Biomedical subjects
Publications and source records attributed to David L Hayes.
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BACKGROUND: Despite the frequent occurrence of bacteremia due to gram-negative organisms in patients with underlying permanent pacemakers (PPMs) or implantable cardioverter defibrillators (ICDs), the outcome and treatment of these patients has received scant attention. In patients with PPMs or ICDs who have Staphylococcus aureus bacteremia, 45% have PPM/ICD infection. METHODS: We conducted a retrospective cohort study over a 7-year period to assess the clinical features and frequency of PPM/ICD infection in patients with gram-negative bacteremia, as well as the incidence of relapse in patients for whom the device was not removed. RESULTS: Forty-nine patients were included in the study; 3 (6%) had either definite (2 patients) or possible (1 patient) PPM/ICD infection. Both patients with definite PPM/ICD infection had clear infection of the generator pocket. None of the other patients with alternate sources of bacteremia developed PPM/ICD infection. Thirty-four patients with retained PPM/ICD were observed for >12 weeks (median time, 759 days), and 2 (6%) developed relapsing bacteremia, although they each had alternative sources of relapse. CONCLUSIONS: In sharp contrast to S. aureus infection, PPM/ICD infection in patients with gram-negative bacteremia was rare, and no patients appeared to have secondary PPM/ICD infection due to hematogenous seeding of the system. Despite infrequent system removal in these patients, relapsing bacteremia among patients who survived initial bacteremia was rarely seen. If secondary PPM/ICD infection occurs in patients with gram-negative bacteremia, it is either uncommon or it is cured with antimicrobial therapy despite device retention.
BACKGROUND: Despite the widespread and growing use of implantable cardioverter-defibrillators (ICDs), little information is available regarding their performance or the impact of advanced pacing functions on ICD reliability and longevity. OBJECTIVES: The purpose of this study was to examine the performance of contemporary ICD pulse generators that failed or were replaced because of manufacturers recalls. METHODS: ICD data were entered prospectively by nine participating centers. ICD pulse generator failure was defined as removal from service because the device was not functioning according to the manufacturer's specifications. A recalled ICD was a normally functioning pulse generator that was replaced as the result of a recall or advisory. RESULTS: From 1998 to 2005, 1,220 ICDs failed and 135 were recalled and replaced. The average implant time of failed ICDs was 4.4 +/- 1.5 years and of recalled ICDs was 1.7 +/- 0.8 years. The average implant time of single- and dual-chamber ICDs with rate responsive or cardiac resynchronization (CRT-D) pacing capabilities was significantly shorter than the average implant time of single- or dual-chamber devices without these features (P <.001). ICDs that provided rate responsive or CRT-D pacing failed earlier because of battery depletion (P <.001) and were significantly more prone to unexpected electronic or housing failure (9% vs 5%, P = .008) and recalls (25% vs 1%, P <.0001). Major adverse events included death (n = 2), failure to convert ventricular tachyarrhythmias (n = 6), and inappropriate shocks (n = 11). CONCLUSION: Based on our analysis of failed and recalled devices, the performance of contemporary ICDs has been adversely affected by premature battery depletion, electronic failure, and manufacturers' recalls. Additional studies are needed to precisely estimate ICD longevity and to determine the incidence of unexpected ICD failure.
BACKGROUND: Cardiac resynchronization therapy (CRT) is an effective therapy for patients with moderate to severe heart failure and prolonged QRS duration. The purpose of this study was to determine whether reverse left ventricular (LV) remodeling and symptomatic benefit from CRT were sustained at 12 months, and if so, in what proportion of patients this occurred. METHODS AND RESULTS: Serial Doppler echocardiograms were obtained at baseline and 6 and 12 months after CRT in 228 patients enrolled in the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) trial. Measurements were made of LV end-diastolic (EDV) and end-systolic (ESV) volumes, ejection fraction, LV mass, severity of mitral regurgitation (MR), peak transmitral velocities during early (E wave) and late (A wave) diastolic filling, and myocardial performance index. At both 6 and 12 months, respectively, CRT was associated with reduced LV EDV (P<0.0001 and P=0.007) and LV ESV (P<0.0001 and P<0.0001), improved ejection fraction (P<0.0001 and P<0.0001), regression of LV mass (P=0.012 and P<0.0001), and reduced MR (P<0.0001 and P<0.0001). LV filling time, transmitral E/A ratio, and myocardial performance index all improved at 12 months compared with baseline (P<0.001, P=0.031, and P<0.0001). Reverse LV remodeling with CRT occurred in more patients at 6 than at 12 months (74% versus 60%, respectively; P<0.05) and was greater in patients with a nonischemic than an ischemic etiology. CONCLUSIONS: Reverse LV remodeling and symptom benefit with CRT are sustained at 12 months in patients with New York Heart Association class III/IV heart failure but occur to a lesser degree in patients with an ischemic versus a nonischemic etiology, most likely owing to the inexorable progression of ischemic disease.
OBJECTIVES: The purpose of this study was to evaluate the safety of implanting a cardiac resynchronization therapy (CRT) system. BACKGROUND: Clinicians and patients require data on the safety of the CRT implant procedure to estimate procedural risk. METHODS: We evaluated outcomes of transvenous CRT system implantation in 2,078 patients from the Multicenter InSync Randomized Clinical Evaluation (MIRACLE) study, the MIRACLE Implantable Cardioverter-Defibrillator (ICD) study, and the InSync III study. We compared the MIRACLE study to the InSync III study and the MIRACLE ICD study randomized phase to its general phase to evaluate the effect of new technologies. RESULTS: The implant attempt succeeded in 1,903 of 2,078 (91.6%) patients. Implant time decreased from 2.7 h in the MIRACLE study to 2.3 h in the InSync III study (p < 0.001), and from 2.8 h in the MIRACLE ICD study randomized phase to 2.4 h in the general phase (p < 0.001). The implant procedure produced 62 perioperative complications in 53 (9.3%) MIRACLE trial patients; 159 in 135 (21.1%) MIRACLE ICD study randomized phase patients and 71 in 62 (13.9%) general phase patients (p < 0.05 vs. randomized); and 41 in 37 (8.8%) InSync III study patients (p = NS vs. the MIRACLE study). We observed 73 postoperative complications in 62 (11.7%) MIRACLE trial patients, 77 in 68 (11.9%) MIRACLE ICD study randomized phase patients and 56 in 45 (11.0%) general phase patients (p = NS), and 37 in 34 (8.6%) InSync III study patients (p = NS). A total of 8% of patients required reoperation to treat lead dislodgement, extracardiac stimulation, or infection during follow-up. CONCLUSIONS: Transvenous CRT system implantation appears safe, well-tolerated, has a high success rate, and improves with operator experience and the addition of new technologies.
Cardiac resynchronization therapy (CRT) has been used extensively over the last years in the therapeutic management of patients with end-stage heart failure. Data from 4,017 patients have been published in eight large, randomized trials on CRT. Improvement in clinical end points (symptoms, exercise capacity, quality of life) and echocardiographic end points (systolic function, left ventricular size, mitral regurgitation) have been reported after CRT, with a reduction in hospitalizations for decompensated heart failure and an improvement in survival. However, individual results vary, and 20% to 30% of patients do not respond to CRT. At present, the selection criteria include severe heart failure (New York Heart Association functional class III or IV), left ventricular ejection fraction <35%, and wide QRS complex (>120 ms). Assessment of inter- and particularly intraventricular dyssynchrony as provided by echocardiography (predominantly tissue Doppler imaging techniques) may allow improved identification of potential responders to CRT. In this review a summary of the clinical and echocardiographic results of the large, randomized trials is provided, followed by an extensive overview on the currently available echocardiographic techniques for assessment of LV dyssynchrony. In addition, the value of LV scar tissue and venous anatomy for the selection of potential candidates for CRT are discussed.
Encouraged by the clinical success of cardiac resynchronization therapy (CRT), the implantation rate has increased exponentially, although several limitations and unresolved issues of CRT have been identified. This review concerns issues that are encountered during implantation of CRT devices, including the role of electroanatomical mapping, whether CRT implantation should be accompanied by simultaneous atrioventricular nodal ablation in patients with atrial fibrillation, procedural complications, and when to consider surgical left ventricular lead positioning. Furthermore, (echocardiographic) CRT optimization and assessment of CRT benefits after implantation are highlighted. Also, controversial issues such as the potential value of CRT in patients with mild heart failure or narrow QRS complex are addressed. Finally, open questions concerning when to combine CRT with implantable cardioverter-defibrillator therapy and the cost-effectiveness of CRT are discussed.
OBJECTIVES: We report a series of patients with severe tricuspid valve regurgitation due to a permanent pacemaker (PPM) or implantable cardioverter-defibrillator (ICD) lead. BACKGROUND: Severe tricuspid regurgitation caused by a PPM or ICD lead is an under-recognized but treatable etiology of severe right heart failure. METHODS: We reviewed the records of 41 patients who underwent tricuspid valve operation for severe tricuspid regurgitation caused by previously placed PPM or ICD leads. RESULTS: During surgery, severe tricuspid regurgitation was found to be caused by the PPM or ICD leads in all 41 patients. There was a perforation of the tricuspid valve leaflet by the PPM or ICD lead in 7 patients, lead entanglement in the tricuspid valve occurred in 4 patients, lead impingement of the tricuspid valve leaflets occurred in 16 patients, and lead adherence to the tricuspid valve occurred in 14 patients. The septal leaflet was most often perforated (6 of 7). In the preoperative evaluation, valve malfunction due to the PPM or ICD lead was diagnosed preoperatively in only 5 of 41 (12%) patients by transthoracic echocardiography. All patients underwent successful tricuspid valve operation (22 tricuspid valve replacement), with one perioperative death occurring. During follow-up (range, 1 to 99 months), there was one patient who died from left-sided heart failure and three patients died of other causes. The remaining patients showed improvement in signs and symptoms of heart failure. CONCLUSIONS: Damage to the tricuspid valve by PPM or ICD leads may result in severe symptomatic tricuspid regurgitation and may not be overtly visualized by echocardiography. This etiology should be considered when evaluating patients with severe right heart failure after PPM or ICD implantation.
BACKGROUND: Pericardial effusion, a sign of cardiac perforation, may complicate permanent pacemaker placement. Risk factors for development of post-permanent pacemaker effusion have not been evaluated. OBJECTIVES: The purpose of this study was to determine the predictors of symptomatic pericardial effusion after permanent pacemaker placement. METHODS: The Mayo Clinic pacemaker and echocardiogram databases were cross-referenced. From 1995 to 2003, 4,280 permanent pacemakers were implanted. Fifty (1.2%) patients developed significant effusion and symptoms consistent with perforation. They were randomly matched with 100 patients without effusion after permanent pacemaker placement. RESULTS: The strongest predictors of postimplant effusion by univariate analysis were the concomitant use of a temporary transvenous pacemaker (hazard ratio [HR] 3.2, 95% confidence interval [CI] 1.6-6.2, P = .001) or steroid use within 7 days prior to implant (HR 4.1, 95% CI 1.1-10, P = .003). Weaker predictors were use of helical screw ventricular leads, body mass index (BMI) <20, older age, and longer fluoroscopy times. Variables associated with lower risk of perforation were right ventricular systolic pressure >35 mmHg (HR 0.70, 95% CI 0.44-0.97, P = .01) or BMI >30 (HR 0.62, 95% CI 0.41-0.93, P = .01). Multivariate predictors were use of temporary pacemaker (HR 2.7, 95% CI 1.4-3.9, P = .01), helical screw leads (HR 2.5; 95% CI 1.4-3.8, P = .04), and steroids (HR 3.2, 95% CI 1.1-5.4, P = .04). Right ventricular systolic pressure >35 mmHg was the only protective factor (HR 0.70, 95% CI 0.50-0.92, P = .02). CONCLUSION: The incidence of postimplant effusions is low. In order to minimize periprocedural permanent pacemaker effusions, temporary pacemaker placement should be avoided unless essential, and particular care should be taken when placing a permanent pacemaker in patients who are taking steroids.
We report the results of a simulation of an adaptive cardiac resynchronization therapy (CRT) device performing biventricular pacing in which the atrioventricular (AV) delay and interventricular (VV) interval parameters are changed dynamically in response to data provided by the simulated IEGMs and simulated hemodynamic sensors. A learning module, an artificial neural network, performs the adaptive part of the algorithm supervised by an algorithmic deterministic module, internally or externally from the implanted CRT or CRT-D. The simulated cardiac output obtained with the adaptive CRT device is considerably higher (30%) especially with higher heart rates than in the nonadaptive CRT mode and is likely to be translated into improvement in quality of life of patients with congestive heart failure.
Kearns-Sayre syndrome (KSS) is a rare genetic abnormality. Classified as a mitochondrial cytopathy, the primary pathology of this syndrome is a disturbance of mitochondrial DNA, which codes for the proteins required for the respiratory chain reaction. Onset occurs before age 20, and is manifest as chronic progressive external ophthalmoplegia and retinal degeneration. Management issues of KSS include prophylactic cardiac pacing for conduction defects, which has been shown to improve survival. Other clinical considerations relate to dietary supplements to attempt to control the progressive effects of the disease.
OBJECTIVE: To assess the potential electromagnetic interference (EMI) effects that new or current-generation cellular telephones have on medical devices. MATERIAL AND METHODS: For this study, performed at the Mayo Clinic in Rochester, Minn, between March 9, 2004, and April 24, 2004, we tested 16 different medical devices with 6 cellular telephones to assess the potential for EMI. Two of the medical devices were tested with both new and old interface modules. The 6 cellular telephones chosen represent the different cellular technology protocols in use: Code Division Multiple Access (2 models), Global System for Mobile communications, Integrated Digital Enhanced Network, Time Division Multiple Access, and analog. The cellular telephones were tested when operating at or near their maximum power output. The medical devices, connected to clinical simulators during testing, were monitored by observing the device displays and alarms. RESULTS: Of 510 tests performed, the incidence of clinically important interference was 1.2%; EMI was Induced in 108 tests (21.2%). Interference occurred in 7 (44%) of the 16 devices tested. CONCLUSIONS: Cellular telephones can interfere with medical equipment. Technology changes in both cellular telephones and medical equipment may continue to mitigate or may worsen clinically relevant interference. Compared with cellular telephones tested in previous studies, those currently in use must be closer to medical devices before any interference is noticed. However, periodic testing of cellular telephones to determine their effects on medical equipment will be required.
All physicians increasingly will encounter patients who have implanted cardioverter-defibrillators (ICDs) for protection from ventricular arrhythmias. This advisory provides a concise summary relevant to the assessment and management of patients with ICDs, including those who present to primary care or emergency department physicians with symptoms suggesting arrhythmia or ICD malfunction and those who require cardiac or surgical procedures.
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