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Biomedical subjects

T B Ferguson

Publications and source records attributed to T B Ferguson.

At least 19 recordsLinked to original sources
PubMed1992

Improved detection of accessory pathways that bridge posterior septal and left posterior regions in the Wolff-Parkinson-White syndrome.

To improve the detection of accessory pathways that bridge the posterior septum and left posterior free wall, catheter maps of the coronary sinus from 21 patients (group I) who needed dissection of both these anatomic regions were compared with data from 23 (group II) with pathways confined to the posterior septum and from 9 (group III) with left posterior pathways. A decapolar catheter was used to map the coronary sinus in 0.5 to 1 cm steps. Intraoperative mapping was performed with a 16-electrode band. Catheter maps during atrial pacing and orthodromic supraventricular tachycardia were analyzed for the site of earliest activation and for differences in a new directional measure of conduction time between adjacent mapping sites. The site of earliest activation alone did not distinguish accessory pathways that bridged both anatomic regions, because 14 of 21 patients (66%) in group I would have been misclassified to either group II or III. In contrast, anterograde and retrograde directional conduction times distinguished patients in group I from those in groups II (p less than 0.01 to less than 0.0003) and III (p less than 0.04 to less than 0.0001). A multivariate model that incorporated the observed differences in directional interelectrode conduction times improved the identification of group I patients, with a sensitivity of 87% and a specificity of 90%. The results define new features in activation patterns measurable during catheter mapping that identify accessory pathways that bridge the posterior septum and left posterior free wall.

Adolescent↗
PubMed1992

Intraaortic balloon counterpulsation: patterns of usage and outcome in cardiac surgery patients.

Between January 1, 1986, and May 6, 1991, 7,884 cardiac surgical procedures requiring cardiopulmonary bypass were performed at our institution, including 672 (9.8% of adult procedures) performed in 669 patients that were associated with preoperative (n = 240), intraoperative (n = 353), or postoperative (n = 79) use of an intraaortic balloon pump. The mean age of recipients was 65.3 years (range, 16 to 89 years). Intraaortic balloon pump usage increased during the study period from 6.4% of patients (83/1,298) in 1986 to 12.7% of patients (169/1,333) in 1990. The relative distribution between preoperative (mean, 35.7%), intraoperative (52.5%), and postoperative (11.8%) insertion remained nearly constant during the study period. The overall operative (30-day) mortality for patients with preoperative, intraoperative, or postoperative insertion of the intraaortic balloon pump was 19.6%, 32.3%, and 40.5%, respectively (X2 = 16.4; p less than 0.001). Although use of the intraaortic balloon pump in the intraoperative and postoperative settings is accompanied by a favorable outcome in most patients, the high associated mortality suggests the need for earlier use of the intraaortic balloon pump or other supportive measures such as the ventricular assist device.

Angina, Unstable↗
PubMed1992

Noninvasive detection of cardiac allograft rejection by prospective telemetric monitoring.

A method for cardiac allograft surveillance that is less invasive than endomyocardial biopsy is needed. A fall in the unipolar peak-to-peak amplitude recorded from cardiac allografts has been shown to detect rejection when retrospectively compared with endomyocardial biopsy. This study was performed to assess the sensitivity and specificity of prospective telemetric unipolar peak-to-peak amplitude surveillance in detecting rejection of heterotopic canine cardiac allografts occurring through triple drug immunosuppression. Native heart and graft amplitudes were telemetrically acquired on a daily basis. A fall in normalized unipolar peak-to-peak graft amplitude to less than 85% was used as an indication for biopsy. A quantitative rejection score was calculated for each endomyocardial biopsy (rejection score greater than 0.66 = histologic rejection). Rejection was documented in all animals. Thirty-six biopsies were performed (10 control biopsies and 26 amplitude-directed biopsies); 25 of the 36 demonstrated rejection. Sensitivity and specificity were 88% and 91%, respectively. A linear correlation between unipolar peak-to-peak amplitude and rejection severity was seen (R = 0.87, p less than 0.001). The first true positive amplitude was associated with mild-to-moderate rejection (rejection score = 1.63 +/- 0.45). Unipolar peak-to-peak amplitude recorded from native hearts remained stable during allograft rejection. It is concluded that prospective, telemetric cardiac allograft surveillance can accurately detect rejection occurring through ongoing immunosuppression.

Animals↗
PubMed1991

Successful surgical treatment of atrial fibrillation. Review and clinical update.

Atrial fibrillation is the most common of all sustained cardiac arrhythmias, yet it has no effective medical or surgical therapy. During the past decade, multipoint computerized electrophysiological mapping systems were used to map both experimental and human atrial fibrillation. On the basis of these studies, a new surgical procedure was developed for atrial fibrillation. Between September 25, 1987, and July 1, 1991, this procedure was applied in 22 patients with paroxysmal atrial flutter (n = 2), paroxysmal atrial fibrillation (n = 11), or chronic atrial fibrillation (n = 9) of 2 to 21 years' duration. All patients were refractory to all antiarrhythmic medications, and each patient failed to receive the desired therapeutic benefits of an average of five drugs administered preoperatively. There were no operative deaths and all perioperative morbidity resolved. All 22 patients have been successfully treated for atrial fibrillation with surgery alone. Three patients developed one late isolated episode of atrial flutter at 5, 6, and 15 months postoperatively, and each of these patient's symptoms is now controlled by a single antiarrhythmic drug. Preservation of atrial transport function has been documented in all patients postoperatively, and all have experienced marked clinical improvement.

Adult↗
PubMed1991

Operations for atrial fibrillation.

Atrial fibrillation is the most common of all sustained cardiac arrhythmias, yet it has no effective medical or surgical therapy. During the past decade, multipoint computerized electrophysiological mapping systems were used to map both experimental and human atrial fibrillation. On the basis of these studies, a new surgical procedure was developed for atrial fibrillation. Between September 25, 1987, and May 1, 1991, this procedure was applied in 22 patients with either paroxysmal atrial flutter (n = 2), paroxysmal atrial fibrillation (n = 11), or chronic atrial fibrillation (n = 9) of 2 to 21 years' duration. All patients were refractory to all antiarrhythmic medications and each patient failed an average of 5.2 drugs preoperatively. There were no operative deaths and all perioperative morbidity resolved. All 22 patients have been cured of atrial fibrillation with surgery alone. One late isolated episode of atrial flutter occurred in a patient who is now receiving encainide. Preservation of atrial transport function has been documented in all of the patients postoperatively and all have experienced marked clinical improvement.

Adult↗
PubMed1991

Temporary external DDD pacing after cardiac operations.

Temporary atrial and ventricular pacing in the DVI, VVI, and AOO modes using atrioventricular sequential DVI devices is routinely used in cardiac operations. This study evaluated a new temporary external DDD pacemaker (Medtronic 5345 External Pulse Generator) capable of ten pacing modes. Thirty-nine devices have been applied to 38 adult patients (27 male, 11 female) after a variety of open heart procedures. Group 1 had atrial pacing wires placed 1.5 to 2.0 cm apart superiorly on the right atrium, group 2 had atrial wires placed 1.0 to 1.5 cm apart on the right atrial free wall, and group 3 had atrial wires placed on the right atrial free wall 0.8 cm apart, using a Silastic ring for fixation. Ventricular wires were placed on the free wall (group 1) or the diaphragmatic surface (groups 2 and 3) of the right ventricle. Postoperative atrial and ventricular sensing and pacing thresholds were obtained on return to the intensive care unit; analysis of variance demonstrated a significantly greater atrial sensing threshold in group 3. Four patients in group 1 permanently lost atrial sensing, 1 patient in group 2 intermittently lost atrial sensing at 24 hours with return at 36 hours postoperatively, and 1 patient in group 1 lost ventricular sensing capability. All other patients had adequate atrial and ventricular sensing capability documented until elective pacemaker removal (mean, 166 hours; range, 17 to 667.5 hours). Nineteen patients required some form of temporary pacing postoperatively; 11 patients demonstrated hemodynamic benefit from a pacing mode that is not available on the currently used DVI devices, and 7 of these required true DDD pacing capability. Six patients benefited from atrial pacing with adequate atrial sensing and simultaneous ventricular backup. Burst pacing with the device was used successfully to treat postoperative atrial flutter in 2 patients. We conclude that temporary external DDD pacing is feasible and effective in postoperative cardiac surgical patients. Atrial sensing is possible in most patients but electrode positioning is important for adequate thresholds. In some patients, hemodynamic as well as electrophysiologic improvement can be demonstrated with universal DDD pacing capability as compared with standard DVI pacing.

Adult↗
PubMed1991

Influence of activation origin, lead number, and lead configuration on the noninvasive electrophysiologic detection of cardiac allograft rejection.

An improved method of cardiac allograft surveillance, less invasive than endomyocardial biopsy (EMB), is required as the scope of cardiac transplantation increases. The correlation between changes in telemetrically recorded intramyocardial electrograms and the degree of rejection was examined. The electrophysiological parameter assessed was the unipolar peak-to-peak amplitude (UPPA), defined as the magnitude of the first, fast negative deflection of the QRS complex in unipolar electrograms. A canine model of intrathoracic heterotopic cardiac transplantation was employed in which each graft was instrumented with four unipolar intramyocardial electrodes (two left ventricle [LV] and two right ventricle [RV]) connected to two telemetric pacemakers. Immunosuppression was begun at operation and continued for a variable period of time following the acquisition of control data (postoperative days 6-10). Graft status was monitored via biweekly EMB. Intramyocardial electrograms were recorded from each lead during sinus rhythm and 36 atrial and ventricular pacing protocols on a daily basis. The daily UPPA was calculated for each rhythm sequence and expressed as percent of control UPPA. EMBs were qualitatively graded and assigned a quantitative rejection score (0 = none; 3 = severe). Criteria for rejection were rejection score (RS) greater than or equal to 0.66 or daily UPPA less than 85% control. Eight animals were included for study and, in all animals, rejection was documented. A total of 30 EMBs were obtained; in 11 EMBs rejection was present by histological criteria. Analysis of grouped UPPA data from all four leads revealed a sensitivity and specificity of 91% and 84%, respectively, in the detection of rejection. Analysis of grouped sinus UPPA data from the two LV leads revealed a sensitivity of 94% and 91%, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Surgical therapy for patients with supraventricular tachycardia.

Surgical techniques have now been developed to treat a variety of supraventricular arrhythmias, including the Wolff-Parkinson-White syndrome, arrhythmias associated with other atrioventricular accessory connections, AV nodal reentrant tachycardia, and automatic (ectopic) atrial tachycardias. In addition, atrial flutter and atrial fibrillation are not potentially curable with surgical intervention. This article will discuss the current surgical techniques used to treat these supraventricular tachyarrhythmias.

Atrial Fibrillation↗
PubMed1990

Functional consequences of the right ventricular isolation procedure.

The right ventricular free wall was surgically isolated from the remainder of the heart in eight dogs to evaluate the functional consequences of this procedure. Each dog was instrumented with ultrasonic dimension transducers in the right and left ventricular free walls, intracavitary micromanometers, and pulmonary artery flow probes. Volume loading and vena caval occlusions were performed to assess diastolic compliance and systolic function. Right ventricular unstressed myocardial segment length increased from 14.2 +/- 0.7 to 15.0 +/- 0.8 mm (p less than 0.5). There was an accompanying significant postoperative loss of right ventricular diastolic compliance (p less than 0.005). Regional right ventricular systolic function and regional left ventricular diastolic compliance and systolic function were preserved after the procedure. Postoperatively, when the right ventricular free wall was not paced and left silent, right ventricular stroke work decreased from 7.0 +/- 0.8 to 2.7 +/- 0.5 gm-m/m2 (p less than 0.05). These data demonstrate that the diastolic compliance of the right ventricular free wall decreases significantly after right ventricular isolation. However, there were no changes in regional right ventricular systolic or regional left ventricular function. The isolated right ventricular free wall contributes significantly to postoperative cardiac performance.

Animals↗
PubMed1990

Perinodal cryosurgery for atrioventricular node reentry tachycardia in 23 patients.

Atrioventricular node reentry tachycardia is the most common cause of paroxysmal supraventricular tachycardia. Available nonpharmacologic therapies include (1) catheter ablation or cryosurgical ablation of the His bundle and insertion of a permanent pacemaker and (2) surgical dissection around the atrioventricular node or discrete cryosurgery of the perinodal tissues, in an attempt to divide or ablate only one of the dual atrioventricular node conduction pathways responsible for the tachycardia while leaving the other intact. This report describes 23 consecutive patients who underwent the discrete cryosurgical procedure between August 13, 1982, and March 16, 1989. The first patient in this series, a 38-year-old woman, is the first patient in whom refractory atrioventricular node reentry tachycardia was cured surgically by a procedure designed to treat this arrhythmia. The ages of the 13 female and 10 male patients ranged from 12 to 56 years with an average age of 29 years. Fourteen of the 23 patients (61%) had the Wolff-Parkinson-White syndrome. Other associated arrhythmias included atrial flutter/fibrillation (n = 2), right atrial reentrant tachycardia (n = 1), junctional tachycardia (n = 1), and a Mahaim fiber (n = 1). Associated anatomic abnormalities included Ebstein's anomaly in two patients and a large right atrial aneurysm in one patient. The perinodal cryosurgical procedure was performed through a right atriotomy in the normothermic beating heart. Multiple 3 mm diameter cryolesions were placed around the borders of the triangle of Koch on the lower right atrial septum to alter the input pathways of the atrioventricular node. There were no operative deaths in this series of patients. Postoperatively, all 23 patients had normal atrioventricular conduction, and no heart block has occurred in any patients during the follow-up period. All patients have remained free of atrioventricular node reentry tachycardia (and of the Wolff-Parkinson-White syndrome) and none has required postoperative antiarrhythmic drugs for either of these arrhythmias. We consider this simple, safe, easily performed, and uniformly successful operation to be the procedure of choice for the treatment of medically refractory atrioventricular node reentry tachycardia.

Adolescent↗
PubMed1989

Toward fifty.

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History, 20th Century↗
PubMed1989

Blood conservation in cardiac surgery. Preliminary results with an institutional commitment.

To evaluate the effect of blood conservation in cardiac surgery, use of blood products was analyzed in patients undergoing CABG before and after implementation of blood conservation techniques. Age, sex, coronary anatomy, ejection fraction, cardiopulmonary bypass time, and the preoperative hematocrit, platelet count, and clotting studies were similar in both groups. Methods of blood conservation included autologous transfusion of blood withdrawn before bypass, autotransfusion of shed mediastinal blood, strict protocols for transfusion, and acceptance of normovolemic anemia. With blood conservation, 25.5% of patients received no transfusions and 54.9% received blood only. Significant reductions (p less than 0.001) were achieved in the transfusion of blood from 6.8 +/- 2.4 to 2.3 +/- 2.6 units per patient and of plasma from 2.5 +/- 2.2 to 0.6 +/- 2.0 units per patient. Reductions in the use of platelets and cryoprecipitate were substantial, although not significant. Total donor exposure was reduced significantly from 13.1 +/- 7.3 to 4.3 +/- 6.7 donors per patient. The postoperative hematocrit was significantly lower and remained so at discharge. However, 30 days later there was no difference. This reduction in transfusion requirements decreased costs and donor exposure.

Aged↗