of these lesions (p <0.001). The diagnostic accuracy of medical students using an HCU device after brief echocardiographic training to detect valvular disease, left ventricular dysfunction, enlargement, and hypertrophy was superior to that of experienced cardiologists performing cardiac physical examinations.

Aged↗
PubMed2005

Ischemic mitral regurgitation: revascularization alone versus revascularization and mitral valve repair.

BACKGROUND: In this study we compared the surgical management of ischemic mitral regurgitation (IMR) by revascularization alone and by revascularization combined with mitral valve repair. METHODS: We studied 355 patients who underwent revascularization alone (n = 168) or revascularization combined with mitral valve repair (n = 187) for IMR from March 1994 to September 2003. Preoperative and operative characteristics, postoperative mitral regurgitation severity, operative mortality, and late survival were examined for each surgical group. RESULTS: No differences were noted between the two groups in age, sex, history of diabetes or hypertension, and number of bypass grafts. The combined surgical group had a lower preoperative left ventricular ejection fraction (0.38 +/- 0.14 versus 0.44 +/- 0.15), greater severity of IMR, higher frequency of prior myocardial infarction, and longer cross-clamp and pump times (p < 0.01). The combined surgical group had a greater reduction in IMR grade (2.7 +/- 0.1 grades versus 0.2 +/- 0.1 grade), a lower postoperative IMR grade (0.9 +/- 0.1 versus 2.3 +/- 0.1), and a higher success with reduction of IMR by two or more grades (89% versus 11%) (p < 0.001). In patients with 3+ or 4+ IMR, both groups had similar operative mortality (11.0% in the combined group compared with 4.7% for revascularization alone, p = 0.11) and actuarial survival at 5 years (44% +/- 5% versus 41% +/- 7%, p = 0.53). Independently predictive of higher early mortality (< or = 30 days) by Cox analysis were longer pump time (p < 0.001) and older age (p < 0.02). Predictive of late mortality (> 30 days) were older age (p < 0.001), fewer bypass grafts (p < 0.01), and lower ejection fraction (p < 0.01). After adjustment for these variables, there was a trend (p = 0.08) toward a higher late survival with the combined surgical procedure. CONCLUSIONS: In patients with IMR, combined mitral valve repair and revascularization resulted in less postoperative mitral regurgitation and similar 5-year survival when compared with revascularization alone. Attempts to reduce pump time by using off-pump techniques may reduce early mortality in these high-risk patients.

Aged↗
PubMed2005

Pseudomyxoma originating from the interatrial septum in a heart transplant patient.

This report describes the echocardiographic diagnosis of an intracardiac mass in a heart transplant patient. The typical morphology of the lesions, its attachment to the interatrial septum, and the absence of a nidus focus for thrombus formation led to the preoperative assumption that it was a myxoma. The mass was successfully excised at the time of operation and the patient had an uneventful recovery. Pathology findings revealed a thrombus. Thus, echocardiography may have limited specificity for the differentiation of intracardiac tumors and thrombus.

Diagnosis, Differential↗
PubMed2005

Predictors of mortality in paravalvular abscess.

BACKGROUND: Paravalvular abscess formation is an ominous complication of infective endocarditis; however, prognostic variables in paravalvular abscess are poorly defined. METHODS: We examined our experience in patients with paravalvular abscess between 1987 and 2004. Clinical, echocardiographic, microbiologic, and surgical data were examined. RESULTS: There were 45 patients (17 females), age 57 +/- 17 years. Twenty-four patients had prosthetic valve endocarditis. Methicillin-sensitive Staphylococcus aureus and coagulase-negative S. aureus were the most common organisms accounting for 25 (56%) cases. Thirty-eight patients (84%) underwent surgery during initial admission. Surgical mortality was 7%, in-hospital mortality was 31%, and 1-year mortality was 38%. Between patients who died and patients who survived, there were no differences in age (61 +/- 20 years vs 55 +/- 15 years, P = .3), type of microorganism, presence of prosthetic heart valves (47% vs 57%), presence of moderate to severe or severe regurgitation of involved valve (47% vs 57%, P = .37), presence of associated valvular vegetation (93% vs 93%), area of abscess (5.6 +/- 2.9 cm2 vs 4.4 +/- 3.2 cm2, P = .39), left ventricular systolic function (56% +/- 13% vs 56% +/- 10%, P = .9), white cell count (13 +/- 4 vs 13 +/- 7, P = .9), or polymorphonuclear leukocytosis (86% +/- 6% vs 81% +/- 9%, P = .1). Patients who died were sicker on admission compared with those who survived (33% had stroke or altered mental status vs 7%, P = .03) and had worse renal function compared with those who survived (creatinine 4 +/- 4 mg/dL vs 1.6 +/- 1.9 mg/dL, P = .009). CONCLUSION: Neurologic impairment and renal impairment are significant determinants of 1-year survival in patients who present with paravalvular abscess.

Abscess↗
PubMed2004

Ultrasound energy improves myocardial perfusion in the presence of coronary occlusion.

OBJECTIVES: We evaluated whether ultrasound improves myocardial tissue perfusion in 14 animals with coronary artery occlusion. BACKGROUND: A recent study demonstrated that low-frequency ultrasound improves tissue perfusion in the rabbit ischemic limb, but there are no data on ultrasound enhancement of myocardial perfusion. METHODS: Fourteen animals (9 dogs, 5 pigs) underwent thoracotomy and occlusion of a diagonal branch of the left anterior descending coronary artery. Myocardial tissue perfusion units (TPUs) and pH were measured before coronary occlusion, after occlusion, and after direct exposure of the ischemic myocardium in the presence of fixed occlusion to low-frequency ultrasound (27 kHz). RESULTS: The TPU decreased from 100.9 +/- 13 at baseline to 71.1 +/- 13 (p < 0.01) after 60 min occlusion but rose by 19.7% to 85.1 +/- 8 (p < 0.01) after ultrasound exposure for 60 min. After 60-min coronary occlusion, myocardial pH fell from 7.43 +/- 14 to 7.05 +/- 0.15 (p < 0.01) but then improved to normal (7.46 +/- 0.32) after ultrasound for 60 min. Administration of L-Nomega-nitro-arginine methyl esther (L-NAME), an inhibitor of nitric oxide synthase, before ultrasound exposure, blocked improvement in myocardial tissue perfusion and pH by ultrasound. Quantitative histomorphology showed a significant increase in the capillary area of myocardium exposed to ultrasound versus non-exposed myocardium (16.2 +/- 7.9 vs. 8.2 +/- 2.1, p < 0.02). CONCLUSIONS: Low-frequency, low-intensity ultrasound improves myocardial tissue perfusion and pH in the presence of a fixed coronary artery occlusion.

Animals↗
PubMed2004

Comparison of frequency of left ventricular wall motion abnormalities in patients with a first acute myocardial infarction with versus without left ventricular hypertrophy.

One hundred fifty patients with their first acute myocardial infarctions (AMIs) were studied. AMIs were confirmed by troponin levels, ST-segment elevation, or angiographic coronary occlusion. In 36% of patients (16 of 45) with left ventricular (LV) hypertrophy, the wall motion score index was normal, whereas in patients with no LV hypertrophy, only 18% (19 of 105) had no segmental wall motion abnormalities (p = 0.03). When adjusting for troponin level, the odds ratio for normal wall motion of patients with LV hypertrophy was 2.86 (95% confidence interval 1.26 to 6.50) compared with those with normal wall thickness. Consequently, normal LV wall motion by echocardiography in the setting of LV hypertrophy does not exclude AMI.

Aged↗
PubMed2004

Hand-carried cardiac ultrasound enhances healthcare delivery in developing countries.

The availability of cardiac ultrasound is limited in developing countries. We evaluated the feasibility and diagnostic capability of a hand-carried cardiac ultrasound device in 126 patients (age 44 +/- 24 years) referred for consultation to a cardiology clinic in rural Mexico. The hand-carried cardiac ultrasound device identified 86 cardiac findings and obviated the need for further comprehensive echocardiographic evaluation in 90% of patients (113 of 126).

Adult↗
PubMed2004

Usefulness of a hand-carried cardiac ultrasound device for bedside examination of pericardial effusion in patients after cardiac surgery.

To identify the incidence of pericardial effusion in patients after cardiac surgery using a hand-carried cardiac ultrasound device, 200 patients were assessed on postoperative day 3. If a pericardial effusion was found, patients were monitored for 3 consecutive days with a hand-carried cardiac ultrasound device. Within 72 hours after surgery, 43 patients (21.5%) had developed an effusion, of whom 2 patients had cardiac tamponade and 41 patients (21%) had a small pericardial effusion. No difference was found in the incidence of effusion based on the type of cardiac surgery. Of patients with a small pericardial effusion on day 3 after surgery, an additional 2 of 41 (5%) developed cardiac tamponade.

Cardiac Surgical Procedures↗
PubMed2004

Utility and diagnostic accuracy of hand-carried ultrasound for emergency room evaluation of chest pain.

This study examined the utility and accuracy of immediate hand-carried echocardiography in patients presenting to the emergency room with chest pain and a normal or nondiagnostic electrocardiogram. Hand-carried echocardiography was highly concordant (kappa = 0.8) with troponin T tests as well as the discharge diagnosis of acute coronary syndrome, had a 100% sensitivity for the detection of acute coronary syndrome, 93% specificity, and 71% and 100% positive and negative predictive values, respectively.

Adult↗
PubMed2004

Usefulness of a hand-carried cardiac ultrasound device to detect clinically significant valvular regurgitation in hospitalized patients.

The accuracy of a hand-carried cardiac ultrasound (HCCU) device for the diagnosis of valvular regurgitations using color-flow Doppler was assessed. One hundred twenty hospitalized patients with at least mild valvular regurgitation by standard echocardiography were evaluated by 2 cardiologists using HCCU. The HCCU operator identified 99% of clinically significant valvular regurgitations and assessed the severity correctly in 83% of cases. For mild regurgitation, the HCCU sensitivity and specificity were 82% and 93%, respectively, resulting in correct assessments of severity in 71% of cases. HCCU used by trained cardiologists has high sensitivity for the detection and accurate assessment of the severity of clinically relevant valvular regurgitation.

Aged↗
PubMed2004

Making an impossible mission possible.

Cardiovascular disease (CVD) is widespread in developing countries. Hypertension is a major contributor of CVD. Left ventricular hypertrophy (LVH) is a risk marker in hypertensive populations. Identification of LVH and treatment of high-risk patients can result in more effective use of the limited resources. LVH is diagnosed by echocardiography, often unavailable in developing countries. In Gambia, we used a hand-carried ultrasound (HCU) to examine 1,997 people. Seventeen percent had hypertension; of these, LVH was found in 65%. The battery-powered HCU permits clinicians to detect LVH in areas with limited access to diagnostic equipment, allowing identification of a high-risk hypertensive population.

Adolescent↗
PubMed2004

Hand-carried ultrasound improves the bedside cardiovascular examination.

OBJECTIVES: We assessed the clinical utility of hand-carried cardiac ultrasound (HCU) devices to assist physicians in the diagnosis of cardiovascular disease. MATERIALS AND METHODS: We reviewed 42 articles published from 1978 to 2004. RESULTS: The capability and simplicity of the HCU device assist physicians in the diagnosis of cardiovascular disease at the initial patients contact. HCU is particularly useful in the setting of emergency or critical care, community screening, or in remote areas with limited access to health care. CONCLUSION: The inherent limitations of the physical examination as well as the reduced focus and training in physical diagnosis of current and recent medical school graduates has set the stage for the HCU device to modify traditional medical practices by complementing the physical examination with real-time cardiovascular imaging.

Ambulatory Care↗