Nonrandomized comparison between stent deployment and percutaneous transluminal coronary angioplasty in acute myocardial infarction.

BACKGROUND: Compared with angioplasty, elective stent implantation has improved short-term and long-term outcome with a decrease in abrupt closure and a reduced 6-month restenosis rate. Although primary angioplasty during acute myocardial infarction has improved outcome, recurrent ischemic events and restenosis are still a problem. METHODS: Outcomes for 166 consecutively treated patients who underwent stent insertion procedures within 24 hours after the onset of acute myocardial infarction were compared with those for a similar group of patients (n = 212) who underwent consecutive balloon angioplasty procedures at one tertiary care institution. The objective of this study was to examine in-hospital and late clinical outcomes for the 2 groups. RESULTS: The procedural success rate for stenting in acute myocardial infarction was 100%; that for angioplasty was 98%. Mortality rates during hospitalization were similar for the stent group and the angioplasty group (4.0% vs 2.0%). The rate of in-hospital acute reocclusion necessitating urgent percutaneous reintervention was significantly lower for the stent group (0% vs 3%, P =.02). Six months after the procedure, the stent group had a significantly lower need for revascularization of the infarct-related artery (8% vs 20%, P =.001) and a significantly lower incidence of combined serious clinical events (death, acute occlusion, emergency bypass, target vessel revascularization, and nonfatal myocardial infarction; 12% vs 30%, P =.00003). CONCLUSION: Compared with balloon angioplasty, stent deployment in the setting of acute myocardial infarction was associated with significantly lower frequency of in-hospital acute occlusion and significantly less need for target-vessel revascularization 6 months after myocardial infarction.

Lead failure due to the subclavian crush syndrome in a patient implanted with both standard and thin bipolar spiral wound leads.

Subclavian crush syndrome is a well-described cause of pacemaker lead failure resulting from an entrapment of a lead or leads between the clavicle and the first rib. A new thinner lead (ThinLine) was designed to minimize this complication. Our patient developed atrial and ventricular lead subclavian crush syndrome with both conventional and thin leads.

The utility of quantitative body surface isoarea mapping for predicting ventricular tachyarrhythmias.

Noninvasive techniques, such as the signal averaged ECG, have been used to assess risk of ventricular tachyarrhythmias (VT). However, these methods produce false positive and negative results. The purpose of this study was to develop body surface map algorithms which would enhance prediction of susceptibility to VT. Fifty-three patients referred for programmed electrical stimulation were enrolled in this study. All patients underwent signal averaged ECG, body surface map, programmed electrical stimulation. Group I patients had no sustained inducible VT and group II patients had either inducible sustained VT at electrophysiology study or previously documented spontaneous, sustained VT. For body surface map analysis, the difference between extrema on isoarea maps was calculated and defined as the gradient range. An abnormal body surface map was defined as a QRST gradient range < or = 109 mv.ms. The mean QRST gradient range in group II was significantly < that in group I (P < 0.05). By logistic regression analysis, the presence of coronary artery disease, a QRST gradient range < or = 109 mv.ms, an EF < 40% and a signal averaged ECG QRS duration > 114 ms predicted VT. The sensitivity, specificity, positive and negative predictive values for predicting VT susceptibility of an algorithm which combines the signal averaged ECG QRS duration and the QRST gradients were 0.93, 0.76, 0.79, and 0.91, respectively, while those for the signal averaged ECG alone were 0.52, 0.69, 0.63, and 0.59 for VT susceptibility. A combined body surface map-signal averaged ECG algorithm was more sensitive in detecting susceptibility to VT than the signal averaged ECG alone.

Electrical cardioversion of atrial fibrillation or flutter with conscious sedation in the age of cost containment.

BACKGROUND: The purpose of this study was to compare the safety, efficacy, and cost of conscious sedation administered by electrophysiologists certified in the use of conscious sedation with sedation administered by anesthesiologists during cardioversion of atrial fibrillation or atrial flutter to sinus rhythm. METHODS AND RESULTS: Patients with hemodynamically stable persistent atrial fibrillation and flutter were included in this study. Group 1 patients (n = 33) were sedated by an anesthesiologist and group 2 patients (n = 26) were sedated by an electrophysiologist. Anesthesiologists used propofol and electrophysiologists used midazolam and morphine for sedation. A cost analysis based on professional charges and cost of medications was performed for both groups and compared. Hospital charges were similar for both groups and were excluded from the cost analysis. Although time to sedation in group 1 was shorter than that in group 2, sedation was adequate in both groups such that no patient in group 1 and only 1 patient in group 2 recalled being shocked. There were no complications in either group. The cost incurred in group 2 was less than that in group 1. CONCLUSIONS: Sedation administered by electrophysiologists for cardioversion of atrial arrhythmias is safe and cost effective. Midazolam and morphine, the sedative agents administered by electrophysiologists, were effective and well tolerated by patients.

Development of an interactive computer-guided method for radiofrequency catheter ablation of ventricular tachycardia.

The purpose of this study was to develop a simple computer-guided approach to localizing ventricular tachycardias during ventricular mapping. Six patients with sustained monomorphic ventricular tachycardia were connected to a 32-lead computer body surface mapping system. Isoarea maps of induced ventricular tachycardia were recorded. Then a pacing probe was placed in either the right or left ventricle, and maps were generated from a variety of sites. Differences between ventricular tachycardia and pace map maxima X, Y coordinates were utilized to guide catheter manipulation and localization. In 6 of 6 patients (100%) this method appeared to provide a systematic approach to ventricular tachycardia localization. Computer-generated correlations as well as the X, Y coordinates of the QRS isoarea maxima were used to determine proximity to the ventricular tachycardia foci and direct catheter manipulation. In the next three patients this method was applied prospectively to help guide catheter manipulation during ventricular tachycardia (two right ventricular outflow tract tachycardias, and one left ventricular tachycardia). After a mean of 4.0 +/- 1.7 radiofrequency applications, ventricular tachycardia was no longer inducible, and at 7 +/- 0 months follow-up there have been no arrhythmia recurrences. We conclude that online computerized body surface mapping can assist in localizing ventricular tachycardia. Differences in maxima during pace maps and in-situ ventricular tachycardias can help with catheter manipulation as well as with more precise identification of focal tachycardias. This technique appears to hold the promise of a simple computer-guided method that may facilitate radiofrequency catheter ablation.

Efficacy of pindolol for treatment of vasovagal syncope.

The purpose of this study was to evaluate the efficacy, safety, and tolerance of pindolol as initial therapy for vasovagal syncope. Head-up tilt table testing (HUT) was performed on 192 patients for syncope or near-syncope of unknown cause. Forty-four (23%) patients had a positive HUT for vasovagal syncope, and 28 (64%) received oral pindolol as initial therapy. Three patients were lost to follow-up; of the remaining 25 patients (mean age 60 +/- 22 years), 15 were women, 14 had syncope, and 11 had near-syncope. At 14 +/- 6 months' follow-up, 16 (64%) patients were without recurrence or side effects from pindolol. Of the 9 patients who stopped taking pindolol, 3 were switched to another regimen for recurrent symptoms, 2 stopped because of side effects, and 4 did not comply with the regimen. In conclusion, pindolol appears to be safe and effective as initial treatment for vasovagal syncope.

Clinical experience with transvenous implantable cardioverter-defibrillators for treatment of malignant ventricular arrhythmias.

The need for thoracotomy has previously limited the use of the implantable cardioverter-defibrillator. Prior investigators have shown the efficacy and reduced risk of the transvenous implantable cardioverter-defibrillator. In this study, we report our experience with the transvenous implantable cardioverter-defibrillator as a first-line system. Thirty-four patients with mean age 63.2 +/- 10.3 years and mean ejection fraction 32.6 +/- 11.4% underwent implantation of a transvenous cardioverter-defibrillator using an Endotak lead with or without a subcutaneous patch. Twenty-one patients received a biphasic device and the remainder a monophasic device. Thirty-three of 34 patients (97%) were successfully implanted. The mean defibrillation threshold was than < or = 15.3 +/- 3.6J. Overall, 25 of 34 (74%) patients were implanted with a single endocardial lead alone. In the group receiving a biphasic device 19 of 21 (90%) were successfully implanted with a single endocardial lead alone whereas in the group receiving a monophasic device only 6 of 12 (50%) were successfully implanted with single endocardial lead alone (p < 0.05). There were no serious complications. One postoperative death was a result of end-staged congestive heart failure. We conclude that the transvenous implantable cardioverter-defibrillator is safe and efficacious and that incorporation of biphasic waveform may lead to higher rates of implantation of single transvenous lead alone without the need for subcutaneous patch.

Implanted devices and electromagnetic interference: case presentations and review.

Electromagnetic interference can cause implanted devices (pacemakers and defibrillators) to malfunction. This article reviews four cases of device interference and provides a review of the literature, and our recommendations for managing these problems.

Radiofrequency catheter ablation as primary therapy for symptomatic ventricular tachycardia.

Most applications of radiofrequency (RF) catheter ablation for treatment of ventricular tachycardia (VT) have been as a treatment of last resort. The purpose of this study was to determine the efficacy and safety of RF catheter ablation as the primary treatment for symptomatic single morphology VT. Eleven of 81 patients (14%) with inducible sustained monomorphic VT underwent RF ablation as the primary treatment. One of these 11 patients had successful RF ablation of bundle branch reentry VT and was excluded from this series. The remaining 10 patients had a mean age of 58 +/- 19 years (range 20 to 73 years), were mostly men (7 of 10 patients), and all presented with documented evidence of symptomatic sustained monomorphic VT, at a mean cycle length of 340 +/- 60 milliseconds (ms) (range 250 to 430 ms). Six patients had coronary artery disease (CAD), one had surgical repair for tetralogy of Fallot, one had surgical repair of a ventricular septal defect, and two had a normal cardiac substrate. The VT origin was mapped using a combination of activation mapping, mid-diastolic potentials, pace mapping, and concealed entrainment. A mean of 5 +/- 3 (range 2 to 11) RF applications were administered to the putative VT foci. Eight of 10 (80%) clinical VTs were successfully ablated. There were no serious complications. Patients with VT originating from the left ventricle were offered implantable cardioverter-defibrillator back-up; however, only one patient accepted this option. At a mean follow-up of 12 +/- 7 months, only one patient had a possible arrhythmia recurrence.

Radiofrequency catheter ablation as a primary therapy for treatment of ventricular tachycardia in a patient after repair of tetralogy of Fallot.

A 20-year-old man with previous surgical repair of tetralogy of Fallot was admitted with hemodynamically significant ventricular tachycardia that was terminated with cardioversion. He was found at electrophysiological study to have easily inducible ventricular tachycardia that was mapped to the right ventricular outflow tract. Radiofrequency catheter ablation of the ventricular tachycardia focus rendered the patient's arrhythmia noninducible. This case represents a successful radiofrequency catheter ablation of a ventricular tachycardia focus associated with tetralogy of Fallot repair.

A comparison of active compression-decompression cardiopulmonary resuscitation with standard cardiopulmonary resuscitation for cardiac arrests occurring in the hospital.

BACKGROUND: Recent studies have demonstrated improved cardiopulmonary circulation during cardiac arrest with the use of a hand-held suction device (Ambu CardioPump) to perform active compression-decompression cardiopulmonary resuscitation (CPR). The purpose of this study was to compare active compression-decompression with standard CPR during cardiac arrests in hospitalized patients. METHODS: All patients over the age of 18 years who had a witnessed cardiac arrest while hospitalized at our center were enrolled in this trial; they were randomly assigned according to their medical-record numbers to receive either active compression-decompression or standard CPR. The study end points were the rates of initial resuscitation, survival at 24 hours, hospital discharge, and neurologic outcome. Compressions were performed according to the recommendations of the American Heart Association (80 to 100 compressions per minute; depth of compression, 3.8 to 5.1 cm [1.5 to 2 in.]; and 50 percent of the cycle spent in compression). RESULTS: Sixty-two patients (45 men and 17 women) with a mean age (+/- SE) of 68 +/- 2 years were entered into the trial. Sixty-two percent of the patients who underwent active compression-decompression were initially resuscitated, as compared with 30 percent of the patients who received standard CPR (P < 0.03); 45 percent of the patients who underwent active compression-decompression survived for at least 24 hours, as compared with 9 percent of patients who underwent standard CPR (P < 0.004). Two of the 62 study patients survived to hospital discharge; both were randomly assigned to receive active compression-decompression. Neurologic outcome, as measured by the Glasgow coma score, was better with active compression-decompression (8.0 +/- 1.3) than with standard CPR (3.5 +/- 0.3; P < 0.02). CONCLUSIONS: In this preliminary study, we found that, as compared with standard CPR, active compression-decompression CPR improved the rate of initial resuscitation, survival at 24 hours, and neurologic outcome after in-hospital cardiac arrest. Larger trials will be required to assess the potential benefit in terms of long-term survival.

Model system oxidations supporting the crystal growth model of ferritin iron uptake.

Fe2+ is oxidized and taken up by ferritin or ápoferritin in the presence of dioxygen. Iodate causes Fe2+ oxidation and uptake by ferritin, but not by apoferritin. Synthetic iron polymer facilitates Fe2+ oxidation by either dioxygen or iodate. Nitrilotriacetic acid or iminodiacetic acid facilitate oxidation of Fe2+ by oxygen but not by iodate. These results support the crystal growth model of ferritin iron uptake, with iron polymer serving as a model for the ferritin core and aminocarboxylic acids mimicking the metal-binding sites of apoferritin.