Search

Thermoplastic polyurethane-silver nanocomposites (PU-Ag NCs) have considerable potential in many medical applications due to their superior mechanical and antimicrobial properties. Herein, a microwave-promoted flow system is successfully employed for continuous in situ manufacturing of PU NCs having spherical silver nanoparticles (AgNPs) without any reducing agent at similar to 40 degrees C in approximately 4 minutes. The main experimental parameters, including microwave power, metal salt concentration, polymer concentration, and flow rate, are optimised for the reproducible synthesis of AgNPs (similar to 5 nm) in the PU matrix, characterised by HRTEM-EDS and DLS analysis. XRD patterns indicate an increase in PU crystallinity with decreased particle size. Conventional heating flow synthesis at similar to 50 degrees C or microwave-batch synthesis (MWB) at similar to 44 and similar to 50 degrees C is ineffective in preparing AgNPs, and only large AgNPs (>100 nm) are synthesised at 70 degrees C in the MWB reactor. PU-Ag NC films bearing small AgNPs (similar to 5 nm) exhibit superior antibacterial activity (>97%) against Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus aureus compared to large NPs (similar to 218 nm). The proposed method may manufacture other metal-polymer matrix composites.

Continuous manufacturing of pure nanocrystals with a narrow size distribution in a polymer matrix is very challenging, although it is highly crucial to get their full potential for advanced applications. A long-lasting nanocomposite (NC) manufacturing challenge is, for the first time, overcome by a microwave-powered fluidic system (MWFS). The effect of microwave power (MWP), flow rate, and the concentration of the reagents are systematically studied. The nylon-6 NC bearing evenly distributed silver nanoparticles (AgNPs) with a mean size of similar to 2.59 +/- 0.639 nm is manufactured continuously in similar to 2 min at similar to 50-55 degrees C using a green solvent, formic acid. The AgNP size becomes smaller when increasing the polymer concentration gradually. Small NPs with a narrow size distribution are produced at high MWP (40 W), but large ones with a broad size distribution at low MWP (10 W). The nylon-6 crystallinity is NP size-dependent, and the gamma-phase (pseudo-hexagonal crystal) is dominant in the presence of small NPs as against the large counterparts. Given the small-sized AgNPs in the MWF-manufactured NCs, the antibacterial activity tests with Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa show superior activity compared to that of the large AgNP-bearing (similar to 50 nm) NCs produced in a conventional heating fluidic system. The proposed MWFS can manufacture other added-value NCs continuously.

Background . Over the past several years, considerable experience has accumulated in performing coronary anastomoses on the beating heart, and various aspects of minimally invasive approaches have been simplified. In an attempt to further simplify and decrease the "invasiveness" of this procedure, performing this operation without endotracheal general anesthesia was deemed feasible in certain subsets of patients. Methods . Between October 1998 and June 1999, 5 patients underwent coronary artery bypass grafting without endotracheal general anesthesia, using high thoracic epidural block to construct extension grafts with a short segment of radial artery, between the in situ left or right internal thoracic arteries and the left anterior descending (n = 4) or right coronary arteries (n = 1). There were 2 female and 3 male patients, with a mean age of 67.4 ± 8.3 years. Results . The perioperative course of the patients was uneventful. There was no perioperative morbidity or mortality. No patient was converted to general anesthesia or to conventional operation. Control angiograms revealed patent anastomoses in all patients. In 1 patient, spasm of the radial artery graft was observed that was relieved 3 weeks later spontaneously. Mean length of hospital stay was 2.2 ± 0.4 days. All patients were symptom free and returned to normal daily life at the first postoperative month. Conclusions . Our initial experience confirms the feasibility of performing coronary bypass grafting in the conscious patient without endotracheal general anesthesia.

Patients who underwent elective surgery for abdominal aortic aneurysms between January 1990 and December 1996 were evaluated retrospectively. Forty-six patients (group 1) with aneurysms of less than 5 cm in diameter were compared with 121 patients (group 2) with larger aneurysms. There were no differences in age, sex, or associated pathology between the two groups. Hypertension, coronary artery disease, and chronic obstructive lung disease were the most frequently associated conditions. Hospital mortality was not significantly different; 4.3% for group 1 and 2.5% for group 2. At 7 years, the cumulative long-term survival rates for group 1 and group 2 were 97% and 90% respectively (p > 0.05). For any infrarenal aortic aneurysm, indication for surgery should be based on the rate of aneurysm expansion, development of increased aneurysm-related symptoms or complications, and patient anxiety.

Between 1986 and 1996, 147 patients underwent valve replacement combined with coronary artery bypass grafting. The mitral valve was replaced in 104 patients, the aortic valve in 34, and both mitral and aortic valves were replaced in 9. One hundred and twenty-two (83%) were male with a mean age of 56 ± 5 years (range, 38 to 77 years). The mean age for female patients was 57.9 ± 5 years (range, 38 to 70 years). All of the patients had rheumatic valve disease. Preoperatively, 68% were in New York Heart Association functional class III or IV and 32% were in class II. A total of 252 distal anastomoses were performed (mean, 1.71 per patient) in these patients of whom 48.9% had single-vessel disease, 45% had two-vessel or three-vessel disease, and 6.1% had left main coronary artery disease. The hospital mortality rate was 10.2%. Three patients died during the follow-up period and the overall actuarial survival rate at 10 years was 96.6% ± 1.9%. Operations that combine both valve replacement and coronary artery bypass are performed more frequently because perioperative risk has decreased through more effective myocardial protection. If untreated, both coronary artery disease and significant valve disease may reduce patient survival.

The Liotta porcine bioprosthesis is a third generation bioprosthesis with a very low profile supraannular configuration with low-pressure glutaraldehyde-fixed tissue. Between May 1986 and December 1990, 670 patients underwent isolated mitral valve replacement with Liotta porcine bioprosthesis. There were 403 (60%) females and 267 (40%) males; the mean age was 39.03 ± 4.57 years (range, 16 to 75 years). The predominant lesion was combined mitral stenosis and mitral insufficiency in 46% of the patients. The operative mortality rate was 5.9% and the most frequent cause of the mortality was low cardiac output. Total follow-up was 3193.5 patient-years. The average follow-up period was 6.1 ± 2.5 years (range, 1 to 10 years). During the late period, 44 patients (1.4% per patient-year) died. The long-term survival estimate at 10 years was 84.8% ± 2.7%. Structural valve deterioration developed in 198 patients (6.2% per patient-year). Actuarial estimates of freedom from structural valve deterioration at 5 and 10 years were 87.6% ± 1.5% and 28.5% ± 4.5% and it was unrelated to sex or age. Most patients (88%) who developed bioprosthesis dysfunction underwent repeat valve replacement. The period between the implantation and development of structural valve deterioration was 5.9 ± 1.8 years for female patients and 6.2 ± 1.8 years for males (no statistically significant difference). We concluded from the early and high rates of structural valve deterioration in this young age group that the Liotta porcine bioprosthesis has limited long-term durability for mitral valve replacement.

Of 602 patients who underwent percutaneous transluminal coronary angioplasty in a 6-year period, 18 required emergency coronary artery bypass grafting within 12 hours of the procedure. The indications for emergency surgery were acute myocardial infarction in 5 patients, coronary artery dissection in 4, ventricular fibrillation in 3, unstable angina pectoris in 2, total coronary occlusion in 3, and cardiogenic shock in 1 patient. All patients were taken to the operating room in a deteriorating hemodynamic state; 4 received vasodilatating agents and another 4 were treated with vasodilators and inotropic agents, intra-aortic balloon pumping was used in 7, an autoperfusion catheter in 1, and 1 other required external cardiac massage. One patient was operated on in the catheterization laboratory. There was 1 death, giving an operative mortality of 5.6%. The internal thoracic artery was used for coronary artery bypass grafting in 7 patients. There were no deaths during the long-term follow-up.

Between 1986 and 1990, 304 females between 11 and 45 (mean, 33.9 ± 6.9) years of age underwent isolated mitral valve replacement with a bioprosthesis. Thirty-nine of the 285 survivors experienced 48 pregnancies during the late follow-up period (group 1). Structural valve deterioration occurred in 25 (64.1%) of these patients and in 70 (28.4%) of the 246 patients (group 2) who did not become pregnant (p < 0.01). The mean time at which structural valve deterioration occurred was 7.01 ± 1.19 years postoperatively (range, 4.74 to 8.36 years) for group 1 patients and 6.76 ± 1.34 years (range, 2.33 to 10.17 years) for group 2 patients (p > 0.05). Freedom from structural valve deterioration at 10 years was 22.9% ± 8.11% for group 1 and 29.24% ± 6.09% for group 2 (p > 0.05). We concluded that pregnancy did not influence the long-term outcome after mitral valve replacement with a bioprosthesis.

Objective: A total of 2052 patients operated on with the off-pump technique (coronary artery bypass grafting on the beating heart without the use of extracorporeal circulation) between June 1993 and March 1996 are retrospectively reviewed. Predictors for early mortality, perioperative myocardial infarction, and low cardiac output state were statistically analyzed. Method: Our indications for an off-pump procedure were either patients with technically suitable coronary lesions (the vast majority) or patients who could not tolerate cannulation, hypothermia, or cardiopulmonary bypass because of the poor left ventricular function (198 patients) and/or associated diseases or conditions (73 patients). Results: Overall operative mortality was 1.9% and perioperative myocardial infarction occurred in 59 patients (2.9%). According to logistic regression analysis, associated bronchial asthma ( p = 0.0001), hypertension ( p = 0.05), poor quality of the left anterior descending artery ( p = 0.02), and ungrafted circumflex coronary artery disease ( p = 0.007) were the early mortality predictors. Nonbypassed circumflex disease was also associated with a high incidence of perioperative myocardial infarction and low cardiac output state. No homologous blood or packed red cell transfusion was required in 74.2% of the patients. Conclusion: On the basis of the presented data, off-pump coronary artery bypass grafting appeared to be a safe and effective technique in selected patients with appropriate coronary lesions. (J Thorac Cardiovasc Surg 1998;116:68-73)

Between 1982 and 1990, 151 patients aged 50 to 65 years of age underwent isolated mitral valve replacement with a bioprosthesis. Overall hospital mortality was 10.6% (16/151). The total cumulative follow-up period was 527.6 patient-years with a mean of 4.34 ± 2.53 years and a range of 2 months to 10.9 years. During the follow-up period, 27 patients (5.11% per patient-year) developed bioprosthesis dysfunction of whom 26 were reoperated and one was treated medically, 4 patients had thromboembolic complications (0.75% per patient-year), one patient (0.18% per patient-year) had anticoagulant-related bleeding, and two patients (0.37% per patient-year) had a paravalvular leak (one was reoperated). Total valve-related complications were 6.44% per patient-year. Late mortality was 2.65% per patient-year (14/151). Ten-year actuarial survival was 78.5%. Freedom from bioprosthesis dysfunction was 56.6%, from thromboembolic complications 95.8%, and from all complications 49.6%. Our findings of a high rate of bioprosthesis dysfunction as well as a low rate of thromboembolic complications after mitral valve replacement with a bioprosthesis in older patients suggests that the use of bioprostheses should be limited.

Objective: Different closure techniques (linear vs. circular), as well as the efficacy of revascularization in the left ventricular aneurysm repair, with regard to immediate and mid-term results, were assessed and factors having influence on the early mortality and morbidity and survival were analyzed. Method: Between January 1991 and November 1996, 248 patients underwent surgical repair for postischemic left ventricular aneurysm. A total of 26 of them were female (10.5%). Linear closure was employed in 121 patients (48.8 %) and circular (patch endoaneurysmorraphy) closure in 127 (51.2%). Coronary revascularization was added in 203 (81.9%) cases. Patients were followed for an average follow-up time of 39.3 months. Results: Early mortality rate was 6% (15 patients). The difference in mortality rate by the repair method was not statistically significant (8.3% in the linear closure group and 3.9% in the circular closure group, P0.15). Absence of preoperative angina pectoris (P 0.029), dyspnea as the presenting symptom, a preoperative left ventricular segmental wall motion scoring of 14 or greater, a cardiopulmonary bypass duration exceedin g2h( P0.004), an aortic clamping time exceedin g1h( P 0.026) were associated with early mortality. Concomitant coronary revascularization had no effect on early mortality. However, low cardiac output state was less frequent in patients with concomitant coronary revascularization (P0.022). Functional status improved in both groups. Follow-up extending to 81st month revealed no difference in survival between the groups (84% for linear closure group and 92% in circular closure group, including operative mortality, P0.12). However, functional status improvement was better in the patients who underwent circular repair (P0.0077). Revascularization appeared as having no important influence on both survival and functional status. A preoperative left ventricular segmental wall motion scoring of 14 or greater was associated with a higher incidence of early mortality, low cardiac output syndrome and poor long-term survival. Conclusion: Left ventricular aneurysm repair is an important therapeutic intervention and can be performed with reliable results, regardless of repair method, either linear or circular. Long term results revealed better functional status in circular repair group. Concomitant coronary revascularization reduced the incidence of low cardiac output state. Performance of the unaffected regions of myocardium was found to be an important determinant of both early and late outcome. © 1998 Elsevier Science B.V.

This study compared the effects of enoximone with those of dopamine on myocardial function after protamine administration for the reversal of heparin. Twelve dogs were intubated and given 300 IU/kg heparin. A femoral artery cannula and two venous cannulae were inserted, and the animals were placed on hypothermic (28°C) cardiopulmonary bypass. The hearts were arrested for one hour with cold crystalloid cardioplegic solution and the animals were rewarmed to 36°C. After weaning from bypass, the heparin was neutralized with 4.5 mg/kg protamine sulfate. The dogs were divided into 3 groups: a control group (group C) received only protamine, another group (group D) received dopamine 10 μg/kg/min and protamine, and the third group (group E) received enoximone 10 μg/kg/min and protamine. Cardiac output was 1,320 ± 50 mL/min in group C, 1,420 ± 30 mL/min in group D, and 1,540 ± 10 mL/min in group E. We concluded that enoximone is an effective drug for relieving the adverse effects of protamine on the myocardium.

Ten rabbits underwent 30 minutes of superior mesenteric artery occlusion to assess the release of tumor necrosis factor, subcellular damage, and hemodynamic changes after intestinal ischemia-reperfusion injury. Five were treated with prostacyclin 5 ng/kg/min 5 minutes before the arterial occlusion. It was increased to 25 ng/kg/min during occlusion, decreased to 5 ng/kg/min for the first 5 minutes of reperfusion, and then discontinued. A control group of 5 rabbits did not receive any pharmacological agent. Specimens were obtained from the small intestine for electron microscopy after 10 minutes and after 60 minutes of reperfusion, while simultaneous blood samples were collected for measurement of tumor necrosis factor. Minimal changes were seen in tissue from the prostacyclin group but severe mitochondrial damage and vacuolation occurred in the control group. The tumor necrosis factor level was 11.97 ± 3.17 U/mL in the control group and 5.06 ± 2.19 U/mL in the prostacyclin group, one hour after the end of mesenteric occlusion ( p < 0.05). Hemodynamic status, assessed by central venous and arterial pressures, was much more affected in the control group than in the prostacyclin group. Mean arterial pressure was 71 ± 5 mm Hg in the control group, and 91 ± 6 mm Hg in the prostacyclin group ( p < 0.05). Central venous pressure was 5.3 ± 0.9 mm Hg in the control group and 2.3 ± 0.7 mm Hg in the prostacyclin group ( p < 0.05). We conclude that intravenous prostacyclin reduced the severity of reperfusion injury occurring during the early period of reperfusion by inhibiting the release of the toxic mediator tumor necrosis factor, thus decreasing distant organ injury.

Exercise and electrical stimulation may result in a decrease in carnitine levels associated with preconditioned latissimus dorsi muscles. Therefore, the effects of exogenous carnitine were studied in a model of latissimus dorsi muscle contraction. Twelve dogs were studied. Under anesthesia, the latissimus dorsi was placed around an implantable mock circulation system. The muscle was made fatigue-resistant with the aid of chronic low-frequency electrical stimulation. Six animals received carnitine 0.15 mmol/kg; the other six served as control. The muscles were stimulated with 20, 43, and 85 Hz pulse training. During the 90-minute stimulation period, the pressure that developed in the mock circulation was measured at 15 minute intervals. The changes in ATP and lactate levels were measured every 30 minutes. Stimulations at 20 and 43 Hz did not result in any change in pressure or metabolic data over the course of 90 minutes of stimulation. When the 85 Hz burst was applied, ATP levels decreased, while lactate levels increased, with an associated drop in pressure in the control group. ATP and lactate levels were, respectively, 13.8 +/- 1.4 mumol/g and 15.0 +/- 4.0 mumol/g in the carnitine group and 10.3 +/- 1.1 mumol/g and 23.0 +/- 3.0 mumol/g in the control group at the end of 90 minutes (p < 0.06). The pressure at the same time interval was 74 +/- 4 mmHg in the control group, and 85 +/- 3 mmHg in the carnitine group (p < 0.05). In this study, we demonstrated that carnitine administration enhances muscle performance in terms of metabolic and pressure changes during high-frequency electrical stimulation at 85 Hz.

Background . A major concern in evaluating dynamic cardiomyoplasty has been whether the synchronous stimulation of latissimus dorsi muscle is essential for benefit or not. We studied 10 patients to determine the efficacy of the systolic augmentation generated by the synchronous electrical stimulation of the latissimus dorsi muscle. Methods . Left ventricular ejection fraction, end-systolic and end-diastolic volume indexes, and stroke volume index obtained during resting, peak exercise, and recovery periods ("on" values) were compared with those obtained 1 week after cessation of electrical stimulus ("off" values). Double product and estimated total body oxygen consumption at peak exercise were also calculated and compared. Results . Higher ejection fractions (0.36 ± 0.07 versus 0.33 ± 0.06 at rest, 0.40 ± 0.07 versus 0.33 ± 0.07 peak exercise, and 0.37 ± 0.06 versus 0.31 ± 0.06 at recovery) and lower end-systolic volume indexes with relatively constant end-diastolic volume indexes were observed with the cardiomyostimulator on. Further, exercise response was better with the cardiomyostimulator on. Double product indirectly reflected better myocardial oxygen supply/demand ratio when on at peak exercise (17 ± 2.2 mm Hg × beats/min × 10 −3 for on versus 19 ± 2.6 mm Hg × beats/min × 10 −3 for off). Estimated total body oxygen consumption was improved at peak exercise when the cardiomyostimulator was functional (12 ± 2.7 mL · kg −1 · min −1 versus 11 ± 2.6 mL · kg −1 · min −1 ). Conclusions . Current data suggest a true systolic assist during synchronous contractions of the latissimus dorsi muscle. It is thought, therefore, that synchronous electrical stimulation is essential for maximum benefit and all the beneficial effect of cardiomyoplasty certainly cannot be attributed to simple wrapping itself.

A retrospective analysis was made of the records of 62 patients who underwent pericardiectomy over a ten year period (1985 to 1996) in our department. Primarily, 43 patients (69.4%) had tuberculosis, 16 patients (25.8%) were diagnosed as idiopathic or viral infection, 2 patients (3.2%) had a previous cardiac operation and 1 patient (1.6%) had a neoplasm. Eight patients were in New York Heart Association functional class I, 22 in class II, 24 in class III, and 8 in class IV. Pericardiectomy was performed through midline sternotomy in all cases; 2 required cardiopulmonary bypass. Subtotal pericardiectomy was performed, in which the phrenic nerves define the posterior extent of pericardial resection. Low cardiac output was present in 8 patients. The early mortality rate was 6.45% (4 patients). During the follow-up period, ranging from 1 to 7 years (mean 3.8 ± 1.42 years), there were 2 late deaths due to the right heart failure. One patient who underwent pericardiectomy after an open-heart operation showed recurrent pericardial constriction. We conclude that pericardiectomy using midline sternotomy with or without cardiopulmonary bypass can be performed with low mortality and can result in good long-term survival and improved functional capacity.

This study was planned to investigate if prostacyclin (PGI2) would reduce spinal cord injury following aortic occlusion. Twelve dogs underwent 90 min of aortic occlusion. Six dogs received PGI2 and the remaining animals did not. PGI2 was administered at a dose of 25 ng/kg/min during occlusion of the aorta. There were five paraplegic animals in the control group and one in the PGI2 group 72 hr after aortic occlusion. Neurological recovery was better in the PGI2 group than in the control group (P0.05). Malondialdehyde level was 3.55 +/- 0.58 nmole/ml in the PGI2 group and 6.35 +/- 1.27 nmole/ml in the control group 60 min after aortic cross-clamp removal (P0.05). At the same time interval, protein thiol groups were 629 +/- 50 micromole/L in the PGI2 group and 376 +/- 69 micromole/L in the control group (P0.05). Distal arterial pressure and central venous pressure were 15 +/- 4 and 12 +/- 3 mm Hg in the control group and 33 +/- 5 and 7 +/- 1.6 mm Hg in the PGI2 group, respectively (P0.05). In this study exogenously administered PGI2 protected the spinal cord from the hazardous effects of aortic occlusion lasting 90 min.

Between 1968 and 1995, a total of 153 patients who were between 35 and 63 years of age (mean 49.8 years), underwent surgery for secundum type atrial septal defect. There were 78 (50.9%) males and 75 females (49.1 %). Mean left-to-right shunt ratio was calculated as 2.49. Mean pulmonary artery pressure was 50.15 mm Hg. Three patients died within 30 days of surgery, giving a hospital mortality of 1.96%. Long-term follow-up was available in 135 cases (90%). Total follow-up was 967.3 patient-years and ranged from 3 months to 11.3 years (mean 7.16 years). There were no late deaths reported. Four patients were readmitted with atrial fibrillation and 2 with pericardial effusion. In our experience, surgical closure of atrial septal defect in adults was found to be successful, safe, and with low morbidity in patients with pulmonary hypertension and congestive heart failure.

The risk of paraplegia associated with thoracic aortic cross-clamping is high even when various methods of spinal cord protection are used. In this study prostacyclin 12 (PGI2) was selected as an agent to reduce the spinal cord injury because of its vasodilator, antiaggregant, and cytoprotective properties. Twelve dogs underwent sixty-minute aortic occlusion. Six dogs received PGI2 whereas the other 6 did not (controls). PG12 administration was started at a rate of 5 ng/kg/minute five minutes before aortic occlusion. This dosage was increased to 25 ng/kg/minute during aortic occlusion. PGI2 at a dosage of 5 ng/kg/minute was maintained for a period of five minutes after the aortic occlusion was released. Three dogs in the control group were paraplegic. There were no paraplegic dogs in the PGI2 group. Distal aortic perfusion pressure was 31 ± mmHg in the PGI2 group and 22 ±3 in the control group (P As a result of this study the authors conclude that PGI2 is a valuable agent for decreasing the risk of spinal cord injury during thoracic aortic cross-clamping lasting sixty minutes.

Coronary and valvular heart diseases are the main causes of mortality and morbidity among the long-term survivors of chronic renal failure. Despite the additional risk factors, open heart surgical procedures have recently been attempted with high rates of success in some patients with chronic renal failure. Forty-three patients with chronic renal failure that have undergone open heart surgery are included in this study. Ten of the patients were female and the mean age was 53.1 ± 11.2 (26 to 71). Twenty-five patients underwent aortocoronary bypass operations and 18 others underwent heart valve replacements. In this group of patients, 38 (88.3%) were in the compensated retention stage of chronic renal failure and 5 (11.7%) were in the end stage. The decompensated chronic renal failure patients were on regular hemodialysis and continued to receive hemodialysis in the preoperative and postoperative period. Sixteen patients of the compensated chronic renal failure group needed hemodialysis postoperatively. Early mortality rate was 7.8% (n = 3). Mean stay in the intensive care unit after the operation was 3.0 ± 3.3 days (2 to 22 days). In the long-term follow-up 3 patients underwent successful renal transplantations within 9 to 18 months after the cardiac operations. Two of these patients had valve replacements and 1 had concomitant valve replacement and coronary artery bypass grafting prior to renal transplantation. We conclude that coronary angiography, catheterization, myocardial revascularization, and valve replacements can be safely performed and should be considered if indicated in chronic renal failure patients.

Background: As cardiac complications constitute the principal cause of early and late morbidity and mortality after the surgical treatment of abdominal aortic aneurysm (AAA), a prospective study was planned to evaluate the effects of revascularization of coronary arteries on survival after AAA repair during early and long-term follow-up periods. Patients and Methods: A total of 125 patients underwent elective repair of AAA between 1986 and 1994. Coronary arteriography was performed in all cases. All cases with critical left anterior descending artery (LAD) lesions underwent a coronary artery bypass operation either simultaneously or shortly before AAA repair. In addition, percutaneous transluminal coronary angioplasty (PTCA) was performed for symptomatic and critical stenosis of arteries other than the LADs, or if noncritical but symptomatic stenosis of the LADs existed. Early and late follow-up data were obtained for all cases, and late-term cumulative survival rates were calculated. Results: Coronary artery lesions were found in 66 (53%) cases. In 24 cases, AAA repairs were performed 2.3 (mean) months after coronary artery bypass grafting (CABG), whereas in 4 cases both procedures were performed simultaneously. PTCA was performed in 4 cases 3 to 4 days prior to the abdominal surgery. Even though the coronary artery lesions were found inoperable in 7 cases, these patients underwent repair of AAA because of rapidly expanding and painful aneurysms. Early mortality rate was 4% (5 cases), in which 3 of these were from the group inoperable for CABG. A mean follow-up of 3.17 years (3 to 87 months) was achieved for all discharged patients. Cumulative survival rates for 6 months and 1, 2, 3, and 6 years were 99%, 99%, 95%, 93%, and 89%, respectively. Conclusions: The results of this study emphasize the importance of coronary artery revascularization for early, and especially for late, survival after AAA repair.

From 1977 to July 1994, 10 patients underwent operation for cardiac cysts in the Department of Cardiovascular Surgery of Türkiye Yüksek Ihtisas Hospital. The ages of the patients ranged from 10 to 39 years (mean 25.2 ± 8.82). Nine patients had cardiac and pericardial cysts, and the first patient of this series had two pericardial cysts. One patient died in the early postoperative period due to rupture of the interventricular septum. Hospital mortality was 10% (1/10). Late follow-up data were obtained for 8 of the 9 hospital survivors, and no recurrence was found.

The hemodynamic effects of intraaortic balloon pumps (IABPs) are well known. The use of IABPs is prone to many complications, including those classified as vascular. These complications are said to be more frequent with percutaneous insertion techniques. These complications and the algorithm for identifying patients who are most likely to suffer vascular complications were evaluated in a retrospective manner in a group of patients that received percutaneous IABPs. The study group consisted of 449 patients. The mean age of these patients was 53.6 +/- 12.8 years (range, 18 to 80 years), and 24.7% were female. The early mortality rate of these patients was 53.2%. The mortality for patients in whom vascular complications developed was significantly higher than that in the patients who did not suffer any vascular complications (65.7% versus 50.8%; p = 0.018). Minor or major vascular complications developed in 17.4% (n = 78) of the patients. There was no statistical difference in the frequency of complications between the patients who received a sheathless IABP and those who received a sheathed IABP. Ischemic complications occurred in 16.6% of the patients who received a sheathless IABP and in 17.6% of the patients with sheathed IABPs (p < 0.05). Diabetic patients (relative risk, 2.5), female patients (relative risk, 1.83), patients with peripheral vascular disease (relative risk, 3.69), and patients undergoing coronary artery bypass operations (relative risk, 2.08) were at increased risk for suffering vascular complications. These risk factors should be evaluated before insertion of an IABP, and routes other than percutaneous femoral insertion are preferred if the patient is IABP dependent.

This study was planned to show the beneficial effects of prostacyclin (PGI2) utilization on adverse effects of protamine. PGI2 was administered at a rate of 5 ng/kg/min. Twenty patients entered this study. Half of them received PGI2 whereas the others did not. Right ventricular end-diastolic volume index and right ventricular stroke work index were 72 mL/m2 and 2.2 g.m/m2, respectively, after patients were weaned off the bypass and 79 and 1.5, respectively, at five minutes after pro tamine administration in the control group; these values were 88 and 3.2, re spectively, and 86 and 3, respectively, in the PGI2 group. Left ventricular stroke work index (g.m/m2) was 27.9 in the control group and 36.7 in the PGI2 group (p < 0.05) after protamine administration. Thromboxane B2 levels (pmoL/mL) in coronary sinus (CS) blood were 251 in the control group and 90 in the PGI2 group at five minutes after protamine administration (p < 0.05). Myocardial blood flow was 174 mL in the control group and 245 mL in the PGI2 group at five minutes after protamine adminis tration (p < 0.05). Cyclic adenosine monophosphate (cAMP) and cyclic guano- sine monophosphate (cGMP) levels in CS blood were 17 pmoL/mL and 2.1 pmoL/mL, respectively, in the control group and 36 and 0.3, respectively, in the PGI2 group at five minutes after protamine administration. Leukotriene B4 level was 129 and 57 pmoL/mL in the control and PGI2 groups, respectively (at the same time as the cAMP measurement) (p < 0.05). From the results of this study the authors conclude that adverse effects of heparin reversal with protamine can be reduced with the use of PGI2.

period variability of preceding sinus rhythm before initiation of paroxysmal atrial fibrillation. Am J Cardiol 1998;81:869–874. 11. Task force of the European Society of Cardiology and the North American Society of Pacing and Electrophysiology. Heart rate variability. Standards of measurement, physiological interpretation, and clinical use. Circulation 1996;93: 1043–1065. 12. Campbell RWF, Smith RA, Gallagher JJ, Pritchett ELC, Wallace AG. Atrial fibrillation in the preexcitation syndrome. Am J Cardiol 1977;40:514–520. 13. Robinson K, Rowland E, Krikler DM. Wolff-Parkinson-White syndrome: atrial fibrillation as the presenting arrhythmia. Br Heart J 1988;59:578–580. 14. Waspe, Brodman R, Kim SG, Fisher JD. Susceptibility to atrial fibrillation and ventricular tachyarrhythmia in the Wolff-Parkinson-White syndrome: role of the accessory pathway. Am Heart J 1986;112:1141–1152. 15. Della Bella P, Brugada P, Talajic M, Lemery R, Torner P, Lezaun R, Dugernier T, Wellens HJJ. Atrial fibrillation in patients with an accessory pathway: importance of the conduction properties of the accessory pathway. J Am Coll Cardiol 1991;17:1352–1356. 16. Jackman W, Yeung Lai Wah J, Friday K, Khan A, Sakurai M, Lazzara, R. Tachycardias originating in accessory pathway networks mimicking atrial flutter and fibrillation (abstract). J Am Coll Cardiol 1986;7:6A. 17. Gaita F, Giustetto C, Riccardi R, Mazza A, Mangiardi L, Rossettani E, Brusca A. Relation between spontaneous atrial fibrillation and atrial vulnerability in patients with Wolff-Parkinson-White pattern. Pac Clin Electrophysiol 1990;13: 1249–1253. 18. Muraoka Y, Karakawa S, Yamagata T, Matsuura H, Kajiyama G. Dependence on atrial electrophysiological properties of appearance of paroxysmal atrial fibrillation in patients with Wolff-Parkinson-White syndrome: evidence from atrial vulnerability before and after radiofrequency catheter ablation and surgical cryoablation. Pac Clin Electrophysiol 1998;21:438–446. 19. Chen YJ, Chen SA, Tai CT, Wen ZC, Feng AN, Ding YA, Chang MS. Role of atrial electrophysiology and autonomic nervous system in patients with supraventricular tachycardia and paroxysmal atrial fibrillation. J Am Coll Cardiol 1998;32:732–737. 20. Ramdat Misier AR, Opthof T, Van Hemel NM, Defauw JJAM, De Bakker JMT, Janse MJ, van Capelle FJL. Increased dispersion of refractoriness in patients with idiopathic paroxysmal atrial fibrillation. J Am Coll Cardiol 1992; 19:1531–1535.

Between January, 1977, and March, 1990, 84 consecutive patients underwent graft replacement of an ascending aortic aneurysm. There were 22 women and 62 men patients, ranging in age from twenty-two to sixty-nine years (mean 44.3). Surgical procedures employed were as follows: composite graft replacement with coronary reimplantation in 53 cases, supracoronary graft replacement (SGR) in 23 cases, SGR + aortic resuspension in 2 cases, and SGR + aortic valve replace ment in 1 case. Twenty-eight patients (33%) underwent concomitant aortic arch replacement. Five cases were operated on by "elephant-trunk" technique for extensive aneurysms involving the ascending, arch, and descending thoracic aorta. In 71 cases, a shunt was inserted between the periprosthetic space and the right atrium. Hospital (thirty-day) mortality was 15.5%. Contemporary (1987-1990) mortality rate was 8.7%. After a mean follow-up period of 42.6 months (range three to one hundred eighteen), there were 2 late deaths (1.1%/patient-year). Late reoperation was necessary in 2 cases (1.1%/patient-year). Ninety-one per cent of the survivors were in NYHA class I or II. The long-term survival rate was 76% ± 12%. The type of operation (ie, composite graft replacement or SGR) or concomitant aortic arch replacement had no influence on surgical outcome. The periprosthetic right atrial shunt was found to be effective in avoid ing complications related to blood accumulating between the aortic graft and the aortic wraparound.

A 10-year-old girl underwent tetralogy of Fallot (TOF) repair and subsequent pulmonary valve replacement with a St. Jude Medical mechanical heart valve prosthesis. Valve replacement was necessary due to right heart failure resulting from pulmonary regurgitation occurring three months after TOF repair. At the age of 25 years, when she became pregnant, routine cardiac evaluation indicated that she had not used oral anticoagulation during the past 15 years. The patient was of rural origin, and of poor socioeconomic status, but is currently in her 15th postoperative year, with neither clinical problems nor any sign of valve failure.

It is accepted universally that the treatment of critical left main coronary artery (LMCA) stenosis is surgical revascularization. This study was designed to evaluate critical LMCA stenosis as a risk factor in coronary artery bypass surgery. We compared the surgical results of 760 patients with critical LMCA disease, including 58 cases who were operated under emergency conditions (LMCA-em) and 702 patients who were operated electively (LMCA-el), with randomly chosen 707 coronary bypass patients (CONT-el) without LMCA disease, but who had double- or triple-vessel disease. Another group of patients (n = 99) who were operated on under emergency conditions (CONT-em) but without LMCA disease were also compared with the corresponding groups. The mortality of LMCA-em group and CONT-em group was markedly higher from the other two groups. Univariate analysis revealed that female gender, older age, presence of diabetes mellitus, poor left ventricular function, and the presence of unstable angina were major risk factors for fatal outcome in LMCA-el and CONT-el groups. Age was also a risk factor in LMCA-em group, as well as unstable angina pectoris. The coexistence of critical right coronary artery disease did not affect the early outcome in both groups with LMCA lesions. In the multivariate analysis, critical LMCA disease was not a risk factor for mortality. Logistic regression analysis revealed diabetes [odds ratio (OR): 3.66], poor left ventricular function (higher left ventricle end-diastolic pressure, OR: 1.08), and emergent operations (OR: 5.09) were risk factors for early mortality. Patients with LMCA disease should have surgery promptly for favorable results, because emergency conditions have higher mortality rates.

We report an unusual outcome of an ascending aorta aneurysm ruptured into the main pulmonary trunk. After successful emergency repair, an acute respiratory distress syndrome developed perioperatively and complicated the postoperative period. The patient could not be weaned from mechanical ventilation for a long time. The patient was discharged on the 62nd day of admission in good condition.

We report preoperative and early postoperative findings of 286 coronary bypass patients operated between 1988 and 1998 who had endarterectomy and/or patchplasty to the right coronary artery. In this retrospective study there were 61 cases with only saphenous vein patchplasty to the right coronary artery (patch group), 57 patients who underwent endarterectomy and patchplasty (open-patch group), and 229 patients having closed endarterectomy to the right coronary artery (closed group). A group of 150 patients having a saphenous vein graft to the right coronary artery without endarterectomy were chosen as a control group. Gender, age, family history, smoking history, diabetes, hyperlipidemia, hypertension, nature of the angina, severity of the coronary artery disease, left ventricular functions, preoperative rhythm, and electrocardio-graphic patterns were evaluated for their effect on early mortality among groups. No significant difference was detected. Positive inotropic and mechanical support need was higher in the closed group at the end of the operation and in the intensive care unit. Duration of cardiopulmonary bypass and clamp time was higher in the open-patch group. Atrial fibrillation in the early postoperative period was more frequent in the patch and closed groups. Complete atrioventricular block development and the need for a pacemaker were higher in the open-patch and closed groups. Non-Q wave myocardial infarction was more frequent in the closed group. Mortality rates were higher in the open-patch and closed groups. We conclude that endarterectomy to right coronary artery should be avoided if possible, and patchplasty with saphenous vein should be preferred.

This report describes mitral valve replacement using a unique subxiphoid approach with a lower ministernotomy and a skin crease incision and compares the operative and echocardiographic results to patients undergoing mitral valve replacements using previously described strategies.Fifty-four patients underwent mitral valve replacement using a subxiphoid approach (group 1); 32 patients underwent mitral valve replacement, 11 patients underwent mitral valve replacement + tricuspid reconstruction, 2 patients underwent mitral valve replacement + tricuspid valve replacement, and 9 patients underwent mitral reconstruction. This group of patients was compared to 11 patients who underwent mitral valve replacement through a superior ministernotomy (group 2) and 29 patients who underwent mitral valve replacement with full median sternotomy (group 3, 22 mitral valve replacements, 2 mitral valve replacements + tricuspid reconstruction, 2 mitral reconstructions, and 3 mitral reconstructions + tricuspid reconstruction).There was no operative mortality in all groups. The operation lasted significantly longer in group 2 patients compared to group 1 and 3 patients (p0.01). Postoperative mediastinal drainage was significantly lower in groups 1 and 2 (p0.001). Pain assessment revealed no difference between the groups. Three patients in group 1 presented with pericardial effusion. Except for this complication, early postoperative echocardiographic findings of the patients were similar in all three groups. All patients were in New York Heart Association functional class I or II at the second postoperative month, irrespective of the surgical technique used.There was no prominent superiority of the ministernotomy approaches over the standard median sternotomy approach. However, the reliability of the subxiphoid approach is documented echocardiographically and any type of mitral replacement can be performed with this approach.

Nosocomial infections are one of the most feared complications after open heart surgery. A large retrospective study was conducted to evaluate the nature and scope of the problem. Between 1992 and 1998,9352 patients who had undergone open heart surgery were evaluated. Bloodstream infections, pneumonia, and deep sternal wound infections were included. Univariate and logistic regression analyses were conducted to identify the high-risk patients that were likely to become infected. Three hundred forty-six infections in 276 patients were diagnosed. Age, preoperative albumin level, banked blood requirement, duration of operation, diabetes mellitus, previous open heart surgery, moderate or severe pericardial adhesions, obesity, postoperative low cardiac output, and postoperative cerebrovascular accident were found to be significant in univariate and logistic regression analyses for infectious outcome. Univariate analysis also revealed additional significant factors: fresh frozen plasma requirement, duration of cardiopulmonary bypass and cross-clamp, preoperative high levels of blood urea and glucose, presence of occlusive peripheral arterial disease, preoperative history of hypertension, and nasal carriage of Staphylococcus aureus. Methicillin resistant S. aureus was involved in 58.4% of the infections. Risk factors should be individualized for patients and every effort should be carried out to minimize infectious outcome. (J Card Surg 1998;13:252–259)

J Thorac Cardiovasc Surg 1998;116:354-6

Background . Optimal synchronization delay (SD) for triggering the implanted cardiomyostimulators in patients undergoing latissimus dorsi dynamic cardiomyoplasty has not been clearly defined. Generally a synchronization delay time of 45 to 60 ms is used in the current practice, in which the implanted cardiomyostimulator stimulates the latissimus dorsi muscle 45 to 60 ms after mitral valve closure acquired with M-mode echocardiography. We investigated the effect of shortening or prolonging the delay time on cardiac functions. Methods . We studied 10 patients who were in their first 2 years postoperatively. Three values for SD (SD = 0 ms, 45 to 60 ms, and 150 to 160 ms) were echocardiographically evaluated for their influence on both systolic and diastolic left ventricular parameters. Results . Ejection fractions were 0.27 ± 0.07, 0.28 ± 0.07, and 0.32 ± 0.06; peak aortic velocities were 0.85 ± 0.8, 0.86 ± 0.11, and 0.92 ± 0.8 m/s; and velocity-time integrals were 0.16 ± 0.03, 0.16 ± 0.03, and 0.19 ± 0.03 m for the SD values of 0, 45 to 60 ms, and 150 to 160 ms, respectively. Diastolic parameters were also measured. Isovolumetric diastolic relaxation time was 97.5 ± 49, 97.20 ± 44, and 111.8 ± 49 ms; deceleration time was 83.67 ± 32, 88.48 ± 35, and 92.68 ± 34 ms; and ratio or velocity-time integral of e wave to velocity-time integral of a wave was 3.09 ± 0.98, 2.48 ± 0.69, and 2.38 ± 0.65 for the SD values of 0, 45 to 60 ms, and 150 to 160 ms, respectively. Systolic functions were better when SD was set at 150 to 160 ms, but there was a diastolic compromise. On the other hand, diastolic parameters were more favorable when SD=0 (ie, cardiomyostimulator triggered without delay) but the systolic assist was suboptimal. Systolic and diastolic parameters seemed relatively well-balanced with the current practice of setting the synchronization delay at 45 to 60 ms. Conclusions . The most favorable systolic effects were obtained with a prolonged delay of synchronization (150 to 160 ms), at some expense of diastolic functions. On the other hand, with a short or absent delay, diastolic parameters were improved but systolic parameters became suboptimal. Therefore, the current practice of setting the SD between 45 and 60 ms after echocardiographic mitral valve closure is suggested for the optimal timing for cardiomyostimulator stimulation in patients who have undergone latissimus dorsi dynamic cardiomyoplasty. Yet a great deal of individualization is necessary, and fixed preset values cannot definitely be determined because one setting does not fit all patients.

This study was performed to assess the functional capacity of the survivors of septal myectomy for the treatment of hypertrophic obstructive cardiomyopathy in long-term follow-up as assessed by dobutamine stress echocardiography.Sixty-nine patients with hypertrophic obstructive cardiomyopathy underwent septal myectomy between 1975 and 1996. The mean age was 25.4 +/- 13.6 years (range, 6-58 years), and 10 of the patients were women. The early mortality was 4.3%. Hospital survivors (95.7%) were followed up for a mean of 43.8 +/- 28.7 months (range, 6-114 months).The postoperative mean functional capacity of the group was 1.47 +/- 0.56. No late deaths were reported. Forty-nine patients (74.2%) were evaluated with standard echocardiographic techniques, and 29 (43.9%) patients underwent dobutamine stress echocardiography. There was a significant decrease in the thickness of the interventricular septum after surgery. The mean preoperative and postoperative septal thickness was 1.99 +/- 0.59 cm (range, 1.3-3.8 cm) and 1.55 +/- 0.41 cm (range, 0.96-2.8 cm), respectively (p0.004). The mean posterior wall thickness was significantly less than the preoperative value (p = 0.008) and the left ventricular end-diastolic diameter was slightly greater in the postoperative measurements, but the difference was not significant (p = 0.162). Postoperative left ventricular outflow systolic gradients were reduced significantly when compared with preoperative values (preoperative mean, 78.4 +/- 33.6 mm Hg, range, 50-212 mm Hg versus postoperative mean, 17.9 +/- 15.9 mm Hg: range, 0-40 mm Hg; p0.0001).Septal myectomy for patients with hypertrophic obstructive cardiomyopathy is a safe procedure with excellent clinical and functional results in the long-term follow-up.

One hundred twenty patients who had diffuse atherosclerotic lesions necessitating reconstruction of the left anterior descending artery with or without open endarterectomy and coronary artery bypass grafting were investigated retrospectively and compared with 130 patients who underwent conventional bypass grafting in the same time frame. Methods: Sixty-one endarterectomies were performed with long arteriotomies (group I) and 59 patch reconstructions were placed over stenosing plaques without an endarterectomy (group II). Patients having only conventional coronary bypass constituted group III. Results: Hospital mortalities were 6.5%, 5.1%, and 1.5% in group I, group II, and group III, respectively ( p = not significant). Five patients in group I (8.1%), six in group II (10.1%), and two in group III (1.5%) had perioperative myocardial infarction (group II vs group III, p = 0.016). Angiographic restudy of grafts to the left anterior descending system revealed a patency rate of 81.5% in group I, 79.1% in group II, and 94.4% in group III patients after mean periods of 6.3, 5.7, and 6.1 years, respectively ( p = not significant). Actuarial survivals at 7 years were 94% ± 5.0%, 74.8% ± 16%, and 90.9% ± 7.4% in groups I, II, and III, respectively (group I vs group II, p = 0.007; group II vs group III, p = 0.008). Freedom from recurrent angina at 7 years was 42.7% ± 15.6% in group I, 33.5% ± 19% in group II, and 71.9% ± 14.2% in group III (group I vs group III, p = 0.03; group II vs group III, p = 0.0001). Thirty-four percent of patients in group I, 24% in group II, and 60.4% in group III were working actively in the late postoperative period ( p = 0.0001). Conclusion: Extended revascularizations of the left anterior descending coronary artery increase surgical risk, although not to a statistically significant degree, and should be performed only of necessity. However, once needed, revascularization is a lifesaving procedure with acceptable early and long-term results. (J THORAC CARDIOVASC SURG 1996;112:745-54)

This study was planned to document the right ventricular function immediately after cardiomyoplasty. Right ventricular volumes were calculated with the use of fast response thermistor. Right ventricular end-diastolic volume was reduced from 91 +/- 8 mL/M2 to 75 +/- 7 mL/M2 (p < 0.05) and right ventricular end-systolic volumes increased from 51 +/- 5 mL/M2 to 59 +/- 4 mL/M2 24 hours after the operation. Central venous pressure was raised from 2 +/- 1 to 9 +/- 3 mm H2O. These changes were interpreted as impairment of the right ventricular diastolic function. Cardiac index raised from 1.8 +/- 0.5 L/M2 per minute to 2.7 +/- 0.3 L/m2 per minute within a period of 7 days (p < 0.05). As a result of this study, we concluded that preoperatively normal right ventricular function deteriorates after the cardiomyoplasty. In the intensive care unit volume balance must be carefully monitored to avoid creating right ventricular dysfunction.

The aim of this study was to demonstrate the beneficial effects of aminophylline on protamine cardiotoxicity. Thirty-four patients were examined, 17 of whom received aminophylline 3 mg/kg before protamine administration, being the study group, while the other 17, being the control group, did not. All cardiac output and biochemical measurements were evaluated 5 min following protamine administration. The cAMP level was 43.4 +/- 3.51 pmol/ml in the study group and 18.7 +/- 2.98 in the control group (P0.0001) before protamine administration, while the oxygen extraction rate decreased from 49% to 44 +/- 2% in the control group, and from 51.2% to 47 +/- 3% in the study group (P0.03). The N-acetyl glucosaminidase value was 16.9 +/- 13.9 pmol/ml in the study group and 27.8 +/- 1.47 pmol/ml in the control group (P0.01), and myocardial lactate extraction was -0.20 +/- 0.03 in the control group and -0.07 +/- 0.07 in the study group (P0.001). The left ventricular stroke work index was 28.6 +/- 3.14 gm/m2 in the control group and 37 +/- 6.77 gm/m2 in the study group (P0.002). The findings of this study led us to conclude that the adverse effects of heparin neutralization using protamine can be relieved by aminophylline.

Forty patients with coronary artery disease were included in this study. Half of them received cold crystalloid and cold blood cardioplegia (group 1) and half received normothermic blood Cardioplegia (group 2). In group 1, left ventricular stroke work index was 24 ± 3 g · m/m 2 1 hour after the operation, 29 ± 8 g · m/m 2 12 hours after the operation, and 33 ± 6 g · m/m 2 24 hours after the operation. In group 2, left ventricular stroke work index was 37 ± 4 g · m/m 2 1 hour after the operation, 37 ± 4 g · m/m 2 12 hours after the operation, and 44 ± 7 g · m/m 2 24 hours after the operation. Myocardial oxygen extraction 20 minutes after the termination of cardiopulmonary bypass was 0.28 ± 0.03 in group 1 and 0.44 ± 0.08 in group 2. Myocardial lactate extraction at the same time was −0.09 ± 0.02 in patients receiving cold blood cardioplegia and 0.17 ± 0.07 in patients receiving normothermic blood cardioplegia. Electron microscopic study revealed no calcium accumulation in the mitochondria in group 2 patients, whereas calcium accumulation was present in the other group.