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Biomedical subjects

A C Pearson

Publications and source records attributed to A C Pearson.

At least 19 recordsLinked to original sources

Evaluation of aortic distensibility with transesophageal echocardiography.

Distensibility of the descending aorta was evaluated during routine transesophageal echocardiography (TEE) in 50 subjects (16 to 80 years, average age 53). M-mode measurements of aortic systolic (SD) and diastolic diameter (DD) were taken distal to the left subclavian artery. Simultaneously, cuff brachial artery systolic (SBP) and diastolic (DBP) pressures were measured. Aortic pressure strain modulus (Ep), calculated as brachial artery pulse pressure/aortic strain, averaged 1.19 +/- 0.95 10(6) dynes/cm2. Elasticity index beta, defined as 1n (SBP/DBP)/aortic strain, averaged 3.77 +/- 2.12. Both Ep and beta were correlated with age (r = 0.65, p less than 0.001; and r = 0.70, p less than 0.0001). In 20 subjects aortic pulse wave velocity was assessed at the same time using simultaneous high fidelity recordings of carotid and femoral artery pressure waveforms. Aortic pulse wave velocity averaged 818 +/- 231 cm/sec and was correlated with Ep (r = 0.60, p less than 0.01) and with age (r = 0.55, p less than 0.05). Intraobserver and interobserver variability for aortic diameter measurement ranged from 0.2 to 0.5 mm.

Adolescent

Comparison of transthoracic and transesophageal echocardiography in evaluation of 47 Starr-Edwards prosthetic valves.

OBJECTIVES: Our objectives were to characterize by transesophageal echocardiography the normal appearance of the Starr-Edwards prosthetic heart valve and to compare the utility of transesophageal and transthoracic echocardiography in detection of valve abnormality. BACKGROUND: The Starr-Edwards prosthetic heart valve, the first mechanical valve to be used, has demonstrated excellent durability. METHODS: Fifty transthoracic and transesophageal echocardiographic studies on 37 patients with 47 Starr-Edwards prosthetic valves were analyzed retrospectively. Six cases of surgically confirmed infective endocarditis were studied. RESULTS: Vegetation or abscess formation, or both, was identified by transesophageal echocardiography in all six cases of infective endocarditis but was found in only one of these cases by transthoracic echocardiography. Thrombus was detected by transesophageal echocardiography in 9 of 11 patients with transient ischemic attacks or stroke and in 2 patients by transthoracic echocardiography with 3 confirmed at surgery. In 26 of the 30 patients with a mitral Starr-Edwards valve, the valve demonstrated a trivial or mild "closing volume" early systolic or holosystolic leak on transesophageal echocardiography alone. Transthoracic evaluation identified significant mitral regurgitation in six of the eight patients who had this finding on transesophageal echocardiography. Serial studies were performed to assess response to treatment or need for surgical intervention in eight patients. Seventeen valves have been implanted for 12 years; six of these had significant leakage without apparent cause, a finding not observed more recently implanted valves. CONCLUSIONS: These observations demonstrated the unique utility of transesophageal echocardiography in patients with Starr-Edwards prosthetic valve dysfunction, endocarditis or thrombus formation, and of the clear superiority of transesophageal echocardiography over transthoracic echocardiography in these situations.

Adult

Comparison of transthoracic and transesophageal echocardiography for assessment of left-sided valvular regurgitation.

To compare transthoracic and transesophageal echocardiography in the clinical assessment of left-sided valvular regurgitation, 118 patients who underwent both transesophageal and transthoracic echocardiographic studies within a 24-hour period were included in this study. Presence or absence of aortic regurgitation was identified concordantly by both techniques in 93 patients (79%). Complete agreement between both techniques was found in 88 patients (75%). Presence or absence of mitral regurgitation was identified concordantly by both techniques in 89 patients (75%). Complete agreement in grade was found in only 74 patients (63%). Twenty-nine patients (25%) had mitral regurgitation detected by transesophageal echocardiography, but not by transthoracic echocardiography. Four of these patients (14%) had significant (2 to 3+) mitral regurgitation. Differences between transesophageal and transthoracic echocardiography do not appear to be clinically important in patients with aortic regurgitation. In mitral regurgitation, significant differences exist between these 2 techniques, with transesophageal echocardiography being much more sensitive.

Aortic Valve

Atrial septal aneurysm and stroke: a transesophageal echocardiographic study.

The prevalence and morphologic characteristics of atrial septal aneurysms identified by transesophageal echocardiography in 410 consecutive patients are described. Two groups of patients were compared: Group I consisted of 133 patients referred for evaluation of the potential source of an embolus and Group II consisted of 277 patients referred for other reasons. An atrial septal aneurysm was diagnosed by transesophageal echocardiography in 32 (8%) of the 410 patients. Surface echocardiography identified only 12 of these aneurysms. Atrial septal aneurysm was significantly more common in patients with stroke (20 [15%] of 133 vs. 12 [4%] of 277) (p less than 0.05); right to left shunting at the atrial level was demonstrated in 70% of patients in Group I and 75% of patients in Group II by saline contrast echocardiography. Four patients in Group I had an atrial septal defect with additional left to right flow. There was no difference between the two groups in aneurysm base width, total excursion or left atrial or right atrial excursion. However, Group I patients had a thinner atrial septal aneurysm than did Group II patients. It is concluded that an atrial septal aneurysm occurs commonly in patients with unexplained stroke, is more frequently detected by transesophageal echocardiography than by surface echocardiography and is usually associated with right to left atrial shunting. Treatment (anticoagulant therapy vs. surgery) of atrial septal aneurysm identified in stroke patients can be determined only by long-term follow-up studies.

Adult

Ultra short-acting intravenous beta-adrenergic blockade as add-on therapy in acute unstable angina.

To assess the efficacy and safety of the ultra short-acting beta-blocking agent, esmolol, in acute unstable angina, we administered esmolol to 21 patients who had persistent angina despite conventional medical therapy. Following a baseline Doppler echocardiographic examination, esmolol was titrated to reduce the rate-pressure product by at least 20%. Once the patients had been receiving a maintenance dosage for 30 minutes, Doppler echocardiographic studies were repeated. Mean esmolol dose at target response was 17 +/- 16 mg/min, with the dosage range of 8 to 24 mg/min. Esmolol was effective in alleviating anginal chest pain in 18 of the 21 patients. Seven patients eventually underwent percutaneous transluminal coronary angioplasty (PTCA) and eight had coronary bypass surgery. The remainder were discharged receiving medical therapy including oral beta-blockade. During esmolol therapy, heart rate and blood pressure decreased significantly (86 +/- 14 to 68 +/- 12 beats/min and 125 +/- 16 to 103 +/- 20 mm Hg, both p less than 0.001). Cardiac output decreased from 5.4 +/- 1.3 to 4.5 +/- 1.1 L/min (p less than 0.001) secondary to a decrease in heart rate as stroke volume remained unchanged. Left ventricular ejection fraction increased from 47 +/- 12 to 49 +/- 13 with esmolol therapy, although this change was not statistically significant. Both the one third filling fraction as well as E/A ratio (ratio of early-to-late diastolic filling velocities) increased with esmolol therapy (35 +/- 8% to 38 +/- 8% and 0.73 +/- 0.2 to 0.85 +/- 0.23, both p less than 0.005), indicating improvement in left ventricular diastolic function.(ABSTRACT TRUNCATED AT 250 WORDS)

Adrenergic beta-Antagonists

Effects of aging on left ventricular structure and function.

To better characterize the cardiac structural and functional changes that are associated with aging, Doppler-echocardiography was performed on 23 young (mean age, 25 years) and 30 old (mean age, 70 years) healthy normotensive subjects. Left ventricular cavity dimensions and wall thickness were determined and left ventricular mass index was calculated from M-mode echocardiograms. Stroke volume was calculated from Doppler-measured aortic flow. Diastolic filling was evaluated by pulsed Doppler echocardiography of mitral inflow. Posterior wall thickness (1.0 vs 0.8 cm, p less than 0.05) and relative wall thickness (0.42 vs 0.35, p less than .05) were significantly greater in the elderly subjects compared with the younger subjects. Left ventricular mass index increased on average 0.25 gm/m2/yr but was not significantly increased in the elderly compared with the younger subjects (89 vs 77 gm/m2). Shortening fraction and stroke volume did not differ between the two groups. Diastolic filling was dramatically altered with aging, and the elderly subjects demonstrated a doubling of percent atrial contribution (37% vs 19%, p less than 0.0001) and halving of peak early-to-peak atrial velocity ratio (0.85 vs 1.77, p less than .01).

Adult

Factors influencing transmitral flow velocity in normal and hypertensive subjects.

Transmitral flow velocity and its determinants were examined with Doppler echocardiography in 53 hypertensive and 32 age-matched healthy normotensive men. Early and late maximal transmitral velocity, and early and late flow velocity integral were evaluated. In comparison with normal subjects, hypertensive patients were characterized by decreased maximal early velocity (66.3 +/- 12.3 versus 72.3 +/- 11.5 cm/sec, p less than 0.05), normalized early flow integral (67 +/- 7% versus 73 +/- 5%, p less than 0.001), increased maximal late flow velocity (45 +/- 10 cm/sec, p less than 0.001), and normalized late flow integral (29 +/- 7% versus 21 +/- 5%, p less than 0.001). Abnormally high late transmitral flow was found in 47% of the hypertensive group. Multiple regression analysis revealed that in normal subjects transmitral flow indexes were determined by age, relative wall thickness, and systolic blood pressure, but not by heart rate. A strong relationship of Doppler transmitral flow indexes with age was confirmed in hypertensive patients; however, relative wall thickness influenced transmitral flow velocity only weakly and systolic blood pressure did not affect transmitral flow. Left ventricular mass and diastolic blood pressure did not influence mitral filling velocity in either group. The altered pattern of mitral inflow found in a large number of hypertensive subjects is not related to elevated arterial blood pressure or to altered left ventricular geometry.

Adult

Pathophysiology of isolated systolic hypertension in elderly patients: Doppler echocardiographic insights.

Systemic hemodynamics were evaluated with aortic pulsed wave Doppler echocardiography in 79 elderly subjects with isolated systolic hypertension participating in the Systolic Hypertension in the Elderly Program (SHEP) and were compared with the values in 39 normal age-matched subjects. Cardiac output was elevated (4.50 +/- 1.13 L/min versus 3.94 +/- 1.12 L/min, p less than 0.05) in patients with isolated systolic hypertension in comparison with values in normal elderly subjects. Systemic vascular resistance did not differ between both groups (2140 +/- 536 dyn.sec/cm-5 versus 2011 +/- 553 dyn.sec/cm-5, p = NS). The mean acceleration of blood during left ventricular ejection was similar in patients with isolated systolic hypertension in comparison with normals (12.6 +/- 5.6 m/sec2 versus 11.5 +/- 3.5 m/sec2, p = NS). Patients with isolated systolic hypertension had significantly decreased arterial compliance, as measured by the stroke volume-to-pulse pressure ratio (0.77 +/- 0.26 cm3/mm Hg versus 1.11 +/- 0.30 cm3/mm Hg, p less than 0.0001). The prevalence of aortic and mitral regurgitation as well as valvular and annular calcification did not differ between analyzed groups. Isolated systolic hypertension in elderly patients appears to be multifactorial, with reduced arterial compliance and increased cardiac output both playing a role.

Aged

Initial clinical experience with a 48 by 48 element biplane transesophageal probe.

Recent technologic advances in ultrasound have resulted in the capability of transesophageal echocardiographic imaging in both transverse and longitudinal planes. Previous biplane probes suffered from inferior images because of reduced scan elements. We evaluated the utility of a prototype 48 X 48 element biplane transesophageal probe in 23 consecutive patients. Examinations were well tolerated with no side effects. In comparison to the single transverse plane, imaging with the longitudinal plane gave superior information on prosthetic valve pathology, atrial septal abnormalities, and pathoanatomy of the ascending aorta and mitral valve. Complementary information was provided by the longitudinal plane in patients with endocarditis and vegetations and in mitral protheses. Images obtained with this 48 X 48 element biplane probe along with color and spectral Doppler information were not perceptibly inferior to those obtained by single-plane probes. In conclusion, biplane transesophageal echocardiography with a 48 X 48 element probe indicates a great potential for enhanced three-dimensional understanding of cardiac pathology and diagnostic yield in specific pathologies.

Echocardiography

Effect of mitral regurgitation on pulmonary venous velocities derived from transesophageal echocardiography color-guided pulsed Doppler imaging.

The effect of mitral regurgitation on pulmonary venous flow velocity was studied in 66 patients undergoing transesophageal echocardiography. Nine patients were studied intraoperatively before and after surgery, so that 75 pulmonary venous flow tracings were analyzed. Fifty-four patients had no significant (0 to 1+) mitral regurgitation and 21 had significant (2 to 3+) mitral regurgitation. Comparison of both groups revealed significant differences in the pulmonary venous flow pattern. In patients with no significant mitral regurgitation, the peak systolic velocity was higher (55 +/- 16 vs. -4 +/- 16 cm/s; p less than 0.0001) and the peak diastolic velocity was lower (43 +/- 13 vs. 59 +/- 17 cm/s; p less than 0.01) when compared with values in patients with significant mitral regurgitation. Consequently, the peak systolic/diastolic velocity ratio was significantly higher in the patients without significant mitral regurgitation (1.4 +/- 0.5 vs. 0.4 +/- 1.3; p less than 0.0001). The same trend was noted with respect to the systolic and diastolic velocity integrals. As the degree of mitral regurgitation increased, the peak diastolic velocity and diastolic velocity integral increased, whereas the peak systolic velocity and systolic velocity integral decreased. In patients with severe mitral regurgitation, the systolic flow became reversed (retrograde). The sensitivity of reversed systolic flow for severe mitral regurgitation was 90% (9 of 10), the specificity was 100% (65 of 65), the positive predictive value was 100% (9 of 9), the negative predictive value was 98% (65 of 66) and the predictive accuracy was 99% (74 of 75).(ABSTRACT TRUNCATED AT 250 WORDS)

Blood Flow Velocity

Superiority of transesophageal echocardiography in detecting cardiac source of embolism in patients with cerebral ischemia of uncertain etiology.

The diagnostic yield of transesophageal and transthoracic echocardiography for identifying a cardiac source of embolism was compared in 79 patients presenting with unexplained stroke or transient ischemic attack. There were 35 men and 44 women with a mean age of 59 years (range 17 to 84); 52% had clinical cardiac disease. Both transthoracic and transesophageal echocardiograms were performed using Doppler color flow and contrast imaging. Transesophageal echocardiography identified a potential cardiac source of embolism in 57% of the overall study group compared with only 15% by transthoracic echocardiography (p less than 0.0005). Compared with transthoracic echocardiography, transesophageal echocardiography more frequently identified atrial septal aneurysm associated with a patent foramen ovale (9 versus 1 of 79 patients, p less than 0.005), left atrial thrombus or tumor (6 versus 0 of 79 patients, p less than 0.05) and left atrial spontaneous contrast (13 versus 0 of 79 patients, p less than 0.0005). All cases of left atrial thrombus or spontaneous contrast were identified in patients with clinically identified cardiac disease. In the 38 patients with no cardiac disease, transesophageal echocardiography identified isolated atrial septal aneurysm and atrial septal aneurysm with a patent foramen ovale more frequently than transthoracic echocardiography (8 versus 2 of 38 patients, p less than 0.05). The two techniques had a similar rate of identifying apical thrombus and mitral valve prolapse. Overall, transesophageal echocardiography identified abnormalities in 39% of patients with no cardiac disease versus 19% for transthoracic echocardiography (p less than 0.005). Thus, transesophageal echocardiography identifies potential cardiac sources of embolism in the majority of patients presenting with unexplained stroke.(ABSTRACT TRUNCATED AT 250 WORDS)

Cerebral Infarction

Echocardiographic evaluation of cardiac structure and function in elderly subjects with isolated systolic hypertension.

One hundred four participants in the Systolic Hypertension in the Elderly Program (SHEP) trial (mean age 71 +/- 6 years) were examined by Doppler echocardiography to gain information on the cardiac structural and functional alterations in isolated systolic hypertension. Participants had a systolic blood pressure greater than 160 mm Hg with diastolic blood pressure less than 90 mm Hg and were compared with 55 age-matched normotensive control subjects. Left ventricular mass index was significantly higher in the participants than in the normotensive subjects (103 +/- 28 versus 87 +/- 23 g/m2, p = 0.0014) and 26% of the participants met echocardiographic criteria for left ventricular hypertrophy compared with 10% of normotensive subjects. Left atrial index was also greater in participants than in normotensive subjects (2.26 +/- 0.32 versus 2.11 +/- 0.24 cm/m2, p = 0.005) and 51% of participants had left atrial enlargement. Doppler measures of diastolic filling were significantly different between the two groups, with peak atrial velocity higher (76 +/- 17 versus 69 +/- 17 cm/s, p = 0.02) and ratio of peak early to atrial velocity lower (0.76 +/- 0.23 versus 0.86 +/- 0.22, p = 0.0124) in participants. There was no correlation between left ventricular mass index and Doppler measures of diastolic function, but relative wall thickness correlated significantly with peak atrial velocity (r = 0.22, p = 0.016) and peak early to peak atrial velocity ratio (r = 0.24, p = 0.007). There was no difference in M-mode ejection phase indexes of systolic performance (shortening fraction and peak velocity of circumferential fiber shortening) between the two groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged

Evaluation of pulmonary venous flow by transesophageal echocardiography in subjects with a normal heart: comparison with transthoracic echocardiography.

Nineteen normal subjects and five patients with atrial fibrillation underwent transesophageal and transthoracic echocardiographic studies to evaluate the normal pulmonary venous flow pattern, compare right and left pulmonary venous flow and assess the effect of sample volume location on pulmonary venous flow velocities. Best quality tracings were obtained by transesophageal echocardiography. Anterograde flow during systole and diastole was observed in all patients by both techniques. Reversed flow during atrial contraction was observed with transesophageal echocardiography in 18 of the 19 subjects in normal sinus rhythm, but in only 7 subjects with transthoracic echocardiography. Two forward peaks during ventricular systole were clearly identified in 14 subjects (73%) with transesophageal echocardiography, but in none with the transthoracic technique. The early systolic wave immediately followed the reversed flow during atrial contraction and was strongly related to the timing of atrial contraction (r = 0.78; p less than 0.001), but not to the timing of ventricular contraction, and appeared to be secondary to atrial relaxation. Conversely, the late systolic wave was temporally related to ventricular ejection (r = 0.66; p less than 0.001), peaking 100 ms before the end of the aortic valve closure and was unrelated to atrial contraction time. Quantitatively, significantly higher peak systolic flow velocities were obtained in the left upper pulmonary vein compared with the right upper pulmonary vein (60 +/- 17 vs. 52 +/- 15 cm/s; p less than 0.05) and by transesophageal echocardiography compared with transthoracic studies (60 +/- 17 vs. 50 +/- 14 cm/s; p less than 0.05). Increasing depth of interrogation beyond 1 cm from the vein orifice resulted in a significant decrease in the number of interpretable tracings.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult

Cardiovascular evaluation in blunt thoracic trauma using transesophageal echocardiography (TEE)

Blunt chest trauma can result in significant cardiothoracic injury, which can include cardiac contusion, aortic injury, and myocardial valvular injury. Nineteen patients with no prior history of cardiac abnormalities who sustained severe blunt chest trauma and had widening of the mediastinum on chest radiographs were prospectively evaluated using transesophageal echocardiography (TEE). In each instance TEE was performed without difficulty, excellent images were obtained of the aorta and heart, and no complications were noted. Abnormalities were seen in 12 (63%) patients, with hypokinetic regional wall motion consistent with cardiac contusion demonstrated in five (26%) patients. Tricuspid regurgitation was found in three (16%) patients, and aortic and mitral regurgitation in one (5%) patient each. Aortic wall hematomas were seen in two patients, one of whom had an intimal tear on aortography, and a pericardial effusion was seen in one patient with an aortic intimal tear confirmed angiographically. Thus TEE can be performed safely in the acute setting of patients sustaining severe blunt chest trauma and yield useful information with respect to cardiovascular function and the aorta.

Adult