Margaret A. Lloyd

Long-term survival after ablation of the atrioventricular node and implantation of a permanent pacemaker in patients with atrial fibrillation

Background In patients with atrial fibrillation that is refractory to drug therapy, radio-frequency ablation of the atrioventricular node and implantation of a permanent pacemaker are an alternative therapeutic approach. The effect of this procedure on long-term survival is unknown. Methods We studied all patients who underwent ablation of the atrioventricular node and implantation of a permanent pacemaker at the Mayo Clinic between 1990 and 1998. Observed survival was compared with the survival rates in two control populations: age- and sex-matched members of the Minnesota population between 1970 and 1990 and consecutive patients with atrial fibrillation who received drug therapy in 1993. Results A total of 350 patients (mean [±SD] age, 68±11 years) were studied. During a mean of 36±26 months of follow-up, 78 patients died. The observed survival rate was significantly lower than the expected survival rate based on the general Minnesota population (P<0.001). Previous myocardial infarction (P< 0.001), a hi...

Risks of spontaneous injury and extraction of an active fixation pacemaker lead: Report of the Accufix Multicenter Clinical Study and Worldwide Registry

BACKGROUND The Telectronics Accufix pacing leads were recalled in November 1994 after 2 deaths and 2 nonfatal injuries were reported. This multicenter clinical study (MCS) of patients with Accufix leads was designed to determine the rate of spontaneous injury related to the J retention wire and results of lead extraction. METHODS AND RESULTS The MCS included 2589 patients with Accufix atrial pacing leads that were implanted at or who were followed up at 12 medical centers. Patients underwent cinefluoroscopic imaging of their lead every 6 months. The risk of J retention wire fracture was approximately 5.6%/y at 5 years and 4.7%/y at 10 years after implantation. The annual risk of protrusion was 1.5%. A total of 40 spontaneous injuries were reported to a worldwide registry (WWR) that included data from 34 672 patients (34 892 Accufix leads), including pericardial tamponade (n=19), pericardial effusion (n=5), atrial perforation (n=3), J retention wire embolization (n=4), and death (n=6). The risk of injury was 0.02%/y (95% CI, 0.0025 to 0. 072) in the MCS and 0.048%/y (95% CI, 0.035 to 0.067) in the WWR. A total of 5299 leads (13%) have been extracted worldwide. After recall in the WWR, fatal extraction complications occurred in 0.4% of intravascular procedures (16 of 4023), with life-threatening complications in 0.5% (n=21). Extraction complications increased with implant duration, female sex, and J retention wire protrusion. CONCLUSIONS Accufix pacing leads pose a low, ongoing risk of injury. Extraction is associated with substantially higher risks, and a conservative management approach is indicated for most patients.

Is there an adverse outcome from abandoned pacing leads

AbstractBackground. Indications for extraction of an abandoned pacemaker lead (APL) are controversial. The purpose of this study was to determine whether or not APLs should be extracted in the absence of pacemaker-related problems. Methods and Results. We retrospectively reviewed, from 1977 through 1998, all patients with retained, non-functional leads and identified 433—266 males and 167 females. Mean age at initial pacemaker implantation was 68[emsp4 ]years. These patients received a total of 259 atrial and 948 ventricular leads. Of the total of 1,207 leads, 611 became non-functional. A total of 531 non-functional leads were abandoned, of which 18 were later extracted: one APL in 345 patients, two in 78, and three in 10. Indications for new lead placement when non-functional leads were abandoned included capture and/or sensing failure (243), lead recall (177), lead fracture (86), pacing system replacement to the contralateral side (11), accommodating patient growth (5), pacemaker function upgrade (5), replacement with implantable cardioverter defibrillator (ICD, 2), interference with ICD (1), and unknown (1). Complications that were associated with pacemakers were found in 24 patients (5.5%)—pacemaker system infection (8 patients) and venous occlusion at the time of a subsequent procedure of new lead placement when APLs had already been in place (16) which resulted in APL extraction (7) or transfer of the pacemaker system to the contralateral side (9). Neither venous thrombosis nor other complications were found in the remaining 409 patients (94.5%). The incidence of complications was higher in patients with three APLs than in patients with two or fewer APLs (40% vs. 4.7%, P=1×10−6), in patients with four or more total lead implantations than in patients with three or fewer total lead implantations (26.2% vs. 0.6%, P<1×10−10), and in patients with three or more procedures of new lead placements than in patients with two or fewer procedures of new lead placements (36.4% vs. 3.9%, P=1×10−10). Patients with complications were younger than those without complications both at the time of initial pacemaker implantation (59±16 vs. 68±17[emsp4 ]y, P=0.01) and when non-functional leads were abandoned (63±15 vs. 71±16[emsp4 ]y, P=0.04). Mean numbers of APLs, total leads implanted, and procedures of new lead placement were significantly larger in patients with complications than in those without complications (1.58±0.78 vs. 1.2±0.44, 4.96±1.23 vs. 2.66±0.8, and 2.13±0.85 vs. 1.25±0.53, P=0.03, 4×10−9 and 4×10−5, respectively). Conclusions. 1. With only 5.5% of patients having had pacemaker-related complications, the adverse outcome of APL is small. 2. Clinical clues to the possible occasion for pacemaker-related complications include three or more APLs, four or more total leads, three or more procedures of new lead placement, and a younger age at initial pacemaker implantation. 3. Patients with a large number of APLs, total lead implantations, and procedures of new lead placement should be carefully observed to detect possible pacemaker-associated complications.

Atrial “J” Pacing Lead Retention Wire Fracture: Radiographic Assessment, Incidence of Fracture, and Clinical Management

In November 1994, Telectronics Pacing Systems issued a voluntary recall of their Accufix™330–801 and 329–701 “J”‐shaped atrial pacemaker leads. To assess the integrity of the lead, 156 consecutive patients with the Accufix™330–801 atrial lead implanted underwent fluoroscopic screening. Leads were visualized in at least two orthogonal views. When identified, fractured retention wires were classified into one of four groups, depending on the degree of wire extrusion outside of the lead insulation. Results; Of the 156 patients, 35 patients (22.4%) had a definite retention wire fracture, and an additional 13 patients (8.3%) had indeterminate leads. Neither the age of the patients, the time since lead implant, nor the site of fracture correlated with the incidence of wire fracture. When analyzed to include indeterminate leads that were re‐evaluated and found to be fractured, as well as two leads that were identified as being radiographically normal but found to be fractured after extraction, the incidence of retention wire fracture is 25.6% (40 of 156 leads evaluated). Conclusions: The incidence of retention wire fracture in the Accufix™ 330–801 lead is significantly higher than originally reported. Patients should be notified of the potential dangers associated with this lead. Cardiac digital fluoroscopy is an effective method of screening for wire fracture. Leads with fractured retention wires should be extracted and those with normal fluoroscopic appearance should undergo regular fluoroscopic screening.

Left Ventricular and Biventricular Pacing in Congestive Heart Failure

Dual-chamber pacing improved hemodynamics acutely in a subset of patients with left ventricular (LV) dysfunction but conveyed no long-term symptomatic benefit in most. More recently, LV pacing and biventricular (multisite) pacing have been used to improve systolic contractility by altering the electrical and mechanical ventricular activation sequence in patients with severe congestive heart failure (CHF) and intraventricular conduction delay or left bundle branch block (LBBB). Intraventricular conduction delay and LBBB cause dyssynchronous right ventricular and LV contraction and worsen LV dysfunction in cardiomyopathies. Both LV and biventricular cardiac pacing are thought to improve cardiac function in this situation by effecting a more coordinated and efficient ventricular contraction. Short-term hemodynamic studies have shown improvement in LV systolic function, which seems more pronounced with monoventricular LV pacing than with biventricular pacing. Recent clinical studies in limited numbers of patients suggest long-term clinical benefit of biventricular pacing in patients with severe CHF symptoms. Continuing and future studies will demonstrate whether and in which patients LV and biventricular pacing are permanently effective and equivalent and which pacing site within the LV produces the most beneficial hemodynamic results.

Dual Chamber Pacing for Patients With Hypertrophic Obstructive Cardiomyopathy: A Clinical Perspective in 2000

In some patients with hypertrophic cardiomyopathy, the dynamic left ventricular outflow tract obstructive gradient results in exercise-limiting symptoms of dyspnea, angina, and syncope. Dual chamber pacing has been proposed as a widely available alternative treatment for a subset of patients with symptomatic hypertrophic obstructive cardiomyopathy. Initial studies showed a reduction in gradient and an improvement in symptoms in almost 90% of patients with severe symptoms. We report the Mayo Clinic experience with dual chamber pacing in 38 patients with hypertrophic obstructive cardiomyopathy who had permanent pacemakers implanted for limiting symptoms intractable to medical therapy. After a mean +/- SD follow-up of 24 +/- 14 months, subjective improvement was reported in 47% of patients. However, there was no statistical difference between the maximal oxygen consumption at last follow-up and AAI pacing (atrial sensing and atrial pacing) (18.6 +/- 1.1 mL.kg-1.min-1) (i.e., when the pacemaker was implanted but not pacing continuously). This article discusses the clinical perspective on the utility of dual chamber pacing for patients with hypertrophic obstructive cardiomyopathy.

Extraction of the Telectronics Accufix 330–801 Atrial Lead: The Mayo Clinic Experience

OBJECTIVE To document a cumulative experience with removal of the Telectronics 330-801 Accufix atrial lead after it was withdrawn from the market. DESIGN We reviewed our results with 96 attempted lead extraction procedures through Dec. 1, 1995. MATERIAL AND METHODS All patients underwent preoperative assessment, including fluoroscopic screening of the lead. Patients had blood typing and screening done before the extraction procedure, and extractions were performed with cardiac surgical intervention available. Pacing dependence was assessed to determine the need for temporary pacing. RESULTS The mean patient age was 65.7 +/- 1.6 years and the mean duration of lead implantation was 31.0 +/- 1.4 months. Of the 96 lead extractions attempted, 94 were successful. Of the 96 cases, the retention wires were normal in 29, fractured without protrusion in 34, and fractured with protrusion in 33. Fifty-three leads were removed with use of simple traction only, and seven leads were removed by using a locking stylet and telescoping sheaths. The Cook workstation was used in the removal of 32 leads through the femoral vein; in 1 of these 32 patients, the retention wire was removed before lead extraction. The retention wire was removed but the lead was left intact in one patient. One lead was removed during an opertive maze procedure. Associated complications were minimal. CONCLUSION Although lead extraction is a potentially fatal procedure, the Telectronics 330-801 Accufix atrial lead can be extracted safely with minimal morbidity when performed by experienced personnel.

Role of renal Na+,K(+)-ATPase in the regulation of sodium excretion under normal conditions and in acute congestive heart failure.

BackgroundCardiac glycosides have traditionally been used as inotropic agents in the treatment of congestive heart failure (CHF). The renal actions of cardiac glycosides independent of inotropic effects are not characterized. The presence of endogenous digitalis-like factors (EDLFs) with characteristic Na+,K+-ATPase activity has been postulated in volume-expanded states such as CHF, and recent studies have demonstrated that at least one EDLF shares structural homology with ouabain. This study was undertaken to evaluate the renal actions of ouabain in normal dogs and those with CHF. Methods and ResultsAfter surgical preparation, normal dogs (n = 6) and dogs in pacing-induced CHF (n = 6) received intrarenal ouabain in sequential doses of 0.167 μg/kg/min, 0.334 μg/kg/min, and 0.668 μg/kg/min. Hemodynamics and renal function were evaluated during the infusion. There was no change in heart rate or mean arterial pressure during the infusion compared with baseline in both groups. Sodium excretion and urine volume significantly increased in both groups. Plasma renin activity, activated by the onset of pacing in the CHF group, was inhibited by the administration of intrarenal ouabain in this group only. ConclusionsThese studies demonstrate that ouabain has diuretic and natriuretic actions independent of cardiac hemodynamics that are preserved in CHF. Furthermore, intrarenal ouabain suppresses activation of renin in CHF.

The synergistic effects of cyclosporine and endothelin--demonstration of an important cardiodepressor action.

Cyclosporine represents the foundation for current immunosuppressive therapy following solid organ transplantation. CsA use is associated with renal insufficiency and systemic hypertension. We hypothesized that CsA would enhance the vascular actions of endo-thelin (ET). Three groups of anesthesized dogs (n=15) were studied. Group 1 received CsA alone (1 mg/kg), group 2 received ET alone (1 ng/kg/min), and group 3 received combined CsA (1 mg/kg) and ET (1 ng/kg/min). The hemodynamic and renal effects were evaluated after 30 min. Combined treatment resulted in a profound reduction in mean arterial pressure (-62±14 mmHg (P<.05) and cardiac output (-2.2±0.4 1/min (P<.05). The reduction in mean arterial pressure and cardiac output were significantly greater than that observed with CsA or ET alone. Systemic vascular resistance was not significantly changed. Combined CsA and ET resulted in a significant reduction in renal blood flow (195±18to 101±11 ml/mm P<.05) but without evidence of active renal vasoconstriction. The decline in GFR (31.8±5.6 ml/min to being unmeasurable) was of greater magnitude than the change in renal blood flow, suggesting enhanced afferent anteriolar vasoconstriction or an alteration in the ultrafiltration coefficient. These studies demonstrate an important and synergistic cardiode-pressor effect when CsA and ET are combined.

Transcutaneous Aortic Valve Implantation

Non-rheumatic, degenerative aortic stenosis is overwhelmingly a disease of the elderly. As many as 300,000 individuals in the United States have symptomatic aortic stenosis (AS). Prior studies suggest that patients with asymptomatic but hemodynamically significant AS have a high risk of dying or developing symptoms. A Mayo Clinic study demonstrated that the 1, 2, and 5 year probabilities of remaining free from operation or death were 80%, 63%, and 25% respectively in a cohort of 622 patients (Pellikka et al. 2005). The development of symptoms portends a high risk of death (Carabello 2002). Surgical intervention with mechanical or tissue prosthetic valves has long been the gold standard for treatment. Improved operative techniques and more durable valvular prostheses have resulted in excellent functional status and patient survival. While operative mortality at experienced centers with careful patient selection is low, frequently patients with calcific AS have increased operative risk (O’Brien et al. 2009). As such, a third to half of elderly patients with symptomatic AS are not candidates for operative intervention due to advanced age or severe co-morbidities (Bouma et al. 1999). Percutaneous aortic balloon valvuloplasty has not resulted in long-term relief, with early restenosis the rule.