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J L Cox

Publications and source records attributed to J L Cox.

At least 91 records · Page 5Linked to original sources
PubMed1996

Lateral tunnel suture line variation reduces atrial flutter after the modified Fontan operation.

BACKGROUND: Atrial flutter (AFL) is a common postoperative sequela of the modified Fontan operation, or total cavopulmonary connection. We hypothesized that injury to the crista terminalis (CT) by the lateral tunnel suture line contributes to the development of AFL in this setting. This study was designed to determine the effects of alteration of the lateral tunnel suture line, relative to the CT, on the inducibility of AFL in an acute canine model of the modified Fontan operation. METHODS: Adult mongrel dogs (n = 25) underwent a median sternotomy and normothermic cardiopulmonary bypass. In groups 1, 2, and 3, through a right atriotomy, a suture line was placed to simulate the lateral tunnel of the modified Fontan operation (n = 20). The lateral aspect of the suture line ran along the CT in group (n = 10), 5 mm medial to the CT in group 2 (n = 5), and 10 mm anterior to the CT, incorporated into the atriotomy closure, in group 3 (n = 5). In group 4 (n = 5), only the lateral portion of the suture line, along the CT, was placed. Form-fitting 253-point unipolar endocardial mapping electrodes were inserted in the left and right atria via bilateral ventriculotomies. Induction of AFL was then attempted using atrial burst pacing. If sustained AFL could not be induced, isoproterenol was administered and the pacing protocol repeated. Endocardial activation sequence maps of spontaneous rhythm and AFT were constructed. RESULTS: Under baseline conditions, after placement of the suture line, sustained AFL could reproducibly be induced in 8/10 dogs in group 1, 0/5 dogs in group 2, 0/5 dogs in group 3, and 5/5 dogs in group 4 (p < 0.001). After isoproterenol administration, sustained AFL was reproducibly inducible in the remaining 2 dogs in group 1, 4/5 dogs in group 2, and 0/5 dogs in group 3 (p = 0.01). The mean cycle length of AFL was 189 +/- 25 ms in group 1, 136 +/- 8 ms in group 2, and 182 +/- 20 ms in group 4 (p < 0.001). Atrial activation sequence maps, during sinus rhythm, demonstrated a line of conduction block along the lateral portion of the suture line in all cases in groups 1 and 4 and in only those cases in group 2 in which sustained AFL was inducible. During AFL this block facilitated unidirectional conduction, permitting propagation of the reentrant wavefront. Mean conduction velocity along the CT during sinus rhythm was 0.63 +/- 0.10 m/s in group 1, 1.04 +/- 0.17 m/s in group 2, 1.01 +/- 0.12 m/s in group 3, and 0.44 +/- 0.13 m/s in group 4 (p < 0.01). CONCLUSIONS: In an acute canine model of the modified Fontan operation, conduction block imposed by the lateral tunnel suture line is an essential component of the AFL circuit. The inducibility of AFL is increased by suture line placement along the CT. Slow conduction, resulting from injury to the CT, promotes this increased inducibility. Avoidance of the CT may reduce the incidence of AFL in children undergoing the modified Fontan operation.

Animals↗
PubMed1996

Characterization and surgical ablation of atrial flutter after the classic Fontan repair.

BACKGROUND: Atrial flutter (AFL) is a frequent postoperative complication of the classic Fontan operation, which uses an atriopulmonary connection. We hypothesized that the suture lines alone, in the absence of any hemodynamic alterations, provide the necessary electrophysiologic substrates for AFL. The objectives of this study were to determine if the Fontan suture lines alone are sufficient to permit sustained AFL in an acute canine model and to characterize any resulting reentrant circuits to surgically ablate the AFL. METHODS: After cardiopulmonary bypass, adult dogs (n = 18) underwent a simulated classic Fontan operation. This included a longitudinal right atriotomy and an incision from the base of the right atrial appendage toward the dome of the left atrium, representing the atriopulmonary connection. In 6 of 18 dogs, an atrial septal defect was created at the level of the fossa ovalis. Unipolar 253-point biatrial endocardial mapping electrodes were placed via bilateral ventriculotomies. Induction of AFL was attempted by atrial burst pacing. If AFL could not be induced, isoproterenol was administered and pacing repeated. Activation sequence maps of the pathways of atrial reentry were generated. In 8 dogs with inducible AFL, an incision was made from the atriotomy to the atriopulmonary connection and burst pacing repeated. RESULTS: Sustained AFL could not be induced after bypass alone in any case. After the simulated Fontan operation, sustained AFL was reproducibly induced in all 18 dogs, 6 of which required isoproterenol. The mean cycle length of all cases was 177 +/- 20 ms. During AFL, atrial activation sequence maps demonstrated lines of conduction block created by both the atriotomy and the atriopulmonary connection. The isthmus of tissue between these two lines of block was essential for propagation of the reentrant wavefront. Interruption of this isthmus with an incision successfully terminated AFL in 8 of 8 dogs. CONCLUSIONS: In an acute canine model, the Fontan suture lines alone, in the absence of atrial hypertension or stretch, permit the induction of AFL. An essential electrophysiologic substrate is an isthmus of myocardium between the atriotomy and the atriopulmonary connection. Interruption of conduction through this isthmus terminates the AFL in this model and suggests a technique for ablation of AFL in patients who have undergone a classic Fontan operation.

Animals↗
PubMed1996

Managed delay for coronary artery bypass graft surgery: the experience at one Canadian center.

OBJECTIVES: This study sought to assess the impact of delaying coronary artery bypass surgery at one Canadian academic tertiary referral center. BACKGROUND: Universal access to medical services in Canada comes at the expense of waiting lists whose impact has been incompletely assessed. METHODS: A prospective, observational study of all residents of Nova Scotia and Prince Edward Island accepted for bypass surgery between 1 April 1992 and 31 October 1992 was undertaken to determine 1) whether triage guidelines were being followed; and 2) the incidence of cardiac death, nonfatal myocardial infarction and worsening symptoms associated with delayed operation. The analysis had 90% power to detect a mortality rate of > or = 3% (alpha 0.05). RESULTS: Of 423 patients referred, 35% were triaged as urgent, 9.7% as semiurgent A, 39% as semiurgent B and 16.3% as elective, with no age or gender bias identified. Operation occurred at < or = 1 week in 25%, < or = 1 month in 47%, and >6 months in 1.4%. There were no nonfatal myocardial infarctions, but five cardiac deaths occurred (1.2%). Of 275 patients not initially classified as urgent, 12.4% required reclassification to higher priorities because of worsening symptoms; none had perioperative myocardial infarction or died. One in four patients queued longer than target waiting times. Only 4% of patients considered prioritization on the basis of medical need unfair, but 64% experienced at least moderate anxiety. CONCLUSION: This triage system equitably stratified patients to a queue. Deaths were rare and could not be attributed to the triage process. Patients with worsening clinical status were safely accommodated with earlier waiting times, but concerns remain regarding excessive waiting times and patient anxiety.

Aged↗
PubMed1996

Anatomically based ablation of atrial flutter in an acute canine model of the modified Fontan operation.

BACKGROUND: Lateral tunnel total cavopulmonary connection, also called the modified Fontan operation, uses a baffle through the right atrium. We established, in an acute canine model, that atrial flutter after total cavopulmonary connection revolves around a line of conduction block imposed by the free wall lateral tunnel suture line. We hypothesized that a line of conduction block between the free wall total cavopulmonary connection suture line and the tricuspid anulus would interrupt atrial flutter in this model. OBJECTIVE: Our objective was to determine whether a cryolesion placed between the free wall total cavopulmonary connection suture line and the tricuspid anulus would terminate atrial flutter in an acute canine model. METHODS: Seven adult dogs underwent median sternotomy and institution of cardiopulmonary bypass. A suture line was placed through a right atriotomy to simulate total cavopulmonary connection lateral tunnel construction. Form-fitting 253-point biatrial endocardial mapping electrodes were placed via bilateral ventriculotomies. Atrial flutter was induced by atrial burst pacing. A cryothermal lesion was then placed between the free wall total cavopulmonary connection suture line and the tricuspid anulus in the low lateral right atrium (i.e., CRYO 1 procedure), and reinduction of atrial flutter was attempted. If atrial flutter was reinduced, the cryolesion was modified superiorly to include the caudal portion of the atriotomy (i.e., CRYO 2 procedure). Activation sequence maps were generated for sinus rhythms before and after the cryolesions were placed and for induced arrhythmias. RESULTS: In all seven cases, atrial flutter was inducible after suture line placement, before placement of a cryolesion. The reentrant circuit incorporated both caval orifices in five of seven cases and was successfully ablated by the CRYO 1 approach in each case. Atrial flutter was not inducible after placement of the CRYO 2 lesion in the remaining two cases, in which breakthrough of the wave front occurred across the lateral tunnel suture line in the intercaval region. Activation sequence maps of sinus rhythm after placement of the cryolesions demonstrated a conduction block at the site of the lesion. CONCLUSIONS: A linear cryothermal lesion placed between the free wall aspect of the total cavopulmonary connection suture line and the tricuspid anulus created a line of conduction block that successfully ablates atrial flutter in the canine model.

Acute Disease↗
PubMed1996

Left-sided atrial flutter: characterization of a novel complication of pediatric lung transplantation in an acute canine model.

BACKGROUND: Postoperative atrial flutter has been observed in approximately 10% of children undergoing lung transplantation at our institution. We hypothesized that the left atrial anastomoses made to establish pulmonary venous continuity provide the primary electrophysiologic substrates for atrial flutter. OBJECTIVES: Our objectives were (1) to determine whether the left atrial suture lines alone are sufficient to produce atrial flutter in an acute canine model of lung transplantation and (2) to characterize any resulting reentrant circuits to surgically ablate the atrial flutter. METHODS: Supported by cardiopulmonary bypass, adult dogs (n = 10) underwent bilateral pneumonectomies. The left atrial anastomotic suture lines were simulated by dividing the tissue between the ostia of the transected superior and inferior pulmonary veins and closing the resulting defects. Bilateral suture lines were placed in group 1 (n = 6) to simulate bilateral lung transplantation. In group 2 (n = 4), only a left-sided suture line was placed to represent single lung transplantation. Unipolar 253-point biatrial endocardial mapping electrodes were inserted via bilateral ventriculotomies. Atrial flutter was induced by atrial burst pacing, and activation sequence maps were generated. In five of six cases in group 1, a T-incision connecting the two suture lines and the mitral anulus was then made. In group 2, a single incision from the suture line to the mitral anulus was performed in each case. Burst pacing was subsequently repeated. RESULTS: Atrial flutter could not be induced after bypass alone in any case. After simulated lung transplantation, sustained atrial flutter was reproducibly induced in 10 of 10 dogs. The mean cycle length in all dogs was 133 +/- 7 msec. There was no significant difference in mean cycle length or activation sequence patterns between groups 1 and 2. The reentrant circuit was confined to the left atrium. Each simulated left atrial anastomosis created a zone of conduction block around which circus movement could occur. In group 1, either suture line functioned as the central obstacle. Atrial flutter was terminated in five of five dogs in group 1 by means of the T-incision and in all four dogs in group 2 with the incision connecting the suture line to the mitral anulus. CONCLUSIONS: (1) In an acute canine model of lung transplantation, each left atrial suture line alone provides an electrophysiologic substrate for atrial flutter by creating a zone of conduction block around which circus movement can occur. (2) Extending this zone of block to the mitral anulus, together with interruption of the isthmus of tissue between the two suture lines present after bilateral lung transplantation, terminates the atrial flutter in this model and may have an application prophylactically at the time of lung transplantation in children to prevent postoperative atrial flutter.

Anastomosis, Surgical↗
PubMed1996

Atrial flutter after lateral tunnel construction in the modified Fontan operation: a canine model.

Intraatrial reentrant tachycardia, or atrial flutter, is a common postoperative problem after Fontan repair, which involves an atriopulmonary connection. A modification of Fontan repair, total cavopulmonary connection, minimizes the portion of the right atrium exposed to stretch and hypertension; however, atrial flutter continues to occur after this procedure. We postulated that the intraatrial lateral tunnel suture line of total cavopulmonary connection, in the absence of physiologic alterations such as atrial hypertension or stretch, provides the necessary electrophysiologic substrate for atrial flutter. The purpose of this study was to produce a canine model of total cavopulmonary connection (1) to establish that the intraatrial suture line alone is sufficient to permit sustained atrial flutter and (2) to characterize the pathways of resulting reentrant arrhythmias. After induction of general anesthesia, 25 to 30 kg dogs (n = 17) underwent median sternotomy, cradling of the pericardium, and placement of a pacing electrode on the right atrial appendage. Normothermic cardiopulmonary bypass was initiated. The total cavopulmonary connection suture line was placed through a standard right atriotomy,simulating construcion of the lateral tunnel. After closure of the atriotomy, 253 point unipolar atrial endocardial form-fitting electrodes were placed through bilateral ventriculotomies. By means of atrial burst pacing and programmed extrastimulation, induction of atrial flutter was attempted. If atrial flutter could not be induced, isoproterenol was infused and the stimulation protocol was repeated. After induction of atrial flutter, mapping of the activation sequence was performed. Before suture line placement, no dog had inducible atrial flutter. After placement of the suture line, sustained atrial flutter was reproducibly induced in every dog, although isoproterenol was required for this in three (17.6%). The mean flutter cycle length was 177 +/- 30 msec. In each case, the atrial flutter circuit was limited to the right atrium, with the left atrium being passively activated. The atrial flutter circuit was dependent on a corridor of myocardium that resulted from conduction block on the free wall, created by the lateral margin of the total cavopulmonary connection. In no case was the atriotomy integral to the atrial flutter circuit. This study establishes that the total cavopulmonary connection baffle suture line alone, without alteration in circulatory physiology, creates a sufficient anatomic substrate for atrial flutter in a short-term canine model. Delineation of the anatomic boundaries of the reentrant circuit raises the possibility of targeting areas within the circuit that could be modified, potentially reducing the incidence of postoperative atrial flutter after total cavopulmonary connection.

Animals↗
PubMed1996

Reexploration for bleeding is a risk factor for adverse outcomes after cardiac operations.

OBJECTIVE: Although previous studies have included early reexploration for bleeding as a risk factor in analyzing adverse outcomes after cardiac operations, reexploration for bleeding has not been systematically examined as a multivariate risk factor for increased morbidity and mortality after cardiac surgery. Furthermore, multivariate predictors of the need for reexploration have not been identified. Accordingly, we performed a retrospective analysis of 6100 patients requiring cardiopulmonary bypass from January 1, 1986, to December 31, 1993. METHODS: Eighty-five patients who had ventricular assist devices were excluded from further analysis because of the prevalence of bleeding and the significant morbidity and mortality associated with placement of a ventricular assist device, unrelated to reexploration. In the remaining 6015 patients, potential adverse outcomes analyzed included operative mortality, mediastinitis, stroke, renal failure, adult respiratory distress syndrome, prolonged mechanical ventilation, sepsis, atrial arrhythmias, and ventricular arrhythmias. To control for the confounding effects of other risk factors, we performed a multivariate logistic regression analysis. Potential covariates considered in the logistic model included age, sex, race, history of reoperation, urgency of the operation, congestive heart failure, prior myocardial infarction, renal failure, diabetes, hypertension, chronic obstructive pulmonary disease or stroke, and the bypass and crossclamp time. RESULTS: The overall incidence of reexploration was 4.2% (253/6015). Four independent risk factors--increased patient age (p < 0.001), preoperative renal insufficiency (p = 0.02), operation other than coronary bypass (p < 0.001), and prolonged bypass time (p = 0.0.3)--were identified as predictors of the need for reexploration. The preoperative use of aspirin, heparin, or thrombolytic agents and the bleeding time were not identified as predictors. Reexploration for bleeding was identified as a strong independent risk factor for operative mortality (p = 0.005), renal failure (p < 0.0001), prolonged mechanical ventilation (p < 0.0001), adult respiratory distress syndrome (p = 0.03), sepsis (p < 0.0001), and atrial arrhythmias (p = 0.006). CONCLUSION: These data indicate that meticulous attention to surgical hemostasis and possibly application of recently developed modalities designed to facilitate perioperative correction of coagulopathy could improve outcomes after cardiac operations.

Age Factors↗
PubMed1996

An 8 1/2-year clinical experience with surgery for atrial fibrillation.

OBJECTIVE: The authors analyzed the clinical results during the first 8 1/2 years' experience with the Maze procedure for the surgical treatment of atrial fibrillation. SUMMARY BACKGROUND DATA: Atrial fibrillation occurs in 0.4% to 2% of the general population and in approximately 10% of patients older than 60 years of age. It is associated with significant morbidity and mortality. The irregular heartbeat causes discomfort, the loss of synchronous atrioventricular contraction compromises hemodynamics and the stasis of blood flow increases the vulnerability to thromboembolism. METHODS: From September 25, 1987 to March 1, 1996, 178 patients underwent the Maze procedure. Thirty-two patients underwent the Maze-I procedure, 15 underwent the Maze-II procedure, and 118 underwent the Maze-III procedure. Patients were analyzed for recurrence of atrial flutter and atrial fibrillation between 3 months and 8 1/2 years after surgery (n = 164). Patients were analyzed for atrial transport function, sinus nodule function, and postoperative pacemaker requirements. RESULTS: Ninety-three percent of all patients were arrhythmia free without any antiarrhythmic medication. Of the remaining patients with arrhythmia recurrence, all were converted to sinus rhythm with medical therapy. All patients were documented to have atrial transport function by either direct visualization, transesophageal echocardiography, or atrioventricular versus ventricular pacing at the same rate. Ninety-eight percent had documented right atrial function, and 94% had left atrial function. Of the 107 patients in this series who were documented to have a normal sinus node preoperatively, only 1 patient required a permanent pacemaker. CONCLUSION: The Maze procedure is an effective treatment for medically refractory atrial fibrillation in properly selected patients.

Adult↗
PubMed1996

Preliminary assessment of patients' opinions of queuing for coronary bypass graft surgery at one Canadian centre.

OBJECTIVES: To explore psychological and socioeconomic concerns of patients who queued for coronary artery bypass surgery and the effectiveness of support existing in one Canadian cardiovascular surgical center. DESIGN: Standardised questionnaire and structured interview. SETTING: Victoria General Hospital, Halifax, Nova Scotia. SUBJECTS: 100 consecutive patients awaiting non-emergency bypass surgery. RESULTS: Most patients (96%) found the explanation of findings at cardiac catheterisation and the justification given for surgery satisfactory. However, 84 patients complained that waiting for surgery was stressful and 64 registered at least moderate anxiety. Anger over delays was expressed by 16%, but only 4% thought that queuing according to medical need was unfair. Economic hardship, attributed to delayed surgery, was declared by 15 patients. This primarily affected those still working--namely, blue collar workers and younger age groups. Only 41% of patients were satisfied with existing institutional supports. Problems related mainly to poor communication. CONCLUSIONS: Considerable anxiety seems to be experienced by most patients awaiting bypass surgery. Better communication and education might alleviate some of this anxiety. Economic hardship affects certain patient subgroups more than others and may need to be weighed in the selection process. A more definitive examination of these issues is warranted.

Anger↗
PubMed1996

Trends in the utilization of noninvasive cardiac diagnostic tests in Ontario from fiscal year 1989/90 to 1992/93.

OBJECTIVE: To describe pattern of utilization of noninvasive cardiac diagnostic test in Ontario. DESIGN: Retrospective analysis using Ontario Health Insurance Plan (OHIP) administrative data. SETTING: Ambulatory care settings in Ontario. MAIN OUTCOME MEASURES: First, the volume of services and expenditures on electrocardiograms (ECG), ambulatory ECG, radionuclide angiocardiograms (RNA), echocardiograms, exercise stress tests (EST), and myocardial perfusion scintigrams from 1989/90 to 1992/93; second, the number and specialty of physicians performing these tests. MAIN RESULTS: Ontario spent $119 million on noninvasive diagnostic cardiology test in 1992/93, representing 2.67% of total OHIP expenditures. Expenditures on these procedures grew by 49.3 % over the four-year period, exceeding the overall OHIP growth rate, and was most rapid for nuclear cardiology and echocardiography. Changing demographics accounted fpr only a minor portion of expenditure growth. Second, age-adjusted utilization rates for EST, myocardial perfusion scintigraphy and RNA were higher for men, but sex differences tended to diminish over time. Third, utilization rates differed markedly by geographic region, and variations were greatest for nuclear medicine studies. Geographic variations tended to be attenuated over time. There was also wide variation in the frequency with which physicians performed Doppler studies with two-dimensional echocardiography. CONCLUSIONS: The use of noninvasive cardiac diagnostic test has grown rapidly in recent years. This growth may have been influenced by practice guidelines, by greater diffusion of, and access to, newer technology and by more testing in women. Wide regional variations suggest that clearer practice guidelines are needed concerning the appropriate use of noninvasive cardiac diagnostic investigations.

Angiocardiography↗
PubMed1996

Arrhythmia surgery.

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Arrhythmias, Cardiac↗
PubMed1995

Single lung transplantation for pulmonary hypertension. Single institution experience in 34 patients.

BACKGROUND: The present study considered the uniformity and durability of the cardiopulmonary response to single lung transplantation in patients with severe pulmonary hypertension, as well as its effect on length and quality of survival. METHODS AND RESULTS: Thirty-four patients with pulmonary hypertension underwent evaluation, single lung transplantation, and follow-up assessment between November 1, 1989, and June 1, 1994. Operative survival for the entire group of patients was reasonable, with 91% (31 of 34 patients) surviving and being discharged from the hospital following transplantation. The actuarial survival for these 34 patients at 1-, 2-, and 3-year follow-up was 78%, 66%, and 61%, respectively. In the subgroup of 24 patients with primary pulmonary hypertension (PPH), 96% (23 of 24) were successfully discharged from the hospital after transplantation. The actuarial survival for this isolated PPH subgroup at 1-, 2-, and 3-year follow-up was 87%, 76%, and 68%, respectively. The uniform, early posttransplant normalization of pulmonary vascular resistance and right ventricular ejection fraction appears to persist throughout the 4-year follow-up period. Despite a high prevalence of bronchiolitis obliterans, the majority of survivors remain in New York Heart Association functional class I or II and are employed. CONCLUSIONS: Single lung transplantation can be performed in patients with end-stage pulmonary vascular disease with reasonable expectations for a relatively low operative mortality; immediate, complete, and durable amelioration of pulmonary hypertension and right ventricular failure; and optimal use of limited donor organ supply.

Actuarial Analysis↗
PubMed1995

Coronary artery disease in patients with type A aortic dissection.

The usefulness of preoperative coronary arteriography in patients with type A dissection of the aorta is controversial. To determine the prevalence of arteriosclerotic coronary artery disease in patients with type A dissection of the aorta, we reviewed our experience in 62 patients (42 with acute dissection and 20 with chronic dissection) who underwent operation between January 1, 1986, and December 31, 1993. Among 23 patients with acute dissection who underwent coronary arteriography, 8 (34.8%) had one or more coronary artery lesions causing a greater than 50% narrowing. Among 14 patients with chronic dissection who underwent coronary arteriography, 6 (42.9%) had one or more coronary artery lesions causing a greater than 50% narrowing. There were no fatal complications associated with coronary arteriography. Four patients with acute dissection and 6 patients with chronic dissection underwent coronary artery bypass grafting at the time of operative repair of the aortic dissection, with no operative deaths. On the basis of these findings and the success of combined coronary artery bypass grafting and aortic repair, we recommend that patients with an acute type A dissection who are in stable condition and all patients with a chronic type A dissection of the aorta should undergo preoperative coronary arteriography.

Acute Disease↗
PubMed1995

Mechanical dysfunction in the border zone of an ovine model of left ventricular aneurysm.

BACKGROUND: The pathophysiology of regional mechanical dysfunction in the border zone (BZ) region of left ventricular aneurysm was studied in an ovine model using magnetic resonance imaging tissue-tagging and regional deformation analysis. METHODS: Transmural infarcts were created in adult Dorsett sheep (n = 8) by ligation of the distal homonymous coronary artery and were allowed to mature into left ventricular aneurysms for 8 to 12 weeks. Animals were imaged subsequently using double oblique magnetic resonance imaging with radiofrequency tissue tagging. Short axis slices were selected for analysis that included predominantly the septal component of the aneurysm as well as adjacent BZ regions in the anterior and posterior ventricular walls. Dark grid patterns of magnetic presaturations were placed on the myocardium and tracked as they deformed during the diastolic, isovolumic systolic, and systolic ejection phases of the cardiac cycle. Regional ventricular wall strains were calculated in BZ regions and regions remote from the aneurysm and compared with strains measured in corresponding regions from normal control sheep (n = 6). RESULTS: Diastolic midwall circumferential strains (fiber extensions) were relatively preserved, but abnormal circumferential lengthening strains were observed in the BZ regions during isovolumic systole. Peak circumferential strains ranged from 0.04 to 0.07 in the BZ regions but averaged -0.05 in the normal hearts (p = 0.002 for the anterior BZ and p = 0.001 for the posterior BZ). Midwall end-systolic fiber strains were depressed in the anterior BZ (-0.03 to -0.09 for the BZ versus -0.11 for the normal heart, p < 0.0001) but not in the posterior BZ (p = 0.19). CONCLUSIONS: Our data support the theory that the stretching of BZ fibers during isovolumic systole contributed to a reduction in fiber shortening during systolic ejection and thus reduced the overall contribution of these fibers to forward ventricular output.

Animals↗
PubMed1995

Modification of the maze procedure for atrial flutter and atrial fibrillation. I. Rationale and surgical results.

The original maze procedure that was described for the treatment of patients with atrial fibrillation was followed by an unacceptable incidence of two problems: (1) the frequent inability to generate an appropriate sinus tachycardia in response to maximal exercise and (2) occasional left atrial dysfunction. In an effort to overcome these problems, we modified the original technique (maze I) twice. The results of these modifications culminated in the maze III procedure, which is associated with a higher incidence of postoperative sinus rhythm, improved long-term sinus node function, fewer pacemaker requirements, less arrhythmia recurrence, and improved long-term atrial transport function. In addition, the maze III procedure is technically less demanding than either the maze I or maze II procedure. Therefore, the maze III procedure is now the technique of choice for the management of medically refractory atrial fibrillation.

Atrial Fibrillation↗
PubMed1995

Swallowing dysfunction after cardiac operations. Associated adverse outcomes and risk factors including intraoperative transesophageal echocardiography.

The frequency, importance to patient outcomes, and independent predictors of postoperative swallowing dysfunction documented by barium cineradiography were examined in 869 patients undergoing cardiac operations over a 12-month period. Swallowing dysfunction was diagnosed in 34 patients (4% incidence) and was associated with documented pulmonary aspiration in 90% of these patients, increased frequency of pneumonia (p < 0.0001), need for tracheostomy (p = 0.0002), length of stay in the intensive care unit (p = 0.0001), and duration of hospitalization after the operation (p = 0.0001). Independent predictors of postoperative swallowing dysfunction determined by multivariate logistic regression included age (p < 0.001), length of tracheal intubation after the operation (p = 0.001), and intraoperative use of transesophageal echocardiography (p = 0.003). Dysfunctional swallowing after cardiac operations, a serious complication significantly related to postoperative respiratory morbidity and extended length of hospitalization, is more common in older patients. An association between intraoperative use of transesophageal echocardiography and swallowing dysfunction was also observed in our patients.

Aged↗