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Biomedical subjects

J R Roelandt

Publications and source records attributed to J R Roelandt.

At least 19 recordsLinked to original sources
PubMed2001

Real-time quantification and display of skin radiation during coronary angiography and intervention.

BACKGROUND: Radiographically guided investigations may be associated with excessive radiation exposure, which may cause skin injuries. The purpose of this study was to develop and test a system that measures in real time the dose applied to each 1-cm(2) area of skin, taking into account the movement of the x-ray source and changes in the beam characteristics. The goal of such a system is to help prevent high doses that might cause skin injury. METHODS AND RESULTS: The entrance point, beam size, and dose at the skin of the patient were calculated by use of the geometrical settings of gantry, investigation table, and x-ray beam and an ionization chamber. The data are displayed graphically. Three hundred twenty-two sequential cardiac investigations in adult patients were analyzed. The mean peak entrance dose per investigation was 0.475 Gy to a mean skin area of 8.2 cm(2). The cumulative KERMA-area product per investigation was 52.2 Gy/cm(2) (25.4 to 99.2 Gy/cm(2)), and the mean entrance beam size at the skin was 49.2 cm(2). Twenty-eight percent of the patients (90/322) received a maximum dose of <1 Gy to a small skin area ( approximately 6 cm(2)), and 13.5% of the patients (42/322) received a maximum dose of >2 Gy. CONCLUSIONS: Monitoring of the dose distribution at the skin will alert the operator to the development of high-dose areas; by use of other gantry settings with nonoverlapping entrance fields, different generator settings, and extra collimation, skin lesion can be avoided.

Adult↗
PubMed2001

Predictors of cardiac events after major vascular surgery: Role of clinical characteristics, dobutamine echocardiography, and beta-blocker therapy.

CONTEXT: Patients who undergo major vascular surgery are at increased risk of perioperative cardiac complications. High-risk patients can be identified by clinical factors and noninvasive cardiac testing, such as dobutamine stress echocardiography (DSE); however, such noninvasive imaging techniques carry significant disadvantages. A recent study found that perioperative beta-blocker therapy reduces complication rates in high-risk individuals. OBJECTIVE: To examine the relationship of clinical characteristics, DSE results, beta-blocker therapy, and cardiac events in patients undergoing major vascular surgery. DESIGN AND SETTING: Cohort study conducted in 1996-1999 in the following 8 centers: Erasmus Medical Centre and Sint Clara Ziekenhuis, Rotterdam, Twee Steden Ziekenhuis, Tilburg, Academisch Ziekenhuis Utrecht, Utrecht, and Medisch Centrum Alkmaar, Alkmaar, the Netherlands; Ziekenhuis Middelheim, Antwerp, Belgium; and San Gerardo Hospital, Monza, Istituto di Ricovero e Cura a Carattere Scientifico, San Giovanni Rotondo, Italy. PATIENTS: A total of 1351 consecutive patients scheduled for major vascular surgery; DSE was performed in 1097 patients (81%), and 360 (27%) received beta-blocker therapy. MAIN OUTCOME MEASURE: Cardiac death or nonfatal myocardial infarction within 30 days after surgery, compared by clinical characteristics, DSE results, and beta-blocker use. RESULTS: Forty-five patients (3.3%) had perioperative cardiac death or nonfatal myocardial infarction. In multivariable analysis, important clinical determinants of adverse outcome were age 70 years or older; current or prior angina pectoris; and prior myocardial infarction, heart failure, or cerebrovascular accident. Eighty-three percent of patients had less than 3 clinical risk factors. Among this subgroup, patients receiving beta-blockers had a lower risk of cardiac complications (0.8% [2/263]) than those not receiving beta-blockers (2.3% [20/855]), and DSE had minimal additional prognostic value. In patients with 3 or more risk factors (17%), DSE provided additional prognostic information, for patients without stress-induced ischemia had much lower risk of events than those with stress-induced ischemia (among those receiving beta-blockers, 2.0% [1/50] vs 10.6% [5/47]). Moreover, patients with limited stress-induced ischemia (1-4 segments) experienced fewer cardiac events (2.8% [1/36]) than those with more extensive ischemia (>/=5 segments, 36% [4/11]). CONCLUSION: The additional predictive value of DSE is limited in clinically low-risk patients receiving beta-blockers. In clinical practice, DSE may be avoided in a large number of patients who can proceed safely for surgery without delay. In clinically intermediate- and high-risk patients receiving beta-blockers, DSE may help identify those in whom surgery can still be performed and those in whom cardiac revascularization should be considered.

Adrenergic beta-Antagonists↗
PubMed2001

Human tissue valves in aortic position: determinants of reoperation and valve regurgitation.

BACKGROUND: Human tissue valves for aortic valve replacement have a limited durability that is influenced by interrelated determinants. Hierarchical linear modeling was used to analyze the relation between these determinants of durability and valve regurgitation measured by serial echocardiography. METHODS AND RESULTS: In adult patients, 218 cryopreserved aortic allografts were implanted with the subcoronary (85) or the root replacement technique (133), and 81 patients had root replacement with a pulmonary autograft. Mean follow-up was 4.2 years (SD 2.7; range, 0 to 10.5). Patient age, operator experience with subcoronary implantation, and allograft diameter were independent predictors for reoperation. With repeated color Doppler echocardiography, the severity of aortic regurgitation was assessed by the jet length method and the jet diameter ratio. Multilevel hierarchical linear modeling was used to estimate initial aortic regurgitation (intercept), its change over time (slope), and the effect of 11 potential determinants of durability on aortic regurgitation. With the jet length method, the intercept was 0.94 grade and the slope was 0.11 grade per year. With the jet diameter ratio, the intercept was 0.34 and the annual increase was 0.01. Subcoronary implanted valves had more initial aortic regurgitation, but progression of aortic valve regurgitation did not differ from root replacement. At midterm follow-up, recipient age <40 years was the only independent predictor of aortic regurgitation. CONCLUSIONS: Subcoronary implantation has a learning curve, resulting in more initial aortic regurgitation and early reoperation compared with root replacement. In both techniques, progression of aortic regurgitation over time is small but accelerated in young adults.

Adolescent↗
PubMed2001

Evaluation of left ventricular function and volumes in patients with ischaemic cardiomyopathy: gated single-photon emission computed tomography versus two-dimensional echocardiography.

UNLABELLED: The objective of this study was to perform a head-to-head comparison between two-dimensional (2D) echocardiography and gated single-photon emission computed tomography (SPET) for the evaluation of left ventricular (LV) function and volumes in patients with severe ischaemic LV dysfunction. Thirty-two patients with chronic ischaemic LV dysfunction [mean LV ejection fraction (EF) 25%+/-6%] were studied with gated SPET and 2D echocardiography. Regional wall motion was evaluated by both modalities and scored by two independent observers using a 16-segment model with a 5-point scoring system (1= normokinesia, 2= mild hypokinesia, 3= severe hypokinesia, 4= akinesia and 5= dyskinesia). LVEF and LV end-diastolic and end-systolic volumes were evaluated by 2D echocardiography using the Simpson's biplane discs method. The same parameters were calculated using quantitative gated SPET software (QGS, Cedars-Sinai Medical Center). The overall agreement between the two imaging modalities for assessment of regional wall motion was 69%. The correlations between gated SPET and 2D echocardiography for the assessment of end-diastolic and end-systolic volumes were excellent (r=0.94, P<0.01, and r=0.96, P<0.01, respectively). The correlation for LVEF was also good (r=0.83, P<0.01). IN CONCLUSION: in patients with ischaemic cardiomyopathy, close and significant relations between gated SPET and 2D echocardiography were observed for the assessment of regional and global LV function and LV volumes; gated SPET has the advantage that it provides information on both LV function/dimensions and perfusion.

Cardiomyopathies↗
PubMed2001

Impact of heart transplantation on the safety and feasibility of the dobutamine stress test.

BACKGROUND: Dobutamine myocardial perfusion imaging is a useful method for evaluation of coronary artery disease. However, this technique does not allow for ischemia monitoring, which may have an impact on the safety of the test in heart transplant recipients due to cardiac sensory denervation. The aim of this study was to assess the impact of heart transplantation on the feasibility and complications of the dobutamine stress test. METHODS: We studied 225 heart transplant recipients (mean age 57 +/- 7 years) and a control group of 225 patients without previous transplant matched for age and gender by dobutamine (up to 40 microg/kg per minute) stress myocardial perfusion imaging. RESULTS: During the test, transplant recipients had a lower prevalence of premature ventricular contractions (23% vs. 37%, p < 0.001) and ventricular tachycardia (0.04% vs 7.5%, p < 0.0001) compared with control patients. By multivariate analysis, heart transplantation was a powerful independent variable associated with a reduced risk of ventricular arrhythmias (chi(2) = 20.8, p < 0.0001) and minor side effects (nausea, dizziness, anxiety, flushing, chills) (chi(2) = 20, p < 0.0001) during dobutamine stress. The target heart rate was reached in 82% of transplant recipients and in 77% of the control group. Overall feasibility (achievement of the target heart rate and/or an ischemic end-point) was 87% in the transplant and 86% in the control group. CONCLUSIONS: Dobutamine stress myocardial perfusion imaging is a safe and feasible method for evaluation of coronary artery disease in heart transplant recipients. The prevalence of arrhythmias and minor complications using the dobutamine stress test is lower in heart transplant recipients compared with control patients. The independent association between heart transplantation and reduced risk of arrhythmias and minor side effects of the dobutamine stress test indicates that cardiac sensory and autonomic nerve function plays a major role in the induction of these complications during the test.

Cardiotonic Agents↗
PubMed2001

Bisoprolol reduces cardiac death and myocardial infarction in high-risk patients as long as 2 years after successful major vascular surgery.

AIM: To assess the long-term cardioprotective effect of bisoprolol in a randomized high-risk population after successful major vascular surgery. High-risk patients were defined by the presence of one or more cardiac risk factor(s) and a dobutamine echocardiography test positive for ischaemia. METHODS: 1351 patients were screened prior to surgery, 846 patients had one or more risk factor(s), and 173 of these patients also had ischaemia during dobutamine echocardiography. One hundred and twelve patients could be randomized for additional bisoprolol therapy or standard care. Eleven patients died in the peri-operative period (up to 1 month after surgery). Randomized patients continued bisoprolol or standard care after surgery. During follow-up of 101 survivors (median 22 months, range 11-30) cardiac death or myocardial infarction was noted. No patient was lost during follow-up. Results The incidence of cardiac events during follow-up in the bisoprolol group was 12% vs 32% in the standard care group (P=0.025). Cardiac death occurred in 15 patients, nine patients in the standard care and in six in the bisoprolol group; myocardial infarction occurred in six patients, five in the standard care and one in the bisoprolol group. The odds ratio for cardiac death or myocardial infarction after surgery in high-risk patients with additional bisoprolol therapy was 0.30 (0.11-0.83). CONCLUSIONS: Bisoprolol significantly reduced long-term cardiac death and myocardial infarction in high-risk patients after successful major cardiac vascular surgery.

Adrenergic beta-Antagonists↗
PubMed2001

Initial clinical experience with a new arrhythmia detection algorithm in dual chamber implantable cardioverter defibrillators.

AIM: Inappropriate therapy, due to poor discrimination of supraventricular tachycardia (SVT) from ventricular tachycardia (VT) remains a major problem in patients with an implantable cardioverter defibrillator (ICD). Theoretically, the addition of atrial sensing in discrimination algorithms should improve this differentiation. The aim of the study is to evaluate the performance of a new tachycardia discrimination algorithm, SMART Detection. METHODS AND RESULTS: Twenty-six patients received a non-thoracotomy ICD system (Phylax AV, Biotronik, Germany). All documented spontaneous arrhythmia episodes were analyzed. During a mean follow-up of 8 months, a total number of 139 events with stored electrograms were recorded in 12 patients. The final diagnosis was ventricular fibrillation (VF) or polymorphic VT (n=20), monomorphic VT (n=69), SVT (n=26), other ventricular arrhythmia (n=3) and T wave oversensing (n=21). In 6 episodes a dual tachycardia was present. Considering SVT episodes, inappropriate therapy occurred in 2 cases of atrial flutter due to stable ventricular rate (<30 ms), 1 case of atrial tachycardia and 2 cases of sinus tachycardia due to a sudden onset (> 10%). CONCLUSION: With the SMART Detection algorithm, discrimination of VT from SVT achieved a sensitivity of 100%, with an accuracy of 95.6% for all ventricular arrhythmias. In the case of SVT, the algorithm appropriately detected and inhibited therapy in 88% of atrial fibrillation.

Adult↗
PubMed2001

Second harmonic imaging improves sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease.

OBJECTIVE: Our purpose was to assess the value of second harmonic imaging compared with fundamental imaging for the diagnosis of coronary artery disease during dobutamine stress echocardiography. PATIENTS AND METHODS: Sixty-four patients underwent dobutamine stress echocardiography with both fundamental imaging and second harmonic imaging. Coronary angiography was performed within 3 months. Ischemia was defined as new or worsening wall motion abnormalities in > or = 1 segment during dobutamine stress echocardiography. Coronary artery disease was defined as a > or = 70% luminal diameter stenosis in > or = 1 coronary artery by coronary angiography. RESULTS: There was a higher prevalence of segments with invisible border with fundamental compared with second harmonic imaging both at rest (11% vs 8%, P < .05) and at peak stress (17% vs 10%, P < .001). Significant coronary artery disease was present in 49 (77%) patients. The sensitivity of dobutamine stress echocardiography for detection of coronary artery disease by fundamental and second harmonic imaging was, respectively, 78% and 94% (P < .05), whereas specificity was similar (73% vs 73%). Second harmonic imaging had a particularly higher sensitivity for the diagnosis of 1-vessel disease (93% vs 50%, P < .05). CONCLUSION: The use of second harmonic imaging improves the sensitivity of dobutamine stress echocardiography for the diagnosis of coronary artery disease compared with fundamental imaging, particularly for 1-vessel coronary artery disease, whereas specificity remains unchanged.

Chi-Square Distribution↗
PubMed2001

Impact of hypertension on the accuracy of exercise stress myocardial perfusion imaging for the diagnosis of coronary artery disease.

AIM: To compare the accuracy of exercise stress myocardial perfusion single photon emission computed tomography (SPECT) imaging for the diagnosis of coronary artery disease in patients with and without hypertension. METHODS: A symptom limited bicycle exercise stress test in conjunction with 99m technetium sestamibi or tetrofosmin SPECT imaging was performed in 332 patients (mean (SD) age, 57 (10) years; 257 men, 75 women) without previous myocardial infarction who underwent coronary angiography. Of these, 137 (41%) had hypertension. Rest SPECT images were acquired 24 hours after the stress test. An abnormal scan was defined as one with reversible or fixed perfusion defects. RESULTS: In hypertensive patients, myocardial perfusion abnormalities were detected in 79 of 102 patients with significant coronary artery disease and in nine of 35 patients without. In normotensive patients, myocardial perfusion abnormalities were detected in 104 of 138 patients with significant coronary artery disease and in 16 of 57 patients without. There were no differences between normotensive and hypertensive patients in sensitivity (77% (95% confidence interval (CI) 69% to 86%) v 75% (95% CI 68% to 83%)), specificity (74% (95% CI 60% to 89%) v 72% (95% CI 60% to 84%)), and accuracy (77% (95% CI 70% to 84%) v 74% (95% CI 68% to 80%)) of exercise SPECT for diagnosing coronary artery disease. The accuracy of SPECT was greater than electrocardiography, both in hypertensive patients (p = 0.005) and in normotensive patients (p = 0.0001). For the detection of coronary artery disease in individual vessels, sensitivity was 58% (95% CI 51% to 65%) v 57% (95% CI 51% to 64%), specificity was 86% (95% CI 82% to 90%) v 85% (95% CI 81% to 89%), and accuracy was 74% (95% CI 70% to 78%) v 74% (95% CI 70% to 78%) in patients with and without hypertension (NS). CONCLUSIONS: In the usual clinical setting, the value of exercise myocardial perfusion scintigraphy for diagnosing coronary artery disease is not degraded by the presence of hypertension.

Aged↗
PubMed2001

Transseptal left heart catheterisation guided by intracardiac echocardiography.

OBJECTIVE: To develop a novel approach of transseptal puncture guided by intracardiac echocardiography and to assess its efficacy. METHODS: Transcatheter intracardiac echocardiography with a 9 MHz rotating transducer was performed to guide transseptal puncture in 12 patients (mean age 43.1 years, range 31-68) who underwent radiofrequency catheter ablation of left sided accessory pathways. Initially, the echocardiography and transseptal catheters were placed adjacent to each other in the superior vena cava and were withdrawn to the level of the fossa ovalis. RESULTS: The successful puncture site was associated with visualisation of the fossa ovalis (12 patients, 100%) and the aorta (12 patients, 100%), tenting of the fossa (six patients, 50%), penetration of the needle visualised by the ultrasound catheter (12 patients, 100 %), and echocardiographic contrast material applied in the left atrium (12 patients, 100%). The characteristic jump of the needle onto the fossa ovalis was observed simultaneously with fluoroscopy and intracardiac ultrasound (12 patients, 100%). All procedures were successful. There were no complications associated with the transseptal procedure. CONCLUSIONS: Intracardiac echocardiography is feasible to guide transseptal puncture. The optimal puncture site can be assessed by simultaneous detection of the characteristic downward jump of the transseptal needle onto the fossa ovalis by intracardiac ultrasound and fluoroscopy.

Adult↗
PubMed2001

Improved identification of viable myocardium using second harmonic imaging during dobutamine stress echocardiography.

OBJECTIVE: To determine whether, compared with fundamental imaging, second harmonic imaging can improve the accuracy of dobutamine stress echocardiography for identifying viable myocardium, using nuclear imaging as a reference. PATIENTS: 30 patients with chronic left ventricular dysfunction (mean (SD) age, 60 (8) years; 22 men). METHODS: Dobutamine stress echocardiography was carried out in all patients using both fundamental and second harmonic imaging. All patients underwent dual isotope simultaneous acquisition single photon emission computed tomography (DISA-SPECT) with (99m)technetium-tetrofosmin/(18)F-fluorodeoxyglucose on a separate day. Myocardial viability was considered present by dobutamine stress echocardiography when segments with severe dysfunction showed a biphasic sustained improvement or an ischaemic response. Viability criteria on DISA-SPECT were normal or mildly reduced perfusion and metabolism, or perfusion/metabolism mismatch. RESULTS: Using fundamental imaging, 330 segments showed severe dysfunction at baseline; 144 (44%) were considered viable. The agreement between dobutamine stress echocardiography by fundamental imaging and DISA-SPECT was 78%, kappa = 0.56. Using second harmonic imaging, 288 segments showed severe dysfunction; 138 (48%) were viable. The agreement between dobutamine stress echocardiography and DISA-SPECT was significantly better when second harmonic imaging was used (89%, kappa = 0.77, p = 0.001 v fundamental imaging). CONCLUSIONS: Second harmonic imaging applied during dobutamine stress echocardiography increases the agreement with DISA-SPECT for detecting myocardial viability.

Cardiotonic Agents↗
PubMed2000

Comparison of mechanical properties of the left ventricle in patients with severe coronary artery disease by nonfluoroscopic mapping versus two-dimensional echocardiograms.

In 40 patients, we compared linear local shortening assessed with nonfluoroscopic electromechanical mapping as a function of regional wall motion with echocardiographic data in a subset of patients with severe coronary artery disease and subsequently decreased left ventricular function. Our study showed that nonfluoroscopic electromechanical mapping can accurately assess regional wall motion. In addition, this study showed a significant decrease in unipolar voltages among segments with declining regional function.

Analysis of Variance↗