Reduced incidence of atrial fibrillation with minimally invasive direct coronary artery bypass.

BACKGROUND: Atrial fibrillation (AF) is a frequent complication after coronary artery bypass graft (CABG) surgery. The purpose of this study was to determine the incidence of postoperative AF after minimally invasive direct coronary artery bypass (MIDCAB) in comparison with CABG. METHODS: Between November 1995 and May 1997, 96 MIDCAB procedures were performed. During the same period, 42 patients underwent traditional single CABG using the left internal mammary artery graft (S-CABG). The incidence of in-hospital AF, defined as a sustained episode requiring treatment, was compared between the two groups. RESULTS: There was no difference in age, ejection fraction, or preoperative risk score between the groups. The use of beta-blockers before or after surgery was not different. The incidence of postoperative AF in the first 6 weeks after surgery was 4% (4 of 96) for MIDCAB and 28% (12 of 42) for S-CABG (p = 0.003). Patients with postoperati

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.

"Keyhole" coronary artery bypass surgery.

OBJECTIVE: The objective of this study was to identify the utility of "keyhole" thoracotomy approaches to single vessel coronary artery bypass surgery. SUMMARY BACKGROUND DATA: Although minimally invasive surgery is efficacious in a wide variety of surgical disciplines, it has been slow to emerge in cardiac surgery. Among 49 selected patients, the authors have used a left anterior keyhole thoracotomy (6 cm in length) combined with complete dissection of the eternal mammary artery (IMA) pedicle under thoracoscopic guidance or directly through the keyhole incision to accomplish IMA coronary artery bypass grafting (CABG) to the left anterior descending (LAD) coronary artery circulation or to the right coronary artery (RCA). METHODS: Keyhole CABG was accomplished in 46 of 49 patients in which this approach was attempted. All patients had significant (> 70%) obstruction of a dominant coronary artery that had failed or that was inappropriate for endovascular catheter treatment (percutaneous transluminal coronary angioplasty or stenting). Forty-four of the 49 patients had proximal LAD and 5 had proximal RCA stenoses. The mean age of the patients (35 men and 14 women) was 61 years, and their median New York Heart Association anginal class was III. The mean left ventricular ejection fraction was 42%. Femoral cardiopulmonary bypass support was used in 9 (19%) of 46 patients successfully managed with the keyhole procedure. Short-acting beta-blockade was used in the majority of patients (38 of 46) to reduce heart rate and the vigor of cardiac contraction. RESULTS: As 49 patients have survived operation, which averaged 248 minutes in duration. Median, postoperative endotracheal intubation time for keyhole patients was 6 hours with 25 of 46 patients being extubated before leaving the operating room. The median hospital stay was 4.3 days. Conversion to sternotomy was required in three patients to accomplish bypass because of inadequate internal mammary conduits or acute cardiovascular decompensation during an attempted off-bypass keyhole procedure Postoperative complications were limited to respiratory difficulty in three patients and the development of a deep wound infection in one patient. Nine (19%) of 46 patients received postoperative transfusion. There have been no intraoperative or postoperative infarctions, and angina has been controlled in all but one patient who subsequently had an IMA-RCA anastomotic stenosis managed successfully with percutaneous transluminal coronary angioplasty. CONCLUSIONS: These early results with keyhole CABG are encouraging. As experience broadens, keyhole CABG may become a reasonable alternative to repeated endovascular interventions or sternotomy approaches to recalcitrant single-vessel coronary arterial disease involving the proximal LAD or RCA.

Cell saver efficacy for routine coronary artery bypass surgery.

A retrospective study was conducted to determine the effect of intraoperative Haemonetics Cell Saver (HCS) usage on postoperative homologous blood product requirements in CABG patients. From 1 January to 31 December 1993, 516 patients without renal disease or postoperative surgical or gastrointestinal haemorrhage had elective, first-time CABG surgery. The HCS was utilized in 435 of these patients (Group CS) and in 81 patients the HCS was excluded (Group NCS). Preoperative patient variables were similar in the group. We evaluated the HCS effect on blood product transfusion by comparing -x units of red blood cells (RBC), fresh frozen plasma (FFP) and platelets (PLTS) transfused per patient between groups CS and NCS. There were no differences in the -x units of RBC (1.9 +/- 2.7 CS vs. 1.8 +/- 1.5 NCS) or in the RBC transfusion rate (48% CS vs 50% NCS). There were also no significant differences between the groups in -x units of FFP (0.9 +/- 0.8 CS vs 0.4 +/- 0.9 NCS) or PLTS (0.7 +/- 3.1 CS vs 0.4 +/- 2.5 NCS), or in the percentage of patients receiving these products (12% CS vs 8% NCS). These data provide no evidence that the use of the HCS decreases the amount of homologous blood bank products required postoperatively in patients having routine first-time CABG surgery. The current era of aggressive blood conservation may have limited the role of the HCS in routine CABG surgery.

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.

Extracorporeal membrane oxygenation: preliminary results in patients with postcardiotomy cardiogenic shock.

Long-term survival at our institution for postcardiotomy cardiogenic shock patients supported with the BioPump is 36% (29/80 patients). A heparin-coated extracorporeal membrane oxygenator (ECMO), first introduced in 1991, may reduce organ injury associated with cardiopulmonary bypass. The device can be employed rapidly because it connects directly to the cardiopulmonary bypass cannula. In an effort to improve our results in the treatment of postcardiotomy cardiogenic shock, we used ECMO in 21 patients with this syndrome and accompanying complications. The patients were divided into three groups: group 1, ECMO after coronary artery bypass grafting; group 2, ECMO after mitral valve operation; and group 3, ECMO after open heart operation with prolonged cardiac arrest. Survival in group 1 was 80% with 12 of 14 patients discharged to home. All three deaths were caused by cardiac failure. Bleeding complications in this group were moderate. There was no evidence of disseminated intravascular coagulation, and levels of fibrin split products remained within the normal range. Postoperative complications included stroke (2), renal failure (1), mediastinitis (1), and prolonged respiratory failure (6). Mortality in group 2 was 100%. The major problem limiting recovery was left ventricular distention secondary to inadequate left ventricular decompression. Mortality in group 3 was 100%; all 4 died of brain death. Extracorporeal membrane oxygenation without left ventricular drainage clearly is not effective in patients undergoing mitral valve operations as it does not effectively decompress the left ventricle, but it was highly effective in treating postcardiotomy cardiogenic shock in our coronary artery bypass grafting patients. Extracorporeal membrane oxygenation also proved to be safe as the patient-related complications of stroke, renal failure, and mediastinitis were low. Our preliminary success with heparin-coated ECMO now needs to be confirmed by studies from other centers with larger groups of patients.

Extracorporeal membrane oxygenation for adult post cardiotomy cardiogenic shock using a heparin bonded system.

Extracorporeal membrane oxygenation (ECMO) for adult post cardiotomy cardiogenic shock has had limited success. The efficacy of a heparin bonded ECMO system was tested in 11 patients (eight men, three women; mean age: 63 +/- 8 years), all of whom were in post cardiotomy shock refractory to inotropes and intra-aortic balloon pumping (IABP). The system consisted of a right atrial-to-aortic loop using a hollow fiber oxygenator driven by a vortex pump. All blood contact surfaces were heparin bonded. Mean duration of support was 47.9 hr (range: 22-92.5 hr). Mean prothrombin time, activated partial thromboplastin time, and activated clotting time during full support were 17 +/- 8, 57.5 +/- 38, and 152 +/- 59 sec, respectively. Mean transfusion requirements for packed red blood cells, fresh frozen plasma, and platelets were 24 +/- 9, 19 +/- 9, and 38 +/- 15 units, respectively. Complications included acute renal failure (1 patient), sepsis (3 patients), elevation of hepatic enzymes (7 patients), and myocardial infarction (11 patients). Oxygenator failure occurred in 4 patients, and 10 patients had plasma hemoglobin levels exceeding 30 mg/L. No patient experienced focal neurologic deficit. Eight (73%) patients were weaned from ECMO. Five (45.4%) of these are alive and have been discharged home with a mean follow-up of 317 +/- 76 days (range: 179-416 days). This heparin-free ECMO system allows rapid and simple deployment and provides effective short-term cardiopulmonary support.

Twenty-five-year review of the Magovern-Cromie sutureless aortic valve.

We reviewed 25 years (4,798 patient-years) of aortic valve replacement with the Magovern-Cromie sutureless valve. Operative mortality was 11% for isolated aortic valve replacement and 15% for aortic valve replacement with concomitant cardiac procedures. Since 1981, operative mortality has declined to 4.9%. Valve-related morbidity was in the lower expected ranges for prosthetic aortic valves: ball variance, 0.3%/patient-year; paraprosthetic leak, 0.41%/patient-year; valve endocarditis, 0.43%/patient-year; valve thrombosis, 0.04%/patient-year; and embolic events, 3.95%/patient-year. The incidence of aortic valve reoperation was 0.76%/patient-year. The 5-year, 10-year, and 20-year probability of survival corrected for normal mortality was 77%, 64%, and 52% for all discharged patients. This review confirms the Magovern-Cromie valve to be a safe, durable, and efficient prosthetic valve.

Surgical therapy for left ventricular aneurysms. A ten-year experience.

We reviewed retrospectively the surgical results of left ventricular aneurysm reduction in 197 consecutive patients operated on in 1977-1987. There were 19 hospital deaths (9.6%) and 38 late deaths. The cumulative 5- and 10-year survival probabilities were 79% and 67%. Of the 140 late survivors, 130 underwent follow-up study in 1988 (mean, 5 years postsurgery). We analyzed preoperative, perioperative, and postoperative variables to evaluate the efficacy of surgical therapy. The risk of early mortality was increased by worsening preoperative New York Heart Association class, operation within 30 days of myocardial infarction, combinations of ventricular arrhythmia and congestive heart failure, renal failure, and preoperative cardiogenic shock. There was a trend toward increased early mortality with multivessel coronary artery disease. Late mortality and length of survival were not predicted by any variable examined.

The control of myocardial Ca++ sequestration with nifedipine cardioplegia.

Myocardial 45Ca sequestration was studied in dogs after an injection of 45CaCl2 during 60 minutes of global ischemia and 30 minutes of reperfusion using cardiopulmonary bypass (CPB) at 32 degrees C. Group I (n = 10) received a standard hyperkalemic cardioplegic solution and Group II (n = 10) received the same cardioplegia solution plus nifedipine (100 micrograms/300 cc). After aortic cross-clamping, 300 cc of cardioplegic solution was delivered at 0 and 30 minutes at 4 degrees C. Tissue specific activity (SA = cpm x 10(4)/gm) and plasma specific activity (SA = cpm x 10(4)/ml) were determined before release of the cross-clamp and serially by biopsy during reperfusion. The ratio of tissue SA to plasma SA, termed relative specific activity (RSA), indicates myocardial 45Ca sequestration. Nifedipine led to a marked decrease in sequestration. Group II RSAs were 31.5%, 82.1%, and 39.6% less than Group I RSAs at 0, 20, and 30 minutes of reperfusion. All differences were highly significant (p less than 0.01). During the first 20 minutes of reperfusion, the Group I RSA increased 498% while the Group II RSA increased only 23.8%. A correlation is shown between the decreased calcium sequestration and improved myocardial performance after CPB, demonstrated in previous experiments using nifedipine. Nifedipine in combination with a hypothermic hyperkalemic cardioplegic solution effectively controls myocardial calcium sequestration during 60 minutes of ischemia arrest and the immediate 30 minutes of reperfusion.