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Biomedical subjects

R Brodman

Publications and source records attributed to R Brodman.

At least 37 records · Page 2Linked to original sources
PubMed1987

Automatic implantable cardioverter/defibrillator: inadvertent discharges during permanent pacemaker magnet tests.

A patient with an automatic implantable cardioverter defibrillator (AICD) received two inadvertent shocks when a magnet was placed over the pacer during a routine permanent pacer check. Analysis of the rhythm strip suggested that both patients' QRS complexes (133 beats/minute) and asynchronous pacer artifacts (70 beats/minute) were counted by the AICD sensing system and exceeded the rate criteria of 153 beats/minute. This resulted in shocks from the AICD during sinus rhythm at 133 beats/minute. To avoid possible inadvertent shocks, an AICD should be deactivated while a magnet is placed over the pacemaker during a permanent pacer check.

Electric Countershock↗
PubMed1986

Susceptibility to atrial fibrillation and ventricular tachyarrhythmia in the Wolff-Parkinson-White syndrome: role of the accessory pathway.

Clinical and electrophysiologic characteristics associated with spontaneous and inducible atrial fibrillation and ventricular tachyarrhythmia were assessed in 20 consecutive patients with Wolff-Parkinson-White (WPW) syndrome undergoing surgical division (n = 12) or transcatheter electrical ablation (n = 8) of accessory pathways. Patients with spontaneous atrial fibrillation were characterized by the trend (not significant) of a shorter antegrade accessory pathway effective refractory period (256 +/- 26 vs 303 +/- 109 msec). However, patients with and without spontaneous atrial fibrillation did not differ with respect to prevalence of structural heart disease (3 of 11 vs 2 of 9), intra-atrial conduction time (34 +/- 10 vs 32 +/- 10 msec), or interatrial conduction time (86 +/- 21 vs 88 +/- 17 msec). Thus, atrial and accessory pathway electrophysiologic properties (per se) were not clear determinants of susceptibility to atrial fibrillation. Among the 20 patients, 10 to 35 beats of nonsustained ventricular tachycardia (seven patients) or ventricular fibrillation (three patients) were induced at electrophysiologic study with one to three programmed extrastimuli. Clinically, a ventricular arrhythmia (ventricular fibrillation during atrial fibrillation) had occurred in only one of these patients. The discordance of these observations was significant (p less than 0.01). Patients with and without inducible ventricular arrhythmias were not distinguished by clinical factors or by electrophysiologic properties of the accessory pathway or ventricles. Accessory pathway conduction was completely or partially eliminated by ablation procedures in 14 of 20 patients. During a mean follow-up of 27 months, atrial fibrillation recurred in two patients with failed ablation procedures and in one patient with left atrial enlargement (despite accessory pathway division) (p = 0.019 vs pre-ablation). Ventricular arrhythmias remained inducible in two patients in whom accessory pathway ablation failed (p = 0.01 vs initial study). However, spontaneous ventricular tachyarrhythmias did not occur during follow-up. We conclude that susceptibility to spontaneous or inducible atrial fibrillation and ventricular tachyarrhythmia in patients with WPW syndrome and no organic heart disease depends primarily on the existence of a functional accessory pathway. These susceptibilities are eliminated by interruption of accessory pathway conduction. Ventricular tachyarrhythmias remain infrequent spontaneous events in the WPW syndrome. Their more frequent induction at electrophysiologic study is not predictive of clinical occurrence.

Atrial Fibrillation↗
PubMed1986

Detection of postcardiotomy bacterial pericarditis with gallium-67 citrate.

A 46-year-old man who had undergone apical cardiac aneurysmectomy with a ventriculotomy graft and implanted automatic cardioverter-defibrillator electrodes, presented with fever, left-sided pleuritic chest pain, and a draining sinus. A Ga-67 scan was performed to aid in determining whether the infection was limited to the chest wall or if it had penetrated deeper to the cardiac structures. Uptake of gallium within the cardiac region, in association with minimal rib uptake of Tc-99m MDP, strongly supported the existence of infection within the pericardium. CT scan demonstrated a pericardial collection which under CT-guided aspiration proved to be purulent. Definitive surgical drainage was performed, and the patient was discharged 4 weeks postoperatively. Ga-67 imaging can provide an accurate and relatively rapid means of localizing infection in the postcardiotomy patient. A thorough bibliography of pericardial gallium uptake is provided.

Cardiac Surgical Procedures↗
PubMed1986

Myosin isoenzyme distribution in overloaded human atrial tissue.

Using nondenaturing polyacrylamide gel electrophoresis, we have identified two distinct myosin isoenzymes in human atrial tissue that correspond to the V1 and V3 isomyosins found in rat ventricular tissue. Normal left and right atrial appendages have approximately 50% V3. When the left atrium was exposed to hemodynamic overload secondary to mitral stenosis, the percent V3 increased to 77 +/- 10% (n = 10); exposure to hemodynamic overload secondary to mitral regurgitation caused an increase to 70 +/- 14% (n = 6). Changes in the isoenzyme pattern were seen in the right atria of patients with mitral stenosis and markedly elevated pulmonary arterial pressures compared with control subjects and patients with mitral stenosis without severe pulmonary hypertension. Several clinical variables were examined to determine which factors might influence isoenzyme expression. Age, sex, the presence of atrial fibrillation, and pulmonary capillary wedge pressure did not predict the isoenzyme pattern. However, patients with mitral valvular disease and only slightly enlarged left atria tended to have a higher percent V3 than those with massively enlarged atria. These data confirm that human atrial tissue, like rat ventricular tissue, can alter its isomyosin composition in response to a hemodynamic load. The data further suggest that the isoenzyme shift is an early adaptation to the imposed load.

Adult↗
PubMed1985

A comparison of flow gradients across disposable arterial perfusion cannulas.

Five-hundred members of The Society of Thoracic Surgeons were canvassed to discover which cannulas are currently used for open-heart surgical procedures in adults; 120 surgeons responded. The mean arterial line pressure produced by 29 disposable arterial perfusion cannulas (size range, 16F to 30F) at flow rates of 1 to 5 liters per minute was compared. A roller pump with perfusion tubing 95 mm (0.75 inch) in diameter was used with water as the test solution. Line pressures in these cannulas ranged from 22.4 +/- 2.30 (standard deviation) to 271.0 +/- 6.60 mm Hg at 5 L/min. Four 24F cannulas had gradients of less than 55 mm Hg at a flow rate of 5 L/min, and 6 cannulas--4 of which were 22F and 2, 24F--had gradients higher than 150 mm Hg at 5 L/min. A number of cannulas kinked easily, and these showed marked increases in line pressure. The following results were obtained from this study: (1) a wide range of line pressures was observed in disposable arterial perfusion cannulas currently in clinical use; (2) some cannulas currently used for cardiopulmonary bypass in adults generated excessive line pressure; and (3) both material and design affect function, with some designs being safer than others. Cardiac surgeons should base the choice of an arterial perfusion cannula on the best performance and safest design available to avoid cannula-related problems at operation.

Aorta↗
PubMed1985

Activation mapping in patients with coronary artery disease with multiple ventricular tachycardia configurations: occurrence and therapeutic implications of widely separate apparent sites of origin.

Catheter or intraoperative activation mapping studies, or both, were performed in 17 patients with coronary artery disease with two to four distinct configurations of ventricular tachycardia, resistant to a mean of 12.1 +/- 6.0 antiarrhythmic drug trials per patient. Mapping studies were performed to guide anticipated surgical ablation of arrhythmias. Activation map data were adequate to determine sites of origin of 30 (64%) of 47 observed tachycardia configurations. These 30 ventricular tachycardias (26 observed clinically) were mapped to 22 separate endocardial sites of origin. Sites of origin of distinct tachycardias were identical or closely adjacent (within 3 cm) in six patients and widely separate (greater than or equal to 4 cm) in eight patients (47% of the group). Activation maps were not adequate to determine sites of origin of 17 (36%) of the 47 tachycardias, including all configurations in three patients. Fifteen patients underwent surgery for control of ventricular tachycardia: aggressive, map-guided endocardial resection (mean 26.5 +/- 14.2 cm2) in 12 patients with identified sites of tachycardia origin and extensive resection of visible endocardial scar (2 patients) or encircling endocardial ventriculotomy (1 patient) in those in whom the sites of origin of all clinical tachycardias remained undetermined. Two inoperable patients were treated with amiodarone. During postoperative electrophysiologic tests (11 of 13 surgical survivors), ventricular tachyarrhythmias were initially uninducible in only 4 of 11 patients. However, in two patients only nonclinical arrhythmias (ventricular flutter) were induced. Six (21%) of 29 clinical tachycardias whose sites of origin were either not determined or not resected (right septum or papillary muscle) remained inducible in five patients. Using previously ineffective antiarrhythmic drugs, initially inducible arrhythmias became uninducible (two patients), or harder to induce than preoperatively (five patients). As a result of surgical resections alone or in combination with previously ineffective drugs (and amiodarone in two inoperable patients), there were no recurrences of ventricular tachycardia in 14 (93%) of 15 patients discharged during 19.0 +/- 14.3 months of follow-up study. Thus, activation mapping may commonly reveal separate apparent sites of origin for clinically observed, morphologically distinct, highly drug-refractory ventricular tachycardias in patients with coronary artery disease with multiple tachycardia configurations. Extensive surgical resection of identified sites of origin may be required to ablate arrhythmias in these patients.(ABSTRACT TRUNCATED AT 400 WORDS)

Adult↗
PubMed1985

Catheter ablation of tachycardias.

Non-surgical electrode catheter ablation appears to be a useful technique for the treatment of selected patients with resistant supraventricular and ventricular tachycardias. Many problems remain, including the need for improved methods of tachycardia localization, the need for permanent pacing with A-V junctional ablation, a variety of potential and demonstrated complications, and the need for specially designed equipment. The relative role of electrical ablation versus other new techniques such as those employing lasers, remains unsettled. The clearly demonstrated benefits of electrical ablation in a growing number of patients ensures that continued development and refinement will occur.

Animals↗
PubMed1984

Attempted nonsurgical electrical ablation of accessory pathways via the coronary sinus in the Wolff-Parkinson-White syndrome.

Previous canine experiments suggested that transvenous catheters placed in the coronary sinus could be used to deliver limited energy shocks, resulting in fibrosis in the atrial wall and coronary sulcus with sparing of the coronary artery. From the distribution of the fibrosis, it appeared that this approach could be used for attempted ablation of accessory pathways in patients with the Wolff-Parkinson-White syndrome. Eight patients with symptomatic Wolff-Parkinson-White syndrome underwent electrophysiologic testing with attempted ablation of 10 accessory pathways. Shocks were limited to 40 to 80 J, except in one patient who received shocks of 100 and 150 J. From 2 to 26 shocks were given to each accessory pathway. All the accessory pathways were blocked completely immediately after the shocks. Subsequently, evidence of accessory pathway conduction recurred in each patient. Three had early promise of long-term improvement after the procedure, with prolongation of the refractory periods of the accessory pathways during the remainder of the initial hospitalization. Several weeks later, however, there was evidence of return toward original values in two of these. Another patient who appeared not to benefit during her initial hospitalization returned 7 weeks later with very depressed accessory pathway conduction, possibly due to developing fibrosis. The only significant complication occurred in the patient receiving shocks of 100 and 150 J; he had apparent rupture of the coronary sinus requiring pericardial drainage. In two patients in whom nonsurgical ablation was not successful, intraoperative mapping showed that the accessory pathway was located in an area of fibrosis at the site of the attempted ablation. In summary, nonsurgical electrical ablation of accessory pathways via the coronary sinus may be successful using limited energy levels in a few patients. The procedure remains experimental, and widespread application must await more effective means of delivering the shocks.

Adolescent↗
PubMed1984

Nonsurgical electrical ablation of tachycardias: importance of prior in vitro testing of catheter leads.

Nonsurgical electrical ablation of tachycardia pathways or foci has been attempted or carried out using a variety of temporary pacing catheter leads. To determine the ability of such leads to withstand the high energies used in such procedures, 34 leads were suspended in saline, and subjected to repeated electrical shocks. Small (4 French) temporary pacing leads made by a variety of manufacturers tolerated multiple shocks up to 100 joules; above this level, failures became increasingly common, although usually the failure mode was benign with respect to patient care implications. Testing of 6, 7, and 8 French leads revealed considerable inter-and intra-manufacturer differences in the ability to withstand higher energy shocks, reflecting differences in materials and fabrication techniques. It is concluded that careful in vitro lead testing is required prior to using identical models in humans for arrhythmia ablation procedures.

Cardiac Catheterization↗
PubMed1984

Implantation techniques of antitachycardia devices.

Implantation of a defibrillator may be by a mixed technique of transvenous leads and subcostal thoracotomy. An alternative approach is placement of all defibrillator leads and possible pacemaker leads via median sternotomy. All sensing leads, either for a defibrillator or a pacemaker, should be bipolar to provide maximal rejection of interference signals. Interpretation of the electrogram requires analysis of the pathologic electrogram to distinguish it from the "normal" electrogram for that patient and may require several leads to determine the activation sequence which will allow diagnosis of a tachycardia in a fashion similar to that performed by a human observer.

Electric Countershock↗
PubMed1984

Implantation of automatic cardioverter-defibrillators via median sternotomy.

15 AICD (automatic implantable cardioverter-defibrillator) Model B units were implanted in 10 patients. The median sternotomy is our preferred surgical approach using a right atrial patch electrode, a left ventricular apex patch electrode, and two closely placed epicardial sensing electrodes. Follow-up is 109 patient months and all patients are alive. AICD units discharged for ventricular tachycardia, ventricular flutter, and ventricular fibrillation. Discharges also occurred for sinus tachycardia and atrial fibrillation above the rate limit in three units. Premature pulse generator depletion has occurred in four AICD-B units 3 to 18 months postimplant and appears due to a defect in original battery design. Discharge of the AICD for supraventricular tachycardia is a problem that will remain until a better means of differentiating supraventricular tachycardia from ventricular tachyarrhythmias is found. The AICD appears to prevent sudden death from ventricular tachyarrhythmias.

Adult↗
PubMed1984

Results of electrophysiologically guided operations for drug-resistant recurrent ventricular tachycardia and ventricular fibrillation due to coronary artery disease.

Over a 39 month period, 143 patients with coronary artery disease had programmed stimulation (PES) for recurrent ventricular tachycardia (VT) or ventricular fibrillation (VF). Twenty-two patients underwent operations. Ages ranged from 40 to 71 years; 20 of the 22 were men. All patients had coronary artery disease and 11 had left ventricular aneurysms. The mean ejection fraction was 31% (16% to 50%). Eighteen of the 22 patients underwent operations for drug-resistant ventricular arrhythmias (more than six different drugs plus drug combinations tested per patient). Nineteen patients had intraoperative mapping, endocardial resection, and/or an encircling endocardial ventriculotomy. Three patients with ischemia-related VT had coronary artery bypass (CABG) alone. The 30 day operative mortality was 14%. Thirteen of 19 (68%) operative survivors were effectively controlled with operation alone or a combination of operation and previously ineffective drug therapy. Of the six patients whose VT was inducible postoperatively, three have experienced episodes of sustained VT and one patient died suddenly. Three of these patients have the automatic implantable defibrillator. Operation guided by endocardial mapping is effective alone or in combination with drugs in this select group of patients. If the patients' VT was uninducible postoperatively with or without the addition of antiarrhythmic therapy, late deaths (3/19) were due to poor myocardial reserve and coronary artery disease, not the reemergence of sustained ventricular arrhythmias during a mean follow-up of 15 months.

Adult↗