Illness representations according to age and effects on health behaviors following coronary artery bypass graft surgery.

OBJECTIVES: To determine if illness representations differ as a function of age and how these representations, in conjunction with age, predict postoperative health behaviors. DESIGN: Prospective study of patients undergoing coronary artery bypass graft (CABG) surgery. SETTING: A large metropolitan hospital providing regional cardiac care for patients in a tri-state area, located in Pittsburgh, Pennsylvania. PARTICIPANTS: All consenting patients (N = 309) from a consecutive series of patients scheduled for CABG surgery between January 1992 and January 1994. To be eligible for participation, patients could not be scheduled for any other coincidental surgery (e.g., valve replacement), and could not be in cardiac intensive care or experiencing angina at the time of the referral. Participants were predominantly male (70%) and married (80%), and averaged 62.8 years of age. MEASUREMENTS: Postoperative self-reported health behaviors. RESULTS: Older participants awaiting CABG surgery were significantly more likely to believe old age to be the cause of their coronary heart disease (CHD) and significantly less likely to believe genetics, health-damaging behaviors, health-protective behaviors, and emotions to be the cause of their CHD than were younger participants awaiting surgery. Furthermore, the older participants were significantly more likely to believe they had no control over the disease and that the disease would be gone after surgery, and reported fewer postoperative health behavior changes than did younger participants. CONCLUSION: These findings demonstrate significant differences in illness representations as a function of age. Furthermore, differences in postoperative health behaviors were consistent with differing illness representations.

Recent clinical experience with left heart bypass using a centrifugal pump for repair of traumatic aortic transection.

OBJECTIVE: To analyze the indications, results, and limitations of using left atrial to femoral artery (LA-FA) bypass to provide distal perfusion during repair of traumatic aortic injuries. SUMMARY BACKGROUND DATA: There is no consensus about the best method for repair of traumatic aortic transection. Distal aortic perfusion with LA-FA bypass and a centrifugal pump has been the authors' preferred technique for injuries to the aortic isthmus and descending thoracic aorta. METHODS: From 1988 to 1998, the authors operated on 30 patients with traumatic aortic transection using LA-FA bypass. The mean age of the group was 36+/-2 years. The mechanism of injury was from a motor vehicle accident in 97% of the cases. Distal aortic perfusion was maintained at 50 to 75 mm Hg with flow rates of 1.5 and 3 L/min. The mean aortic cross-clamp time was 38+/-2 minutes, and the mean bypass time was 49+/-2 minutes. RESULTS: No complications related to cannulation, arterial thromboembolism, renal failure, mesenteric ischemia, or hepatic insufficiency occurred. There were no cases of postoperative paraplegia and no deaths. CONCLUSION: Left atrial to femoral artery bypass is a safe, simple, and effective adjunct to the repair of traumatic injuries to the thoracic aorta. Active distal aortic perfusion preserves spinal cord, mesenteric, and renal blood flow and eliminates the potential catastrophic consequence of spinal cord ischemia from an unexpectedly prolonged aortic cross-clamp time.

Extracorporeal membrane oxygenation for adult cardiac support: the Allegheny experience.

BACKGROUND: A mix of cardiac assist options is necessary to meet the diverse indications for cardiac support in a comprehensive heart failure program. At our institution, an adult extracorporeal membrane oxygenation (ECMO) system comprising a centrifugal pump and hollow fiber membrane oxygenator is used for short-term and temporary cardiac assist. METHODS: Between December 1991 and August 1997, 82 adult cardiac patients were supported on ECMO. Indications for cardiac assist included postcardiotomy cardiogenic shock (PCCS, 55 patients), high-risk cardiology intervention (27 patients), perioperative cardiac graft failure (4 patients), and emergency cardiac resuscitation (6 patients). Data for analysis were collected by prospective completion of standardized ECMO report forms and retrospective review of hospital charts. RESULTS: The ECMO system was inexpensive to operate, uncomplicated to implant, and adaptable for diverse indications. Survival in PCCS was 20 of 55 patients (36%), with an increased survival rate of 56% (18 of 32 patients) in patients with PCCS after isolated coronary bypass. Catheter-based revascularizations were successfully performed in 26 of 27 (96%) high-acuity patients temporarily supported by ECMO, and 23 of 27 patients (85%) survived to discharge. Survival in the cardiac graft failure group was 2 of 4 (50%). No patient supported on ECMO for cardiac resuscitation survived. CONCLUSIONS: ECMO provides good cardiopulmonary and end-organ support; survival rates are similar to or higher than those seen with centrifugal pump support in comparable patient populations.

The AB-180 circulatory support system: summary of development and plans for phase I clinical trial.

BACKGROUND: The AB-180 circulatory support system is a small, durable, efficient centrifugal pump with low thrombogenic potential. The device was designed to provide a fully implantable, left ventricular assist system for short-term support to address the issues of systemic anticoagulation, thrombus formation, infection, and cost. METHODS: Extensive bench and animal studies were performed to validate the mechanical integrity of the device and its functionality as an implant. RESULTS: These studies demonstrated anticoagulation requirements, established operating guidelines, incorporated safety systems, and demonstrated safety and efficacy. CONCLUSIONS: The AB-180 fulfills the stated goals on initial evaluation. A phase I human trial is underway.

Optimism and rehospitalization after coronary artery bypass graft surgery.

OBJECTIVE: To determine whether optimism predicts lower rates of rehospitalization after coronary artery bypass graft surgery for the 6 months after surgery. METHODS: A prospective, inception cohort design was used. The sample consisted of all consenting patients (N=309) from a consecutive series of patients scheduled for elective coronary artery bypass graft surgery at a large, metropolitan hospital in Pittsburgh, Pa. To be eligible, patients could not be scheduled for any other coincidental surgery (eg, valve replacement) and could not be in the cardiac intensive care unit or experiencing angina at the time of the referral. Participants were predominantly men (69.9%) and married (80.3%), and averaged 62.8 years of age. Recruitment occurred between January 1992 and January 1994. RESULTS: Compared with pessimistic persons, optimistic persons were significantly less likely to be rehospitalized for a broad range of aggregated problems (including postsurgical sternal wound infection, angina, myocardial infarction, and the need for another bypass surgery or percutaneous transluminal coronary angioplasty) generally indicative of a poor response to the initial surgery (odds ratio=0.50, 95% confidence interval=0.33- 0.76; P=.001). The effect of optimism was independent of traditional sociodemographic and medical control variables, as well as independent of the effects of self-esteem, depression, and neuroticism. All-cause rehospitalization also tended to be less frequent for optimistic than for pessimistic persons (odds ratio=0.77, 95% confidence interval=0.57-1.05; P=.07). CONCLUSIONS: Optimism predicts a lower rate of rehospitalization after coronary artery bypass graft surgery. Fostering positive expectations may promote better recovery.

Partial versus full sternotomy for aortic valve replacement.

BACKGROUND: Recent trends suggest that smaller incisions reduce postoperative morbidity. This study tests the hypothesis that a partial upper sternotomy improves patient outcome for aortic valve replacement. METHODS: A group of 50 patients who underwent aortic valve surgery through a partial upper sternotomy (group I) were compared to 50 patients who underwent aortic valve replacement through a median sternotomy during the same time period (group II). The mean age (60+/-2 versus 63+/-2 years; mean +/- SEM) and preoperative ejection fractions (53+/-2 versus 54+/-2) were similar. Operations were performed with central cannulation, and antegrade/retrograde blood cardioplegia. RESULTS: There was one death in each group. No differences were found in aortic occlusion time, mediastinal drainage, transfusion incidence, narcotic requirement, length of stay, or cost. The incidence of pleural and pericardial effusions was increased (18.4% versus 3.9%, p < 0.03), and the need for postoperative inotropic support was higher (38.7% versus 19.6%, p < 0.03) in the partial sternotomy group. CONCLUSIONS: Aortic valve replacement can be performed through a partial sternotomy with results comparable to full sternotomy. The partial sternotomy offers a cosmetic benefit, but does not significantly reduce postoperative pain, length of stay, or cost.

Left ventricular support with the implantable AB-180 centrifugal pump in sheep with acute myocardial infarction.

A small, 257 g centrifugal pump was tested as a left ventricular assist device (LVAD) in sheep given a myocardial infarction. Pump performance, hemolysis, end organ function, weaning, explant procedure, and the incidence of thromboemboli at autopsy were studied over intervals of 1 to 44 days. Twelve sheep were given acute myocardial infarction by ligation of the anterior descending coronary artery and 11 had insertion of the AB-180 Circulatory Support System (CSS). One sheep served as a control for the space occupying effects of the pump in the left chest. Inflow was from the left atrium and outflow was to the descending thoracic aorta. Heparin (57-83 U/ml) in sterile water was infused into the pump at a rate of 10 ml/hr. Pump flows of 1-5.7 L/min were tested. The AB-180 CSS supported 73.5% of the total cardiac output (pump + heart) of 3.89 L/min, with a mean arterial pressure of 86 +/- 7 mmHg at a pump speed of 4,162 +/- 276 rpm immediately after implant. Hemolysis was <10 mg/dl and activated partial thromboplastin time (aPTT) values were in the normal range for sheep (<52 sec) after 48 hr of pumping. Liver enzyme concentrations returned to normal within 2 weeks. There was no evidence of thrombocytopenia. No signs of infection were present during assist and none was found at autopsy. The device was successfully removed three times without the use of pressor agents or blood transfusion. Alarm systems performed appropriately. During the 106 days of cumulative pumping, two sheep showed small (<1.5 cm) renal infarcts. Both were associated with intervals of pump stasis. The AB-180 CSS pump was easily implanted into the left chest without the use of cardiopulmonary bypass. It appears to have a low thromboembolic potential in sheep, without the need for large doses of heparin to elevate aPTT values. This characteristic may ameliorate the excessive bleeding seen clinically with current LVAD systems used for post cardiotomy cardiogenic shock, which require anticoagulation with heparin. The small size and weight of the device permit implantation within the chest and allow chest closure. This may reduce the incidence of infection associated with temporary left ventricular assist and an open sternum.

AB-180 circulatory support system: summary of development and phase I clinical trial.

The AB-180 Circulatory Support System (AB-180 CSS; Cardiac Assist Technologies, Pittsburgh, PA) is a left ventricular assist system for investigational use in patients with postcardiotomy cardiogenic shock who are refractory to standard treatment with an intra-aortic balloon pump, pharmacologic treatment, or both. The intent of the AB-180 CSS is to provide temporary (up to 14 days) mechanical circulatory support until the heart recovers adequate mechanical function. The system consists of a small implantable centrifugal pump and a controller. A unique infusion system produces a hydrodynamic bearing between rotational and stationary components of the AB-180 CSS pump. This infusion system also provides a source of heparin for localized anticoagulation. Extensive bench and animal work has illustrated anticoagulation requirements, established operating guidelines, and demonstrated safety and efficacy. An investigational device exemption has been granted for a Phase I, five patient feasibility study at Allegheny General Hospital in Pittsburgh, Pennsylvania. To date, the pump has been implanted in one patient. The results from this first case are presented here.

Morbidity, cost, and six-month outcome of minimally invasive direct coronary artery bypass grafting.

BACKGROUND: Minimally invasive direct coronary artery bypass grafting (MIDCABG) promises to reduce the morbidity of coronary bypass, but this has not been proved. METHODS: This retrospective study compares the morbidity, mortality, cost, and 6-month outcome of patients less than 80 years old undergoing elective left internal mammary artery to left anterior descending artery bypass grafting via MIDCABG (n = 60) or sternotomy (n = 55) between January 1995 and December 1996. There were no differences between the groups in mean age, sex distribution, or preoperative risk level. The left internal mammary artery was mobilized from the fifth costal cartilage to the subclavian artery in all patients. The anastomoses were done with a beating heart in the MIDCABG group and with cardioplegic arrest in the sternotomy group. RESULTS: There were no operative deaths in either group. The MIDCABG patients had a lower transfusion incidence (10/60 [17%] versus 22/55 [40%]; p< or =0.02) and a shorter postoperative intubation time (2.1+/-4.2 versus 12.6+/-9 hours; p< or =0.0001). One patient in each group was reexplored for bleeding. Three sternotomy patients (3/55, 5%) required ventilatory support for greater than 48 hours, but no MIDCABG patient was ventilated for more than 24 hours. Median postoperative length of stay was 4 days for MIDCABG and 7 days for sternotomy. Estimated hospital costs were $11,200+/-3100 for MIDCABG and $15,600+/-4200 for CABG (p < 0.001). The reduced morbidity and cost of MIDCABG was found mostly in high-risk patients. At 6-month follow-up, 5 MIDCABG patients (5/60, 8%) had evidence of recurrent ischemia involving the left anterior descending artery, primarily the result of anastomotic stricture. CONCLUSIONS: This analysis shows that MIDCABG reduces the initial morbidity and cost of coronary bypass, but some patients require subsequent reintervention. Long-term follow-up is needed before MIDCABG can be judged better than traditional bypass, but the initial results are promising, especially in high-risk patients.

A model that predicts morbidity and mortality after coronary artery bypass graft surgery.

OBJECTIVES: This study was performed to develop a method for identifying patients at increased risk for morbidity or mortality after coronary artery bypass graft surgery. BACKGROUND: Postoperative morbidity is more common than mortality and is important because of its relation to cost. METHODS: Univariate and forward stepwise logistic regression analysis was used to retrospectively analyze a group of 1,567 consecutive patients who underwent bypass surgery between July 1991 and December 1992. We developed a model that predicted postoperative morbidity or mortality, or both, which was then prospectively validated in a group of 1,235 consecutive patients operated on between January 1993 and April 1994. A clinical risk score was derived from the model to simplify utilization of the data. RESULTS: The following factors, listed in decreasing order of significance, were found to be significant independent predictors: cardiogenic shock, emergency operation, catheterization-induced coronary artery closure, severe left ventricular dysfunction, increasing age, cardiomegaly, peripheral vascular disease, chronic renal insufficiency, diabetes mellitus, low body mass index, female gender, reoperation, anemia, cerebrovascular disease, chronic obstructive pulmonary disease, renal dysfunction, low albumin, elevated blood urea nitrogen, congestive heart failure and atrial arrhythmias. Observed morbidity and mortality for the validation group fell within the 95% confidence interval of that predicted by the model. Costs were closely related to the incidence of postoperative morbidity. CONCLUSIONS: Analysis of preoperative patient variables can predict patients at increased risk for morbidity or mortality, or both, after bypass surgery. Increased morbidity results in higher costs. Different strategies for high and low risk patients should be used in cost reduction efforts.

A model for predicting transfusion after coronary artery bypass grafting.

BACKGROUND: Blood conservation has become an important issue in cardiac surgery. This study was undertaken to determine if the need of blood transfusion could be predicted from preoperative patient variables. METHODS: From January 1, 1992, to December 31, 1993, 2,033 patients having isolated coronary artery bypass grafting procedures were studied; 1,446 (71%) were male and 587 (29%), female. The mean age was 65.1 +/- 9.9 years (range, 31 to 88 years). Emergency operation, urgent operation, and reoperations were done in 78 (4%), 188 (9%), and 189 (9%) patients, respectively. In the entire group, 1,245 (61%) received transfusion during hospitalization, and 788 (39%) did not. Logistic regression analysis was used to construct a model that predicted the need of transfusion of packed red blood cells after coronary artery bypass grafting. A transfusion risk score was constructed by assigning points to independent predictive factors on the basis of the logistic regression coefficient and the odds ratio. Preoperative predictors of transfusion were emergency operation, urgent operation, cardiogenic shock, catheterization-induced coronary occlusion, low body mass index, left ventricular ejection fraction lower than 0.30, age greater than 74 years, female sex, low red cell mass, peripheral vascular disease, insulin-dependent diabetes, creatinine level greater than 1.8 mg/dL, albumin value lower than 4 g/dL, and redo operation. RESULTS: The mean transfusion risk score for patients receiving 0, 1 to 4, and greater than 4 units of packed red blood cells was 2.3 +/- 0.9, 5.2 +/- 3.0, and 9.6 +/- 3.5, respectively (p = 0.001). Patients with a score higher than 6 had a 95% transfusion incidence. The predictive model was validated on 422 patients having coronary artery bypass grafting from January 1 to May 31, 1994. The observed rates of the validation group fell within the 95% confidence intervals of the predicted rates. CONCLUSIONS: These data demonstrate that readily available patient variables can predict patients at risk for transfusion. Routine use of aprotinin and other adjustments of cardiopulmonary bypass should be considered to reduce transfusion in high-risk patients.

Clinical cardiomyoplasty: review of the ten-year United States experience.

BACKGROUND: Clinical trials of dynamic cardiomyoplasty were pioneered at Allegheny General Hospital beginning in September 1985. Data from 9 years of experience with the procedure at this institution and more recent data from newer cardiomyoplasty centers have been analyzed for outcome analysis and future trends. METHODS: Each patient underwent a cardiomyoplasty procedure using the left or right latissimus dorsi muscle. Thirty-four patients were studied at Allegheny: 5 patients implanted with dual chamber pacemakers as single stimulus myostimulators, 11 patients composing the phase I Food and Drug Administration trial of the Medtronic burst myostimulator, and 18 patients entered in the phase II Medtronic trial. Patients from seven additional centers entered the phase II trial in 1991. Fifty-seven patients completed follow-up studies to 1 year after operation in this trial. RESULTS: Operative mortality was 5/57 (11%) in the American phase II group and 5/34 (15%) in the Allegheny group (1/18, 6% for Allegheny phase II). Nineteen patients (19/57, 33%) from the combined phase II population died in the first year, and 10/34 (29%) in the Allegheny study. The predominant cause of postdischarge death was arrhythmia (12/19, 63% American; 7/10, 70% Allegheny). In all groups significant improvement was seen in quality of life and functional class. Phase II patients demonstrated significant increases in ejection fraction and stroke work. CONCLUSIONS: Failure to sustain improvement and arrhythmia-related death are complex challenges for this procedure; however, realistic solutions have been proposed and are under investigation.

Small, low-cost implantable centrifugal pump for short-term circulatory assistance.

BACKGROUND: In 1991, Allegheny General Hospital and Allegheny-Singer Research Institute purchased a centrifugal pump, then a 2-year-old technology, from Medtronic Bio-Medicus, as part of its research program for novel treatments of acute and chronic heart failure. During a 4-year development program, we then established and met goals of durability, performance, thromboresistance, and low cost. METHODS: In vitro testing involved extensive hydraulic characterizations using Penn State mock loops. Calorimetry was used to determine efficiency. Durability studies used heated (37 degrees C) seawater for 28 to 45 days. In vivo studies used 46 sheep to test performance and engineering changes and to determine myocardial oxygen consumption, thromboresistance, and long-term durability. A left atrium-to-aorta circuit was used in all. RESULTS: Hydraulic testing showed no preload sensitivity but moderate afterload sensitivity at all impeller speeds (2,000 to 6,000 rpm). The heat load was low, and overall efficiency was 13% to 15%. Bench durability studies showed no electrical malfunction of the stator or console without degradation of the biomaterials used. Acute in vitro studies showed a near-linear relationship of myocardial oxygen consumption and left ventricular stroke work, pump flow, and pump speed. At speeds of 2 to 3 L/min (50% bypass), left ventricular stroke work and myocardial oxygen consumption were decreased approximately 50%. Additionally, 5 animals have had implants for 28 to 154 days with no macroemboli or microemboli detected in any animal. Hematologic and biochemical studies became normal 3 to 7 days after implantation. Hemolysis was low at less than 10 mg/dL. Clinical costs of the device are estimated to be 80% less than those of currently available devices. CONCLUSIONS: We conclude that an old technology has been made into new technology by application of sound engineering design principles, microchips, and new biomaterials. Qualifying trails for a Food and Drug Agency investigational device exemption application are in progress.

End organ function with prolonged nonpulsatile circulatory support.

The hypothesis tested in these studies was that long-term circulatory support with a nonpulsatile device is safe and causes no end organ dysfunction. An inexpensive, small centrifugal pump with a 7 L/min capacity was implanted in 6 sheep (15 acute implants have previously been reported). The inlet cannula was placed in the left atrium and the outlet graft anastomosed to the descending aorta. A percutaneous cable supplied DC power and heparinized saline (10 ml/hr) for lubrication. Outputs of pump flow, stator, animal core temperature, pump power consumption, and RPM were monitored throughout the course of each experiment. The sheep moved freely within a large pen using an overhead swivel/tether system that carried all input and output lines. Four sheep survived longer than 4 weeks, and the indices of end organ function were analyzed at 28 days. No animal revealed any neurologic dysfunction. Hemoglobin was 9.075 +/- 0.78 g/dl at 28 days, as opposed to 7.475 +/- 0.68 (p = 0.002) before surgery. The blood urea nitrogen was 9.250 +/- 4.57 versus 14 +/- 5.72 mg/dl (p = 0.041), creatinine was 0.775 +/- .10 versus 0.775 +/- 0.05 mg/dl (p > or = 0.999), total bilirubin was 0.425 +/- 0.2 versus 0.225 +/- 0.05 mg/dl (p = 0.092), serum glutamic oxaloacetic transaminase was 74.75 +/- 24 versus 106.25 +/- 15.84 IU/L (p = 0.015), serum glutamic pyruvic transaminase was 36 +/- 28.7 versus 28.3 +/- 5.7 IU/L (p = 0.25), and total protein was 6.675 +/- 0.49 versus 5.47 +/- 0.15 g/dl (p = 0.025). It is concluded that these animals adapted very well to pulseless circulatory support. The results of these studies support the concept of an inexpensive, implantable, centrifugal pump as a ventricular assist device.

Microemboli during coronary artery bypass grafting. Genesis and effect on outcome.

Cerebral dysfunction after coronary artery bypass operations represents some of the most serious and costly complications of cardiac surgery. We used transcranial Doppler ultrasonography to detect and quantify the number of microemboli in the right middle cerebral artery of patients undergoing elective first coronary bypass operations (n = 117) and second coronary bypass operations (n = 10). We hypothesized that total microemboli were related to clinical outcome. A 2 MHz transducer was positioned in front of the ear above the zygomatic arch and depth gated to 50 mm. Microemboli were recorded as perturbations of the blood flow velocity in the middle cerebral artery and aurally monitored. Each episode of microembolism was specified both by clock time and as a perfusion or surgical event. Forty-one patients (32%) completed neuropsychologic evaluation with a battery of tests for cognitive function. Anxiety states and traits were also assessed. The distribution of microembolism showed that there were three groups of patients: < 30 microemboli (n = 83); 30 to 59 (n = 24); and > 60 (n = 20). Seven of 10 patients with cerebral complications (stroke, coma, delirium, aberrant behavior) were in the > 60 microemboli group. Those with cerebral complications had 20.7 +/- 4.5 microemboli from perfusion and 57.4 +/- 15.6 from surgical events. The 13 patients in the > 60 microemboli group without central nervous system symptoms had 95.5 +/- 19.5 microemboli from perfusion and 36.0 +/- 6.9 from surgical events. Neuropsychologic scores were most often depressed for memory (73%), comprehension (49%), attention (46%), and constructional ability (44%). The greatest change was in total score in the > 60 microemboli group (-3.3 +/- 0.6) compared with -1.1 +/- 0.2 and -1.9 +/- 0.2 for the 30 to 59 and < 30 groups, respectively. The incidences of cardiac and pulmonary complications and mortality were different between those patients with < 60 microemboli versus those with > 60 microemboli. Cardiac and pulmonary complications and mortality percentages were 4.7%, 3.7%, and 0.9%, respectively, for the < 60 microemboli group and 20%, 20%, and 15%, respectively, for the > 60 microemboli group. We concluded that transcranial Doppler ultrasonography is a useful technique to quantify and detect the source of microemboli during coronary artery bypass operations and may be useful in assessing new operative strategies, the quality of the perfusion, and potentially as an indicator for pharmacologic therapy in the operating room in patients with high microemboli counts.

Myocardial regeneration. Transplanting satellite cells into damaged myocardium.

Millions of Americans suffer from chronic heart failure. Despite treatments with heart transplantation, cardiomyoplasty, and artificial assist devices, an ideal therapy is yet to be found. Since 1988, we have studied the transplantation of myogenic stem cells from skeletal muscle into injured myocardium in the hope that these cells would multiply and differentiate, thereby improving the function of the failing heart. We have achieved 2 goals thus far: the 1st was improving the culture technique to obtain high yield and purity of the satellite cells; the 2nd was successfully implanting cultured satellite cells in dog hearts and later identifying them as new myocardium. We share our findings here to encourage more study in this promising area.