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Open heart operations, results in 100 consecutive cases, using extracorporeal circulation.

In one hundred consecutive cases in which operations were done on the heart with the surgical field exposed to view and circulation was shunted to extracorporeal apparatus, there were six deaths. None were attributable to the by-pass procedure. The lesions were of various kinds, congenital and acquired. In one case a fibromyxosarcoma that was obstructing the right ventricular outflow tract and invading the main pulmonary artery was successfully excised.

Cardiac Surgical Procedures↗

Cardiac resuscitation by extracorporeal circulation after failure of conventional CPR.

After cardiac arrest, return of cardiac function and effective circulation are contingent on prompt restoration of myocardial blood flow. Because conventional closed-chest CPR has limited hemodynamic efficiency, we investigated venoarterial ECC utilizing peripheral vascular access as an alternative for cardiac resuscitation. Ventricular fibrillation was induced in domestic pigs by alternating current delivered to the endocardium of the right ventricle. Conventional closed-chest CPR was begun after 10 minutes. In each instance, precordial compression and external defibrillation failed to restore a viable rhythm. ECC was begun at 15 minutes at an average flow rate of 183 ml/kg/min. In each of eight animals, sinus rhythm was restored. In six of these eight animals, spontaneous circulation was reestablished after an average interval of 152 minutes. When epinephrine was administered concomitantly with ECC in an additional eight animals so as to maintain mean aortic pressure between 60 and 100 mm Hg, sinus rhythm and spontaneous circulation were reestablished in each pig after an average of only 23 minutes. The effects of ECC in conjunction with epinephrine were then compared with those of conventional precordial compression in conjunction with epinephrine (sham ECC). In contrast to ECC, which successfully resuscitated each of five animals, none of five sham ECC-treated animals was resuscitated by continued precordial compression and maximal doses of epinephrine (p less than 0.01). We conclude that ECC in conjunction with epinephrine emerges as a highly effective experimental intervention for resuscitation when conventional techniques of precordial compression and external defibrillation fail to reverse cardiac arrest.

Animals↗

Cerebral perfusion in dogs during pulsatile and non pulsatile extracorporeal circulation.

Eight dogs were cannulated for left heart bypass. Conventional roller pumps were used for bypass with one of the pump console modified to deliver pulsatile bypass. The experiments were performed at normothermia. Each dog was used as its own control. For measurement of cerebral blood flow (CBF) Xe133 was injected into vertebral artery and the gamma activity elimination over the skull was registered. In addition blood samples were withdrawn from the axillary artery and the sagittal sinus for measurement of blood gases. The CBF to the gray matter of the brain was significantly higher during the periods with pulsatile perfusion (P less than 0.01). This was probably due to decreased total cerebral vascular resistance (P less than 0.001). Mean aortic pressure also decreased when the mode of perfusion was changed from non pulsatile to pulsatile (P less than 0.05), indicating a general decrease of the peripheral vascular resistance. A good correlation was noted between the arteriovenous oxygen saturation difference (AV-O2 diff) across the brain and the CBF (R = -0.77, P less than 0.01).

Animals↗

[Experiences with "etomidate pro infusione" in heart surgery interventions with extracorporeal circulation].

The results of experimental studies with etomidate demonstrating positive hemodynamic effects as well as a decrease in intracranial pressure induced a study using etomidate during cardiac surgery. This randomized study including 506 patients should prove the influence of etomidate on the rate of psychic disturbances after cardiac surgery. Patients treated with etomidate received a loading dose of 1 mg/kg b.w. etomidate within 15 minutes followed by a continuous infusion of 1 mg/kg b.w./h until the end of ECC. Patients without etomidate were the control group. Psychic disturbances were observed in 25% of the control group and in 30% of the etomidate group. In both groups of patients there was a fair number of patients with perioperative cardiopulmonary problems (artificial ventilation longer than 24 hours; catecholamine therapy: epinephrine greater than 5 micrograms/min longer than 3 hours): 8% in the control group and 20% in the etomidate group. These results indicate that etomidate does not beneficially influence the rate of psychic disturbances after open-heart surgery; it may induce, however, cardiopulmonary side effects after cardiac surgery. The results of recent studies indicating drug induced adrenal insufficiency are discussed.

Adolescent↗

Individual responses to heparinization for extracorporeal circulation.

It has been proposed that wide variations in individual response to heparin lead to deficiencies in popular heparinization protocols for extracorporeal circulation (ECC). Thirty-nine patients undergoing open cardiac operations with ECC were anticoagulated with the heparinization protocol in use at St. Thomas' Hospital. The coagulation state was monitored with the blood activated recalcification time (BART) test. Wide variations in heparin dose-response and heparin activity-decay curves were observed. No patient was underheparinized, but many had markedly prolonged BART's. The total dose of heparin declined because BART monitoring allowed elimination of incremental heparin doses up to 180 minutes of ECC. Adequate reversal with protamine was achieved in all patients regardless of response to herparin. Alternative approaches for heparinization for ECC can be developed with the aid of rapid tests of the intraoperative coagulation state.

Adolescent↗

[High-dose thiopental infusion in cerebral dysfunction following extracorporeal circulation].

Thiopentone (thp) infusion was administered to 33 patients with cerebral dysfunction or convulsions out of 2986 patients operated on via extracorporeal circulation because of valvular disease, coronary insufficiency, septum defects and intrathoracic aortic aneurysms. If phenytoin, diazepam and clonazepam proved ineffective, thp 10-15 mg/kg was injected slowly, followed by infusion of 2-4 mg/kg/h for 0.5-5 days. 9 patients died. 18 survivors had a good recovery, 6 were moderately disabled. In the survivors embolisation of particulate matter prevailed as a cause of cerebral dysfunction while in nonsurvivors prolonged pre- and postoperative hypotension was the main cause, with one patient suffering a hemispheric infarction. The amelioration of convulsions and psychosyndromes in the survivors is compatible with the known anticonvulsive effect of thp and its alleged influence on cerebral focal ischaemia. However, in protracted cerebral hypoperfusion as a cause of cerebral dysfunction no protection can be expected from thp. The known effects of barbiturates do not justify the use of these substances for the purpose of cerebral protection.

Adolescent↗

Direct myocardial revascularization without extracorporeal circulation. Experience in 700 patients.

Between May 1978 and March 1990, 700 patients were operated on with direct coronary surgery without extracorporeal circulation (ECC): 529 (76 percent) were male and 171 (24 percent) were female. The average age was 64 years (range, 35 to 86 years), 454 (65 percent) had unstable angina, 163 (23 percent) had stable angina, 51 (7 percent) had postmyocardial infarction angina, and 32 (5 percent) had acute myocardial infarction at the moment of the operation. In this series of patients, all branches of the coronary arteries were bypassed; the mammary artery was used in 40 percent of the cases, the average bypass per patient was 2.2 (range, 1 to 5), and 26 percent had associated disease of high risk to undergo ECC. The morbidity was 4 percent and the mortality for this series of patients was 1 percent; the probability of survival at seven years was 90 percent. This experience shows us that this surgery is an alternative in the treatment of coronary disease, especially for aged patients with associated disease, in some cases of acute transmural infarction, and also for patients who need coronary angioplasty. Also, it can improve the relation cost/benefit in coronary surgery.

Adult↗

[Aortic arch reconstruction without aortic cross-clamping using separate extracorporeal circulation].

Between March 1991 and October 1992, 21 consecutive patients underwent aortic arch reconstruction without aortic cross-clamping using separate extracorporeal circulation in combination with retrograde blood cardioplegia (Non-clamping selective cerebral perfusion). Twelve patients had true arch aneurysm, 3 had acute aortic dissection and 6 had chronic aortic dissection including 2 redo cases. Cardiopulmonary bypass (CPB) was instituted with an arterial cannula in the femoral artery and 2 cannulae in both vena cavae. When tympanum temperature was lowered to 20 degrees C by central cooling, CBP was stopped temporarily. As soon as the aortic arch was incised longitudinally together with aneurysm, flexible 12 Fr. balloon cannulae were inserted into the three arch arteries via their orifices and selective cerebral perfusion was started. The perfusion flow was kept between 0.3 L/m2/min and 0.35 L/m2/min with the pressure of catheter tip from 30 to 60 mmHg to keep tympanum temperature 18 degrees C. Heart was protected by retrograde continuous cold blood cardioplegia. During arch correction, the descending aorta was occluded by a balloon then abdominal viscera were perfused via a femoral return cannula and rewarming to 25 degrees C was started to prevent visceral organ failure and coagulopathy. The time of separate perfusion ranged 20 to 161 minutes with a mean of 99.9 minutes. Except one patient who died of pneumonia, 20 patient (95.2%) were discharged and doing well. No cerebral complication, myocardial infarction, lung bleeding and coagulopathy occurred. In order to prevent the infarction by debris and to protect vital organs, this method is reliable for aortic arch reconstruction.

Aged↗

[Cerebral oximetry during cardiac surgery under extracorporeal circulation].

The time course of changes in rSO2 were studied in 58 patients during the uncomplicated course of cardiac operations under extracorporeal circulation (EC) and moderate hypothermia. rSO2 was also compared with central hemodynamic parameters, bioelectrical cerebral activity, and hemoglobin oxygen saturation of the bulb of the internal jugular vein (jbSO2). In the pre- and postperfusion period there was a significant correlation of rSO2 and jbSO2 (p = 0.01), yet with a low correlation coefficient (r = 0.348). During EC, no correlation was found between rSO2 and jbSO2 (p = 0.09, r = 0.386). Changes in rSO2, blood pressure, EEC, body temperature were analyzed in 2 groups of patients at the stages of an operation under EC. Group 1 comprised patients with cardiac valvular apparatus lesions and Group 2 included those with coronary heart disease who differed not only in age, but also in the history of mainly cerebrovascular atherosclerotic lesions, hypertensive disease, myocardial infarction, etc. In patients from both groups, a reduction in rSO2 occurred at the beginning of EC and at the maximum of cooling. But if in Group 1 patients, the significant reductions in rSO2 at the beginning of EC coincided both with that in mean blood pressure (BPmean), as compared to the baseline values (from 75.55 +/- 10.68 to 66.5 +/- 11.73 mm Hg, p = 0.01), and with the change in the frequency spectrum of EEC (a decrease in the frequency of the right edge, as compared to the baseline values, from 20.77 +/- 1.44 to 19.58 +/- 1.14 Hz, p = 0.01), in Group 2 patients, all significant decreases in rSO2 were accompanied only by a significant reduction in BPmean, but without changes in the frequency spectrum of EEG. It should be noted that over the uncomplicated course of an operation all changes in rSO2 were in the normal range of age-related values.

Adult↗

[Transcranial Doppler sonography during pulsatile and non-pulsatile extracorporeal circulation].

Transcranial Doppler sonography (TCD) was used to determine the mean blood flow velocity of the middle cerebral artery (Vm-MCA) and pulsatility (systolic/diastolic flow velocity = S/D) in 25 patients undergoing aortocoronary bypass grafting before, during, and after extracorporeal circulation (ECC). Preoperatively, none of the patients had signs or symptoms of cerebrovascular disease. ECC was performed with 2.4 l/min per m2 under mild hypothermia (34 degrees C) using membrane oxygenators. After 20 min of nonpulsatile perfusion, ECC was switched to the pulsatile mode for 20 min. Nonpulsatile perfusion was applied for the remaining ECC period. Vm-MCA, S/D, mean arterial blood pressure (MABP), and nasopharyngeal temperature (T.np) were recorded continuously throughout the operation. Hematocrit and paCO2 were determined before, during, and after ECC. Following hemodilution after the introduction of ECC, Vm-MCA was significantly increased compared with the baseline values before ECC. With hematocrit and paCO2 varying insignificantly during ECC, the onset of pulsatile ECC decreased Vm-MCA and MABP simultaneously. After the re-establishment of nonpulsatile ECC, both Vm-MCA and MABP increased again. However, a linear relationship between the two variables could not be documented statistically. During pulsatile ECC, pulsatility (S/D) of the obtained TCD wave forms did not reach baseline values. In 4 cases, TCD showed cessation of diastolic blood flow velocity after induction of ECC or onset of pulsatile ECC. An increase in MABP or changes in ECC regimen promptly restored diastolic TCD signals in these cases. Our results support the concept of increased cerebral blood flow under mild hypothermic ECC. Compared with the nonpulsatile perfusion mode, we found Vm-MCA reduced during pulsatile ECC.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗