Return cycle mapping: Have we come full cycle?
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Cryosurgery↗
Biomedical subjects
Y Mahomed
Publications and source records attributed to Y Mahomed.
Left internal mammary artery graft perforation due to high-pressure stent deployment.
Perforation of newly placed left internal mammary artery (LIMA) grafts due to stent deployment is an infrequent but potentially dangerous complication of coronary interventions. It may lead to brisk hemorrhage and massive cardiac tamponade requiring emergent pericardiocentesis and surgery. We report a case of a LIMA graft perforation following stent deployment with a high-pressure balloon 12 days after surgery. The patient was treated with emergent pericardiocentesis, rapid autotransfusion of the pericardial aspirate into the systemic circulation, and surgical repair of the ruptured vessel.
Aged↗
Establishment of a clinically correlated human pericardial fluid bank: evaluation of intrapericardial diagnostic potential.
The development of a clinically correlated human pericardial fluid bank and database is described. A unique feature of this registry is the availability of a large number of pericardial fluid samples for testing with respect to multiple factors and for correlation with angiographic findings and clinical syndromes expressed by the patients. The collection of data at the present time comprises frozen pericardial fluid samples obtained from patients who have undergone cardiac surgery; and historical, clinical, and laboratory data obtained from the patient records. Nearly 400 samples have been stored and analyzed thus far, with sample entry continuing. This registry is designed to evaluate the local factors that play a role in mediating or reflecting myocardial or coronary responses. Pathophysiologic processes of particular interest include restenosis, plaque ruptures, and angiogenesis. Study of the pericardial fluid bank should lead to enhanced understanding of molecular mechanisms, as well as to the explanation for the reasons underlying interpatient variability in these processes. It is further anticipated that this information might provide a foundation for the diagnostic use of pericardial fluid to individualize therapies targeting angiogenesis or plaque physiology.
Coronary Angiography↗
Cardiac transplantation in infants and children.
Cardiac transplantation has become a more frequently used therapeutic modality for select cardiac pathology in infants and children. Since June 1986, 30 pediatric patients (19 male and 11 female) ranging in age from 4 days to 15 years (11 < or = 1 month old) have undergone orthotopic cardiac transplantation at our institution. Indications included idiopathic cardiomyopathy (n = 8), hypoplastic left heart syndrome (n = 13), and other forms of complex congenital heart disease (n = 9). There have been four operative and three late deaths only in the groups with hypoplastic left heart syndrome and other forms of complex congenital heart disease. Cumulative survival is 77% after a mean follow-up of 30 months (range, 6 to 77 months). Three operative deaths were attributable to pulmonary hypertension, and the other was due to pulmonary hemorrhage. Two late deaths were secondary to allograft rejection, and the third was due to infection. There has been uniform survival in the group with idiopathic cardiomyopathy, and intermediate-term survival rates are 78% and 62% in the groups with complex congenital heart diseases and hypoplastic left heart syndrome, respectively (p = 0.15). Although longer-term results are necessary, orthotopic cardiac transplantation appears to be an acceptable mode of therapy for endstage heart disease in the pediatric age group and technically can be performed despite complex malformations of the great arteries or atria.
Adolescent↗
Characteristics of Ca(2+)-activated K+ channels isolated from the left ventricle of a patient with idiopathic long QT syndrome.
Early afterdepolarizations (EADs), possibly caused by reduced K+ conductance, have been hypothesized to cause the long QTU interval and ventricular tachyarrhythmias (VT) in patients with the long QT syndrome (LQTS). In a 26-year-old woman with aborted sudden death as a consequence of the idiopathic LQTS, we recorded with a contact electrode left ventricular endocardial EADs that were enhanced by epinephrine and phenylephrine. Because of uncertain efficacy and side effects achieved with beta-adrenoceptor blockade, the patient underwent left-sided cardiac sympathectomy, at which time we obtained left ventricular biopsy tissue. Crude membrane vesicles were prepared from this tissue and single-channel activity was studied after incorporation of the vesicles in an artificial lipid bilayer (phosphatidylserine, phosphatidylethanolamine, 4:5 weight ratio in decane) in the tip of a patch clamp pipette. Bath and pipette contained 100 mmol/L KCI and 25 mmol/L N-2-hydroxyethylpiperazine-N'-2-ethanesulfonic acid (HEPES) at pH 7.4. We recorded K+ conducting channels with a mean slope conductance of 49.9 +/- 4.7 picosiemens (pS) (n = 5). Channel open probability was increased by the addition of 1 to 10 mumol/L Ca2+ to the experimental chamber. Addition of charybdotoxin (1-3 nmol/L), a known specific inhibitor of Ca(2+)-activated K+ channels, blocked channel activity. These results are the first to demonstrate Ca(2+)-activated K+ channels from a patient with idiopathic LQTS. These channels appear to show normal characteristics when studied in an artificial planar lipid bilayer.
Action Potentials↗
Surgery for atrioventricular node reentry tachycardia. Results with surgical skeletonization of the atrioventricular node and discrete perinodal cryosurgery.
Surgical treatment options for interruption of atrioventricular node reentrant tachycardia include (1) skeletonization of the atrioventricular node by dissecting it from most of its atrial inputs and (2) discrete cryosurgery of the perinodal tissues by applying a series of sequential cryolesions to the atrial tissues immediately adjacent to the atrioventricular node. Both these techniques attempt to interrupt one of the dual atrioventricular node conduction pathways while preserving the other. This report describes 17 consecutive patients who underwent surgical treatment, 10 patients with skeletonization of the atrioventricular node and seven patients with discrete perinodal cryosurgery. There were 10 female and seven male patients and their ages ranged from 28 to 56 years (mean 38). Two of the 17 patients had Wolff-Parkinson-White syndrome and their accessory pathways were interrupted before the atrioventricular nodal reentrant tachycardia was ablated. All the procedures were performed in a normothermic beating heart while atrioventricular conduction was monitored closely. In the skeletonization technique, the right atrial septum was mobilized and the atrioventricular node exposed anterior to the tendon of the Todaro. The perinodal cryosurgical procedure was also performed through a right atriotomy and a series of sequential 3 mm cryolesions were placed around the borders of the triangle of Koch on the inferior right atrial septum. There were no operative deaths. Two patients who underwent the skeletonization operation had heart block necessitating pacemaker therapy. At postoperative electrophysiologic study, no echoes or atrioventricular nodal reentrant tachycardia were inducible in any of the 17 patients. All patients have remained free of arrhythmia recurrence and have required no antiarrhythmic therapy after a follow-up of 5 to 28 months (mean 14). In conclusion, both atrioventricular node skeletonization and perinodal cryosurgery successfully ablate atrioventricular nodal reentrant tachycardia; however, perinodal cryosurgery appears to be safer in avoiding heart block, is more easily performed, and is our procedure of choice for the management of medically refractory atrioventricular nodal reentrant tachycardia.
Adolescent↗
Anterior wall left ventricular aneurysm repair. A comparison of linear versus circular closure.
To determine the efficacy of ventricular closure techniques, we reviewed our experience with 62 patients who survived the repair of aneurysms of the anterior wall of the left ventricular from 1984 through 1989. Forty of these patients underwent aneurysm repair by standard linear closure and 22 by a circular closure technique. After a mean follow-up interval of 3 years, there were no demonstrable differences in angina class, New York Heart Association functional classification, or survival. In 41 surviving patients, postoperative left ventricular dimensions and function were satisfactorily evaluated by standard echocardiographic measurements. No significant differences were found in postoperative long-axis left ventricular systolic diameter or in short-axis systolic or diastolic areas. There was a significantly larger long-axis diastolic diameter in the circular closure group; however, there was no difference in this parameter when the ratios of postoperative to preoperative lengths were compared. Further intragroup comparisons demonstrated an increase in short-axis areas postoperatively within the circular closure group in contrast to a decrease in patients in the linear closure group; these changes were not statistically significant. There was no significant difference in postoperative ejection fraction between the two closure groups, although minor reductions were found in the circular closure group. These data demonstrate no significant difference between the linear and circular closure techniques with respect to standard echocardiographic parameters, functional classification, and survival.
Actuarial Analysis↗
Surgical myocardial revascularization for the 1990s.
After two decades, coronary artery surgery remains a reliable mainstay in the treatment of select patients suffering from ischemic heart disease. However, surgical myocardial revascularization has undergone continuous evolution. Several trends have emerged, including increased use of autogenous artery for bypass conduit, extending indications to include patients with poor ventricular function or following recent myocardial infarction and new techniques, such as surgical angioplasty of the left main coronary artery.
Humans↗
Anterior pericardial tracheoplasty for congenital tracheal stenosis.
Congenital tracheal stenosis may be a life-threatening anomaly not relieved by airway intubation. Over the past 7 years, anterior pericardial tracheoplasty has been used at our institution for treatment of congenital long-segment tracheal stenosis in infants with impeding airway obstruction. Case histories of eight patients undergoing nine anterior pericardial tracheoplasties have been reviewed to assess this technique. Of these patients, six have required preoperative tracheal intubation before repair to maintain ventilation. The surgical technique of anterior pericardial tracheoplasty includes a median sternotomy approach with partial normothermic cardiopulmonary bypass. An anterior tracheotomy through all hypoplastic rings allows enlargement with autologous pericardium to 1.5 times the predicted normal diameter. After insertion, the pericardium and hypoplastic tracheal cartilages are suspended to surrounding mediastinal structures, which prevents airway collapse. Seven of eight infants have survived without tracheoplasty dehiscence or wound infections. Five were ultimately extubated and are currently free of symptoms from 6 months to 5 years after anterior pericardial tracheoplasty. The other two survivors had residual stenosis as a result of complications of prior tracheostomy. One of these patients has undergone a successful second anterior pericardial tracheoplasty and is currently extubated and well. The other is palliated at 6 months with a tracheostomy awaiting a second anterior pericardial tracheoplasty. Our review of anterior pericardial tracheoplasty has demonstrated the safety, utility, and at least medium-term benefit of this procedure in infants of any age and weight.
Adolescent↗
Effect of omental, intercostal, and internal mammary artery pedicle wraps on bronchial healing.
Bronchial transection and devascularization is necessary in the course of sleeve resection or lung transplantation, leaving distal bronchial segments ischemic and subject to stricture or dehiscence. Thirty mongrel dogs underwent left lung autotransplantation. The bronchial anastomosis was wrapped with omentum (n = 9), intercostal muscle pedicle (n = 9), or internal mammary artery pedicle grafts (n = 6). Six control animals underwent bronchial anastomosis without an external wrap. Bronchial revascularization by capillary ingrowth from the pedicle to the bronchial submucosal plexus was demonstrated with all three types of vascular pedicle grafts; however, more consistent and confluent vascular ingrowth was provided by internal mammary artery pedicle grafts. Additionally, the bronchial anastomotic cross-sectional area was significantly better in the internal mammary artery group (84.5 +/- 3.3) as compared with that of the omental (68.4 +/- 8.3), intercostal muscle (66.9 +/- 10.9), or control groups (70.2 +/- 7.6). An internal mammary artery pedicle graft and the presence of dense confluent submucosal vascular ingrowth from any pedicle graft were independently predictive (p less than 0.05) of minimizing bronchial anastomotic narrowing. These data are consistent with previous findings suggesting that omental and intercostal muscle pedicle grafts promote early bronchial revascularization; moreover, the data demonstrate the superiority of an internal mammary artery pedicle graft to provide submucosal vascular ingrowth and to minimize anastomotic stenosis.
Anastomosis, Surgical↗
Bronchoesophageal fistula with an esophageal web.
Congenital bronchoesophageal fistulas in the adult age group are rare, with only approximately 20 cases having been recognized. All of these cases have been an isolated esophageal anomaly without other associated esophageal pathology. We present an interesting case of an adult with both symptomatic congenital bronchoesophageal fistula and proximal esophageal web.
Bronchial Fistula↗
Primary mediastinal nonseminomatous germ cell tumors. Results of a multimodality approach.
Before cisplatin-based chemotherapy, long-term survival after resection of primary mediastinal nonseminomatous germ cell tumors was unusual. We reviewed the case histories of 48 patients who underwent multimodality treatment for mediastinal nonseminomatous germ cell tumor between 1976 and 1988. Twenty-eight patients received initial therapy at Indiana University and 20 were referred after having had unsuccessful initial therapy elsewhere. In 44 patients (92%) the levels of either one or both serum tumor markers were elevated at the time of diagnosis. Five patients had choriocarcinoma, three embryonal carcinoma, 12 yolk sac carcinoma, four teratocarcinoma, 22 mixed cell type, and two had an unclassified type. Twenty-two of the 28 patients in our initial therapy group had a complete response to treatment, as defined by normal serum tumor markers and absence of residual tumor. In this group, 16 patients had resection of residual disease after chemotherapy, four had total or near total resection before chemotherapy, and only two had chemotherapy alone. Seventeen patients are surviving after this treatment with a median survival of 64 months and a 57% 5-year Kaplan-Meier survival rate. Only two of the 20 patients who were referred for salvage chemotherapy had a complete response. Both required resection of residual disease after salvage chemotherapy. Only one patient survived after this treatment. There was no significant treatment morbidity or mortality. A multimodality approach to primary mediastinal nonseminomatous germ cell tumor with intensive cisplatin-based chemotherapy, emphasis on normalizing serum tumor markers, and aggressive resection of residual disease now offers survival to a significant number of patients.
Adolescent↗
Surgical division of Wolff-Parkinson-White pathways utilizing the closed-heart technique: a 2-year experience in 47 patients.
Kent bundle interruption for ventricular preexcitation has been successfully accomplished utilizing several different surgical techniques. The external closed-heart technique of Guiraudon combining surgical dissection and cryoablation has been used to interrupt 52 accessory pathways in 47 consecutive patients since May, 1985. The 35 male and 12 female patients ranged in age from 10 to 67 years (mean, 30 years). There were 25 left free wall, 13 right free wall, 13 posterior septal, and 1 anterior septal accessory pathways. Preoperative and intraoperative electrophysiological studies were performed in all patients to induce the arrhythmia and localize all accessory pathways. The operation consisted of dissection of the atrioventricular fat pad. Following this, the delta wave and retrograde accessory pathway conduction disappeared, thereby indicating successful pathway ablation. In 4 patients with right-sided accessory pathways, interruption of the pathway required cryoablation. Cryolesions (made with cryoprobe at -60 degrees C for two minutes) were created in the region of the accessory pathway insertion. All accessory pathways were successfully ablated without any deaths or heart block. Concomitant surgical procedures were performed in 4 patients. Two patients required a second operation the next day for an accessory pathway not found at the initial operation. Three patients had postpericardiotomy syndrome, and 4 had recurrent atrial fibrillation requiring therapy. The remaining patients have had no arrhythmia recurrence and have remained drug free after a follow-up of 1 month to 22 months (mean, 12.5 months). We conclude that the closed-heart technique of accessory pathway ablation is safe and reproducible, obviates the necessity for aortic cross-clamping and cardioplegic arrest, and allows instantaneous monitoring of conduction over the pathway.
Adolescent↗
Use of a caval-atrial shunt for resection of a caval tumor thrombus in renal cell carcinoma.
Extraction of a tumor thrombus in the vena cava from a renal cell carcinoma is a technically demanding but gratifying procedure. We describe a technique for isolation of the superior vena cava during thrombus extraction using an inferior vena caval to atrial shunt.
Carcinoma, Renal Cell↗
Surgery for Wolff-Parkinson-White syndrome interrupts efferent vagal innervation to the left ventricle and to the atrioventricular node in the canine heart.
The hypothesis that cardiac surgery to interrupt accessory pathways also interrupts autonomic nerves to the canine ventricle and to the atrioventricular node was tested in four groups of dogs. Group 1 (n = 6) underwent dissection of the atrioventricular fat tissue and cryolesion created by application of a cryoprobe at -60 degrees C for 2 min along the lateral left atrioventricular groove, the same surgical procedure as carried out in patients with Wolff-Parkinson-White syndrome with accessory pathways located in the left ventricular free wall. Group 2 (n = 6) underwent dissection of the atrioventricular fat pad alone and group 3 (n = 6) dissection and cryolesion along the posterior left atrioventricular groove as performed in patients with Wolff-Parkinson-White syndrome with accessory pathways located in the posterior paraseptal area. Group 4 consisted of 11 non-operated control dogs. Four to 13 days after surgery the ventricular effective refractory period (ERP) was determined during bilateral ansae subclaviae stimulation (4 ms pulses, 2-3 Hz, and 2-3 mA), noradrenaline infusion (0.5 micrograms.kg-1.min-1), and bilateral vagal stimulation (4 ms pulses, 20 Hz, and current strength to induce asystole or complete atrioventricular block). Atrioventricular nodal conduction (AH interval) and spontaneous sinus cycle length were also determined in group 3 dogs. Ansae subclaviae stimulation and noradrenaline infusion shortened effective refractory period significantly at each left ventricular test site. The amount of effective refractory period shortening induced by ansae subclaviae stimulation did not differ among the test sites except for the posterior left ventricle in group 1 dogs.(ABSTRACT TRUNCATED AT 250 WORDS)
Animals↗
Electrophysiologic directed endocardial resection and cryoablation in the treatment of ventricular tachyarrhythmias.
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Cardiac Catheterization↗
Effects of hypothermia on brainstem auditory evoked potentials in humans.
Ten adult patients who underwent open heart surgery under induced hypothermia had brainstem auditory evoked potentials (BAEPs) recorded at 1 degree- to 2 degrees C-steps as body temperature was lowered from 36 degrees C to 20 degrees C to determine temperature-dependent changes. Hypothermia produced increased latencies of BAEP waves I, III, and V; the prolongation was more severe for the later components with the result that interpeak latencies I-III, III-V, and I-V were also prolonged. The temperature-latency relationship was nonlinear and best expressed by exponential curve. The latencies of waves I, III, V and the interpeak latency I-V increased roughly 7% for each 1 degree C drop; they doubled at a temperature around 26 degrees C. The amplitude of the BAEP components had a quasiparabolic relationship to temperature; the amplitude rose with hypothermia to 28 degrees or 27 degrees C, but decreased linearly with further cooling. All BAEP components were present at temperatures above 23 degrees C and absent below 20 degrees C. With rewarming, the changes reversed and BAEPs returned to initial prehypothermia status.
Acoustic Stimulation↗
Chemical ablation of ventricular tachycardia in the dog.
Sustained ventricular tachycardia was induced in dogs following occlusion-reperfusion of the left anterior descending coronary artery. While dogs were supported by cardiopulmonary bypass, the left ventricle was opened and the endocardium was mapped during electrically induced ventricular tachycardia to determine the earliest site of ventricular activation. Phenol (carbolic acid) application at that site necrosed myocardium to a depth of 1 to 3 mm and prevented electrical reinduction of ventricular tachycardia in 9 of 15 dogs. These data suggest that chemical ablation may be used as an alternate means to destroy areas of myocardium involved in the genesis or maintenance of ventricular tachycardia, particularly if these areas cannot be resected surgically because of their size or location.
Animals↗