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Biomedical subjects

A S Geha

Publications and source records attributed to A S Geha.

At least 19 recordsLinked to original sources
PubMed2004

Surgery for aortic arch thrombosis.

A localized thrombus involving the ascending aorta and arch rarely occurs in the absence of an underlying etiology such as chest trauma, atherosclerosis, a hypercoagulable state or instrumentation. A review of the literature between 1966 - 2003 yielded 38 reported cases of localized aortic arch thrombi, 21 of which were treated by surgical excision of the thrombus using different approaches. In this communication, we describe this clinical entity, with its diagnosis and management. The technical details that are important to ensure the safe conduct of the procedure are discussed.

Aorta, Thoracic↗
PubMed2001

Increased coronary artery blood flow with aortomyoplasty in chronic heart failure.

BACKGROUND: We hypothesized that diastolic counter-pulsation using aortomyoplasty will increase coronary blood flow. METHODS: In dogs (n = 6, 20 to 25 kg), the left latissimus dorsi muscle was isolated, wrapped around the descending thoracic aorta, and conditioned by chronic electrical stimulation. Heart failure was induced by rapid ventricular pacing. In a terminal study, left ventricular and aortic pressures, and blood flow in the left anterior descending coronary artery and descending aorta were measured. The endocardial-viability ratio was calculated. RESULTS: Aortomyoplasty increased mean diastolic aortic pressure (70 +/- 5 to 75 +/- 5 mm Hg, p < 0.05) and reduced peak left ventricular pressure (86 +/- 4 to 84 +/- 4 mm Hg, p < 0.05), leading to a 16% increase in endocardial-viability ratio (1.29 +/- 0.05 to 1.49 +/- 0.05, p < 0.05). Coronary blood flow was increased by 15% (8.2 +/- 1.5 to 9.4 +/- 1.6 mL/min, p < 0.05). During muscle contraction, 2.7 +/- 0.5 mL was ejected from the wrapped aortic segment. CONCLUSIONS: These data demonstrate that aortomyoplasty provides successful diastolic counterpulsation after muscle conditioning and heart failure.

Animals↗
PubMed2001

Dysphagia caused by a fetus-in-fetu in a 27-year-old man.

Mechanical obstruction of the distal esophagus by a fetus-in-fetu is an extremely rare condition that has not been previously reported. We present the case of a 27-year-old man who presented with dysphagia caused by fetus-in-fetu contained within a retroperitoneal cystic cavity. The tumor, noticed since childhood, did not cause any symptoms until a year before presentation when symptoms of dysphagia developed. We propose including this entity in the differential diagnosis of a retroperitoneal mass.

Adult↗
PubMed2001

Pulmonary venous drainage into the left atrial appendage facilitates transplantation of the left lung with difficult exposure.

Heterotopic implantation of the pulmonary venous confluence into the left atrial appendage during left lung transplantation is a reasonable alternative technique to reestablish venous drainage when exposure of the native left pulmonary veno-atrial connection may be problematic. We used this approach in a 39-year-old woman with chronic bronchiectasis who underwent bilateral sequential lung transplantation through a clam-shell approach. Dense hilar scarring and a small left atrial size made exposure of the native left pulmonary veno-atrial connection difficult.

Adult↗
PubMed2001

Closed chest hypothermic circulatory arrest for complex intracranial aneurysms.

BACKGROUND: Recent advances in techniques of cardiopulmonary bypass permitted hypothermic circulatory arrest (HCA) using groin cannulation with the chest closed (CC-HCA) and without direct access to the heart. Herein we describe our experience with this technique for complex intracranial aneurysms. METHODS: Between 1992 and 1999, 16 patients (4 men and 12 women) with a mean age of 52 years (range 32 to 61 years) with complex intracranial aneurysms underwent resection or clipping of their aneurysms at our institution using the technique of CC-HCA and groin cannulation. Groin access was obtained with 16F to 19F arterial and 18F to 20F venous cannulas placing the tips at the aortoiliac and atriocaval junctions, respectively. Patients were cooled to a nasopharyngeal temperature of 16 degrees C. RESULTS: Mean circulatory arrest time was 32 minutes. No patient required conversion to standard sternotomy and central cannulation. There were no intraoperative deaths. The 30-day hospital mortality was 2 of 16 patients (12%). Of the 14 surviving patients (88%), 1 developed bilateral third nerve palsy and another left hemiparesis that improved on follow-up. Both were discharged to an extended care facility and continued to do well at home after discharge. Two patients developed deep venous thrombosis postoperatively and required anticoagulation. All patients continued to do well at a mean follow-up of 42 months. CONCLUSIONS: The less invasive technique of CC-HCA through groin cannulation avoids complications associated with a sternotomy, is safe and is associated with little morbidity, reduced operative time, and early hospital discharge and rehabilitation.

Adult↗
PubMed2001

Replacement of degenerated mitral and aortic bioprostheses without explantation.

BACKGROUND: The most common indication for reoperation in patients with a bioprosthetic valve is primary tissue failure. Explantation of the bioprosthesis is time consuming, and for a mitral valve, may be complicated by cardiac rupture at the atrioventricular junction or the posterior left ventricular wall where a strut is imbedded, injury to the circumflex artery, and late perivalvular leak; for an aortic valve, annular disruption and perivalvular leak may complicate explantation. A new approach to simplify these procedures and avoid these complications, by excising only the bioprosthetic tissue and attaching a bileaflet mechanical valve to the intact stent, was developed in 1991 and was evaluated over a 9-year period in 50 patients who had had one (34), two (10), three (4), or four (2) previous open cardiac operations. METHODS: Since 1991, we have replaced degenerated mitral bioprostheses in 34 patients (25 to 84 years of age; 12 male, 22 female) by preserving the stent and suturing a St. Jude or Carbomedics bileaflet valve to the atrial side of the bioprosthetic cuff; the mitral valve was exposed through a median sternotomy in 21 patients and through a right anterolateral thoracotomy in 13. Using a similar approach, starting in 1995, 16 additional patients (55 to 73 years of age; 11 male, 5 female) with degenerated aortic bioprostheses had the aortic valve replaced by excising the bioprosthetic tissue and amputating the struts, then suturing a Carbomedics valve to the aortic side of the bioprosthetic cuff. This allows the use of a bileaflet valve similar in size to the bioprosthesis with exact matching of the orifices. RESULTS: Bypass time averaged 61 +/- 14 minutes and aortic cross-clamp time 43 +/- 12 minutes. There has been no operative mortality. Three late deaths occurred at 9, 37, and 58 months, and were not valve related. No gradients of hemodynamic significance have been detected on transesophageal echocardiographic follow-up. CONCLUSIONS: Leaving the bioprosthetic cuff intact eliminates the need for extensive dissection, thus shortening and simplifying the procedure and diminishing its attendant mortality and morbidity. This valve-on-valve approach also allows replacement of a degenerated bioprosthesis with a bileaflet valve of comparable size rather than a smaller one jammed into the orifice of the bioprosthetic stent, thus avoiding undue trauma to the bileaflet valve and maintaining excellent hemodynamic function.

Adult↗
PubMed2000

Pneumothorax necessitans presenting as a presternal pneumothoracocele.

A 31-year-old woman who is an intravenous drug abuser developed sternoclavicular joint infection with mediastinal and subcutaneous tissue abscesses that communicated through an erosion in the manubrium caused by osteomyelitis. Air entrapment from a subsequent apical pneumothorax formed a localized anterior "pneumothoracocele." We referred to this condition as "pneumothorax necessitans," and we suggest including it in the differential diagnosis of anterior chest wall masses.

Abscess↗
PubMed2000

A 32-year experience in 100 patients with giant paraesophageal hernia: the case for abdominal approach and selective antireflux repair.

BACKGROUND: Giant paraesophageal hiatal hernia (GPEH) presents a risk of catastrophic complications that include massive bleeding, strangulation, and perforation and should be repaired. Controversy persists as to the surgical approach and whether an antireflux repair is required. METHODS: This study reviews the experience with 100 patients with GPEH who underwent surgical repair between 1967 and 1999. Eighty patients underwent an elective operation, and 20 patients underwent an emergency procedure for complications of GPEH. The gastroesophageal junction was above the hiatus ("combined" hernia with sliding component) in 23 patients and in the abdomen in 77 patients, including 3 patients with a true parahiatal hernia. RESULTS: A thoracic approach was used in 18 patients, mostly early in our experience; postoperative gastric volvulus requiring transabdominal repair developed in 2 patients. The remaining 82 patients underwent an abdominal repair, with temporary gastrostomy to prevent gastric displacement in 75 patients; the hernial sac was resected, and the hiatus was reconstructed in all of the patients. Thirty-five patients with reflux on preoperative work up underwent a fundoplication, with gastroplasty in 2 patients because of a short esophagus. No patient has experienced hernia recurrence. Whereas symptomatic relief was excellent in all patients with elective repair, mild reflux was present in 2 patients after emergency operation. There were no deaths among the patients who underwent elective operation; there were 2 hospital deaths among those patients who underwent emergency operation (10%). CONCLUSIONS: GPEH should be repaired soon after recognition. Reflux should be evaluated before the operation, and if present, fundoplication should be part of the repair along with the reduction of the hernia, excision of the sac, gastropexy, and crural closure. These are best achieved with an abdominal approach.

Abdomen↗
PubMed1999

Fast track recovery of elderly coronary bypass surgery patients.

BACKGROUND: To ascertain whether early extubation and fast-track treatment protocols are feasible in elderly patients, we analyzed 487 consecutive patients who had isolated coronary artery bypass grafting between January 1995 and June 1997, constituting the experience of a single surgeon. METHODS: Management consistently applied to all patients emphasized early extubation protocol, tepid cardioplegia and normothermic bypass to reduce pump times, early mobilization and chest tube removal, and protocol treatment of atrial fibrillation. Elderly patients at least 70 years old (n = 176, mean age 75 years) were compared with younger patients (n = 311, mean age 58 years). RESULTS: The hospital mortality rate was 0.8% (4 of 487 patients), and there was no difference in the operative mortality rate of the older cohort versus the younger cohort (0.6% versus 0.9%; p > 0.05). Older patients had a higher incidence of peripheral vascular disease, congestive heart failure, prior strokes, renal failure, and cerebrovascular disease (p < 0.05). Early extubation was achieved in 71% of younger patients versus 57% of older cohort (95% confidence interval, 14%+/-9%; p = 0.002). Older patients had significantly higher incidence of postoperative atrial fibrillation (27% versus 14%; 95% CI, 13%+/-7%; p < 0.001), a factor responsible for shorter length of stay among younger patients (5.6+/-2.8 days versus 7.2+/-3.7 days; 95% CI, 1.6+/-0.3 days; p < 0.001). Nonetheless discharge before the fifth postoperative day was achieved in 34% of the elderly patients. CONCLUSIONS: Although elderly patients have a higher acuity of illness, critical pathways for accelerated discharge are safe and feasible in most elderly patients.

Adult↗
PubMed1999

Immune-deficient bronchiectasis associated with X-linked lymphoproliferative disease.

Bronchiectasis may occur with various congenital and acquired immunodeficiency diseases. The association of bronchiectasis and the X-linked lymphoproliferative disease (XLP), also known as Duncan's disease is unknown. We describe the case of a 39-year-old man with XLP, the oldest surviving, who developed chronic bronchiectasis with hemoptysis and required a pneumonectomy to control his symptoms.

Adult↗
PubMed1999

Characterization of sinoatrial parasympathetic innervation in humans.

INTRODUCTION: The response to sinoatrial parasympathetic nerve stimulation (shortened atrial refractoriness) was used to determine the atrial distribution of these nerve fibers in humans. We hypothesized that, in humans, parasympathetic nerves that innervate the sinoatrial node also innervate the right atrium and that the greatest density of innervation is near the sinoatrial nodal fat pad. METHODS AND RESULTS: Temporary epicardial wire electrodes were sutured in pairs in the sinoatrial nodal fat pad, high right atrium, and right ventricle by direct visualization during coronary artery bypass surgery in nine patients. Appropriate electrode placement was confirmed by electrically stimulating the fat pad in the operating room to prolong sinus cycle length by 50%. Experiments were performed in the electrophysiology laboratory 1 to 5 days after surgery. Programmed atrial stimulation was performed via an endocardial electrode catheter advanced to the right atrium. The catheter tip electrode was moved in 1-cm concentric zones around the epicardial wires by fluoroscopic guidance. Atrial refractoriness was determined in the presence and absence of sinoatrial parasympathetic nerve stimulation at each catheter site. In 8 of 9 patients, parasympathetic nerve stimulation reproducibly prolonged sinus cycle length by 50%. There was no effect on AV nodal conduction (no prolongation of PR interval) and no change in AV nodal refractoriness. Atrial effective refractory periods reproducibly shortened in response to parasympathetic nerve stimulation in 1-cm zones up to 3 cm surrounding the fat pad, by a mean (+/- SEM) of 26.6+/-4.3 msec (zone 1), 11.4+/-1.8 msec (zone 2), and 10.0+/-2.5 msec (zone 3), respectively (P = 0.0001). At distances > 3 cm from the fat pad, the effective refractory period did not shorten. CONCLUSION: Stimulation of parasympathetic nerves that innervate the sinoatrial node shortened atrial refractoriness in humans.

Adult↗
PubMed1998

Safety and efficacy of early extubation of elderly coronary artery bypass surgery patients.

OBJECTIVE: Early extubation and fast-track management protocols on younger, low-risk patients result in shorter hospital stays and decreased costs. The impact of such protocols on elderly patients undergoing coronary artery bypass graft (CABG) surgery is not presently known. DESIGN: A matched retrospective cohort study. SETTING: A university teaching hospital. PARTICIPANTS: Six hundred ninety-eight consecutive patients undergoing isolated CABG between January 1995 and September 1996. INTERVENTIONS: Three hundred seventy-seven patients underwent early extubation, defined as extubation within 8 hours of arrival in the intensive care unit. They were divided into groups of patients 70 years of age and younger (n = 263) and patients older than 70 years of age (n = 114). RESULTS: The mean length of stay (LOS) for all patients extubated within 8 hours or less was 5.5 days versus 8.4 days for patients who underwent later extubation (p < 0.0001). The percentage of patients undergoing early extubation was greater for the younger cohort (59% v 48%; p < 0.003) compared with the older cohort of patients. Analysis of demographics showed the older patients to have a greater incidence of peripheral vascular disease, congestive heart failure, and prior strokes (p < 0.05). Although the intensive care unit LOS was similar, postoperative LOS was 5.3 +/- 1.8 days for the younger patients versus 6.1 +/- 2.6 days for the older patients (p = 0.001). The overall surgical mortality rate was 2.6% (18/698), and there were no deaths among patients undergoing early extubation. Reintubation rate was negligible in both groups of patients. CONCLUSION: This study confirms the safety and efficacy of early extubation among elderly patients undergoing CABG. Elderly patients have more comorbid conditions, yet a significant number can be extubated early, with resultant shortened LOSs.

Adult↗
PubMed1997

Coronary bypass in vascular patients: a relatively high-risk procedure.

A premise of cardiac risk stratification is that the added risk of coronary artery bypass grafting (CABG) is offset by the improved safety of subsequent vascular reconstruction (VR). We questioned if elective CABG is patients with severe peripheral vascular disease (PVD) is a relatively high-risk procedure. A cohort study of 680 elective CABG patients from January 1993 to December 1994 was performed using three mutually exclusive outcomes of complication-free survival, morbidity, and mortality. Patient characteristic, operative, and outcome data were prospectively collected. Retrospective review determined that 58 patients had either a standard indication for or a history of VR. Overall CABG mortality was 2.5%, with statistically similar but relatively higher rates for PVD as compared to non-PVD patients. In contrast, major morbidity occurred at rates 3.6-fold higher in PVD patients (39.7%) than in disease-free patients (16.7%) after adjustment for the effects of patient and operative variables (odds ratio [OR] 3.67, 95% confidence interval [CI] 1.93-6.99). CABG morbidity in the PVD patient was most likely in those patients with aortoiliac (OR 9.51, CI 3.20-28.27) and aortic aneurysmal (OR 5.24, CI 1.28-21.41) disease types. CABG in PVD patients is associated with significant major morbidity. Such morbidity may preclude or alter the timing of subsequent VR.

Adult↗
PubMed1997

Favorable results of implantable cardioverter-defibrillator implantation in patients older than 70 years.

BACKGROUND: The clinical results of implantable cardioverter-defibrillator (ICD) implantation in the elderly have received limited documentation. As the longevity of the U.S. population has increased, so has the need for ICD implantation in the elderly. We evaluated the efficacy and outcome of ICD implantation in elderly patients (>70 years) compared with younger patients. METHODS: The case records of all consecutive patients who underwent ICD implantation at our institution between 1986 and 1994 were reviewed. Of a total of 238 patients, 78 patients were 70 years of age or older and 160 patients were younger than 70 years of age. RESULTS: The mean age of the younger group was 58 years and that of the elderly group was 74 years. There were no statistical differences in the presence of coronary artery disease, left ventricular systolic function, the inducibility of arrhythmias, or the history of sudden cardiac death. The hospital morbidity rate was similar in both groups (6.9% in the younger group and 7.7% in the elderly group; p = not significant). The operative mortality rate was 1.9% for the younger group and 1.3% for the elderly group (p = not significant). At a mean follow-up of 33 +/- 26 months, Kaplan-Meier survival curves demonstrated similar survival rates, with 93%, 82%, and 65% of the patients alive at 1, 3, and 6 years, respectively. CONCLUSIONS: Implantable cardioverter-defibrillator implantation was equally effective in the treatment of patients older than 70 years as in younger patients. No differences in theoretic survival or morbidity were observed.

Age Factors↗
PubMed1997

Risk analysis of coronary bypass surgery after acute myocardial infarction.

BACKGROUND: Current strategies for management of acute myocardial infarction (MI) include thrombolysis, angioplasty, and coronary bypass surgery singly or in combination. This study was designed to identify contemporary risk factors for coronary bypass surgery among patients in this high-risk group. METHODS: Between June 1992 and December 1995, 1181 consecutive patients underwent isolated coronary bypass surgery. Of these, 316 underwent coronary bypass surgery within 21 days of MI. Mean age was 65 years (range, 33 to 87 years), and 73% were male. There were 166 patients with stable angina (group 1), 107 patients with unstable angina requiring intravenous nitroglycerin for a control of ischemia (group 2), 20 patients with angina requiring intraaortic balloon counterpulsation for stabilization (group 3), and 23 patients with severe postinfarction ischemia complicated by cardiogenic shock (group 4). RESULTS: The overall in-hospital mortality rate was 5.1% (16 of 316), which was higher (p < 0.05) than the 2.5% (22 of 865) among patients undergoing coronary bypass surgery without recent myocardial infarction. Mortality increased with severity of clinical preoperative status and was 1.2% in group 1, 3.7% in group 2, 20.0% in group 3, and 26% in group 4. Serious postoperative morbidity occurred in 7.3% of patients. Multivariate logistic regression analysis identified preoperative intraaortic balloon counterpulsation, left ventricular dysfunction, and renal insufficiency as the only independent correlates of mortality. CONCLUSIONS: Coronary bypass surgery can be safely performed in stable patients at any time after acute MI, with an operative mortality similar to elective surgery. Thus, in this era of medical cost containment, there is no apparent indication for prolonged stabilization attempts that delay surgery.

Adult↗
PubMed1997

Optimizing muscle-to-cardiac timing for aortomyoplasty.

A new surgical approach to support failing hearts is known as aortomyoplasty-a technique in which the latissimus dorsi muscle is wrapped around the aorta and stimulated during cardiac diastole to provide chronic diastolic counterpulsation. We hypothesized that the timing of muscle contraction within the cardiac cycle effects the amount of diastolic augmentation during counterpulsation. In dogs (n = 9, 20-25 kg), the effect of muscle-to-cardiac timing on hemodynamic outcome of aortomyoplasty was measured. Muscle stimulation was initiated at the dicrotic notch and stimulus durations were systematically increased. Mean diastolic aortic pressure was maximized when stimulation terminated at the ensuing R-wave. Peak left-ventricular pressure was minimized when muscle stimulation terminated before the ensuing R-wave. The endocardial-viability ratio (a ratio of aortic diastolic pressure augmentation to left-ventricular pressure reduction) was maximized when stimulus terminated at the ensuing R-wave. Muscle-to-cardiac timing influences the effectiveness of counterpulsation during aortomyoplasty.

Animals↗
PubMed1996

Successful atrial defibrillation with very-low-energy shocks by means of temporary epicardial wire electrodes.

Sustained atrial fibrillation is very common after cardiac surgical procedures. We hypothesized that atrial defibrillation could be accomplished consistently and safely by means of low-energy shocks delivered by temporary stainless steel wire electrodes placed at the time of the operation. Sterile pericarditis was created in five mongrel dogs (20.9 +/- 2.1 kg), and pairs of standard temporary stainless steel wire electrodes were placed on the right atrial appendage, on Bachmann's bundle, and on the right ventricular apex for pacing, sensing, and recording. Temporary stainless steel wire electrodes, insulated except for the distal 6 cm and used to deliver defibrillation shocks, were placed adjacent to both atrial free walls and secured to the pericardium. All electrodes were brought out through the skin, and the sternotomy was closed. Dogs were tested in the conscious state on postoperative day 2. Sustained atrial fibrillation was induced by rapid atrial pacing. A customized software program was used to control the defibrillator, which delivered R wave-synchronous biphasic shocks to the atria through the temporary defibrillation electrodes. The shock intensity began at 50 volts and was increased by 10-volt increments until atrial fibrillation was terminated. Atrial fibrillation was terminated in all dogs at 112 +/- 7 volts, with an energy of 0.42 +/- 0.07 joule and an impedance of 67.8 +/- 4 ohms (all values mean +/- standard error of the mean). The mean percent success for atrial defibrillation at this minimal threshold was 49%. Thus at low-threshold voltages atrial fibrillation could be terminated with every other shock. A 25% increase in the minimal threshold voltage improved the conversion rate to 73% (mean energy 0.66 +/- 0.19 joule and mean impedance of 67 +/- 3.8 ohms). No complications were detected with the use of the electrodes or after their removal on the seventh postoperative day. One instance of electrode migration on the right atrial free wall was detected by roentgenography, but this did not adversely affect atrial defibrillation threshold. No ventricular arrhythmias or hemodynamic complications were noted during shock delivery. We conclude that successful conversion of atrial fibrillation to sinus rhythm can be achieved consistently with shock energies below 0.5 joule delivered with temporary epicardial defibrillation wire electrodes in this canine pericarditis model. These results suggest that this approach to the management of sustained atrial tachyarrhythmias has considerable promise in the management of atrial fibrillation in patients who have had cardiac operations.

Animals↗