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Biomedical subjects

Peter Buser

Publications and source records attributed to Peter Buser.

At least 19 recordsLinked to original sources
PubMed2006

Transesophageal Doppler echocardiographic detection of intramyocardial collateral flow to the right coronary artery and changes in the flow to the inferior left ventricular wall immediately after coronary artery bypass grafting.

This study examined the feasibility of Doppler transesophageal echocardiography (TEE) to detect collateral flow to the myocardium supplied by the right coronary artery (RCA) in the inferior left ventricular wall. Forty-four patients who underwent elective coronary artery bypass grafting (CABG) were prospectively studied. Presence of collateral flow to the RCA was diagnosed on preoperative angiography using the Rentrop score and by intraoperative Doppler TEE. Agreement of the 2 methods was analyzed by calculating the kappa coefficient. Collateral flow was present on preoperative angiography in 19 patients and absent in 25 patients. Intraoperative TEE detected collateral flow in the inferior wall in 15 patients (79%) with and 3 patients (12%) without angiographic collaterals, resulting in a kappa coefficient for agreement of 0.67 (95% confidence interval 0.45 to 0.90). Baseline collateral flow disappeared after CABG in 12 of 14 patients with grafting of the RCA but persisted in all patients without such grafting. Physiologic flow in the inferior wall was detected by TEE in a total of 27 patients at baseline and in 38 patients after CABG (p = 0.0018); its peak velocity increased after surgery only in the subgroup of patients with grafting of the RCA. In conclusion, these findings indicate that Doppler TEE may detect collateral flow in the inferior left ventricular wall, and that there are typical changes in collateral and physiologic flow after CABG.

Adult↗
PubMed2006

Diffusion-weighted imaging in stroke attributable to patent foramen ovale: significance of concomitant atrial septum aneurysm.

BACKGROUND AND PURPOSE: Patent foramen ovale (PFO) is an established cause of stroke in young patients without other determined etiologies (ie, cryptogenic stroke). The additional presence of atrial septum aneurysm (ASA) possibly increases stroke risk, but it remains undetermined which factors best predict thromboembolism in patients with PFO. Diffusion-weighted imaging (DWI) may help to distinguish the characteristics of cerebral embolism associated with different features of the interatrial septum in PFO stroke. METHODS: In a stroke databank-based cohort study, DWI and transthoracic/transesophageal echocardiography findings were assessed in 48 consecutive patients with cryptogenic ischemic stroke associated with PFO. The number, size, and distribution of acute ischemic lesions on DWI were correlated with PFO size, degree of interatrial right-to-left shunt (RLS), and the presence of ASA. RESULTS: Patients with PFO plus ASA combined more often had multiple acute DWI lesions (16 of 30, 53%) than those with PFO alone (3 of 18, 17%; P=0.01). This association remained significant after correction for PFO size, degree of RLS, and vascular risk factors in a logistic-regression analysis (P=0.04). No significant associations between DWI lesion characteristics and PFO size or degree of RLS were found. CONCLUSIONS: The presence of concomitant ASA is independently associated with multiple cerebral ischemic lesions in PFO stroke, which may indicate an increased embolic risk.

Adult↗
PubMed2006

Inferior sinus venosus defect associated with incomplete cor triatriatum dexter and patent foramen ovale.

Sinus venosus atrial septal defect (SVD) is a rare cardiac abnormality in adults. Particularly, the inferior type is difficult to depict by transthoracic echocardiography because of its infero-posterior location to the fossa ovalis. We describe the case of a 33-year-old woman whose chest X-ray taken during bronchopneumonia revealed a cardiomegaly. Further echocardiographic investigations showed an underlying inferior SVD, an incomplete cor triatriatum dexter and a large patent foramen ovale (PFO). The diagnosis was confirmed by cardiac magnetic resonance imaging (CMR) and during surgical repair.

Adult↗
PubMed2006

Coronary artery imaging with contrast-enhanced MDCT: extracardiac findings.

OBJECTIVE: The purpose of our study was to evaluate the incidence of extracardiac findings on contrast-enhanced MDCT of the coronary arteries and to assess the effect of different field-of-view settings. SUBJECTS AND METHODS: Patients with suspected coronary artery disease (n = 166) were examined with contrast-enhanced MDCT (16 x 0.75 mm focused on the heart) during injection of contrast material (80 mL injected at a rate of 4 mL/sec) followed by saline (20 mL injected at 4 mL/sec). Retrospectively gated images were reconstructed at a 1-mm slice thickness and a 0.5-mm increment with isotropic voxels of 1 mm3. Images were reviewed for extracardiac findings, which were then classified as none, minor, or major with respect to their impact on patient management and treatment. In a different group of patients (n = 20), chest scans (16 x 1.5 mm) were used for measuring volumes of displayed body structures on wholechest scans, coronary artery MDCT images, and coronary artery MDCT images reconstructed with the maximum field of view. RESULTS: Extracardiac findings were detected in 41 patients (24.7%). Findings were classified as minor (19.9%) or major (4.8%). Among the major findings, which had an immediate impact on patient management and treatment, were bronchial carcinoma and pulmonary emboli. Volume analysis revealed that 35.5% of the total chest volume was displayed on dedicated coronary artery MDCT focused on the heart, whereas 70.3% of the chest was visible when coronary artery MDCT raw data were reconstructed with the maximal field of view (p < 0.001). CONCLUSION: Coronary artery MDCT can reveal important findings and disease in extracardiac structures. Thus, the entire examination should be reconstructed with the maximum field of view and should be reviewed by a qualified radiologist.

Adult↗
PubMed2005

Myocarditis: the immunologist's view on pathogenesis and treatment.

Viral myocarditis is a frequent and often unrecognised cause of post-inflammatory cardiomyopathy. The role of viral persistence and heart-specific autoimmunity in the development of myocarditis and heart failure is still controversial. This review updates the current view on the immunological mechanisms of disease development and addresses the current and future role of immunomodulation and immunosuppression as treatment options for defined subgroups of patients with myocarditis or dilated cardiomyopathy.

Animals↗
PubMed2005

Limited diagnostic yield of non-invasive coronary angiography by 16-slice multi-detector spiral computed tomography in routine patients referred for evaluation of coronary artery disease.

AIMS: Multislice spiral computed tomography (MSCT) is a promising non-invasive method to diagnose coronary artery disease (CAD). As no detailed comparative evaluation in consecutive patients referred for evaluation of CAD has been reported, this prospective study evaluating 2384 coronary segments in 149 consecutive patients was performed. METHODS AND RESULTS: The coronary artery tree was analysed in 16 segments both for coronary angiography (CA) and MSCT; a luminal narrowing > or = 50% based on visual assessment was considered significant. By MSCT, 77% of 2110 angiographically assessable segments could be evaluated, 94% per patient in proximal and 70% in distal segments (P<0.001). Sensitivity of MSCT to detect significant stenoses was 30% in all, but only 10% in peripheral segments. The main limitations were calcifications in 34% of segments and motion artefacts in 24% of patients. Overall diagnostic sensitivity for the presence of significant CAD was 86% but specificity was only 49%. CONCLUSION: When compared with invasive CA, 16-slice MSCT is of limited diagnostic value for the diagnosis of CAD in consecutive patients. Despite a clinically useful sensitivity for the overall diagnosis of significant CAD, specificity is low. Thus, relevant decisions regarding the need of and suitability for possible revascularization procedures cannot be based on MSCT findings alone.

Coronary Angiography↗
PubMed2005

Right atrial pacing impairs cardiac function during resynchronization therapy: acute effects of DDD pacing compared to VDD pacing.

OBJECTIVES: We aimed to compare the hemodynamic effects of right-atrial-paced (DDD) and right-atrial-sensed (VDD) biventricular paced rhythm on cardiac resynchronization therapy (CRT). BACKGROUND: Cardiac resynchronization therapy improves hemodynamics in patients with severe heart failure and left ventricular (LV) dyssynchrony. However, the impact of active right atrial pacing on resynchronization therapy is unknown. METHODS: Seventeen CRT patients were studied 10 months (range: 1 to 46 months) after implantation. At baseline, the programmed atrioventricular delay was optimized by timing LV contraction properly at the end of atrial contraction. In both modes the acute hemodynamic effects were assessed by multiple Doppler echocardiographic parameters. RESULTS: Compared to DDD pacing, VDD pacing resulted in much better improvement of intraventricular dyssynchrony assessed by the septal-to-posterior wall motion delay (VDD 106 +/- 83 ms vs. DDD 145 +/- 95 ms; p = 0.001), whereas the interventricular mechanical delay (difference between onset of pulmonary and aortic outflow) did not differ (VDD 20 +/- 21 ms vs. DDD 18 +/- 17 ms; p = NS). Furthermore, VDD pacing significantly prolonged the rate-corrected LV filling period (VDD 458 +/- 123 ms vs. DDD 371 +/- 94 ms; p = 0.0001) and improved the myocardial performance index (VDD 0.60 +/- 0.18 vs. DDD 0.71 +/- 0.23; p < 0.01). CONCLUSIONS: Our findings suggest that avoidance of right atrial pacing results in a higher degree of LV resynchronization, in a substantial prolongation of the LV filling period, and in an improved myocardial performance. Thus, the VDD mode seems to be superior to the DDD mode in CRT patients.

Atrial Fibrillation↗
PubMed2004

Multiscale motion mapping: a novel computer vision technique for quantitative, objective echocardiographic motion measurement independent of Doppler: first clinical description and validation.

BACKGROUND: Objective, quantitative, segmental noninvasive/bedside measurement of cardiac motion is highly desirable in cardiovascular medicine, but current technology suffers from significant drawbacks, such as subjectivity of conventional echocardiographic reading, angle dependence of tissue Doppler measurements, radiation exposure by computer tomography, and infrastructure requirements in MRI. We hypothesized that computer vision technology could represent a powerful new paradigm for quantification in echocardiography. METHODS AND RESULTS: We present multiscale motion mapping, a novel computer vision technology that is based on mathematical image processing and that exploits echocardiographic information in a fashion similar to the human visual system. It allows Doppler- and border-independent determination of motion and deformation in echocardiograms at arbitrary locations. Correctness of the measurements was documented in synthetic echocardiograms and phantom experiments. Exploratory case studies demonstrated its usefulness in a series of complex motion analyses that included abnormal septal motion and analysis of myocardial twisting. Clinical applicability was shown in a consecutive series of echocardiograms, in which good feasibility, good correlation with expert rating, and good intraobserver and interobserver concordance were documented. Separate assessment of 2D displacement and deformation at the same location was successfully applied to elucidate paradoxical septal motion, a common clinical problem. CONCLUSIONS: This is the first clinical report of multiscale motion mapping, a novel approach to echocardiographic motion quantification. For the first time, full 2D echocardiographic assessment of both motion and deformation is shown to be feasible. Overcoming current limitations, this computer vision-based technique opens a new door to objective analysis of complex heart motion.

Algorithms↗
PubMed2004

Cardiac resynchronization in severe heart failure and left bundle branch block: a single center experience.

OBJECTIVE: To assess the feasibility and longterm outcome of cardiac resynchronization therapy (CRT) in patients with impaired left ventricular function (LVEF <35%), left bundle branch block (QRS >120 ms) and dyspnoea NYHA 0 III at a single centre. METHODS AND RESULTS: Forty-seven patients were referred for implantation of a CRT device. In only 4 patients (9%) the device could not be implanted due to technical problems during the procedure. In the remaining 43 patients (65 +/- 10 years; 7 female) a CRT device was implanted. Follow-up time was 12 +/- 10 months. Twenty-one patients had dilated cardiomyopathy (DCM) and 22 patients had coronary artery disease (CAD). NYHA functional class improved from 3.0 +/- 1.4 to 2.5 +/- 0.7 (p <0.0001), accompanied by an improvement of LVEF [median 20% (range 15-25) vs 32% (range 20-40); p <0.0001]. A significant reduction of hospitalisation time for heart failure was found when the year before and the year after device implantation [18 days (range 5-27) vs 1 day (range 0-3); p <0.0001] were compared. Twelve (28%) patients, 9 with CAD, and 3 with DCM died. Two CAD patients and all patients with DCM who died had a combined CRT device with implantable cardioverter/defibrillator. CONCLUSION: In patients with severely impaired LVEF and wide QRS due to LBBB, CRT is feasible and safe. It improved dyspnoea and LVEF and reduced hospitalisation stays for heart failure during long-term follow-up.

Aged↗
PubMed2004

Use of B-type natriuretic peptide in the evaluation and management of acute dyspnea.

BACKGROUND: B-type natriuretic peptide levels are higher in patients with congestive heart failure than in patients with dyspnea from other causes. METHODS: We conducted a prospective, randomized, controlled study of 452 patients who presented to the emergency department with acute dyspnea: 225 patients were randomly assigned to a diagnostic strategy involving the measurement of B-type natriuretic peptide levels with the use of a rapid bedside assay, and 227 were assessed in a standard manner. The time to discharge and the total cost of treatment were the primary end points. RESULTS: Base-line demographic and clinical characteristics were well matched between the two groups. The use of B-type natriuretic peptide levels reduced the need for hospitalization and intensive care; 75 percent of patients in the B-type natriuretic peptide group were hospitalized, as compared with 85 percent of patients in the control group (P=0.008), and 15 percent of those in the B-type natriuretic peptide group required intensive care, as compared with 24 percent of those in the control group (P=0.01). The median time to discharge was 8.0 days in the B-type natriuretic peptide group and 11.0 days in the control group (P=0.001). The mean total cost of treatment was 5,410 dollars (95 percent confidence interval, 4,516 dollars to 6,304 dollars) in the B-type natriuretic peptide group, as compared with 7,264 dollars (95 percent confidence interval, 6,301 dollars to 8,227 dollars) in the control group (P=0.006). The respective 30-day mortality rates were 10 percent and 12 percent (P=0.45). CONCLUSIONS: Used in conjunction with other clinical information, rapid measurement of B-type natriuretic peptide in the emergency department improved the evaluation and treatment of patients with acute dyspnea and thereby reduced the time to discharge and the total cost of treatment.

Acute Disease↗
PubMed2004

Risks and benefits of optimised medical and revascularisation therapy in elderly patients with angina--on-treatment analysis of the TIME trial.

AIM: To assess treatment effects of optimised medical therapy and PCI or CABG surgery on one-year outcome in patients 75 years old with chronic angina. METHODS AND RESULTS: On-treatment analysis of the TIME data: all re-vascularised patients (REVASC n=174: 112 randomised to revascularisation and 62 to drugs with late revascularisation) were compared to all patients on continued drug therapy (MED n=127: 86 randomised to drugs and 41 to revascularisation only). Baseline characteristics of both groups were similar (age 80 +/- 4 years). Risk of death at one year (adjusted hazard ratio (HR)=1.31; 95%-CI: 0.58-2.99; P=0.52) and of death/infarction (adjusted hazard RATIO=1.77; 95%-CI 0.91-3.41; P=0.09) were comparable between REVASC and MED patients. Furthermore, the risk of death within 30 days was even slightly lower among REVASC patients (unadjusted hazard RATIO=0.73; 95%-CI: 0.21-2.53; P=0.98). Overall, REVASC patients had greater improvements in symptoms and well-being than MED patients (P<0.01). Surgical patients had similar mortality rates as angioplasty patients, but they also had greater symptomatic improvements (P<0.01). CONCLUSION: Treated medically, elderly patients with chronic angina have a similarly high 30-day and one-year mortality as patients of the same age being re-vascularised; however, they can expect lower improvements in symptoms and well being.

Aged↗
PubMed2004

Cost-effectiveness of invasive versus medical management of elderly patients with chronic symptomatic coronary artery disease. Findings of the randomized trial of invasive versus medical therapy in elderly patients with chronic angina (TIME).

AIM: To compare benefits and costs of invasive versus medical management in elderly patients with chronic angina. METHODS AND RESULTS: In a predefined subgroup of 188 patients of the Trial of Invasive versus Medical therapy in Elderly patients with chronic angina (TIME), one-year benefits were assessed as freedom from major events and improvements in symptoms and quality of live. Costs were determined as one-year costs of resource utilisation. Invasive patients had higher 30-day, but lower months 2-12 hospital and intervention costs than medical patients, resulting in somewhat higher one-year costs for invasive management (p=0.08). However, billing data available for a subgroup of patients showed higher practitioner's charges in the medical patients (adjusted p=0.0015). Incremental costs to prevent one major event by invasive management averaged CHF 10100 (95% CI: -800 to 28300) or 6965, ranging from average CHF 5100 (euro 3515) to CHF 11600 (euro 8000) in a best, compared to a worst, case scenario. CONCLUSIONS: Early increased costs of revascularization in invasive patients were balanced after one year by increased practitioners' charges and symptom-driven late revascularizations in medical patients. Therefore, the invasive strategy with improved clinical effectiveness at only marginally higher costs as medical management was cost-effective. Costs should not be an argument against invasive management of elderly patients with chronic angina.

Aged↗
PubMed2004

Transesophageal echocardiography for monitoring segmental wall motion during off-pump coronary artery bypass surgery.

In this prospective, observational study, we evaluated whether transesophageal echocardiography allows for monitoring left ventricular segmental wall motion during cardiac displacement for off-pump coronary artery bypass (OPCAB) surgery. On the basis of a pilot study that showed frequent loss of transgastric views during OPCAB surgery, we analyzed only midesophageal views. The midesophageal 4-chamber view, 2-chamber view, and long-axis view were recorded in 60 patients after opening the chest and placing an epicardial stabilizer on the displaced heart. Using the 16-segment model, 2 echocardiographers independently performed offline analysis of segmental wall motion. The percentage of patients in whom >or=14 left ventricular segments were readable was calculated at baseline and after cardiac displacement and placement of an epicardial stabilizer. At baseline, >or=14 segments were readable in 59 (98%) of 60 patients. After cardiac displacement, >or=14 segments were readable during 58 (76%) of 76 revascularizations of the left anterior descending coronary artery (P < 0.01 versus baseline), during 33 (83%) of 40 revascularizations of the left circumflex coronary artery (P < 0.01 versus baseline), and during 29 (94%) of 31 revascularizations of the right coronary artery (not significant). We conclude that the number of readable segments decreased after cardiac displacement but that availability of >or=14 readable segments allowed for reliable monitoring of segmental wall motion in 4 of 5 patients during OPCAB surgery.

Aged↗
PubMed2003

Outcome of elderly patients with chronic symptomatic coronary artery disease with an invasive vs optimized medical treatment strategy: one-year results of the randomized TIME trial.

CONTEXT: The risk-benefit ratio of invasive vs medical management of elderly patients with symptomatic chronic coronary artery disease (CAD) is unclear. The Trial of Invasive versus Medical therapy in Elderly patients (TIME) recently showed early benefits in quality of life from invasive therapy in patients aged 75 years or older, although with a certain excess in mortality. OBJECTIVE: To assess the long-term value of invasive vs medical management of chronic CAD in elderly adults in terms of quality of life and prevention of major adverse cardiac events. DESIGN: One-year follow-up analysis of TIME, a prospective randomized trial with enrollment between February 1996 and November 2000. SETTING AND PARTICIPANTS: A total of 282 patients with Canadian Cardiac Society class 2 or higher angina despite treatment with 2 or more anti-anginal drugs who survived for the first 6 months after enrollment in TIME (mean age, 80 years [range, 75-91 years]; 42% women), enrolled at 14 centers in Switzerland. INTERVENTIONS: Participants were randomly assigned to undergo coronary angiography followed by revascularization (if feasible) (n = 140 surviving 6 months) or to receive optimized medical therapy (n = 142 surviving 6 months). MAIN OUTCOME MEASURES: Quality of life, assessed by standardized questionnaire; major adverse cardiac events (death, nonfatal myocardial infarction, or hospitalization for acute coronary syndrome) after 1 year. RESULTS: After 1 year, improvements in angina and quality of life persisted for both therapies compared with baseline, but the early difference favoring invasive therapy disappeared. Among invasive therapy patients, later hospitalization with revascularization was much less likely (10% vs 46%; hazard ratio [HR], 0.19; 95% confidence interval [CI], 0.11-0.32; P<.001). However, 1-year mortality (11.1% for invasive; 8.1% for medical; HR, 1.51; 95% CI, 0.72-3.16; P =.28) and death or nonfatal myocardial infarction rates (17.0% for invasive; 19.6% for medical; HR, 0.90; 95% CI, 0.53-1.53; P =.71) were not significantly different. Overall major adverse cardiac event rates were higher for medical patients after 6 months (49.3% vs 19.0% for invasive; P<.001), a difference which increased to 64.2% vs 25.5% after 12 months (P<.001). CONCLUSIONS: In contrast with differences in early results, 1-year outcomes in elderly patients with chronic angina are similar with regard to symptoms, quality of life, and death or nonfatal infarction with invasive vs optimized medical strategies based on this intention-to-treat analysis. The invasive approach carries an early intervention risk, while medical management poses an almost 50% chance of later hospitalization and revascularization.

Aged↗
PubMed2003

[B-type natriuretic peptide--current use in the diagnosis and management of heart failure].

Abstract B-natriuretic peptide (BNP) is a 32-amino acid polypeptide secreted from the cardiac ventricles in response to ventricular volume expansion and pressure overload. BNP levels are elevated in patients with symptomatic left ventricular dysfunction, and levels correlate with severity of symptoms and with prognosis. Numerous studies indicate that BNP may considerably improve the management of patients with heart failure and may become a routine serum parameter in clinical medicine. In this review, the utility of BNP in different clinical settings will be discussed.

Aged↗
PubMed2002

B-type natriuretic peptide (BNP): can it improve our management of patients with congestive heart failure?

Until recently no simple specific test existed for the differentiation of decompensated heart failure from other causes of acute dyspnoea, or to assess the prognosis of patients with severe heart failure or to optimize heart failure therapy in an individual patient. Measurement of B-type natriuretic peptide has become available as an easy-to-per-form bedside test. Several studies have demonstrated it's usefulness in the emergency room to differentiate heart failure from other causes of acute dyspnoea or to guide the complex drug therapy in an individual patient with heart failure. This article gives a short overview on the clinical experience to use BNP-blood levels for the diagnosis and treatment guidance of heart failure.

Atrial Natriuretic Factor↗
PubMed2002

Women do have an improved long-term outcome after non-ST-elevation acute coronary syndromes treated very early and predominantly with percutaneous coronary intervention: a prospective study in 1,450 consecutive patients.

OBJECTIVES: This study sought to assess gender-based differences in long-term outcome after very early aggressive revascularization for non-ST-elevation acute coronary syndromes (NSTACS). BACKGROUND: The Fragmin and fast Revascularization during InStability in Coronary artery disease (FRISC) II study suggested that women have less to gain from an early invasive strategy. METHODS: We conducted a prospective cohort study in 1,450 consecutive patients with NSTACS undergoing coronary angiography and subsequent coronary stenting of the culprit lesion as the primary revascularization strategy within 24 h of admission. The combined primary end point was defined as death or nonfatal myocardial infarction (MI) and recorded for a mean of 20 months. RESULTS: Percutaneous coronary intervention was performed in more than 50% of patients in women and men and accompanied with stenting in 80%. The percutaneous coronary intervention:coronary artery bypass grafting ratio was 4:1 in men and 5:1 in women. The primary end point occurred in 29 (7.0%) women as compared with 108 (10.5%) men (hazard ratio for women, 0.65; 95% confidence interval [CI] 0.42 to 0.99; p = 0.045). Backward-stepwise multivariate Cox regression analysis identified female gender as an independent predictor of death or MI (hazard ratio for female gender, 0.51; 95% CI, 0.28 to 0.92; p = 0.024). Kaplan-Meier analysis showed that women had consistently lower event rates during the entire follow-up period (p = 0.037 by log-rank for death or MI). CONCLUSIONS: Women treated with very early aggressive revascularization with coronary stenting of the culprit lesion as the primary revascularization strategy have a better long-term outcome as compared with men.

Acute Disease↗