Misinterpretation about the contribution of the left ventricular long-axis shortening to the stroke volume.
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Biomedical subjects
L A Brodin
Publications and source records attributed to L A Brodin.
Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography: optimal diagnostic models using off-line tissue Doppler in the MYDISE study.
AIMS: To develop optimal methods for the objective non-invasive diagnosis of coronary artery disease, using myocardial Doppler velocities during dobutamine stress echocardiography. METHODS AND RESULTS: We acquired tissue Doppler digital data during dobutamine stress in 289 subjects, and measured myocardial responses by off-line analysis of 11 left ventricular segments. Diagnostic criteria developed by comparing 92 normal subjects with 48 patients with coronary disease were refined in a prospective series of 149 patients referred with chest pain. Optimal diagnostic accuracy was achieved by logistic regression models, using systolic velocities at maximal stress in 7 myocardial segments, adjusting for independent correlations directly with heart rate and inversely with age and female gender (all p<0.001). Best cut-points from receiver-operator curves diagnosed left anterior descending, circumflex and right coronary disease with sensitivities and specificities of 80% and 80%, 91% and 80%, and 93% and 82%, respectively. All models performed better than velocity cut-offs alone (p<0.001). CONCLUSION: Non-invasive diagnosis of coronary artery disease by quantitative stress echocardiography is best performed using diagnostic models based on segmental velocities at peak stress and adjusting for heart rate, and gender or age.
Adult↗
Feasibility and reproducibility of off-line tissue Doppler measurement of regional myocardial function during dobutamine stress echocardiography.
AIMS: Off-line post-processing of colour tissue Doppler from digital loops may allow objective quantification of dobutamine stress echocardiography. We assessed the reproducibility of off-line measurements of regional myocardial velocities. METHODS AND RESULTS: Nine observers analysed 10 studies, each making 2400 observations. Coefficients of variation in basal segments from apical windows, at rest and maximal stress, were 9-14% and 11-18% for peak systolic velocity, 16-18% and 17-19% for time-to-peak systolic velocity, 9-17% and 18-24% for systolic velocity time integral, and 18-23% and 21-27% for systolic acceleration. Coefficients of variation for diastolic velocities in basal segments at rest were 11-40%. Coefficients of variation for peak systolic velocity were 10-24% at rest and 14-28% at peak in mid segments, and 19-53% and 29-69% in apical segments. From parasternal windows coefficients of variation for peak systolic velocity were 14-16% in basal posterior, and 19-29% in mid-anterior segments. High variability makes measurement unreliable in apical and basal anterior septal segments. The feasibility of obtaining traces was tested in 92 subjects, and >90% in all basal and mid segments apart from the anterior septum. CONCLUSION: Quantification of myocardial functional reserve by off-line analysis of colour tissue Doppler acquired during dobutamine stress is feasible and reproducible in 11 segments of the left ventricle. The most reliable measurements are systolic velocities of longitudinal motion in basal segments.
Blood Flow Velocity↗
Analysis of atrioventricular plane movements by Doppler tissue imaging and M-mode in children with atrial septal defects before and after surgical and device closure.
Our objective was to compare the effects of surgical and device closure of atrial septal defects (ASDs) on atrioventricular plane function. In healthy individuals, both short- and long-axis motion contribute to ventricular pump function. Short-axis function (i.e., the amplitude and velocity of atrioventricular plane movements) may be evaluated by M-mode and Doppler tissue imaging. The study group consisted of 19 children with ASD of the secundum type before and after surgical (n = 12) or device (n = 7) closure and 10 healthy controls. Surgical and device closures were uncomplicated and all defects were completely closed. Registrations of atrioventricular plane systolic and diastolic amplitude and velocity were made from the tricuspid and the mitral annulus and from the septum in the apical four-chamber view. Comparisons were made between examinations before and after closure, between the two subgroups of patients treated by surgical and device closure, respectively, and between the patient group and the control groups. Before ASD closure, all measurements were normal or near normal. After surgery, systolic amplitudes and velocities of the tricuspid annulus and in the septum decreased significantly, whereas no changes were seen in the device group. Less marked changes were seen in diastolic measurements. However, in the surgical group significant decrease to subnormal values were found in the tricuspid annulus and in the septum, which may indicate a decreased diastolic function postoperatively. Mitral valve annulus amplitude and velocity were not affected by the treatment. Atrioventricular function is normal in children with right ventricular volume overload. The decrease to subnormal values after open-heart surgery is not seen after device closure of the ASD, indicating that surgery affects right ventricular function.
Adolescent↗
Analysis of the O-wave in acute right ventricular apex impedance measurements with a standard pacing lead in animals.
Modern pacemakers (implantable devices used for maintaining an appropriate heart rate in patients) can use an intracardiac ventricular impedance signal for physiological cardiac stimulation control. Intracardiac ventricular impedance from nine animal subjects is analysed and presented (seven sheep: 49.0 +/- 6.5 kg, sinus rhythm 100.3 +/- 16.5 beats min(-1), average impedance 629.8 +/- 72.6 ohms; and two dogs: 30 kg each, sinus rhythm 86.0 beats min(-1), 862.1 ohms and 134.0 beats min(-1), 1114.6 ohms, respectively). The averaged curve and standard deviation curve of the impedance in sinus rhythm were analysed in MATLAB to clarify and study consistent impedance shape over one heart cycle. In eight of nine (89%) animal subjects, a consistent impedance slope change (notch) was observed in the early stage of the cardiac filling phase. This result was reproduced in an additional subject with simultaneous echocardiographical measurements of mitral valve blood flow. The notch occured soon after rapid early filling (E-wave in mitral flow) but prior to ventricular filling caused by atrial contraction, indicating that the impedance notch was caused by rapid ventricular filling and that it might be a sensed feature of diagnostic value. The intracardiac impedance notch in the present study had similar features to the non-invasive transthoracic impedance O-wave reported by others, and it is shown here that an O-wave is found in intracardiac impedance signals, strongly suggesting that the non-invasive O-wave is caused by cardiac events.
Animals↗
Eleven years' experience with the Biocor stentless aortic bioprosthesis: clinical and hemodynamic follow-up with long-term relative survival rate.
OBJECTIVE: The long-term durability and hemodynamics of stentless valves are largely unknown. Our aim was to prospectively investigate long-term hemodynamic function and clinical outcome after aortic valve replacement with the Biocor stentless aortic bioprosthesis. PATIENTS AND METHODS: Between October 1990 and November 2000 we inserted the Biocor stentless aortic valve in 112 patients (male/female: 38:74) with a mean age of 78.5 years (median 79.3, range 60-88). The predominant diagnosis was aortic stenosis in 86% of the patients. Concomitant coronary artery bypass surgery was performed in 31% of the patients. Average prosthetic valve size was 23.3+/-1.6 mm. All patients were followed in a prospective study with a mean follow-up of 66+/-33 months. The follow-up was 100% complete with a closing interval from October 1 to December 31, 2001. The observed actuarial survival of patients was compared to expected survival for an age- and gender-matched comparison population as calculated from Swedish life tables by Statistics Sweden. Relative survival rates were calculated annually for the patient population. RESULTS: Early mortality was 7% (8/112). Late mortality was 38% (43/112). Actuarial survival at 5 and 9 years was 74+/-5% and 38+/-7%, respectively. Observed survival among patients was not different from the expected survival for the comparison population and calculation of relative survival rates indicates a 'normalized' survival pattern for the patient population. At 5 and 9 years the actuarial freedom from valve-related death was 94+/-3% and 86+/-6%; from cardiac death, 82+/-4% and 57+/-8%; from valve reoperation, 96+/-2% and 87+/-6%; from structural valve degeneration, 96+/-2% and 87+/-6%; from thromboembolism, 89+/-4% and 71+/-9%; and from endocarditis, 96+/-2% and 90+/-5%. At 9 years the transvalvular mean pressure difference for all valves was 7.3+/-1.3 mmHg (range 6-10 mmHg) measured with Doppler echocardiography. Aortic regurgitation progressed slowly over time in a few patients and necessitated reoperation in two patients. CONCLUSION: The Biocor stentless bioprosthesis has an excellent hemodynamic function and confers a good long-term outcome. This patient population could be regarded as 'cured' from valve disease since the observed survival did not differ from the expected survival for an age- and gender-matched Swedish comparison population, a conclusion that is also supported by a constant relative survival after the first postoperative year. However, despite excellent long-term hemodynamics, patients with stentless bioprostheses need to be evaluated with echocardiography at regular intervals to discover the rare cases of progressive aortic regurgitation.
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Analysis of temporal requirements for myocardial tissue velocity imaging.
AIMS: Movements of myocardial walls include components of high velocity and short duration calling for a high sampling rate in the acquisition of tissue velocity imaging data. This study aims at establishing the optimal sampling requirements for tissue velocity imaging measurements. METHODS AND RESULTS: In 16 healthy individuals, tissue velocity imaging data were acquired at a frame rate of 141-203 frames/s for a subsequent off-line analysis using software enabling a reduction of the sampling rate to 50%, 25% and 12.5% of the initial frame rate. Different components of the myocardial velocity profile were measured at each of these frame rates. The deviation of the results from the initial values increased markedly at decreasing frame rates, producing an underestimation of peak systolic and diastolic velocities, most other measured parameters being overestimated. A cut-off point for an acceptable < or =10% deviation of the results corresponded to at least 70 frames/s for peak systolic and early diastolic velocity, and to at least 100 frames/s for other systolic and diastolic parameters. CONCLUSION: A high sampling rate is essential for a proper rendering of tissue velocity imaging signals, too low frame rates resulting in inferior accuracy of the results. This should be kept in mind while viewing reported tissue velocity imaging data.
Adolescent↗
Deterioration in peak systolic velocity is closely related to ischaemia during angioplasty: a vectorcardiographic and tissue Doppler imaging study.
We tested the hypothesis that the extent of signs of ischaemia detected by vectorcardiography (VCG) during elective coronary angioplasty (percutaneous transluminal coronary angioplasty; PTCA) is related to systolic and diastolic myocardial velocities, as determined by tissue Doppler echocardiography. A total of 15 patients undergoing PTCA (12 men/three women; age 61+/-9 years), without prior myocardial infarction and with an ejection fraction of >50%, were included. The balloon inflation was repeated three times, with minimum intervals of 2 min between inflations. Tissue Doppler echocardiography was performed, in an apical two- or four-chamber view, before and at the end of each inflation. Peak systolic velocity, time-to-peak systolic velocity (TTP), peak early (E(m)) and late (A(m)) diastolic velocities, the E(m)/A(m) ratio and isovolumic relaxation time were measured in the basal segments of the left ventricle. VCG recordings were carried out during the whole procedure. ST vector magnitude (ST-VM) and ST change vector magnitude (STC-VM) were monitored. The total duration and area of each VCG change during inflation were calculated for each patient. Isovolumic relaxation time, peak E(m) and A(m) values and the E(m)/A(m) ratio did not change significantly during inflation. Peak systolic velocity decreased (6.7+/-2.0 to 5.3+/-1.9 cm/s; P<0.001) and TTP increased (157+/-60 to 192+/-60 ms; P<0.01) during inflation. Both STC-VM time (r=-0.68, P<0.01) and STC-VM area (r=-0.68, P<0.01) were related to peak systolic velocity during inflation. STC-VM time was also related (r=0.55, P<0.05) to the difference in peak systolic velocity during compared with before inflation. ST-VM was less closely related to peak systolic velocity. Thus the duration and degree of ischaemia, as measured by VCG, are related to peak systolic velocity in the basal segments of the left ventricle.
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Effects of intramyocardial injection of phVEGF-A165 as sole therapy in patients with refractory coronary artery disease--12-month follow-up: angiogenic gene therapy.
OBJECTIVE: To test the safety and bioactivity of phVEGF-A165 after intramyocardial injection during 12-month follow-up. DESIGN: Open-labelled study. SUBJECTS: Inclusion criteria were angina pectoris, Canadian Cardiovascular Society (CCS) class III-IV, unamenable to further revascularization, ejection fraction (EF) >30%, perfusion defects extending over >10% of the anterolateral left ventricle wall detectable with adenosine single photon emission computerized tomography (SPECT) and at least one patent vessel visible by coronary angiography. Seven of 39 patients referred for gene therapy were included. INTERVENTION: Via a mini-thoracotomy under general anaesthesia. phVEGF-A165 was injected directly into the myocardium at four sites in the anterolateral region of the left ventricle. RESULTS: Operative procedures were uneventful. Perioperative release of myocardial markers and electrocardiogram (ECG) changes were detected in two patients. There were no perioperative deaths but one patient died 7 months postoperatively because of myocardial infarction. Plasma vascular endothelial growth factor (VEGF)-A levels increased two to threefold peaking 6 days postoperatively (P < 0.004) and returning to baseline by day 30. A significant reduction in angina pectoris was reported. The CCS class improved from 3.3+/-0.2 to 1.9+/-0.3 (P < 0.01) and nitroglycerine intake decreased from 39+/-15 to 12+/-5 tablets week(-1) (P < 0.001) 2 months after gene transfer. Improvements remained after 12 months when nitroglycerine consumption approached zero. Improved myocardial function in the phVEGF-A165 injection region was documented in all patients (P < 0.016) by tissue velocity imaging (TVI). Reduced reversible ischaemia was detected by adenosine SPECT in four patients. Improved collateralization was detected in four patients with coronary angiography. CONCLUSION: Intramyocardial injection of phVEGF-A165 is safe and may lead to improved myocardial perfusion and function with longstanding symptomatic relief in end-stage angina pectoris. Based on these results this therapeutic potential is being tested in a double-blind placebo controlled multicentre trial.
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Correlation between a mid-ventricular volume segment and global left ventricular volume measured by the conductance catheter.
OBJECTIVES: To investigate whether acute volume changes in single volume segments of the left ventricle can be correlated with global volume changes. If so, changes in global volume might be predicted from changes in segmental volumes. DESIGN: Volume changes were recorded in six pigs in five intraventricular segments, from apex to heart base, using the conductance catheter (at baseline, after 60 min of apical ischaemia, during preload reduction and afterload increase). A computer algorithm was created to calculate the instantaneous absolute difference between the curve shape of global and normalized segmental volume as a percentage of global stroke volume. RESULTS: For a mid-cardiac volume segment constituting 34 (14-39)% [median (range)] of global stroke volume, the mean difference over a cardiac cycle was 4 (1-8)% at baseline. Apical ischaemia resulted in apical dyskinesia, but did not influence the mid-cardiac segment. CONCLUSIONS: The volume curve from a segment at mid-cardiac level seems to be a good estimator of the global volume curve, thus giving a foundation for estimation of global volume changes from such a segment.
Animals↗
Death related to coronary artery fistula after rupture of an aneurysm to the coronary sinus.
Large coronary fistulas are considered to cause myocardial ischemia due to diversion of the coronary blood flow. In this case the authors report the reverse effect--the spontaneous closure of a large fistulation between the left circumflex artery and the coronary sinus evoked angina pectoris in a middle aged man, who died several years later. Postmortem examination revealed a coronary aneurysm that had ruptured and dissected into the coronary sinus and finally thrombosed. The origin of the aneurysm could be congenital but perhaps also represents a healed stage of Kawasaki disease.
Autopsy↗
Myocardial Doppler tissue velocity improves following myocardial gene therapy with VEGF-A165 plasmid in patients with inoperable angina pectoris.
BACKGROUND: Myocardial tissue velocity and perfusion were studied in patients with severe angina pectoris following gene therapy by intramyocardial injection of phVEGF-A165 via thoracotomy. Plasma concentrations of VEGF-A increased postoperatively. Two months after treatment anginal status and myocardial tissue velocity improved and perfusion showed a tendency to improve. Tissue velocity imaging appears to be a sensitive, objective method for detecting changes in myocardial function following gene therapy. OBJECTIVE: To study effects on myocardial tissue velocity and perfusion in patients with angina pectoris following intramyocardial injection of phVEGF-A165 via thoracotomy. DESIGN: Open label, phase I/II. METHODS: Six patients with Canadian Cardiovascular Society (CCS) angina pectoris functional class III - IV and with major defects at adenosine stress single-photon emission computerized tomography (SPECT) were studied. In addition to SPECT, coronary angiography and dobutamine stress echocardiography with tissue Doppler velocity imaging were performed before and two months after gene transfer. RESULTS: Plasma concentrations of VEGF-A increased 2 to 3 times (P < 0.04) over baseline from 2 to 14 days after injection with normalization after 4 weeks. The CCS class improved about 40%, from 3.3 +/- 0.2 to 2.0 +/- 0.3 (P < 0.02) and nitroglycerine consumption decreased 30 - 40%, from 44 +/- 17 to 15 +/- 5 tablets per week (P < 0.05). The maximal systolic myocardial tissue velocity increased in all patients about 25% (P < 0.02) but did not reach the reference range. Myocardial perfusion at SPECT improved in four of the six patients. CONCLUSIONS: Anginal status, myocardial tissue velocity and perfusion can be improved by phVEGF-A165 intramyocardial injection. Tissue velocity imaging appears to be a sensitive, objective method for detecting changes in myocardial function following gene therapy.
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[Hopeful future for echocardiography. Progress within both the function and perfusion areas].
Echocardiography is presently a feasible method for quantitative estimation of intracardiac flows, pressure levels and for hemodynamic evaluation of valvular disease. The evaluation of regional myocardial function is still based on subjective scrutiny, and no routine method for the estimation of myocardial blood flow is available. We present an overview of newly developed techniques that are beginning to gain purchase in clinical practice. The use of native second harmonic imaging to improve image quality and of tissue Doppler to provide objective measurements of regional myocardial function is discussed. This article describes the transformation of tissue Doppler information into parametric images as in strain rate imaging, and overviews the use of ultrasound contrast agents. Used together with new imaging modalities, myocardial contrast echocardiography holds promise for future quantification of myocardial blood volume and flow. Other emerging echocardiographic technologies discussed are non-invasive measurement of coronary flow reserve and three dimensional cineloop visualization, developed to increase our understanding of cardiovascular physiological and anatomical coupling.
Contrast Media↗
Retrograde crystalloid cardioplegia preserves left ventricular systolic function better than antegrade cardioplegia in patients with occluded coronary arteries.
OBJECTIVE: To investigate retrograde and antegrade crystalloid cardioplegia in terms of cardiac cooling and postoperative cardiac function. DESIGN: Prospective, randomized, and blinded. SETTING: University hospital. PARTICIPANTS: Twenty male patients with triple-vessel disease and proximal occlusion of the circumflex or the left anterior descending coronary artery. INTERVENTIONS: Left ventricular ejection fraction at rest and during exercise was evaluated by nuclear ventriculography the day before and 3 months after surgery. After induction of anesthesia and hourly for the first 5 postoperative hours, hemodynamic, echocardiographic, and electrocardiographic data were acquired. Myocardial temperature was measured with needle thermistors in 3 myocardial regions. MEASUREMENTS AND MAIN RESULTS: Demographic and temperature data were analyzed by t-test. Hemodynamic and echocardiographic data were analyzed by analysis of variance. The groups were similar in baseline characteristics. Retrograde cardioplegia cooled the region distal to an occlusion better than antegrade cardioplegia (9.6 degrees C +/- 4.8 degrees C v 21.8 degrees C +/- 5.9 degrees C; p < 0.01). Hemodynamic, echocardiographic, and electrocardiographic data did not differ between the groups. Three months after surgery, the retrograde cardioplegia group showed a higher left ventricular ejection fraction at rest (58% +/- 10% v 47% +/- 10%; p < 0.02) and during exercise (58% +/- 13% v 47% +/- 10%; p < 0.05) compared with the antegrade cardioplegia group. CONCLUSIONS: Retrograde cardioplegia provides more homogenous myocardial cooling than antegrade cardioplegia in hearts with coronary artery occlusions. The use of retrograde cardioplegia seems to benefit long-term left ventricular function.
Cardioplegic Solutions↗
Angiotensin-converting enzyme gene polymorphism influences degree of left ventricular hypertrophy and its regression in patients undergoing operation for aortic stenosis.
Insertion (I)/deletion (D) polymorphism of the angiotensin-converting enzyme (ACE) gene has been associated with increased left ventricular hypertrophy (LVH) in patients with cardiomyopathy and congestive heart failure. Patients with aortic stenosis (AS) have varying degrees of LVH at a given valve area. The aim of this study was to examine the relation between ACE gene polymorphism and the degree of LVH in patients undergoing operation for AS. Eighty-two patients who underwent operation for AS with a stentless valve were followed prospectively with echocardiographic assessments of left ventricular mass index (LVMI). ACE gene polymorphism was determined by polymerase chain reaction. The genotype (DD, ID, and II) frequency was the same as in healthy controls. The pressure difference across the aortic valve did not differ between genotypes. Patients with the DD genotype of the ACE gene had a higher LVMI (197 +/- 47 g/m2) preoperatively than those with ID (175 +/- 41 g/m2) or II (155 +/- 43 g/m2) genotypes (p = 0.01). LVMI decreased significantly in DD (p <0.001) and ID (p <0.001) genotypes but not in the II genotype during follow-up (mean 15 months). There was a significant difference in regression of LVMI over time between genotypes (p = 0.0056), with no significant difference between genotypes at follow-up. The DD genotype of the ACE gene is associated with increased preoperative LVH in patients treated surgically for AS. The DD genotype appears to be an important factor which increases hypertrophic myocardial reactivity to pressure overload.
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Effects of exercise on Doppler-derived pressure difference, valve resistance, and effective orifice area in different aortic valve prostheses of similar size.
The effects of increased transvalvular volume flow on Doppler-derived measurements were compared in similarly sized, normally functioning, mechanical prostheses, stented and stentless porcine bioprostheses, and homografts. Homograft and stentless valves showed the largest effective orifice area and the lowest pressure differences and valve resistance at rest and during exercise-induced increase in flow rates.
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Temporal variability of exercise Doppler echocardiography in patients with nonstented aortic bioprostheses.
Temporal variability and reproducibility of Doppler-derived variables obtained during supine symptom-limited exercise was investigated in 26 patients who were in clinically and hemodynamically stable condition with normally functioning nonstented aortic bioprostheses (stentless porcine, n = 13; cryopreserved homografts, n = 13). All patients had normal systolic left ventricular function and underwent 2 similar exercise tests within 12 months (mean time interval 7.2 +/- 1.9 months). The coefficient of variation was 8% to 9% for primary Doppler-derived variables (ie, velocities and velocity time integrals) at rest and during exercise. The coefficient of variation for calculated maximal pressure difference was 16% at rest and 15% at peak exercise. Measurement variability assessed from repeated measurements from the same videotaped recording was approximately 2%. High reproducibility was shown for most variables with intraclass correlation coefficients of 0.85 or more. We conclude that Doppler echocardiography can be used in patients with nonstented aortic bioprostheses with the same high reproducibility during exercise as at rest. The results provide clinically useful information regarding temporal variability for Doppler-derived variables.
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The extended Biocor stentless aortic bioprosthesis. Early clinical experience.
In the "Extended" Biocor stentless aortic bioprosthesis, supra- and subvalvular extensions to a bovine pericardium ring carry three porcine leaflets. The extensions cover the "non-coronary" sinus of the prosthesis and allow optional enlargement of the aortic root down towards the mitral valve as well as upwards into the aortotomy. Seventy-one patients with this stentless valve (62 with predominantly aortic stenosis, 28 with concomitant CABG) are being prospectively studied. This paper reports follow-up one year after insertion. The upper and lower pericardial extensions were used in 61 and 11 patients, respectively. The average prosthetic valve size was 23.2 +/- 1.6 mm. Early mortality was 7% (5/71); late mortality (4/66, 5%/patient year) was not valve-related. Symptoms of thromboembolism (new neurological defects) occurred in four patients. There was no valve failure or late endocarditis. One year postoperatively the transvalvular mean pressure difference for all valves was 7.9 (3.1-18.4) mmHg. None of the patients had haemodynamically significant aortic regurgitation at follow-up; nine had trivial regurgitation. The "Extended" Biocor stentless bioprosthesis thus has a favourable haemodynamic profile and can be advantageous in elderly patients with narrow aortic roots, and often with thin and/or calcified aortic walls.
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