Outcome of mild periprosthetic regurgitation detected by intraoperative transesophageal echocardiography.

OBJECTIVES: The goal of this study was to determine the outcome of trivial or mild periprosthetic regurgitation (PPR) identified by intraoperative transesophageal echocardiography (TEE). BACKGROUND: The clinical significance, natural history and correlates of trivial or mild PPR detected early after surgery are unknown. METHODS: Between 1992 and 1997, 608 consecutive patients underwent isolated aortic valve replacement or mitral valve replacement at Dartmouth-Hitchcock Medical Center. Of these, 113 patients (18.3%) were found to have trivial or mild PPR at surgery by TEE. Follow-up transthoracic echocardiograms (early TTEs) were obtained within six weeks of surgery in 99.0% of patients and late TTEs (mean 2.1 years) in 54.3%. Clinical, intraoperative and outcome variables associated with PPR were identified using t test, chi-square and logistic regression analyses. RESULTS: By univariate analysis, compared with patients without PPR, patients with PPR were older, of smaller body surface area (BSA), had degenerative valve disease more often and were more likely to receive a bioprosthetic valve. By multivariate analysis, smaller BSA and the use of a bioprosthesis were the strongest predictors of PPR (p < 0.01). At early TTE, PPR was not observed (n = 56) or remained unchanged (n = 44) in all patients. At late TTE, four patients were found to have progression of their PPR. All four patients had bioprosthetic valves. Two of these patients had endocarditis, and one had primary valvular degeneration. The fourth patient had progressive PPR. CONCLUSIONS: Trivial or mild PPR is a frequent finding on intraoperative TEE. Smaller body size and the use of a bioprosthetic valve are significantly associated with PPR. The clinical significance and natural history of PPR is benign in most cases.

Lowest hematocrit on bypass and adverse outcomes associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Cardiac surgery patients' hematocrits frequently fall to low levels during cardiopulmonary bypass. METHODS: We investigated the association between nadir hematocrit and in-hospital mortality and other adverse outcomes in a consecutive series of 6,980 patients undergoing isolated coronary artery bypass graft surgery. The lowest hematocrit during cardiopulmonary bypass was recorded for each patient. Patients were divided into categories based on their lowest hematocrit. Women had a lower hematocrit during bypass than men but both sexes are represented in each category. RESULTS: After adjustment for preoperative differences in patient and disease characteristics, the lowest hematocrit during cardiopulmonary bypass was significantly associated with increased risk of in-hospital mortality, intra- or postoperative placement of an intraaortic balloon pump and return to cardiopulmonary bypass after attempted separation. Smaller patients and those with a lower preoperative hematocrit are at higher risk of having a low hematocrit during cardiopulmonary bypass. CONCLUSIONS: Female patients and patients with smaller body surface area may be more hemodiluted than larger patients. Minimizing intraoperative anemia may result in improved outcomes for this subgroup of patients.

Using an integrated measurement system as a common language: lessons from the U.S. Army medical department.

The Process of developing an integrated measurement system for the U.S. Army Medical Department (AMEDD) is examined in this study. A fundamental issue is whether the measures of performance accumulated by any information system are the correct ones and whether these measures appropriately reflect managers' decision making. Measurement is proposed as a solution to performance barriers. The four steps involved in building the AMEDD integrated measurement system (IMS) model are set out. Strategy is explored as the key input to the IMS model. An activity-based management (ABM) model that can support the required IMS cost-based measures is also described and the interrelationship between the two models is illustrated. The key test for application of the IMS model will be whether linking strategy and measurement results in information that improves decision making.

Decreasing mortality for aortic and mitral valve surgery in Northern New England. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Although numerous reports have documented declining mortality rates associated with coronary artery bypass surgery in recent years, it is unknown whether similar trends have occurred with valve surgery during this time. METHODS: We conducted a regional, prospective study to assess trends in patient casemix and in-hospital mortality rates over time with aortic valve replacement (AVR), mitral valve replacement (MVR), and mitral valve repair. Data were collected from all patients undergoing AVR (n = 2,596), MVR (n = 759), or mitral valve repair (n = 522) in Northern New England between January 1992 and December 1997. Logistic regression was used to identify significant predictors of in-hospital mortality and to calculate risk-adjusted mortality rates. RESULTS: For AVR, the trend in patient casemix was toward increased risk with increases in patient age and in the proportion of patients with: body surface area less than 1.7, diabetes, coronary artery disease, and prior valve surgery. A decrease was noted in the proportion of patients undergoing additional surgical procedures. For MVR, patient risk improved over the time period with fewer female patients and fewer patients with coronary artery disease. For mitral valve repair patient risk increased over the time period with increases in the proportion of patients with coronary artery disease, diabetes, and whose surgical priority was classified as urgent. In addition, there was a borderline significant increase in the proportion of mitral valve repair patients in New York Heart Association class IV preoperatively. Risk-adjusted mortality decreased 44% from 9.3% in 1992 through 1993 to 5.3% in 1996 through 1997 for patients undergoing AVR (p = 0.01) and decreased 53% from 13.6% in 1992 through 1993 to 8.2% in 1996 through 1997 for patients undergoing MVR (p = 0.01). We observed a statistically insignificant increase in risk-adjusted mortality over the time period for patients undergoing mitral valve repair (from 3.6% in 1992 through 1993 to 5.0% in 1996 through 1997; p = 0.34). CONCLUSIONS: Significant improvement in mortality rates with valve replacement was observed in northern New England during this time period. This improvement persisted following adjustment for changes in patient casemix over this time. These trends mirror improvements in mortality with other cardiac surgical interventions that have been observed in recent years in our region and nationally.

Prosthetic valve type for patients undergoing aortic valve replacement: a decision analysis.

BACKGROUND: In two large, randomized, clinical trials long-term survival after aortic valve replacement (AVR) was similar for patients receiving tissue and mechanical aortic heart valve prostheses. Higher bleeding rates among patients with mechanical valves, who must receive permanent oral anticoagulation to prevent thromboembolism, were offset by higher reoperation rates for valve degeneration among patients with tissue valves. Because the average age of patients undergoing AVR and clinical practices have changed considerably since the randomized clinical trials were conducted, we performed a decision analysis to reassess the optimal valve type for patients undergoing AVR. METHODS: We used a Markov state-transition model to simulate the occurrence of valve-related events and life expectancy for patients undergoing AVR. Probabilities of clinical events and mortality were derived from the randomized clinical trials and large follow-up studies. RESULTS: Although the two valve types were associated with similar life expectancy in 60-year-old patients (mean age of patients in the randomized clinical trials), tissue valves were associated with greater life expectancy than mechanical valves (10.7 versus 11.1 years) in 70-year-old patients (currently mean age of AVR patients). For 70-year-old patients, the effects of major bleeding complications (24%) with mechanical valves substantially outweighed those of reoperation for valve failure (12%) with tissue valves at 12 years. Of the clinical practice changes assessed, the recommended valve type was most sensitive to changes in bleeding rates with anticoagulation. However, bleeding rates would have to be 68% lower than those reported in the European randomized clinical trial to affect the recommended valve type for 70-year-old patients. Reoperation rates would have to be five times higher, and mortality rates at reoperation would have to be four times higher to affect the recommended valve type for 70-year-old patients. CONCLUSIONS: Although mechanical valves are preferred for AVR patients less than 60 years old, most patients currently undergoing AVR are elderly and would benefit more from tissue valves.

Mediastinitis and long-term survival after coronary artery bypass graft surgery.

BACKGROUND: Mediastinitis is a dreaded complication of coronary artery bypass surgery (CABG). The long-term effect of mediastinitis on mortality after CABG has not been well studied. METHODS: We examined the survival of 15,406 consecutive patients undergoing isolated CABG surgery from 1992 through 1996. Patient records were linked to the National Death Index. Mediastinitis was defined as occurring during the index admission and requiring reoperation. RESULTS: Mediastinitis occurred in 193 patients (1.25%). Patients with mediastinitis were older and more likely to have had emergency surgery, diabetes, peripheral vascular disease, chronic obstructive pulmonary disease, and preoperative dialysis-dependent renal failure. Patients with mediastinitis were also more likely to be severely obese and had somewhat lower preoperative ejection fraction. After multivariate adjustment for these factors, the first year post-CABG survival rate was 78% with mediastinitis and 95% without, and the hazard ratio for mortality during the entire follow-up period was 3.09 (CI 95% 2.28, 4.19; p < 0.0001). CONCLUSIONS: Mediastinitis is associated with a marked increase in mortality during the first year post-CABG and a threefold increase during a 4-year follow-up period.

Insulin infusion improves neutrophil function in diabetic cardiac surgery patients.

UNLABELLED: Diabetic patients are at increased risk of wound infection after major surgery, but the effect of perioperative glucose control on postoperative wound infection rates after surgery is uncertain. We tested the effect of an insulin infusion on perioperative neutrophil function in diabetic patients scheduled for coronary artery bypass surgery. Participants (n = 26) were randomly allocated to receive either aggressive insulin therapy (AIT) or standard insulin therapy (SIT) during surgery. Blood was drawn for neutrophil testing before surgery, 1 h after the completion of cardiopulmonary bypass, and on the first postoperative day. Neutrophil phagocytic activity decreased to 75% of baseline activity in the AIT group and to 47% of baseline activity in the SIT group (P < 0.05 between groups). No important differences in neutrophil antibody-dependent cell cytotoxicity were found. This study documents a potentially beneficial effect of continuous insulin therapy in diabetic patients who require major surgery. IMPLICATIONS: A continuous insulin infusion and glucose control during surgery improves white cell function in diabetic patients and may increase resistance to infection after surgery.

Results of a regional study of modes of death associated with coronary artery bypass grafting. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: It is well known that surgeon-specific in-hospital mortality rates for coronary artery bypass grafting vary, but this aggregate measure does not suggest specific opportunities for improvement. METHODS: We performed a regional prospective study of 8,641 consecutive patients undergoing isolated coronary artery bypass grafting by all of the 23 cardiothoracic surgeons practicing in northern New England during the study period. Mode of death was assigned by an end points committee using predetermined definitions. Surgeons were ranked according to risk-adjusted mortality rates and grouped in terciles, and cause-specific mortality rates were determined. RESULTS: The mortality rate was 3.3% in the lowest surgeon mortality tercile and 5.8% in the highest tercile. Fatal heart failure accounted for 80.0% of the difference in aggregate mortality rates, ranging from 1.9% in lowest surgeon mortality tercile to 4.0% in the highest tercile (p < 0.001). Rates of other causes did not differ significantly across surgeon mortality terciles. Differences in rates of fatal heart failure could not be explained by differences in preoperative left ventricular dysfunction or other patient characteristics. CONCLUSIONS: Most of the difference in observed mortality rates across surgeons is attributable to differences in rates of heart failure.

Obesity and risk of adverse outcomes associated with coronary artery bypass surgery. Northern New England Cardiovascular Disease Study Group.

BACKGROUND: Obesity is frequently cited as a risk factor for adverse outcomes of major surgery. The results of prior studies of the relationship between obesity and risk of adverse outcomes of coronary artery bypass grafting (CABG) have been contradictory because of insufficient power to assess relatively infrequent outcomes or data to adjust for confounding factors. METHODS AND RESULTS: Data on patient age, sex, height, weight, medical history, current clinical status, and treatment factors were assessed prospectively among 11101 consecutive patients undergoing CABG. Body mass index (BMI) was used as the measure of obesity and was categorized as nonobese (1st to 74th percentiles), obese (75th to 94th percentiles), or severely obese (95th to 100th percentiles). Adverse outcomes occurring in-hospital, including mortality, intraoperative/postoperative cerebrovascular accident (CVA), postoperative bleeding, and sternal wound infection, were defined prospectively. Associations between obesity and postoperative outcomes were assessed by use of logistic regression to adjust for potentially confounding variables. Although obesity was not associated with increased mortality (adjusted odds ratio [OR], 1.16; P=.261) or postoperative CVA (adjusted OR, 1.06; P=.765), risks of sternal wound infection were substantially increased in the obese (adjusted OR, 2.10; confidence interval [CI], 1.45 to 3.06; P<.001) and severely obese (adjusted OR, 2.74; CI, 1.49 to 5.02; P=.001). On the other hand, rates of postoperative bleeding were significantly lower in the obese (adjusted OR, 0.66; CI, 0.49 to 0.90; P=.009) and severely obese (adjusted OR, 0.40; CI, 0.20 to 0.81; P=.011). CONCLUSIONS: With the exception of sternal wound infection, the perception among clinicians that obesity predisposes to various postoperative complications with CABG is not supported by these data. Further work is needed to understand the apparent protective effect of obesity on risks of postoperative bleeding.

Hybrid myocardial revascularization after previous left pneumonectomy.

Previous intrapericardial left pneumonectomy and irradiation necessitated an unorthodox, staged approach to myocardial revascularization in a patient with unstable angina pectoris, left main artery, and three-vessel coronary artery disease. A saphenous vein bypass graft was constructed from the descending thoracic aorta to the left anterior descending coronary artery via left thoracotomy, without cardiopulmonary bypass. Two days later the patient underwent stenting of the left main and circumflex coronary arteries. Recovery was uneventful.

Clinical process cost analysis.

BACKGROUND: New systems of reimbursement are exerting enormous pressure on clinicians and hospitals to reduce costs. Using cheaper supplies or reducing the length of stay may be a satisfactory short-term solution, but the best strategy for long-term success is radical reduction of costs by reengineering the processes of care. However, few clinicians or institutions know the actual costs of medical care; nor do they understand, in detail, the activities involved in the delivery of care. Finally, there is no accepted method for linking the two. METHODS: Clinical process cost analysis begins with the construction of a detailed flow diagram incorporating each activity in the process of care. The cost of each activity is then calculated, and the two are linked. This technique was applied to Diagnosis Related Group 75 to analyze the real costs of the operative treatment of lung cancer at one institution. RESULTS: Total costs varied between $6,400 and $7,700. The major driver of costs was personnel time, which accounted for 55% of the total. Forty percent of the total cost was incurred in the operating room. The cost of care decreased progressively during hospitalization. CONCLUSIONS: Clinical process cost analysis provides detailed information about the costs and processes of care. The insights thus obtained may be used to reduce costs by reengineering the process.

Clinical process cost analysis: a promising tool for clinical improvement.

In today's environment, health care organizations are expected to provide the best possible care at the lowest possible cost. Neither aspect can be considered independently, but correlating the two with traditional systems of cost analysis is very difficult. This article presents a new method for linking costs to the process of care that also promises to be a powerful tool for clinical improvement and redesign.

A hemodynamic comparison of Omniscience and Medtronic Hall aortic prostheses.

BACKGROUND AND AIMS OF THE STUDY: Preliminary reports have suggested hemodynamic disparities between single leaflet tilting disc prostheses. We tested the hypothesis that similarities in prosthetic design may not necessarily indicate hemodynamic equivalence. MATERIALS AND METHODS: In a retrospective analysis, we compared the functional characteristics of two single tilting disc (Omniscience and Medtronic Hall) prostheses implanted in the aortic position in 30 patients matched for valve size and left ventricular systolic function. RESULTS: Echocardiographic and Doppler analysis blinded to patient and valve type indicated similar quantitative left ventricular ejection fractions (64% +/- 6% for both) and cardiac outputs (4.8 +/- 1.2 vs. 4.6 +/- 1.2 l/min, p = 0.65) in the Onmiscience and Medtronic Hall groups, respectively. Transprosthetic instantaneous peak gradients were greater for Omniscience than for Medtronic Hall valves (44 +/- 8 vs. 35 +/- 11 mmHg, p < or = 0.02), as were the mean values (24 +/- 6 vs. 18 +/- 6 mmHg, p = 0.01). Even when 21 and 23 mm prostheses were analyzed separately to allow for unequal sewing ring diameters in the smallest valve sizes (Omniscience = 19 mm, Medtronic Hall = 20 mm), higher gradients were noted in the Omniscience prostheses. Effective orifice areas were smaller in the Omniscience than Medtronic Hall prostheses whether data from all prostheses (0.92 +/- 0.11 cm2 vs. 1.09 +/- 0.18 cm2, p < or = 0.05), or only data from 21 and 23 mm valves (0.94 +/- 0.11 cm2 vs. 1.10 +/- 0.18 cm2, p < 0.05) were included. Similarly, the dimensionless obstructive index, a parameter independent of left ventricular flow and annular size, was reduced in the Omniscience valves, indicating greater obstruction, whether all valves (0.31 +/- 0.04 vs. 0.36 +/- 0.07, p < or = 0.01) or only 21 and 23 mm valves (0.31 +/- 0.04 vs. 0.36 +/- .04, p < 0.001) were analyzed. CONCLUSION: Despite prosthetic design similarities, resting hemodynamic assessment indicates greater stenosis in Omniscience than Medtronic Hall valves when placed in the aortic position. The long term effects of these differences in terms of ventricular diastolic and systolic function and mass regression requires further evaluation.

A regional intervention to improve the hospital mortality associated with coronary artery bypass graft surgery. The Northern New England Cardiovascular Disease Study Group.

OBJECTIVE: To determine whether an organized intervention including data feedback, training in continuous quality improvement techniques, and site visits to other medical centers could improve the hospital mortality rates associated with coronary artery bypass graft (CABG) surgery. DESIGN: Regional intervention study. Patient demographic and historical data, body surface area, cardiac catheterization results, priority of surgery, comorbidity, and status at hospital discharge were collected on CABG patients in Northern New England between July 1, 1987, and July 31, 1993. SETTING: This study included all 23 cardiothoracic surgeons practicing in Maine, New Hampshire, and Vermont during the study period. PATIENTS: Data were collected on 15,095 consecutive patients undergoing isolated CABG procedures in Maine, New Hampshire and Vermont during the study period. INTERVENTIONS: A three-component intervention aimed at reducing CABG mortality was fielded in 1990 and 1991. The interventions included feedback of outcome data, training in continuous quality improvement techniques, and site visits to other medical centers. MAIN OUTCOME MEASURE: A comparison of the observed and expected hospital mortality rates during the postintervention period. RESULTS: During the postintervention period, we observed the outcomes for 6488 consecutive cases of CABG surgery. There were 74 fewer deaths than would have been expected. This 24% reduction in the hospital mortality rate was statistically significant (P = .001). This reduction in mortality rate was relatively consistent across patient subgroups and was temporally associated with the interventions. CONCLUSION: We conclude that a multi-institutional, regional model for the continuous improvement of surgical care is feasible and effective. This model may have applications in other settings.

Subxiphoid approach for insertion of ICDs after previous median sternotomy.

To avoid the risks both of repeat median sternotomy and of thoracotomy, the modified subxiphoid approach was adopted for insertion of implantable cardioverter-defibrillators in 10 patients who had previously undergone cardiac operations via median sternotomy. Effective implantable cardioverter-defibrillator systems were implanted in all patients. There were no operative deaths and no hemorrhagic or respiratory complications. One patient underwent repositioning of a dislodged superior vena caval electrode, and an infected generator pocket developed in 1 patient. Early extubation was routine. Two patients were observed in the coronary care unit for the first postoperative night. Postoperative pain was controlled with oral analgesic agents. The subxiphoid approach is safe and effective, and it carries a substantially lower risk of complications than other techniques, even in this high-risk group of patients. By minimizing the need for admission to the intensive care unit, invasive monitoring, and prolonged ventilatory support, by reducing surgical complications, and by shortening the hospital stay, the subxiphoid approach saved an average of $3,295 per patient.

Should a patient with a treated cancer be offered an open heart operation?

The unknown but presumably reduced life expectancy of patients with malignant neoplasms may dissuade surgeons from performing necessary coronary and valvular heart operations. There is also concern for recrudescence of cancer as a result of an impaired immune system after cardiopulmonary bypass. We analyzed the records of 2,190 patients who underwent cardiac operations requiring extracorporeal circulation between 1988 and 1990. Of these, 46 patients had previously been treated for malignancy other than nonmelanoma skin cancer. Open heart operations were performed in patients with cardiac symptoms only in the absence of tumor recurrence. Tumor staging indicated reduced life expectancy in all patients. Thirty-eight patients (82.7%) had myocardial revascularization; 8 patients (17.3%) underwent valve operations. Postoperatively, all but 2 patients were free from complications. In-hospital mortality was 4.3% (2/46). One patient died of cardiogenic shock after combined aortic and mitral valve replacement; the second patient succumbed to pulmonary embolism after reoperative coronary artery bypass grafting. Actuarial survival at 3 years was 96%, and all patients reported a satisfactory quality of life. This experience suggests that cardiac operations in selected patients with previously treated cancer are safe and offer clinical improvement at a reasonable operative risk.

Autologous pericardial flap for prevention of reentry injury in cardiac reoperations.

Cardiac injury during sternal reentry to the heart is a rare but dangerous complication of cardiac reoperations. Positioning a pericardial flap between the heart and sternum at the time of the initial operation may consistently facilitate cardiac reoperation by providing a reliable plane of dissection and by reducing adhesion formation.

Should patients with Björk-Shiley valves undergo prophylactic replacement?

About 85,000 patients have undergone replacement of diseased heart valves with prosthetic Björk-Shiley convexo-concave (CC) valves. These valves are prone to fracture of the outlet strut, which leads to acute valve failure that is usually fatal. Should patients with these valves undergo prophylactic replacement to avoid fracture? The incidence of strut fracture varies between 0% and 1.5% per year, depending on valve opening angle (60 degrees or 70 degrees), diameter (less than 29 mm or greater than or equal to 29 mm), and location (aortic or mitral). Other factors include the patient's life expectancy and the expected morbidity and mortality associated with reoperation. We have used decision analysis to identify the patients most likely to benefit from prophylactic reoperation. The incidence of outlet strut fracture was estimated from the data of three large studies on CC valves, and stratified by opening angle, diameter, and location. A Markov decision analysis model was used to estimate life expectancy for patients undergoing prophylactic valve replacement and for those not undergoing reoperation. Prophylactic valve replacement does not benefit patients with CC valves that have low strut fracture risks (60 degrees aortic valves and less than 29 mm, 60 degrees mitral valves). For most patients with CC valves that have high strut fracture risks (greater than or equal to 29 mm, 70 degrees CC), prophylactic valve replacement increases life expectancy. However, elderly patients with such valves benefit from prophylactic reoperation only if the risk of operative mortality is low. Patient age and operative risk are most important in recommendations for patients with CC valves that have intermediate strut fracture risks (less than 29 mm, 70 degrees valves and greater than or equal to 29 mm, 60 degrees mitral valves). For all patients and their doctors facing the difficult decision on whether to replace CC valves, individual estimates of operative mortality risk that take account of both patient-specific and institution-specific factors are essential.

Transesophageal echocardiography. Preliminary results in patients with traumatic aortic rupture.

Eleven patients with blunt chest trauma at risk for traumatic aortic rupture underwent transesophageal echocardiography to image the descending aorta. Diagnoses were compared with the results of radiographic studies. Ten of the 11 patients underwent arch aortography, with positive results in six cases. In one patient, the results of a computed tomographic scan were interpreted as consistent with aortic rupture. The results of transesophageal echocardiography were positive for ruptured descending aorta in three of six patients with positive aortographic findings, and negative in eight patients. All three patients with positive findings had the diagnosis of ruptured descending aorta confirmed at surgery. The remaining eight patients demonstrated no aortic morbidity. These preliminary findings suggest that transesophageal echocardiography is a useful technique for the diagnosis of ruptured descending aorta following blunt chest trauma.