Using tracking data to find complications that physicians miss: the case of renal failure in cardiac surgery.

BACKGROUND: Health Data Research, Inc (HDR) develops, manages, and maintains clinical registries from physicians and hospitals, including the Merged Cardiac Registry. Quarterly reports indicate data that are inconsistent, out of range, or outside the norms found in other medical centers. CASE STUDY: In reports on cardiac surgery patients, HDR noted that for the 1992-1996 period, 3 of the 30 contributing centers experienced a significant increase in the incidence of moderate and severe renal failure. One of these three contributors gave HDR access to its detailed clinical database, and HDR ruled out most of the suspected causes for this increase in renal failure. A risk model for renal failure identified 20% of the patients to be at high risk. HDR then isolated a fast-track protocol as the culprit. One of the 30 contributing centers found that the protocol was associated with significant decreases in the intensive care unit (ICU) and hospital lengths of stay. However, as the severity of renal failure increased, charges, average length of stay, transfusions, and ICU times increased. At one of the three sites, after protocol changes were instituted in mid-1995 for the high-risk patients, the rate of renal failure reverted to below baseline levels. SUMMARY AND CONCLUSIONS: Analysis of run charts led to protocol changes for patients at high risk of renal failure, while retaining the positive outcomes associated with rapid extubation and shorter ICU stays for the remaining 80% of the patients.

Serial follow-up of an experimental bovine pericardial aortic bioprosthesis. Usefulness of pulsed Doppler echocardiography.

Echocardiography was used in the serial evaluation of 50 patients at 1, 3, and 7 years after aortic valve replacement with a new bovine pericardial aortic bioprosthesis. For valve sizes of 19-27 mm, at 7 years of follow-up mean transvalvular gradients (xGrad) ranged from 15.2 to 8.0 mm Hg, and calculated mean valve areas (AVA) ranged from 1.06 to 1.79 cm2. Acceptable xGrad and AVA were directly related to valve size and did not change in 48 asymptomatic patients. One patient at 7 years had marked calcific stenosis and degeneration requiring explanation. Echocardiography is useful in the long-term evaluation of bioprosthetic function, yielding information equivalent to cardiac catheterization data. This bovine pericardial valve offers good clinical and hemodynamic results at 7 years and is a suitable alternative when a bioprosthesis is indicated.

Early experience with mitral valve reconstruction for mitral insufficiency.

Mitral valve repair for mitral regurgitation has been reported to have more favorable early and late results than mitral valve replacement. From July 1985 through July 1990, 63 patients have undergone valve repair at Good Samaritan Hospital. Twenty-two men and 41 women whose ages ranged from 34 to 81 years (mean 67.9 years) were treated. Twenty-eight patients were in New York Heart Association functional class III or IV. Twelve (19%) had undergone prior cardiac surgery. Isolated valve repair was performed in 18 patients. Valve repair was combined with coronary artery bypass grafting, other valve procedures, or aneurysm resection in the remainder (71%). Two patients (3%) died while in the hospital, and four deaths (one valve-related) occurred after discharge. Leaflet resection for ruptured chordae was done in 24 patients (38%), chordal shortening in 5 patients (8%), and leaflet transposition in 2 patients. Rigid ring annuloplasty (Carpentier) was performed in 62 patients. Eight patients required mitral valve replacement at the same operation because of unsatisfactory valve repair. Results of valve repair evaluated by echocardiography at discharge show that 48 patients (88%) are free of significant regurgitation. Follow-up to date reveals that all surviving patients who underwent valve repair have clinically improved and are stable. Four of five patients with moderate mitral regurgitation are currently asymptomatic. There have been two valve-related late failures requiring reoperation. Based on this early experience, we conclude that valve repair compared with mitral valve replacement has a low operative mortality with good early results. Continued efforts to preserve native mitral valve function in the presence of mitral regurgitation appear justified.

Coronary artery bypass grafting in elderly patients. Comparative results in a consecutive series of 469 patients older than 75 years.

A consecutive series of 7104 patients undergoing isolated coronary artery bypass grafting during an 18-year period (1971 to 1988) included 469 patients older than 75 years. Results were analyzed to determine comparative risk factors for morbidity, early and late survival, and functional outcome. Patients younger than 75 years (group I) and patients older than 75 years (group II) were identical for ejection fraction and standard hemodynamic indices. Mean number of grafts and crossclamp time were greater for group II patients (p less than 0.01). Mean age of group I was 58.6 years and group II, 77.6 years (p less than 0.01). Women composed 19.7% (1308/6635) of group I and 36.2% (170/469) of group II patients (p less than 0.05). Mammary grafts were placed in 57.7% (3830/6635) of group I and 41.6% (195/469) of group II patients (p less than 0.05). Overall perioperative mortality rate was 2.1% for group I and 6.8% for group II (p less than 0.05). Perioperative myocardial infarction rate was similar for the two groups. Ventricular and supraventricular arrhythmias, renal insufficiency, neurologic complications, prolonged ventilatory support, increased hospital cost, and prolonged hospitalization were significantly more prevalent (all p less than 0.05) in patients older than 75 years. Five and 10 years postoperatively, there were no significant differences between groups I and II with regard to event-free status including angina, myocardial infarction, and reoperation. The 5-year survival rate was 92% for group I and 80% for group II (p less than 0.05), similar to that of age-matched control subjects. The significantly increased potential for complications and expense of coronary bypass in patients over 75 years of age mandates judicious patient selection and preoperative counseling. Despite a significantly increased early mortality and an anticipated decreased long-term survival paralleling normal life table survival curves, good intermediate functional improvement can be realized in patients older than 75 years, comparable with that expected in a much younger age group.

Reoperative coronary surgery. Comparative analysis of 6591 patients undergoing primary bypass and 508 patients undergoing reoperative coronary artery bypass.

During an 18-year period a consecutive series of 6591 patients underwent primary coronary bypass grafting and 508 patients underwent reoperative bypass. The mean patient age for the reoperative group was identical to that of the primary group, 59.8 years, but the mean age at initial operation for the reoperative group was 55.2 years. Mammary grafts were done at initial operation in 59% of patients who have had one operation versus only 46% of patients who subsequently required reoperation (p less than 0.001). The overall operative mortality rate was 2.0% (134/6591) for primary coronary bypass versus 6.9% (35/508) for reoperations (p less than 0.001). Patients with a reoperative interval of 1 to 10 years had a 6.0% (18/312) mortality rate, compared with 17.6% (13/74) for those in whom the interval between operations was greater than 10 years (p less than 0.01). Ventricular arrhythmias, excessive bleeding, prolonged ventilatory support, intraaortic balloon pump insertion (all p less than 0.05), and perioperative myocardial infarction (p less than 0.001) were all more prevalent after reoperations. Including perioperative mortality, the actuarial survival rate at 5 years was 80% for reoperations versus 90% for primary operations. The corresponding figures at 10 years were 65% and 75%. The probability of undergoing reoperation within 5 and 10 years was 0.034 +/- 0.003 and 0.055 +/- 0.005, respectively. Ten years postoperatively, 36% of patients having the initial operation had recurrent angina whereas 58% of the reoperative group had significant recurrent angina. Ten years after reoperation, 30% of operative survivors were free of heart-related morbidity and mortality compared with 50% of patients having a primary operation. Univariate analysis of factors increasing the probability of reoperation include the absence of a mammary graft and younger age at operation. Patients undergoing a second bypass operation represent a substantially higher risk subgroup than patients undergoing initial operation in terms of perioperative morbidity, mortality, decreased long-term survival, and decreased relief of recurrent cardiac morbidity.

Percutaneous transluminal coronary angioplasty. A growing surgical problem.

The incidence of prior percutaneous transluminal coronary angioplasty in surgical cases is nearly doubling yearly. In 1985, 11.4% of our bypass patients had one or more prior angioplasties. One hundred thirty-five patients with prior angioplasty are compared to 2,205 patients without angioplasty undergoing surgical revascularization. The mortality is 3.2 times higher in the angioplasty patients than in the control patients and the perioperative infarction rate is 2.5 times higher. Forty-four patients were taken directly to the operating room from the catheterization laboratory, 50 were operated on within 10 days, and 41 underwent operation more than 10 days after angioplasty. All of these late failures were of the lesion previously dilated. The infarction rate was less in patients taken immediately to the operating room on an emergency basis than in those whose operation was delayed up to 10 days (30% versus 70%). All patients who died had angioplasty of the anterior descending coronary artery. Angioplasty of this artery increases operative mortality should surgical treatment become necessary acutely. Patients should be informed before angioplasty of the increased surgical risks after a failed angioplasty procedure.

The impact of electroencephalography, pressure, and pO2 monitoring on the risk of stroke during cardiopulmonary bypass.

Currently it is possible to account for an incidence of perfusion-related perioperative stroke of about 1%. The sources of stroke over which cardiac surgeons have some control relate to the perfusion circuit, the conducting of coronary pulmonary bypass, the operative approach to the patient with intracardiac clot, maneuvers that eliminate air during left heart procedures, control of biochemical factors such as hyperglycemia, and to the choice of anesthetic agents and drugs given during the procedure. The availability of equipment that allows in-line continuous monitoring of arterial and venous O2 saturations, control of physiologic parameters within certain limits, selective use of encephalographic monitoring for high-risk patients, along with careful attention to the details of the procedure, may allow the surgeon to alter favorably the numbers of patients suffering neurologic complications as a consequence of cardiac surgery. We have limited our investigation in this study to those neurologic events occurring from the onset of anesthesia through the recovery from anesthesia when the patient can be neurologically examined.

Early experience with the intraluminal graft prosthesis.

Surgical therapy for dissection of the thoracic aorta has been associated with a high mortality rate due in part to intraoperative bleeding at the suture lines and through the prosthesis. A technique has been devised to obviate some of these problems which utilizes a sutureless prosthesis that can be placed within the aorta. This device is now commercially available. Because of the infrequent use and the need to maintain a wide variety of lengths and diameters of these grafts, several Portland area hospitals jointly purchased grafts to reduce inventory and cost. From November 1981 through September 1982, four patients in two Portland area hospitals were treated with intraluminal grafts for descending thoracic dissections. All patients survived the surgical treatment and were discharged without complications. Based on a review of the literature and our initial experience, the intraluminal prosthesis appears to represent a significant improvement over conventional graft placement for treatment of both acute and chronic aortic dissection.

Diabetes mellitus and coronary artery bypass. Short-term risk and long-term prognosis.

A consecutive series of 3,707 patients over a 12 year period undergoing isolated coronary artery bypass grafting (CABG) included 250 diet/oral medication-controlled and 162 insulin-dependent patients with diabetes mellitus. Analysis of 20 pre- and 18 intra-operative variables revealed a higher incidence of hypertension, left ventricular hypertrophy, and tobacco consumption for both diabetic groups. The extent of diffuse coronary disease as judged angiographically and at operation was significantly greater in both diabetic groups than in nondiabetic CABG patients. No difference was noted in the incidence of localized coronary disease between the groups. Average number of grafts was greater in both diabetic groups. The perioperative mortality was greater for both diabetic groups (5.1% for non-insulin-dependent diabetes, 4.5% for insulin-dependent diabetes) than for nondiabetic CABG patients (2.5%). The incidences of sternotomy complications and renal insufficiency were equal in the diabetic groups and both were significantly greater than in the nondiabetic group. The number of total hospital days was also greater in both diabetic groups. Actuarially determined survival and cardiac event-free curves revealed no difference between the diabetic groups but a significant difference between both diabetic groups as compared to the nondiabetic patient population, with follow-up extending to 10 years after CABG. Results indicate that diabetic patients have quantitatively and qualitatively more coronary artery disease than nondiabetic patients and have higher perioperative morbidity and mortality and a lower long-term survival rate than nondiabetic patients. However, results continue to justify selection of patients for CABG based on clinical and anatomic criteria regardless of diabetic status. Diabetes mellitus should be considered a patient-related risk factor, both short- and long-term, following CABG.

Reoperation in symptomatic patients after direct coronary artery revascularization.

Seventy-nine patients underwent 85 reoperations to revascularize the myocardium at intervals from 2 days to 5 years (mean 13 months) after primary direct revascularization procedures. A total of 122 bypass grafts including 43 individual veins, 43 double or triple sequential veins, and 17 internal mammary arteries (IMA) were utilized. Failure of previous bypass grafting was the most common reason for recurrent symptoms, partially due to the high failure rate of radial artery segments used as bypass conduits. One operative and three late deaths have occurred. Coronary arteriography, performed after reoperation (mean 14 months) in 15 patients, revealed a graft patency rate of 68 percent. Significant differences in postoperative complications between the first and subsequent operation could not be demonstrated. Combined nonfatal perioperative infarctions with the first and subsequent operations decreased ventricular function and probably contributed to the improved symptomatic state of some patients. It is concluded that good symptomatic relief and long-term survival can be achieved by reoperation in selected patients who have recurrent symptoms after primary direct myocardial revascularization.

Long-term follow-up of sequential aortocoronary venous grafts.

In 1972 we reported myocardial revascularization of 130 patients using multiple sequential aortocoronary anastomoses to a single saphenous vein ]1]. Of the 122 survivors described in that report, 121 (99%) have been followed an additional 3 years. Twelve deaths occurred during the interval. The 110 currently followed patients represent 290 anastomoses; 54 have been studied angiographically since operation. Angiographic patency at 3 years in the studied group (18) was 70%. These figures exceed our follow-up data for 135 patients revascularized during the same period using individual vein grafts. Comparison of life table survival curves demonstrates this result. We believe the improved patency and decreased operating time that have resulted from employing this technique have outweighed the likelihood of a proximal stenosis causing closure of the whole graft system. We continue to use this technique in combination with internal mammary artery grafts in the management of multiple-vessel coronary disease. Good early results using this technique have been reported by other authors [2, 3, 5].