Hemodynamic effects of chest closure in adult patients undergoing cardiac surgery.

OBJECTIVE: To evaluate hemodynamic effects of sternal retractor removal and sternal closure after cardiopulmonary bypass and to correlate these changes with preoperative and intraoperative variables. DESIGN: Prospective. SETTING: University hospital. PARTICIPANTS: Fifty adults undergoing cardiac surgery. MEASUREMENTS AND MAIN RESULTS: Arterial, pulmonary artery, and transesophageal echocardiography measurements were obtained immediately before and 1 minute after removal of the sternal retractor and immediately before and 1 minute after sternal closure. Retractor removal caused a significant decrease in cardiac index by 5.6% (p < 0.01), stroke volume index by 4.0% (p < 0.05), and mean pulmonary artery pressure by 4.8% (p < 0.001). Sternal closure caused a significant decrease in cardiac index by 7.7%, stroke volume index by 10.2%, and left ventricular end-diastolic area by 9.2% (p < 0.001) There were significant increases in pulmonary capillary wedge pressure and systemic vascular resistance by 9.1% and 10.8% (p < 0.01). There was no significant change in the ejection fraction area. The magnitude of decrease in stroke volume index with sternal closure correlated positively with end-diastolic area immediately before the closure. CONCLUSION: Chest closure is associated with significant hemodynamic changes and a change in the ventricular transmural pressure-volume relationship. Patients with lower preload immediately before closure are more vulnerable to a decrease in cardiac index. Based on the results of this study, volume appears to be the appropriate preventive and treatment option to limit the impact of chest closure.

Association of ABO-mismatched platelet transfusions with morbidity and mortality in cardiac surgery.

BACKGROUND: The transfusion of ABO-mismatched platelets has been associated with increased morbidity and mortality during induction therapy for acute leukemia and allogeneic progenitor cell transplantation. STUDY DESIGN AND METHODS: Reported here is a cohort study of 153 patients undergoing primary coronary artery bypass graft or coronary valve replacement surgery by two surgeons in one institution during 1997 and 1998. All statistics employed nonparametric two-sided tests (Mann-Whitney; Fisher's exact test). RESULTS: Patients receiving at least one ABO-mismatched pool of platelets had a significantly longer hospital stay, more days of fever, greater total hospital charges, and more RBC transfusions. Mortality, hours in the intensive care unit, days on antibiotics, and numbers of platelet transfusions were also greater in recipients of ABO-mismatched platelets, but these differences were of less statistical significance. When the analysis was restricted to the 139 patients who received no more than two pools of platelets, the trends for increased morbidity and mortality (8.6% vs. 1.9%; p = 0.10) in recipients of ABO-mismatched platelets persisted. The number of RBC transfusions required in this latter cohort was 50 percent greater (mean, 6.1 vs. 9.2; p = 0.02), despite the fact that the number of platelet transfusions given was similar (mean, 1.2 vs. 1.3 pools; p = 0.22). CONCLUSIONS: ABO-mismatched platelet transfusions are associated with unfavorable outcomes in cardiac surgery, a relationship that remains unexplained. As this association has been found in three cohort studies in various clinical settings, further investigation of this association is warranted.

Lack of lung hemorrhage in humans after intraoperative transesophageal echocardiography with ultrasound exposure conditions similar to those causing lung hemorrhage in laboratory animals.

This study investigated the phenomenon of ultrasonically induced lung hemorrhage in humans. Multiple experimental laboratories have shown that diagnostic ultrasound exposure can cause hemorrhage in the lungs of laboratory animals. The left lung of 50 patients (6 women, 44 men, mean age 61 years) was observed directly by the surgeon after routine intraoperative transesophageal echocardiography was performed. From manufacturer specifications the maximum derated intensity in the sound field of the system used was 186 W/cm2, the maximum derated rarefactional acoustic pressure was 2.4 MPa, and the maximum mechanical index was 1.3. The lowest frequency used was 3.5 MHz. This exposure exceeds the threshold found for surface lung hemorrhage seen on gross observation of laboratory animals. No hemorrhage was noted on any lung surface by the surgeon on gross observation. We conclude that clinical transesophageal echocardiography, even at field levels a little greater than the reported thresholds for lung hemorrhage in laboratory animals, did not cause surface lung hemorrhage apparent on gross observation. These negative results support the conclusion that the human lung is not markedly more sensitive to ultrasound exposure than that of other mammals.

Photo-irradiation improved functional preservation of the isolated rat heart.

BACKGROUND AND OBJECTIVE: Photo-irradiation causes a variety of effects in different cells and tissues. We hypothesized that photo-irradiation may improve cardiac preservation based on these observations. STUDY DESIGN/MATERIALS AND METHODS: For pre-storage treatment (Pre), the heart in an anesthetized open-chest rat was irradiated using an Argon-dye laser with a wavelength of 660 nm at a fluence of 16.8 J/cm2 or sham-operated. The heart was excised, perfused with Krebs-Henseleit Buffer, cardioplegically arrested, and stored by immersion at 0 degree C for 18 hrs. Functional recovery was evaluated by working reperfusion for 30 min. For post-storage treatment (Post), the isolated hearts were stored for 18 hrs at 0 degree C; laser irradiation at a fluence of 36 J/cm2 was administered during working reperfusion. Hearts which did not receive irradiation during reperfusion served as control. Furthermore, isolated cardiomyocytes were used to study laser effect on cellular ATP content, catalase activity, and nitric oxide (NO) release. RESULTS: Both Pre and Post groups showed significant improvement in recovery of aortic flow, cardiac output, and work compared to the corresponding control groups (P < 0.05). Combined Pre/Post laser treatment did not improve function. Investigation using isolated rat cardiomyocytes found that both end-storage ATP and end-reperfusion catalase activity in the laser-treated group were significantly higher than those in the untreated cells (P < 0.05). NO release increased by 15% in the laser group after 18 hrs of 37 degrees C incubation. CONCLUSION: Photo-irradiation improves functional recovery of the cold-stored rat heart possibly via conservation of ATP and antioxidant enzyme activity.

Obliteration of empyema tract with deepithelialized unipedicle transverse rectus abdominis myocutaneous flap.

Four patients with chronic empyema after pneumonectomy have undergone successful obliteration of the empyema tract with a deepithelialized transverse rectus abdominis myocutaneous flap. The deepithelialized skin island has provided sufficient bulk for tract obliteration. Rotation of the skin island into the long axis of the rectus muscle has added considerable length to this flap, allowing it to reach the apex of the thoracic cavity. A recurrent loculation developed 4 months after the obliteration procedure in one patient. This was successfully treated with open pleural drainage and a second Clagett procedure. Over a mean follow-up period of 35 months, all four patients are free of further infectious sequelae. Chest roentgenograms have confirmed eradication of the tracts in all four patients.

Enalaprilat, an angiotensin-converting enzyme inhibitor, enhances functional preservation during long-term cardiac preservation. Possible involvement of bradykinin and PKC.

We investigated the effect of enalaprilat (ET) on long-term preservation of cardiac explant. Isolated rat hearts (n = 7/group) were pretreated with 0 to 40 nM ET and stored at 0 degree C for 16 h. Functional viability was assessed after 30-min working reperfusion without ET. Prestorage control function (mean +/- S.E.M.) (n = 7) included heart rate (HR), 291 +/- 12 bpm; aortic flow (AF). 49.8 +/- 1.9 ml/min; coronary flow (CF), 25.2 +/- 1.3 ml/min; cardiac output (CO), 75.0 +/- 1.2 ml/min; and work, 89.4 +/- 4.7 g-m/min. Post-storage function of untreated hearts was: AF, 61%; CF, 43%; CO, 55%; work, 48% of control. ET (20 nM) enhanced AF recovery to 85%; CF, 58%; CO, 76%; work, 73% of control (P < 0.05 v untreated). Hoe 140 (D-Arg-[Hyp2, Thi5,8, D-Phe7]BK) (1 nM) a bradykinin receptor antagonist, inhibited ET effect; function returned to the untreated level. Protein kinase C (PKC) inhibitors staurosporine (15 nM) and bisindolylmaleimide I (0.5 microM) also blocked ET effect. After 4 h of cold storage, membrane PKC activity changed little from the prestorage level in the untreated hearts, but was elevated significantly from 52.8 +/- 5.2 pmol/min/mg to 74.7 +/- 8.2 by 20 nM ET (P < 0.05 v untreated). Cytosol PKC did not change during 4 h cold storage with or without ET. Neither end-storage nor end-reperfusion myocardial ATP content was affected by 20 nM ET treatment. In conclusion, ET improves cardiac preservation possibly via bradykinin receptor and PKC without affecting ATP metabolism.

Twenty-four-hour intermittent perfusion storage of the isolated rat heart. II. Perfusion pressure and functional preservation.

This study investigated the effect of intermittent perfusion (IP) pressures on functional preservation of the cold-stored isolated rat heart. The heart was flushed with cardioplegic solution #11 with ethylene diamine-tetraacetic acid and 2, 3-butanedione monoxime (CP-11EB), and stored at 0 degree C for 24 hr. During storage, the heart was intermittently perfused for 3 min at 10 and 17 hr of storage with 25 degrees C oxygenated CP-11EB. The IP pressures studied were: 20, 30, 40, 50, 60, 70, 80, and 100 mm Hg. Poststorage recovery of function was assessed with 30 min of working reperfusion. Control function of the unstored heart was: aortic flow (AF), 51.3 +/- 2.2 ml/min; coronary flow (CF), 25.8 +/- 1.2 ml/min; cardiac output (CO), 77.7 +/- 2.3 ml/min; work, 92.0 +/- 4.9 g-m/min; and coronary vascular resistance (CVR), 2.64 +/- .21 mm Hg-min/ml. Functional return in the 30,40,50,60,70, and 80 mm Hg groups was similar. Recovery in a representative group (60 mm Hg) was: AF, 52 +/- 3%; CF, 41 +/- 2%; CO, 48 +/- 3%; work, 42 +/- 3%; and CVR, 225 +/- 10% of the control. The total IP volume in this group was 71.0 +/- 1.7 ml; total lactate dehydrogenase (LDH) release during IP was 8.62 +/- .37 units/g dry; and end-storage tissue lactate was 52.6 +/- 6.4 mumole/g dry. As IP pressure decreased to 20 mm Hg, cardiac functional recovery declined significantly to AF, 35 +/- 6%; CF, 33 +/- 2%; CO, 34 +/- 5%; and work, 27 = 4% of control (P < .05 vs. 60 mm Hg group). The total IP volume decreased to 10.1 +/- .9 ml, tissue lactate content rose to 87.1 +/- 10.9 (P < .05 vs. 60 mm Hg group), but LDH release fell to 5.59 +/- .46 (P < .05 vs. 60 and 100 mm Hg groups). When IP pressure increased to 100 mm Hg, cardiac function was depressed with AF recovered to 25 +/- 3%; CF, 30 +/- 3%; CO, 26 +/- 3%; work, 21 +/- 3%; and CVR, 294 +/- 26% of control (P < .05 vs. 60 mm Hg group). IP volume increased to 100.7 +/- 2.4 ml; total LDH release increased to 19.1 +/- 1.2 (P < .05 vs. 60 mm Hg group), although tissue lactate (58.9 +/- 3.9) was not different from the 60 mm Hg group. End-storage tissue wet/dry weight ratio and myocardial adenosine triphosphate content were not different among the 20, 60, and 100 mm Hg groups. In conclusion, IP has a broad pressure optimum ranging from 30 to 80 mm Hg for 24-hr hypothermic preservation of the rat cardiac explant.

Twenty-four hour intermittent perfusion storage of the isolated rat heart: the effect of perfusion intervals on functional preservation.

We investigated the effect of intermittent perfusion intervals on heart preservation. The isolated rat heart was flushed with a cardioplegic solution, CP-11EB, and stored at 0 degrees C for 24 hours. During storage, the heart was perfused periodically at 60 mm Hg for 3 minutes with 25 degrees C oxygenated CP-11EB. The perfusion schedules were as follows: group I, every 4 hours; group II, every 6 hours; group III, every 8 hours; group IV, every 10 hours; group V, 10 and 17 hours of storage; group VI, every 11 hours. Poststorage function was assessed after 30 minutes of working reperfusion. Function of the unstored hearts including aortic flow (51.5 +/- 2.5 ml/min), coronary flow (24.5 +/- 1.3 ml/min), cardiac output (75.6 +/- 3.0 ml/min) and work (85.0 +/- 5.4 g-ml/min) served as controls. Group V hearts were best preserved with aortic flow recovered to 65%; coronary flow 44%; cardiac output 58%; and work 53% of the control. Recovery in group IV was comparable with group V. Groups I, II, III, and VI recovered significantly less than group V. Myocardial adenosine triphosphate content (micromoles per gram dry) in group V was 23.8 +/- 1.7, 20.8 +/- 0.9, 13.5 +/- 2.4, and 15.0 +/- 4.0, at 0, 10, 17, and 24 hours of storage, respectively. Intermittent perfusion at 10 and 17 hours elevated adenosine triphosphate to 99% and 88% of prestorage level. Poststorage reperfusion did not improve improve adenosine triphosphate content (16.2 +/- 2.4) over the end-storage level.(ABSTRACT TRUNCATED AT 250 WORDS)

Enhanced functional preservation of cold-stored rat heart by a nucleoside transport inhibitor.

This study investigates the hypothesis that inhibition of nucleoside transport during hypothermic storage elevates tissue adenosine (ADO) content and improves the function of the isolated rat heart. The hearts, flushed with a cardioplegic solution containing varying concentrations (0-100 nM) of a nucleoside transport inhibitor, S-(4-nitrobenzyl)-6-thioinosine (NBTI), were immersion-stored at 0 degrees C for 9 hr. Function was assessed after 30 min of working reperfusion. Function of unstored fresh hearts served as controls and poststorage recovery is reported as percentage of control function. Poststorage heart rate in all groups returned to control level after reperfusion. Recovery of other functional parameters in the no-NBTI group was as follows: aortic flow (AF), 56.2 +/- 4.6%; coronary flow (CF), 53.9 +/- 3.2%; cardiac output (CO), 55.5 +/- 4.0%; systolic pressure, 81.6 +/- 2.5%; work, 47.0 +/- 4.2%; and coronary vascular resistance (CVR), 157.1 +/- 7.8% of control. NBTI improved functional recovery in a dose-dependent fashion; the maximal improvement was seen at a dose of 5 nM, in which the recovery was: AF, 78.1 +/- 3.4%; CF, 73.5 +/- 4.4%; CO, 76.7 +/- 3.6%; work, 70.7 +/- 5.0%; and CVR, 127.5 +/- 4.5% of control (P < 0.05 vs. no-NBTI). The ADO A1-receptor antagonist, 1,3-dipropyl-8-cyclopentylxanthine (0.1 microM) blocked the effects of 5 nM NBTI; the recovery of AF, CF, CO, work, and CVR decreased to 62.8 +/- 8.0%, 58.3 +/- 5.0%, 61.5 +/- 3.9%, 54.4 +/- 4.5%, and 163.8 +/- 12.7% of control, respectively (P < 0.05 vs. 5 nM NBTI). Tissue ADO content in 5 nM NBTI hearts at the end of storage was 0.075 +/- 0.025 mumol/g dry wt, which was significantly elevated from 0.016 +/- 0.004 mumol/g dry wt in no-NBTI hearts. Purine release during initial reperfusion was delayed in 5 nM NBTI hearts, indicating the inhibition of nucleoside transport by NBTI. But NBTI treatment did not improve end-storage or end-reperfusion myocardial ATP. In conclusion, the addition of NBTI to cardioplegic solution enhanced tissue ADO and improved poststorage function of the hypothermically stored rat heart. The effect is ADO A1-receptor mediated without invoking energy conservation.

Deferoxamine given at reperfusion improves function of the cold-stored rat heart.

In this study deferoxamine (DF), a strong iron chelator, was administered either before storage or during reperfusion, in an attempt to inhibit the iron-dependent hydroxyl radical production and improve the functional recovery of the cold-stored/reperfused cardiac explant. Excised rat hearts were flushed with Krebs-Henseleit buffer (KHB), arrested with a cardioplegic solution, CP11-EB, with or without DF, and immersion stored in CP11-EB at 0 degree C for 16 hr. To assess function, the stored hearts were reperfused in the working mode with KHB for 30 min. Experimental groups included: (i) DF treatment during prestorage flush [CP11-EB + 0.01 mM (n = 5), 0.05 mM (n = 13), 0.1 mM (n = 5), 0.2 mM (n = 5), or 0.75 mM DF (n = 5)]; (ii) DF treatment during reperfusion [KHB + 0.3 mM (n = 5), 0.6 mM (n = 7), 0.75 mM (n = 11), 1.0 mM (n = 6), 1.5 mM (n = 4), or 2.5 mM DF (n = 7)]; and (iii) untreated group (n = 8) received no DF during flush or reperfusion. Function of unstored hearts (n = 7) including aortic flow (AF, 54.6 +/ 2.6 ml/min); cardiac output (CO, 76.5 +/- 3.3 ml/min), systolic pressure (SP, 135.7 +/- 1 mm Hg), diastolic pressure (DP, 70.7 +/- 3.8 mm Hg), and work (96.7 +/- 6.4 g-meter/min) served as controls. Functional recovery of the untreated group was AF, 59%; CO, 58%; SP, 71%; DP, 73%; work, 41% of control values. DF treatment at any dose during the initial flush did not improve functional recovery.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine deaminase inhibitor in cardioplegia enhanced function preservation of the hypothermically stored rat heart.

Adenosine (ADO) has been shown to be protective to the ischemic-reperfused myocardium. This study tested the hypothesis that inhibition of myocardial adenosine deaminase during cold storage will elevate tissue ADO content, improve the cardiac function, and preserve ATP. The isolated rat hearts (6-9 hearts/group) were flushed with a cardioplegic solution containing 0-75 microM erythro-9-(2-hydroxy-3-nonyl)adenine (EHNA) and immersion-stored at 0 degree C for 9 hr. Function was assessed after 30 min working reperfusion. Function of the unstored hearts (n = 11, mean +/- SE) including heart rate (293 +/- 13 bpm), aortic flow (AF; 52.5 +/- 1.1 ml/min), coronary flow (CF; 23.5 +/- 1.3 ml/min), cardiac output (CO; 76.0 +/- 2.1 ml/min), systolic pressure (SP; 136 +/- 2 mmHg), diastolic pressure (DP; 63 +/- 1 mm Hg), work (90.5 +/- 3.4 g-m/min), and coronary vascular resistance (CVR; 2.77 +/- 0.14 mmHg-min/ml) served as controls. Heart rate in all stored hearts returned to normal after reperfusion. Recovery of other function in no-EHNA group was: AF, 52 +/- 7; CF, 55 +/- 5; CO, 53 +/- 6; SP, 79 +/- 4; DP, 93 +/- 3; work, 47 +/- 7; and CVR, 171 +/- 15% of control. EHNA improved functional recovery in a dose-dependent fashion. At the optimal concentration of 25 microM, the recovery was: AF, 83 +/- 6; CF, 68 +/- 4; CO, 78 +/- 5; SP, 90 +/- 3; DP, 105 +/- 5; work, 77 +/- 8; and CVR 151 +/- 9% of control. ADO A1 receptor antagonists, 8-phenyltheophylline (1 microM) and 1,3-dipropyl-8-cyclopentylxanthine (0.1 microM) blocked the effects of 25 microM EHNA; the recovery of CO was reduced to 65 +/- 3 and 50 +/- 2% of the control, respectively. Tissue ADO content in 25 microM EHNA hearts at the end of storage was 95 +/- 19 nmol/g dry wt, which was significantly elevated from 15 +/- 3 nmol/g dry wt in no-EHNA hearts. EHNA also caused a 45-fold increase in the release of ADO over no-EHNA group during the first 10 min of reperfusion. But EHNA treatment did not cause any change in either end-storage or end-reperfusion myocardial ATP levels. Thus EHNA in cardioplegic solution inhibited cardiac ADO catabolism during long-term hypothermic storage and improved function preservation partially via an ADO A1 receptor-mediated mechanism without invoking ATP conservation.

Transthoracic and transesophageal echocardiographic sizing of the aortic annulus to determine prosthesis size.

To assess the accuracy of 2-dimensional echocardiography versus transesophageal echocardiography (TEE) in predicting aortic annulus diameter, and to determine which part of the cardiac cycle should be used for measuring the size of the aortic valve prosthesis in patients undergoing aortic valve replacement, the aortic annulus was measured retrospectively in a blinded fashion in a group of 94 patients who had undergone aortic valve replacement: 66 had preoperative transthoracic echocardiography (TTE), 69 had intraoperative TEE, and 41 had both. Accuracy of measurements was calculated by the mean biases (differences between annular size by echo and actual valve size chosen by intraoperative mechanical sizing of the aortic annulus). TTE was compared with TEE and end-diastolic (ED) measurements with end-systolic (ES) measurements. The mean biases +/- SD were -1.7 +/- 3.4 mm by TTE-ES versus -0.9 +/- 3.5 mm by TEE-ES measurements (p = NS), and +0.03 +/- 3 mm by TTE-ED versus +0.5 +/- 2.8 mm by TEE-ED (p = NS). Examination of the magnitudes of the biases gave the same result. ED measurements were found to have a smaller amount of bias than ES measurements, both by TTE and by TEE: -1.7 +/- 3.4 mm by TTE-ES versus +0.03 +/- 3 mm by TTE-ED (p = 0.0001) and -0.9 +/- 3.5 mm by TEE-ES versus +0.5 +/- 2.8 mm by TEE-ED (p = 0.0001). Examination of the magnitudes of the biases also gave the same result.(ABSTRACT TRUNCATED AT 250 WORDS)

Subzero nonfreezing storage of the mammalian cardiac explant. I. Methanol, ethanol, ethylene glycol, and propylene glycol as colligative cryoprotectants.

We employed hyperosmotic concentrations of penetrating cryoprotective agents (CPA) to store the isolated rat hearts unfrozen at subzero temperatures. The effect of acute exposure to CPA was assessed by flushing the hearts with CP-14, a cardioplegic solution, containing methanol (MeOH), ethanol (EtOH), ethylene glycol (EG), or propylene glycol (PG) for 2 min and reperfusing immediately with Krebs-Henseleit buffer in a working-heart model. The maximal doses that did not cause irreversible suppression of heart function were: MeOH, 1.78 M; EtOH, 1.27 M; EG, 0.84 M; and PG, 0.87 M. For nonfreezing storage, the hearts were flushed with CP-14 containing the highest tolerable concentrations of MeOH, EtOH, EG, or PG, stored for 6 h at -3.7, -2.8, and -1.4 degrees C, respectively, and then reperfused. Control cardiac output (CO) was 76.2 +/- 1.8 ml/min. Post-reperfusional recovery of CO was 86% in MeOH hearts, 82% in EtOH hearts, 76% in EG hearts, and 79% in PG hearts. Thus MeOH offered not only the least cardiac-suppressing effect but the lowest nonfreezing storage temperature. When storage time was extended, recovery and myocardial ATP level decreased with time in hearts flushed with CP-14 + 1.78 M MeOH and stored at -3.7 degrees C. The decay of function was faster than the decay of ATP level, suggesting energy was better preserved than function. The low return of function, however, may be related to CPA toxicity, osmotic stress, and ischemia/reperfusion injury. Nonfreezing storage at subzero temperatures using these CPAs may provide a novel approach to long-term cardiac preservation.

Homologous blood transfusion as a risk factor for postoperative infection after coronary artery bypass graft operations.

Homologous transfusions are immunosuppressive and associated with a higher risk of postoperative infection. In this retrospective analysis, we studied 238 consecutive patients who underwent first-time coronary operations by a single surgeon in 1988 to 1989 and collected clinical and laboratory data relevant to postoperative infections including pulmonary, urinary, and wound sites. Culture-proved postoperative infections occurred in 16 of the 238 patients (6.7%), with only 3 (1.3%) being deep sternal wound infections. Seven of 16 (44%) of the infections were away from the wound sites, suggesting that nonsurgical variables contributed to at least some infections. Factors significantly associated with an increased risk of postoperative infection by univariate analysis included female sex, diabetes mellitus, and transfusion dose. Infections occurred in 3.9% of patients receiving up to 2 units of red cells and whole blood, 6.9% receiving 3 to 5 units, and 22% of those receiving 6 units or more. Multiple linear and logistic regression analysis showed that transfusion dose was the most significant predictor of infection, days of fever, days of antibiotic therapy, and length of hospital stay. Homologous transfusion is associated (in a dose-dependent fashion) with a threefold to eightfold increased risk of postoperative infection in patients undergoing coronary artery operations. This increased risk of infection may be due to transfusion-induced immunosuppression of the patient.

Coronary artery bypass graft surgery in older women and men.

OBJECTIVE: To compare women and men younger than 70 years of age and 70 years or older undergoing coronary artery bypass surgery. DESIGN: Retrospective chart review, case-control series. SETTING: University medical center. PATIENTS: All women (n = 465) having first-time isolated coronary artery bypass surgery between 1983 and 1988, and 465 men matched for age and year of surgery. Predominantly white; 33% were 70 years or older. MEASURES: Medical record data: demographics, preoperative comorbidities, perioperative and postoperative complications, mortality, length of stay. RESULTS: Preoperatively, women 70 years of age or older had a higher incidence of congestive heart failure, renal disease and hypertension, and a lower incidence of smoking history compared with women less than 70 years old. Men 70 years or older had a higher incidence of congestive heart failure and renal disease, and a lower incidence of smoking history compared with men less than 70 years old. There was no difference in mortality between older and younger women, whereas the mortality rate for older men was higher than that for younger men. There were fewer differences between women younger than 70 and those 70 years or older in incidence of postoperative complications than between men of those same age groups. Among patients 70 years or older, incidence of postoperative congestive heart failure was greater in women than in men. There were no other differences between women and men younger than 70 and those 70 years or older in incidence of postoperative complications. Controlling for the influence of postoperative complications, age was related to length of stay for women and men. CONCLUSIONS: Older women were at no greater risk of mortality or the occurrence of postoperative complications compared with younger women or older men. A functional component influencing recovery and length of hospital stay needs to be considered to provide optimal nursing care after surgery.

Freezing preservation of the mammalian cardiac explant. V. Cryoprotection by ethanol.

We studied the colligative cryoprotective effect of ethanol (EtOH) in preserving the isolated rat heart frozen at -3.4 degrees C or unfrozen at -1.4 degrees C. Addition of 4.7% (v/v) EtOH to a cardioplegic solution, CP-14, raised the osmolality from 280 to 1100 mOsm/kg H2O and lowered the melting point from -0.52 to -2.1 degrees C. Freezing of the cardiac explant at -3.4 degrees C for 6 h resulted in 34.3 +/- 1.9% of the tissue water as ice; recovery of cardiac output (CO) was 50%. Polyethylene glycol, which at 5% (w/v) has been shown to cryoprotect the hearts during freezing at -1.4 degrees C, did not improve the protective effect of 4.7% EtOH. CP-14 + 4.7% EtOH did not freeze at -1.4 degrees C. After 6 h storage, CO in hearts flushed with CP-14 + 4.7% EtOH oxygenated with 95% O2/5%CO2 returned to almost control level and was much higher than that in hearts flushed with 100% O2 saturated-CP-14 + 4.7% EtOH. Storage of 8 and 12 h reduced CO to 87 +/- 9 and 60 +/- 5% of control. By employing EtOH as a colligative cryoprotectant, we preserved the adult mammalian heart frozen at -3.4 degrees C or unfrozen at -1.4 degrees C, suggesting that this small molecular weight, penetrating substance may be a suitable cryoprotectant for long-term storage of the cardiac explant at high subzero temperatures.

Freezing preservation of the mammalian cardiac explant. VI. Effect of thawing rate on functional recovery.

This study investigated the effect of thawing rate on the preservation of frozen isolated rat hearts. The hearts were flushed with a hyperosmotic cardioplegic solution, CP-14/EtOH (1.15 Osm/kg), frozen at a rate of 0.18 degree C/hr for 6 h to -3.2 degrees C. Thereafter, the hearts were thawed at rates ranging from 0.08 to 1.1 degrees C/min for 1 to 14 min until the heart temperature reached -2.1 degrees C, the melting point (MP) of the flush solution; then they were held at -1 degree C for 11 to 24 min so that the total thaw time was 25 min. Post-thaw function was assessed by working reperfusion and expressed as percentage of unstored control function. Cardiac output (CO) and other hemodynamic performance showed biphasic responses to the thaw rate. At 0.08 degree C/min rate, CO recovered to 29.1 +/- 4.1 ml/min (40.8 +/- 5.8% of control). Thawing at 0.13 degree C/min enhanced the recovery of CO to 60.5 +/- 4.9%. Between 0.13 and 0.34 degree C/min, recovery was statistically insignificant. Faster thawing at 0.59 and 1.1 degrees C/min caused progressively less recovery. Overall, 0.13 degree C/min offered the highest recovery. In conclusion, function in slowly frozen heart is intimately affected by the thawing rate; there was an optimal intermediate thawing rate and both too slow and too fast thawing were detrimental.

Freezing preservation of the mammalian heart explant. III. Tissue dehydration and cryoprotection by polyethylene glycol.

Isolated rat hearts perfused with hyperosmotic Krebs-Henseleit buffer containing 60 mmol/L NaCl lose 10% of their tissue water. Perfusion of the rat hearts with Krebs-Henseleit buffer containing polyethylene glycol 8000 caused a concentration-dependent reduction in tissue water. In a study of the effect of different cryoprotectants on cardiac preservation, isolated rat hearts were flushed with a cardioplegic solution (CP-14), or CP-14 with either 50 mmol/L glycerol (CP-15), or 5% polyethylene glycol (CP-16) and frozen at -1.4 degrees C for 5 hours. Thawed hearts were reperfused in working mode to assess function. There was no recovery in CP-14 hearts. Hearts treated with CP-15 recovered 39.3% +/- 2.9% (mean +/- SEM) of control cardiac output. CP-16 boosted the recovery of cardiac output to 54.4% +/- 5.7% (p less than 0.05 vs CP-15). Glycerol significantly reduced tissue ice content; PEG further decreased the ice content to 31.7% +/- 0.6%, which was distinctively lower than that in CP-14 (44.7% +/- 1.1%) and in CP-15 hearts (34.6% +/- 1.1%). Tissue water content of CP-14 and CP-15 hearts was similar (3.83 and 3.87 gm H2O/gm dry weight). Polyethylene glycol reduced the tissue water content to 3.24 +/- 0.04 gm H2O/gm dry (p less than 0.01 vs CP-14 and CP-15 by ANOVA). Thus both glycerol and polyethylene glycol offered cryoprotection to the heart explant by reducing tissue ice formation. Polyethylene glycol was superior to glycerol by dehydrating myocardial tissue and further minimizing freezing damage.