Intravascular extraction of problematic or infected permanent pacemaker leads: 1994-1996. U.S. Extraction Database, MED Institute.

Of the 400,000-500,000 permanent pacemaker leads implanted worldwide each year, around 10% may eventually fail or become infected, becoming potential candidates for removal. Intravascular techniques for removing problematic or infected leads evolved over a 5-year period (1989-1993). This article analyzes results from January 1994 through April 1996, a period during which techniques were fairly stable. Extraction of 3,540 leads from 2,338 patients was attempted at 226 centers. Indications were: infection (27%), nonfunctional or incompatible leads (25%), Accufix or Encore leads (46%), or other causes (2%). Patients were 64+/-17 years of age (range 5-96); 59% were men, 41% women. Leads were implanted 47+/-41 months (maximum 26 years), in the atrium (53%), ventricle (46%), or SVC (1%). Extraction was attempted via the implant vein using locking stylets and dilator sheaths, and/or transfemorally using snares, retrieval baskets, and sheaths. Complete removal was achieved for 93% of leads, partial for 5%, and 2% were not removed. Risk of incomplete or failed extraction increased with implant duration (P<0.0001), less experienced physicians (P<0.0001), ventricular leads (P<0.005), noninfected patients (P<0.0005), and younger patients (P<0.0001). Major complications were reported for 1.4% of patients (<1% at centers with >300 cases), minor for 1.7%. Risk of complications increased with number of leads removed (P<0.005) and with less experienced physicians (P<0.005); risk of major complications was higher for women (P<0.01). Given physician experience, appropriate precautions, and appropriate patient selection, contemporary lead removal techniques allow success with low complication rates.

Interactions between electronic article surveillance systems and implantable cardioverter-defibrillators.

BACKGROUND: In patients with implantable cardioverter-defibrillators (ICDs). inappropriate shocks have been reported with exposure to electronic article surveillance systems. The risk to patients with ICDs of walking through or lingering near surveillance systems requires further investigation. METHODS AND RESULTS: We evaluated the response in ICD function in 170 subjects during a 10- to 15-second midgate walk-through of and during extreme (2 minutes within 6 in of the gate) exposure to 3 common article surveillance systems. Complete testing was done in 169 subjects. During a 10- to 15-second (very slow) walk-through of the 3 surveillance systems, no interactions were observed that would negatively affect ICD function. During extreme exposure (169 subjects) and during extreme exposure and pacing via the ICD (126 subjects), interactions between the ICD and the article surveillance systems were observed in 19 subjects. In 7 subjects, this interaction was clinically relevant and would have likely (3 subjects) and possibly (4 subjects) resulted in ICD shocks. In 12 subjects, the interaction was minor. CONCLUSIONS: It is safe for a patient with an ICD to walk through electronic article surveillance systems. Lingering in a surveillance system may result in an inappropriate ICD shock.

Surgical management of ventricular tachycardia.

Advances in portable high-speed computer technology have allowed intraoperative mapping of the ventricular endocardium. Accurate and highly precise endocardial maps have rendered certain types of ventricular tachycardia curable. This article discusses the options available to patients with ventricular tachycardia and places special emphasis on high-speed precision mapping and endocardial resection for cure.

Subxiphoid approach for implantable cardioverter defibrillator in patients with previous coronary bypass surgery.

From February 1988 until August 1991, 28 patients with prior coronary artery bypass grafting (CABG) received implantable cardioverter defibrillator (ICD) therapy via a subxiphoid approach. Only one patient required conversion to a median sternotomy incision. The mean defibrillation threshold was 11.9 +/- 4.4 J. The mean R wave was 8.2 +/- 3.7 mV. One perioperative death occurred due to heart failure (mortality rate 1/28 [3.50%]). No patient required reexploration for bleeding. The subxiphoid method for ICD electrode implantation is safe and reliable in patients with prior CABG surgery.

Bradycardic responses to vagally mediated bedside maneuvers in healthy volunteers.

PURPOSE: To determine the relative potency in healthy individuals of the vagally mediated reflexes used clinically to inhibit sinoatrial and atrioventricular node function. SUBJECTS AND METHODS: Twenty healthy volunteers with no history of heart disease performed face immersion in cold water and the Valsalva maneuver twice, to maximum endurance and to the subjective point of first discomfort, and face immersion in warm water and the Müller maneuver to maximum endurance only. Right and left carotid massage and left, right, and bilateral eyeball compression were each performed for 15 seconds. Change in heart rate was taken as baseline minus the rate over the slowest three consecutive QRS cycles elicited by each maneuver. Fisher's least-significant-difference multiple comparison procedure was used to analyze heart rate responses. Significance was defined as p less than or equal to 0.05. RESULTS: Maximum pulse decrements from baseline and 95% confidence intervals in beats/minute were as follows: cold-water face immersion to maximum endurance 15.5 (12.3 to 18.5), cold-water face immersion to first discomfort 10.1 (6.7 to 13.1), Valsalva maneuver to maximum endurance 9.2 (6.3 to 12.4), Valsalva maneuver to first discomfort 8.3 (5.0 to 11.3), right carotid massage 7.3 (4.3 to 10.3), left carotid massage 5.2 (2.3 to 8.4), right eyeball compression 6.0 (3.1 to 9.2), left eyeball compression 6.6 (3.6 to 9.5), bilateral eyeball compression 6.0 (3.1 to 9.2), warm-water face immersion 7.0 (3.2 to 9.8), and Müller maneuver 1.6 (-1.3 to 4.9). Bradycardia was significantly greater for cold-water immersion of the face performed to maximum endurance than for all other maneuvers. CONCLUSION: In healthy subjects, the diving reflex is the most potent of the vagally mediated reflexes utilized in clinical practice. Immersion of the face in cold water may prove effective at the bedside when other maneuvers fail to augment vagal tone adequately.

Long-term efficacy of oral pirmenol in suppressing ventricular premature depolarizations.

Pirmenol is an investigational type 1A antiarrhythmic drug the long-term efficacy of which has not been fully determined. Therefore the long-term efficacy of oral pirmenol in suppressing ventricular premature depolarizations (VPDs) was assessed in an open-label, dose-titration study. Twelve patients (eight men and four women; mean age 57 +/- 12 years) were treated for 24 to 36 months (mean 33 +/- 4). Seven had structural heart disease (three valvular heart disease, two ischemic heart disease, and two hypertensive heart disease) and five did not. The mean left ventricular ejection fraction was 0.63 +/- 0.13. Exclusion criteria included less than 30 VPDs/hr, greater than 15 beats of ventricular tachycardia (VT), or prior failure of more than two antiarrhythmic drugs. Drug efficacy was assessed by 24-hour ambulatory ECG monitoring performed every 3 months during the first year, every 4 months during the second year, and at 6-month intervals during the third year. The mean hourly frequency of VPDs during the placebo phase was 732 +/- 608. Seven patients (58%) were treated successfully with effective (greater than 75%) long-term suppression of VPDs. Two patients (17%) had a partial response with effective suppression of VPDs for the first 16 months and 5 months of treatment, respectively. Three patients failed to show consistent suppression of VPDs while receiving pirmenol. The daily dose of pirmenol ranged from 200 to 500 mg (mean 317 +/- 94 mg at the beginning of the study and 375 +/- 97 mg at the end). No proarrhythmic effects were identified during long-term treatment, and none of the patients withdrew from the study prematurely.(ABSTRACT TRUNCATED AT 250 WORDS)

Occurrence of exercise-induced and spontaneous wide complex tachycardia during therapy with flecainide for complex ventricular arrhythmias: a probable proarrhythmic effect.

Flecainide acetate, a new antiarrhythmic agent, possesses favorable pharmacokinetic and hemodynamic properties and demonstrates highly favorable antiarrhythmic activity in patients with ventricular arrhythmias. However, the proarrhythmic potential of flecainide deserves further evaluation. In 7 (13%) of 55 consecutive patients treated with oral flecainide, 200 to 600 mg/day, for complex ventricular arrhythmias (including sustained ventricular tachycardia in 14), we observed the appearance of new or more sustained exercise-induced (five patients) or spontaneous (two patients) wide complex tachycardia. The mechanism of wide complex tachycardia appeared to be ventricular tachycardia in all seven. In our series, episodes were self-remitting or successfully treated. In four patients, wide complex tachycardia did not recur during exercise testing during alternative antiarrhythmic therapy (three patients) or no antiarrhythmic therapy (one patient). These observations raise the possibility of flecainide-related proarrhythmia, manifested as an increased propensity to exercise (activity)-induced wide complex tachycardia, which was not reliably predicted by results of Holter recordings or programmed electrical stimulation. Patients with complex ventricular arrhythmias beginning long-term treatment with oral flecainide should be considered for treadmill exercise testing together with ambulatory monitoring as part of the initial assessment of drug efficacy.

Prognostic usefulness of programmed ventricular stimulation in idiopathic dilated cardiomyopathy without symptomatic ventricular arrhythmias.

Twenty-four patients, mean age 42 years, with idiopathic dilated cardiomyopathy (DC) and no history of symptomatic ventricular arrhythmias underwent right ventricular programmed stimulation with up to 3 extrastimuli. Ventricular tachycardia (VT) was induced in 8 patients and ventricular fibrillation (VF) in 2. The VT was unimorphic in 2 and polymorphic in 6. No significant differences were noted between patients in whom arrhythmias were inducible and and those in whom they were not with regard to age, symptomatic class, arrhythmia severity or hemodynamic indexes. Over a mean follow-up of 12 months, 4 patients died, 3 suddenly and 1 with progressive heart failure. Only 1 of the 3 who died suddenly had inducible VT. One other patient with induced sustained unimorphic VT later presented with spontaneous sustained VT similar in rate and configuration to induced VT. In conclusion, VT or VF may be induced in approximately 40% of patients with DC and no history of symptomatic VT or VF. Inducibility of polymorphic VT or VF does not correlate with clinical or hemodynamic variables or with the risk of sudden death. However, induction of unimorphic VT may predict later occurrence of spontaneous unimorphic VT.

Interrelationships between serum levels of amiodarone, desethylamiodarone, reverse T3 and the QT interval during long-term amiodarone treatment.

The interrelationships between serum levels of amiodarone, desethylamiodarone, and reverse T3, and changes in the corrected QT interval (delta QTc) were examined in 22 patients during long-term treatment with amiodarone. At 1, 3, and 6 months of follow-up, the correlation coefficient between serum levels of amiodarone or desethylamiodarone and reverse T3 ranged from 0.01 to -0.2 (p greater than 0.4). At the same time intervals, the correlation coefficient between both amiodarone and desethylamiodarone levels and delta QTc ranged from 0.1 to -0.1 (p greater than 0.6), and the correlation coefficient between reverse T3 and delta QTc also ranged between 0.1 to -0.1 (p greater than 0.5). Substituting percent delta QTc for delta QTc also did not reveal a significant correlation. These data demonstrate that serum levels of reverse T3 cannot be used as a substitute for serum levels of amiodarone in monitoring patients being treated with amiodarone. The absence of a correlation between serum reverse T3 levels and delta QTc suggests that the delay in repolarization which occurs during amiodarone therapy is not secondary to an amiodarone-induced abnormality in thyroid hormone metabolism.

Coexistent posteroseptal and right-sided atrioventricular bypass tracts.

Twelve patients with a posteroseptal accessory pathway underwent complete electrophysiologic studies, and four were found to have a second atrioventricular (AV) bypass tract that was right anterior, right anteromedial or right anterolateral in location. In two of these four patients, the presence of the right-sided AV bypass tract was confirmed by intraoperative epicardial mapping or after catheter-induced abolition of retrograde conduction through the posteroseptal bypass tract. In three of the four patients with a dual AV bypass tract, the delta wave pattern was clearly atypical of the pattern seen with an isolated posteroseptal accessory pathway. Instead of a transition from an isoelectric or slightly positive delta wave in lead V1 to markedly positive delta waves in leads V2 to V6, the delta waves were negative or only slightly positive in leads V2 to V5. However, in a fourth patient with dual AV bypass tracts, the only atypical electrocardiographic finding was an intermittently positive delta wave in lead II; at times this patient's electrocardiogram was consistent with an isolated posteroseptal bypass tract, with negative delta waves in the inferior leads. There appears to be an association between posteroseptal and right-sided accessory pathways. In patients with a posteroseptal accessory pathway who are candidates for catheter or surgical bypass tract ablation, a complete mapping study of the tricuspid anulus is mandatory, even when the electrocardiogram is typical of an isolated posteroseptal bypass tract.

Pulmonary gas exchange during exercise in patients with chronic obliterative pulmonary hypertension.

The effect of exercise on pulmonary gas exchange was investigated in 7 patients with pulmonary hypertension resulting from primary pulmonary hypertension or recurrent pulmonary emboli. During supine bicycle exercise averaging 2.4 times baseline O2 consumption there was a significant fall in the arterial PO2 (64 +/- 1.1 to 56 +/- 5.4) and widening of the alveolar-arterial gradient for O2 (50 +/- 4.6 to 62 +/- 5.5). Measurement of the distribution of ventilation-perfusion (VA/Q) ratios by the multiple inert gas technique demonstrated no increase in VA/Q inequality. The increased hypoxemia was due to the fall in the mixed venous PO2 and its impact on the end-capillary blood of the shunt and low VA/Q units present at both rest and exercise. A concomitant shift in the mean VA/Q ratio for the normal lung units mitigated but could not eliminate the fall in the arterial PO2. We conclude that the increased hypoxemia seen during exercise in these patients is due to the widened arterial-venous O2 difference expected with exercise and its effect on the mild VA/Q inequality characteristic of this disorder.

A proposal for the clinical use of flecainide.

Effective antiarrhythmic therapy requires a carefully considered approach, including an understanding of the arrhythmia, the underlying cardiac disease and the drug's pharmacokinetics. Flecainide is a new antiarrhythmic drug that may soon be released for general use. Flecainide demonstrates unsurpassed efficacy in chronic ventricular arrhythmias in stable patients and may become a first-choice drug because of its ease of administration, efficacy and favorable tolerance. Twice-daily dosing with 100 to 200 mg usually provides effective therapy. Clinical experience suggests flecainide to be indicated in the treatment of uniform and multiform ventricular premature complexes, coupled ventricular premature complexes, and episodes of nonsustained ventricular tachycardia. A lower response rate is observed in preventing induction of sustained ventricular tachycardia, and these patients should be carefully selected. Flecainide is promising in the treatment of supraventricular tachycardias using atrioventricular nodal or extranodal reentrant pathways, although this use is still investigational in the United States. The drug's use for arrhythmias during acute myocardial infarction requires further study. Flecainide possesses modest negative inotropic potential. Proarrhythmic or other adverse reactions have occurred primarily in settings of high drug level, poor ventricular function or refractory, malignant arrhythmias, suggesting caution in these groups.

Oral hydralazine therapy for acute pulmonary embolism and low output state.

Shortly after pelvic surgery, massive bilateral pulmonary emboli and shock developed in an elderly woman. Despite fluids, dopamine hydrochloride, and heparin sodium, her condition steadily deteriorated. Two trials of hydralazine hydrochloride were given and each was associated with pronounced clinical and hemodynamic improvements. Ninety minutes and 24 hours after the first trial, her pulmonary vascular resistance decreased 44% and 67%, respectively, and cardiac index increased 40% and 90%, respectively. There were insignificant changes in heart rate and blood pressure. The hemodynamic improvements reversed when the hydralazine therapy was stopped but improved again during the second trial. Hydralazine may be of substantial benefit to patients with hemodynamic compromise secondary to pulmonary embolism.