Feasibility of heart sounds measurements from an accelerometer within an ICD pulse generator.

OBJECTIVE: The feasibility of detecting heart sounds (HS) from an accelerometer sensor enclosed within an implantable cardioverter defibrillator (ICD) pulse generator (PG) was explored in a noninvasive pilot study on heart failure (HF) patients with audible third HS (S3). METHODS: Accelerometer circuitry enhanced for HS was incorporated into non-functional ICDs. A study was conducted on 30 HF patients and 10 normal subjects without history of cardiac disease. The devices were taped to the skin surface over both left and right pectoral regions to simulate subcutaneous implants. A lightweight reference accelerometer was taped over the cardiac apex. Waveforms were recorded simultaneously with a surface electrocardiogram for 2 minutes. Algorithms were developed to perform off-line automatic detection of HS and HS time intervals (HSTIs). RESULTS: S1, S2, and S3 vibrations were detected in all accelerometer locations for all 40 subjects, including 16 subjects without an audible S3. A substantial proportion of S3 energy was infrasonic (<20 Hz). Extending the signal bandwidth accordingly increased HS amplitudes and the ability of S3 to separate HF patients from the normal subgroup. HSTIs also separated the subgroups and were less susceptible to patient-dependent acoustic propagation properties than amplitude measures. CONCLUSION: HS, including S3 amplitude and HSTIs, may be measured using PG-embedded circuitry at implant sites without special purpose leads. Further study is warranted to determine if relative changes in heart sounds measurements can be effective in applications such as remote ambulatory monitoring of HF progression and the detection of the onset of HF decompensation.

Results of the Prospective Minnesota Study of ECHO/TDI in Cardiac Resynchronization Therapy (PROMISE-CRT) study.

BACKGROUND: Retrospective single-center studies have shown that measures of mechanical dyssynchrony before cardiac resynchronization therapy (CRT), or acute changes after CRT, predict response better than QRS duration. The Prospective Minnesota Study of Echocardiographic/TDI in Cardiac Resynchronization Therapy (PROMISE-CRT) study was a prospective multicenter study designed to determine whether acute (1 week) changes in mechanical dyssynchrony were associated with response to CRT. METHODS AND RESULTS: Nine Minnesota Heart Failure Consortium centers enrolled 71 patients with standard indications for CRT. Left ventricular (LV) size, function, and mechanical dyssynchrony (echocardiography [ECHO], tissue Doppler imaging [TDI], speckle-tracking echocardiography [STE]) as well as 6-minute walk distance and Minnesota Living with Heart Failure Questionnaire scores were measured at baseline and 3 and 6 months after CRT. Acute change in mechanical dyssynchrony was not associated with clinical response to CRT. Acute change in STE radial dyssynchrony explained 73% of the individual variation in reverse remodeling. Baseline measures of mechanical dyssynchrony were associated with reverse remodeling (but not clinical) response, with 4 measures each explaining 12% to 30% of individual variation. CONCLUSIONS: Acute changes in radial mechanical dyssynchrony, as measured by STE, and other baseline mechanical dyssynchrony measures were associated with CRT reverse remodeling. These data support the hypothesis that acute improvement in LV mechanical dyssynchrony is an important mechanism contributing to LV reverse remodeling with CRT.

Ultrafiltration versus usual care for hospitalized patients with heart failure: the Relief for Acutely Fluid-Overloaded Patients With Decompensated Congestive Heart Failure (RAPID-CHF) trial.

OBJECTIVES: The purpose of this research was to assess the safety and efficacy of ultrafiltration (UF) in patients admitted with decompensated congestive heart failure (CHF). BACKGROUND: Ultrafiltration for CHF is usually reserved for patients with renal failure or those unresponsive to pharmacologic management. We performed a randomized trial of UF versus usual medical care using a simple UF device that does not require special monitoring or central intravenous access. METHODS: Patients admitted for CHF with evidence of volume overload were randomized to a single, 8 h UF session in addition to usual care or usual care alone. The primary end point was weight loss 24 h after the time of enrollment. RESULTS: Forty patients were enrolled (20 UF, 20 usual care). Ultrafiltration was successful in 18 of the 20 patients in the UF group. Fluid removal after 24 h was 4,650 ml and 2,838 ml in the UF and usual care groups, respectively (p = 0.001). Weight loss after 24 h, the primary end point, was 2.5 kg and 1.86 kg in the UF and usual care groups, respectively (p = 0.240). Patients tolerated UF well. CONCLUSIONS: The early application of UF for patients with CHF was feasible, well-tolerated, and resulted in significant weight loss and fluid removal. A larger trial is underway to determine the relative efficacy of UF versus standard care in acute decompensated heart failure.