Porcine small intestine submucosa as a pulmonary valve leaflet substitute.

BACKGROUND AND AIM OF STUDY: Isolated porcine small intestine submucosa has been used as a resorbable bio-scaffold for site-specific tissue remodeling. This study performed in swine evaluated the functional competency and remodeling characteristics of cardiac pulmonary leaflets constructed from porcine-derived small intestine submucosa. METHODS: Four clinically normal swine were used for this study. Under general anesthesia and cardiopulmonary bypass, each swine had one pulmonary valve leaflet excised and replaced with a leaflet constructed from a single layer of porcine small intestine submucosa. The animals were sacrificed one each, at 56, 63, 88 and 111 days postoperatively. Histopathological evaluation was carried out to compare substitute leaflets with normal host valve leaflets, and valve functional competence was determined using echocardiography. RESULTS: Histopathological analysis of the substituted valve leaflet at the time of sacrifice revealed that, simultaneous with resorption of the submucosal matrix, progressive replacement with fibrous connective tissue and microvasculature similar to mature host tissue had occurred. Factor VIII staining demonstrated progression of endothelialization of all substitute leaflet surfaces with time. Normal valvular competence was noted immediately following surgery, and at the time of sacrifice. CONCLUSION: This study supports the hypothesis that single-layer porcine small intestine submucosa can be used to replace mature pulmonary valve leaflets. The implanted matrix is resorbed, and a leaflet with histologically identifiable features, normal functional competency and anatomic apposition to the host leaflets remains.

Right heart circulatory support facilities coronary artery bypass without cardiopulmonary bypass.

BACKGROUND: Revascularization of the posterior wall often causes hemodynamic instability in beating heart coronary artery bypass (CAB). Our previous clinical studies have shown that tilting the heart primarily alters right-heart hemodynamics. The purpose of this study was to evaluate right-heart support in clinical cases. METHODS: Seventeen patients underwent beating heart CAB with right-heart support. The right-heart support system (A-Med Systems, West Sacramento, CA) consisted of a coaxial cannula placed through the right atrium and the tip of the cannula positioned in main pulmonary artery. Blood was removed from the right atrium and returned to the main pulmonary artery. RESULTS: Elective beating heart CAB was accomplished successfully in 17 patients with right-heart support. Anastomoses performed were left anterior descending coronary artery (11), diagonal (3), circumflex (5), obtuse marginal artery (11), and right coronary artery (10). Right-heart support between 1 and 3 L/min improved hemodynamics especially in the circumflex position. No device-related patient incidents occurred, nor were there incidents of infection or air embolism. All 17 patients were discharged to their homes. CONCLUSIONS: The right-heart support system was safe without complications. Exposure of the posterior wall was possible in all cases without hemodynamic compromise.

Outcomes improvement following minimally invasive direct coronary artery bypass surgery.

The most progressive movement in the standardization of MIDCAB has occurred within the past 5 years. Standardization of care and continuous quality improvement are essential to improve outcomes and reduce costs for MIDCAB. At the authors' institution, perioperative clinical outcomes demonstrated no significant differences among a traditional single-vessel CABG and a MIDCAB in myocardial infarction rates, reoperations for bleeding, and cerebrovascular accidents. Differences were found in new-onset atrial fibrillation, extubation in the operating room, required transfusions, length of stay in the critical care unit, and overall length of hospital stay. Optimal perioperative critical care recovery may result from an evidence-based approach in the design and delivery of patient care. Standardized nursing interventions may be designed to improve efficiency and reduce inappropriate variations in perioperative care. Because MIDCAB is a palliative intervention for single-vessel CAD, multifactorial CRF management is a necessary adjunct for the achievement of optimal long-term outcomes. CRFs must be managed to maintain long-term arterial conduit patency rates (e.g., 20 y) and to prevent further progression of CAD in the native coronary arteries for MIDCAB patients. Nurse-managed, physician-directed CRF management programs are the avenue to provide such services. The reported clinical outcomes are appropriate variables to track for continuous quality improvement. These clinical outcomes are meaningful, measurable, and appropriate for evaluating the effectiveness of care but do not address quality of life, patient satisfaction, and efficacy of pain management. Nursing care must continue to evolve as more data become available.

Endoscopic versus traditional saphenous vein harvesting: a prospective, randomized trial.

BACKGROUND: Saphenous vein harvested with a traditional longitudinal technique often results in leg wound complications. An alternative endoscopic harvest technique may decrease these complications. METHODS: One hundred twelve patients scheduled for elective coronary artery bypass grafting were prospectively randomized to have vein harvested using either an endoscopic (group A, n = 54) or traditional technique (group B, n = 58). Groups A and B, respectively, were similar with regard to length of vein harvested (41 +/- 8 cm versus 40 +/- 14 cm), bypasses done (4.1 +/- 1.1 versus 4.2 +/- 1.4), age, preoperative risk stratification, and risks for wound complication (diabetes, sex, obesity, preoperative anemia, hypoalbuminemia, and peripheral vascular disease). RESULTS: Leg wound complications were significantly (p < or = 0.02) reduced in group A (4% [2 of 51] versus 19% [11 of 58]). Univariate analysis identified traditional incision (p < or = 0.02) and diabetes (p < or = 0.05) as wound complication risk factors. Multiple logistic regression analysis identified only the traditional harvest technique as a risk factor for leg wound complications with no significant interaction between harvest technique and any preoperative risk factor (p < or = 0.03). Harvest rate (0.9 +/- 0.4 cm/min versus 1.2 +/- 0.5 cm/min) was slower for group A (p < or = 0.02) and conversion from endoscopic to a traditional harvest occurred in 5.6% (3 of 54) of patients. CONCLUSIONS: In a prospective, randomized trial, saphenous vein harvested endoscopically was associated with fewer wound complications than the traditional longitudinal method.

Routine surveillance endomyocardial biopsy: late rejection after heart transplantation.

BACKGROUND: Transplant programs use routine surveillance endomyocardial biopsies (RSEMB), which are performed at preset intervals to diagnose cardiac rejection. This retrospective study determined the incidence of graft rejection detected by RSEMB. METHODS: The records of 95 patients who underwent heart transplantation between 1987 and 1995 were reviewed. Rejection incidence was recorded for 80 patients who survived at least 30 days, with a mean follow-up of 35 months. RESULTS: One thousand five hundred sixteen total biopsies were performed; 1,170 were RSEMB. Four hundred seventy-five total rejection episodes occurred and 269 (56%) were diagnosed by RSEMB. Two distinct patient groups were identified. The majority (70 patients), had a decline in the incidence of rejection and no rejection episodes were identified by RSEMB after 36 months. In contrast, the high rejection group (10 patients) had a significantly higher ongoing rejection rate (p < or = 0.04 to p < or = 0.001) throughout their postoperative course up to 72 months. CONCLUSIONS: The majority of our transplant patients demonstrate a decrease in rejection with time and do not require RSEMB beyond 30 months. We identified a group of patients who exhibited a higher rate of rejection and need continued RSEMB.

Minimally invasive versus conventional reoperative coronary artery bypass.

BACKGROUND: Conventional reoperative (redo) coronary artery bypass grafting (CABG) is associated with significant morbidity. This retrospective study compared perioperative outcomes of conventional single-vessel redo CABG versus redo CABG done by a minimally invasive technique. METHODS: Group A consisted of 23 consecutive patients from September 1995 to July 1996 who underwent single vessel redo CABG of the left anterior descending artery with the left internal mammary artery using a limited anterior thoracotomy without cardiopulmonary bypass; group B consisted of 12 consecutive patients from November 1984 to July 1994 who underwent the same procedure using a median sternotomy with cardiopulmonary bypass. The two groups were similar with regard to age, sex, preoperative ejection fraction, and risk stratification. RESULTS: Mortality, cerebrovascular accidents, myocardial infarctions, and reoperations for bleeding were not significantly different between the groups. However, the patients in group A had significant reductions in atrial fibrillation, time to extubation, transfusions required, and length of cardiac recovery and hospital stay. With a mean of 12 +/- 6 months of follow-up, 87% of the patients in group A (20 of 23) are alive and asymptomatic. Actuarial survival rates for the patients in group B at 1, 2, and 10 years are 83%, 83%, and 72%, respectively. CONCLUSIONS: Minimally invasive single-vessel redo CABG can be performed safely and may reduce the morbidity associated with conventional single-vessel redo CABG.

Vagus nerve stimulation as a method to temporarily slow or arrest the heart.

BACKGROUND: Electrical stimulation of nerves is used to study nervous system and body function relationships. Electrical stimulation of the vagus nerve was used to slow the heart during coronary artery bypass grafting. METHODS: A 48-year-old man with multivessel coronary artery disease, scheduled for revascularization, gave informed consent for the surgeon to stimulate his vagus nerve. As part of the operation the left internal mammary artery was harvested as a pedicle and the patient was placed on cardiopulmonary bypass. The vagus nerve was isolated as it crossed the aorta just lateral to the phrenic nerve. Pacing wires were placed (1 cm apart) allowing prodromic conduction. With the patient fully supported by cardiopulmonary bypass and after administration of neostigmine (2.5 mg intravenously) eight separate continuous 5-second electrical pulse trains (25 Hz, 20 V, pulse width of 0.1 ms) were delivered to the nerve with 30-second rest periods between each stimulation. During the periods of stimulation the mammary artery to left anterior descending artery anastomosis was completed. RESULTS: Electrical stimulation caused cessation of the heartbeat, termination of the same resulted in normal sinus rhythm, although it was slowed by the neostigmine. Suturing of the anastomosis was done during periods of stimulation. Additional anastomoses were completed using cardiopulmonary bypass-delivered cardioplegia and aortic cross-clamping. CONCLUSIONS: Electrical stimulation of the vagus nerve slowed and temporarily arrested the heart for brief periods to allow critical placement of anastomotic sutures.

Atrial fibrillation/flutter induced by implantable ventricular defibrillator shocks: difference between epicardial and endocardial energy delivery.

INTRODUCTION: We evaluated the incidence and energy dependence of atrial fibrillation/flutter (AF) induced by implantable ventricular defibrillator shocks in 63 patients tested in the operating room or electrophysiology laboratory. METHODS AND RESULTS: Defibrillator shocks were epicardial monophasic in 32 patients, and through an Endotak lead endocardial monophasic in 19 and biphasic in 12 patients. The epicardial and endocardial patient groups had similar clinical characteristics. A total of 517 defibrillator shocks were given. The epicardial group received 336 total defibrillator shocks and 10 +/- 6 shocks (mean +/- SD) per patient compared with the endocardial group, which received 181 total shocks and 6 +/- 4 defibrillator shocks per patient (P = 0.004). In the epicardial group, AF occurred in 13 (41%) patients and in 17 (5%) of the 336 shocks. No AF was induced with endocardial defibrillator shocks. The epicardial mean energy was 16 +/- 9 J, lower than the endocardial mean energy of 20 +/- 9 J (P < 0.004). In the epicardial monophasic group, energy correlated with AF induction. Each patient received 7 +/- 6 defibrillator shocks < 15 J and 4 +/- 2 shocks > or = 15 J, yet AF occurred in only 2.3% versus 9.6% (P < 0.05) of defibrillator shocks < 15 J and > or = 15 J, respectively. Of note, AF was not induced with energy < 4 J or > 31 J. CONCLUSIONS: In the epicardial configuration, AF induction is energy dependent, with an apparent lower and upper limit of vulnerability. AF induction by defibrillator shocks delivered through an Endotak lead is very rare, possibly related to an apparent upper limit of vulnerability of less energy, avoidance of thoracotomy, or different energy field distribution.

Omental pedicle graft to improve ischemic anastomoses.

An end-to-end anastomosis was done in the center of a 5-cm devascularized jejunal segment in 5 control laboratory rabbits and 14 experimental rabbits. A second group consisted of 5 control animals and 11 experimental animals having end-to-end jejunojejunostomy in the center of a 10-cm devascularized jejunal segment. In the experimental animals, the anastomosis was wrapped circumferentially by a vascularized omental pedicle. Anastomotic leaks or fistulas developed in five 10-cm controls (100%), five 5-cm controls (100%), nine 10-cm omental wraps (82%), and four 5-cm omental wraps (29%). The remaining animals had strictures of various degrees. Injection of methylene blue into the omental vessels showed perfusion to the mucosa from the omentum. The difference between the 10-cm segment and the 5-cm segment indicates some limitation to the available blood flow from the omentum. The anastomotic stricturing was due to ischemic injury before reperfusion by ingrowth of omental vessels. A vascularized omental pedicle wrap can augment blood flow; however, the time required for neovascular ingrowth allows ischemic mucosal injury if there is no other available blood supply.

A limited axillary thoracotomy as primary treatment for recurrent spontaneous pneumothorax.

Recurrent spontaneous pneumothorax often requires surgical treatment following variable periods of chest tube therapy. A limited axillary thoracotomy provides sufficient exposure to isolate or excise pulmonary blebs and perform a pleurodesis. Prompt use of this surgical approach in lieu of the initial placement of a thoracostomy tube avoids prolonged hospitalization and a significant failure rate of thoracostomy tubes to resolve this problem. This operation can also prevent recurrence, a significant problem for this pathologic process. Fourteen patients with recurrent spontaneous pneumothorax underwent an axillary thoracotomy as either primary treatment or within 72 h of thoracostomy tube placement. The average follow-up was 38 months for the initial 10 patients and 23 months for the entire group. The procedure averaged 66 min in duration. The average incision was 3.3 cm in length. There was an equal male/female ratio and right-left distribution. The patients were discharged an average of 4.2 days after surgery. There were no complications. The most recent six patients with a recurrent pneumothorax were surgically treated on the day of admission without a preoperative chest tube. The other eight patients had a thoracostomy tube for control of the pneumothorax, with surgery performed within 72 h of tube placement. A limited axillary thoracotomy corrected the underlying pathology, hastened hospital discharge, limited pain, prevented short-term recurrence, and was cosmetically acceptable. A limited axillary thoracotomy is the operation of choice when a spontaneous pneumothorax requires surgery. This surgical approach has become our primary treatment for recurrent pneumothorax, avoiding the use of a preoperative thoracostomy tube and unnecessary delay, with excellent results for the patient.

Stimulation of hematopoiesis as an alternative to transfusion.

Optimal parenteral nutritional support, provided concomitantly with extraordinarily large replacement doses of intravenous iron dextran can be safe, effective, and life-saving for severely anemic patients who cannot or will not accept erythrocyte transfusion. Five patients who had sustained massive acute blood loss and two who had severe chronic anemia received as much as 140 ml of iron dextran intravenously. The average initial hemoglobin value in the patients with acute blood loss was 4.7 gm/dl (range 2.6 to 8.4 gm/dl), increasing to an average of 9.8 gm/dl (range 7.5 to 12.8) in 23.4 days (range 17 to 30 days), a 166% increase. The average initial hemoglobin value in the patients with chronic anemia was 3.7 gm/dl, increasing to 10.5 gm/dl over an average period of 121 days, a 182% increase. Total abdominal colectomy, pyloroplasty with truncal vagotomy, and highly selective vagotomy were accomplished without complications in four of the patients. There were no adverse reactions to the therapeutic regimen, and all patients were discharged in good condition.

Rapid restoration of red blood cell mass in severely anemic surgical patients who refuse transfusion.

Optimal parenteral nutritional support, concomitant with replacement doses of intravenous iron dextran injection, can be safe, effective, and lifesaving for severely anemic patients who are unable to receive blood transfusions. Six patients who had sustained massive acute blood loss and two who had severe chronic anemia received as much as 140 mL of iron dextran injection intravenously. The average initial hemoglobin level in the acute group was 5.0 g/dL (range, 2.6 to 8.4 g/dL) and increased to an average of 10.6 g/dL (range, 7.5 to 12.8 g/dL) in 23 days (range, 17 to 30 days); the hemoglobin level in the chronic group was 3.8 g/dL and increased to 10.6 g/dL over an average period of 121 days. Two total abdominal colectomies, a right transverse colectomy and fistulectomy, a pyloroplasty and vagotomy, and a highly selective vagotomy were accomplished without complications in five of the patients. There were no adverse reactions to the hematopoietic therapy.

Long-term alimentation by a new indwelling tube gastrostomy technique.

Use of a Gore-Tex peritoneal catheter as a feeding gastrostomy tube can virtually eliminate the complications associated with long-term feeding gastrostomy. The tube consists of a radiopaque 18 F silicone rubber catheter having a toadstool-shaped, expanded polytetrafluorethylene flange and cuff around its midportion. Epithelial tissue grows into the interstices of the Gore-Tex flange, and fibroplasia incorporates the cuff into the tissue, fixing the tube firmly in place and preventing its inadvertent removal. In addition, the tissue ingrowth creates a physiologic barrier that prevents efflux of intragastric contents and discourages influx of microorganisms or other contaminants along the gastrostomy tract. Thus far, Gore-Tex feeding gastrostomies have been placed for two to 11 months in six critically ill malnourished patients who required long-term or permanent gastrostomy feeding. No complications have occurred, patient safety and satisfaction have been greatly increased, efficacy of nutritional rehabilitation has been enhanced, and the patients' quality of life has been vastly improved.

100 patient-years of ambulatory home total parenteral nutrition.

More than 100 patient-years' experience has been acquired in the treatment of 133 patients with ambulatory home total parenteral nutrition (TPN) between May 1974 and December 1983. Indications for chronic or permanent home TPN include short bowel syndrome, malabsorption, scleroderma, and vasoactive intestinal polypeptide syndrome. Indications for acute or temporary home TPN include Crohn's disease, malignancies, gastrointestinal fistulas, ulcerative colitis, anorexia nervosa, and numerous other disorders. Eighty-two patients in the acute group were treated primarily with percutaneously placed standard subclavian catheters and 51 patients in the chronic group have been treated thus far with implanted silicone rubber, Dacron-cuffed catheters for a cumulative total of 38,939 patient days. Of the 125 implanted catheters, 115 were placed in the superior vena cava and ten in the inferior vena cava for an average duration of 250 catheter-days, the longest single catheter remaining in situ for more than 8 1/2 years. Catheter-related sepsis occurred 33 times with the implanted catheters, or once every 2.6 catheter-years. One hundred and fourteen temporary catheters were placed percutaneously in the superior vena cava via a subclavian vein for an average duration of 68 days, the longest single catheter remaining in situ for 213 days. Catheter-related sepsis occurred seven times, equivalent to one episode per 3 catheter-years. Total catheter-related complications were quite infrequent and were directly related to duration of catheterization. They included venous thrombosis (12), clotted catheter (11), catheter failure or rupture (8), catheter compression (5) and inadvertent catheter removal (4). Twenty-six catheters were repaired or spliced in situ when the external segment was accidentally damaged or deteriorated secondary to long-term material fatigue. One remarkable patient has been maintained exclusively by TPN originally as an inpatient and subsequently as an outpatient for the entire 13 years of his life.