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Biomedical subjects

Beat Schaer

Publications and source records attributed to Beat Schaer.

8 recordsLinked to original sources
PubMed2006

Cardiac resynchronization therapy in chronic heart failure.

Cardiac resynchronisation therapy (CRT) has emerged as a treatment option for patients with severe, drug-refractory heart failure and signs of intraventricular dyssynchrony. In clinical trials CRT reduced the overall mortality, improved symptoms, exercise tolerance, and left ventricular function, as compared with optimised medical therapy alone. One of the challenging fields in patient selection for CRT is to identify the 20-30% of heart failure patients with bundle branch block that will not respond to this novel therapy. Other fields of uncertainty, such as CRT in patients with atrial fibrillation or chronic right ventricular stimulation as well as the role of a back-up defibrillator will be discussed.

Atrial Fibrillation↗
PubMed2006

Ventricular tachycardia in an ice-hockey player after a blunt chest trauma.

A case of a professional ice-hockey with a blunt chest trauma is presented. A year after the first cardiac evaluation, he experienced sustained ventricular tachycardia after another slight chest trauma. An implantable cardioverter-defibrillator was implanted. The pathophysiological background of tachycardias after a blunt chest trauma and its management are discussed.

Adult↗
PubMed2005

An electrocardiogram-based algorithm to detect loss of left ventricular capture during cardiac resynchronization therapy.

BACKGROUND: Loss of left ventricular capture in patients with cardiac resynchronization devices may account for worsening heart failure and can be difficult to diagnose without a programmer. OBJECTIVE: To determine whether distinct morphologic changes on the surface electrocardiogram indicate loss of left ventricular capture. DESIGN: After analysis of the R-S spike ratio in the 12-lead electrocardiogram during right ventricular and biventricular pacing in 10 patients, an algorithm to detect loss of left ventricular capture was developed. SETTING: University hospital. PATIENTS: 54 patients with a cardiac resynchronization device and underlying left bundle-branch block. MEASUREMENTS: Leads V1 and I of a 12-lead electrocardiogram were assessed after biventricular pacing was confirmed and after the device was programmed to right ventricular pacing only (simulating loss of left ventricular capture). RESULTS: The sensitivity of the algorithm to correctly identify loss of left ventricular capture was 94% (95% CI, 88.2% to 97.7%), and the specificity was 93% (CI, 86.3% to 95.8%). The likelihood ratio of a positive test result was 12.8 (CI, 6.443 to 23.310), and the likelihood ratio of a negative test result was 0.06 (CI, 0.024 to 0.137). LIMITATIONS: The algorithm was tested in patients in whom the right ventricular electrode was placed in the apex of the right ventricle only. CONCLUSION: Presence of biventricular capture--the prerequisite for successful cardiac resynchronization therapy--and loss of left ventricular capture can be accurately detected by an algorithm based on analysis of the R-S ratio on leads V1 and I of the surface electrocardiogram.

Algorithms↗
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

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↗