Transcapillary forces of the subcutaneous tissue in patients with coronary artery disease: a comparison between pulsatile and nonpulsatile flow during extracorporeal circulation

The aim of this study was to evaluate subcutaneous transcapillary fluid balance during pulsatile and nonpulsatile extracorporeal circulation (ECC). Changes in the transcapillary fluid balance were studied by measuring subcutaneous interstitial fluid pressure (Pif) using the 'wick in needle' (WIN) method, as well as measuring subcutaneous interstitial fluid colloid osmotic pressure (COPif), using either the wick technique or the blister suction technique. The measurements were performed on the chest wall at the heart level. Simultaneous recordings of plasma colloid osmotic pressure (COPpl) were carried out. Nineteen male patients undergoing aortocoronary bypass grafting were subjected to nonpulsatile flow (group I, n = 11) or pulsatile flow (group II, n = 8) during ECC. Preoperatively there was no difference in the Starling forces between the two groups. During ECC the COP gradient (COPpl-COP if) was reversed to the same extent in the two groups. At three hours and six hours following ECC, COPif in the pulsatile group (12.1 mmHg and 11.4mmHg respectively) was significantly higher than in the nonpulsatile group (10.8mmHg and 10.3mmHg respectively). When weaning from ECC as well as three hours and six hours following ECC, Pif in the pulsatile group was significantly lower than in the nonpulsatile group. Conclusion: in the early postoperative period there is less dilution of the subcutaneous interstitial tissue following application of pulsatile flow during ECC compared to nonpulsatile flow.

Long-term outcomes after transcatheter aortic valve implantation: the impact of intraoperative tissue Doppler echocardiography

OBJECTIVES

Transcatheter aortic valve implantation improves survival in patients with severe aortic stenosis who are ineligible for surgical valve replacement; however, not all patients benefit from the procedure. We endeavoured to identify these patients using intraoperative echocardiography and hypothesized that intraoperative left ventricular function in response to the acute afterload reduction during the procedure was related to long-term outcomes.

METHODS

We prospectively included 64 patients who were scheduled for transcatheter aortic valve implantation and divided them into responders and non-responders based on their left ventricular intraoperative responses to the acute afterload reduction after valve deployment. Responders were defined by increases of ≥20% in left ventricular longitudinal peak systolic velocities determined by tissue Doppler echocardiography. All patients were assessed for the following outcomes at 12 months: cardiac mortality, adverse cardiac events, quality of life, New York Heart Association class, N-terminal pro-brain natriuretic peptide (NT-proBNP) and echocardiography.

RESULTS

Thirty-five patients (55%) were classified as responders and 29 patients (45%) as non-responders. Compared with responders, non-responders had higher risks of death (28 vs 9%, respectively, P = 0.04) and cardiac events (66 vs 26%, respectively, P < 0.01) during the 12-month follow-up. Significant long-term improvements in quality of life, NT-proBNP and left ventricular function were observed only in the responders. Preoperative risk stratification, intraoperative handling, aortic gradient and valve area were similar between groups.

CONCLUSIONS

Intraoperative assessment of left ventricular function by tissue Doppler echocardiography predicted long-term outcomes after transcatheter aortic valve implantation. Our results suggest that a preoperative test of myocardial contractile reserve might improve risk stratification and patient selection prior to the procedure.

Transcatheter aortic valve implantation and intraoperative left ventricular function: a myocardial tissue Doppler imaging study

OBJECTIVE

Transcatheter aortic valve implantation in patients turned down for surgical aortic valve replacement is a high-risk procedure. Severe aortic stenosis is associated with impaired left ventricular longitudinal motion, and myocardial peak systolic velocity is a measure of left ventricular function in these patients. The present study aimed to quantify the acute changes in left ventricular function during the procedure by using myocardial tissue Doppler imaging and transthoracic cardiac output measurements.

DESIGN

Prospective observational study.

SETTING

Tertiary care university hospital.

PARTICIPANTS

40 patients with severe aortic stenosis scheduled for transcatheter aortic valve implantation.

INTERVENTIONS

Transesophageal 4-chamber and 2-chamber echocardiograms were performed immediately before and ~15 minutes after valve implantation. Longitudinal myocardial peak systolic velocity was obtained by tissue Doppler imaging from 8 basal segments and averaged. Cardiac output was measured by the lithium dilution method, and systemic vascular resistance index and stroke volume were calculated.

MEASUREMENTS AND MAIN RESULTS

Longitudinal myocardial peak systolic velocity improved immediately after valve implantation, from -2.3±0.8 to -3.0±1.1 cm/sec (p<0.001); this represented an average increase of 31%±33%. Cardiac output increased from 3.2±0.8 L/min to 3.6±0.9 L/min (15%±33%; p = 0.04). This was due to increased heart rate (59±9 beats/min to 72±12 beats/min; p<0.001) and not to an improved stroke volume. Systemic vascular resistance index was reduced from 2,937±984 dynes*sec/cm(5)/m(2) to 2,436±730 dynes*sec/cm(5)/m(2) (p = 0.003).

CONCLUSION

Intraoperative echocardiography tissue Doppler imaging detected immediate improvement in left ventricular long-axis motion after transcatheter aortic valve implantation. The method provided detailed information not obtainable by routine hemodynamic monitoring.

Cerebral Ischemic Injury and Cognitive Impairment After Off-Pump and On-Pump Coronary Artery Bypass Grafting Surgery

BACKGROUND

Off-pump coronary artery bypass grafting surgery reduces the intraoperative cerebral embolic load and may therefore cause less brain injury. The main aim of this study was to compare off-pump and on-pump surgery with regard to the frequency of new postoperative cerebral ischemic lesions and the prevalence of postoperative cognitive impairment. We also assessed whether preoperative cerebral ischemic injury predicts the risk for cognitive dysfunction after surgery.

METHODS

One hundred twenty patients with ischemic coronary artery disease were prospectively randomized to undergo off-pump or on-pump surgery. A detailed neuropsychological assessment and a cerebral magnetic resonance imaging examination were performed on the day before and at 3 months postoperatively. The neuropsychological assessment was repeated at 12 months.

RESULTS

There was no significant (p = 0.17) difference between off-pump (8.2%) and on-pump (17.3%) surgery with regard to new postoperative cerebral lesions. The prevalence of cognitive impairment after surgery was also similar in the two groups (3 months: off-pump 20.4%, on-pump 23.1%, p = 0.74; 12 months: off-pump 24.1%, on-pump 23.1%, p = 0.90). The degree of preoperative cerebral ischemic injury was significantly associated with cognitive dysfunction after on-pump (p = 0.02) but not after off-pump (p = 0.22) surgery. None of the patients with normal preoperative radiologic findings were found to have cognitive impairment at 3 months postoperatively (p = 0.04).

CONCLUSIONS

Long-term cognitive function and magnetic resonance imaging evidence of brain injury were similar after off-pump and on-pump coronary artery bypass grafting surgery. Preoperative cerebral magnetic resonance imaging can be used to predict the risk for cognitive dysfunction after coronary artery bypass grafting surgery.

Patient-Reported Outcome After Randomization to On-Pump Versus Off-Pump Coronary Artery Surgery

BACKGROUND

Clinical experience with off-pump coronary artery bypass surgery raises the question of a patient experienced benefit compared with on-pump surgery. This prospective and randomized study compared patient-reported outcome between surgical groups, as change scores at 3 months after surgery and longitudinally as time-averaged change from baseline through the first year after surgery.

METHODS

In all, 120 patients were randomly assigned to on- or off-pump coronary artery surgery. A questionnaire for patient self-report of angina (Canadian Cardiovascular Society scale), health status (Short Form 36, sleep and sexual difficulty), and overall quality of life (Quality of Life Scale) was administered at baseline and at 3, 6, and 12 months after surgery.

RESULTS

Patient groups were comparable with regard to age, symptoms, comorbidity, and surgical characteristics. Both groups experienced a median of two classes relief of angina at 3 months (p < 0.0005), maintained throughout follow-up. Paired t tests revealed significant improvement on all Short Form 36 subscales at 3 months after surgery, with the exception of physical role functioning in the on-pump group. No independent main effects of surgical group were observed in the between-groups covariance models. The longitudinal effect of sex was significant in four Short Form 36 subscales: physical functioning, bodily pain, and role limitation due to physical or emotional problems. Overall quality of life scores were stable in both groups.

CONCLUSIONS

Both on-pump and off-pump patients reported less angina and improved health status after surgery. There were no significant differences between surgical groups in health status or overall quality of life, neither cross-sectionally nor longitudinally.

Graft control by transit time flow measurement and intraoperative angiography in coronary artery bypass surgery

BACKGROUND

The aim of this study was to compare the relationship between intraoperative transit time flow measurements and angiographic findings with long-term graft patency in 72 patients who underwent coronary artery bypass surgery.

METHODS

Transit time flow measurements with recording of mean flow and pulsatility indexes were performed after completion of the anastomoses. Coronary angiography was performed on-table while the patients were still in general anesthesia, and then at follow-up three months and 12 months after surgery. Based on angiography, the grafts were graded as type A (fully patent), type B (having more than 50% diameter reduction), or type O (occluded).

RESULTS

Of the 67 left internal mammary artery (LIMA) grafts, 51 (76%) were type A on-table, 14 (21%) were type B, and two (3%) were type O. Of the 57 saphenous vein grafts, 49 (86%) were type A, 7 (12%) were type B, and one (2%) was type O. For both LIMA and vein grafts, there were no differences in flow (p = 0.69 and 0.47, respectively) or pulsatility index (p = 0.79 and 0.83) between type A and B. There were also no differences in flow (p = 0.37 and 0.7) or pulsatility index (p = 0.37 and 0.24) between type B on-table that either normalized or persisted occluded at the follow-up. Transit time flow measurement failed to detect an occluded LIMA graft as shown by intraoperative angiography.

CONCLUSIONS

Blood flow measurements performed intraoperatively could not identify significant lesions in arterial or vein grafts, and could not predict graft patency. We have become cautious in interpreting flow measurements alone and combine blood flow recordings with intraoperative angiography in the assessment of graft quality.

Heparin-coated circuit during cardiopulmonary bypass. A clinical study using closed circuit, centrifugal pump and reduced heparinization

A prospective randomized study was performed to investigate the effect of surface coating with covalently endpoint-attached heparin (Carmeda Bio Active Surface) and reduced general heparinization on haematological indices and complement C5 activation. Care was taken to optimize the rheological design of the system using centrifugal pump and a closed system without venting or machine suction. Twenty patients scheduled for aortocoronary bypass grafting (EF > 0.5) participated in the study. Ten patients were randomized to be treated with heparin-coated equipment (CBAS) and reduced i.v. heparin (1.5 mg.kg-1) while 10 patients treated with identical but noncoated equipment and full heparinization (3 mg.kg-1) served in a Control group. A vacuum suction was used to collect the blood from the operating field and it was autotransfused at weaning from extracorporeal circulation (ECC). Blood samples were obtained from the venous (precircuit) and arterial (postcircuit) side. We used a new and very specific method for detection of C5a based on monoclonal antibodies. The concentration of C5a was low in both groups during the operation but a significant increase was seen on days 1 and 2. In the Control group there was an increase from 10.2 ng.ml-1 +/- 1.2 to 27.5 ng.ml-1 +/- 4.8 on day 2 and in the CBAS group from 10.7 ng.ml-1 +/- 1.2 to 35.6 ng.ml-1 +/- 11.6 on day 2 (NS between groups). The granulocytes and total leukocyte count increased at the end of ECC and was maintained at the elevated level throughout the study period. The amount of free haemoglobin was high in the autotransfused blood in both groups.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise hemodynamics in small (< or = 21 mm) aortic valve prostheses assessed by Doppler echocardiography

Exercise Doppler echocardiography was used to assess hemodynamics in 25 patients with a < or = 21 mm aortic valve prosthesis (14 with a Medtronic-Hall 21 mm valve, three with a Medtronic-Hall 20 mm valve, three with a Sorin 21 mm valve, one with a Duromedics 21 mm valve, and four with a Carpentier-Edwards 21 mm valve). A symptom-limited upright bicycle exercise test was performed, and Doppler gradients were recorded during exercise. Gradients increased with exercise from 30 +/- 8/16 +/- 4 mm Hg (peak/mean) at rest to 46 +/- 12/24 +/- 7 mm Hg during exercise; both p < 0.001. Mean exercise gradient exceeded 30 mm Hg in five patients, and the highest mean gradient recorded was 37 mm Hg. Within the group of mechanical valves, gradients at exercise were similar for different types of valves. A linear relationship was found between gradients at rest and during exercise (peak r = 0.75, mean r = 0.77; both p < 0.001). Additional findings were midventricular velocities exceeding 1.5 m/sec in late systole in 10 patients (40%) and intraventricular flow (> or = 0.2 m/sec) toward the apex during isovolumic relaxation in 11 patients (44%). The patients with these velocity patterns had significantly smaller left ventricular cavities (end-diastolic diameter 39.8 +/- 4.8 vs 46.5 +/- 4.2 mm, p < 0.01; end-systolic diameter 24.2 +/- 3.0 vs 28.5 +/- 4.5 mm, p = 0.013).(ABSTRACT TRUNCATED AT 250 WORDS)

The influence of thoracic epidural analgesia on transcapillary fluid balance in subcutaneous tissue. A study in patients undergoing aortocoronary bypass surgery

Clinical observation and calculation of fluid balance have shown that patients undergoing aortocoronary bypass surgery with thoracic epidural analgesia (TEA) in addition to general anesthesia retain less fluid than patients having general anesthesia only. The present study was designed to investigate whether this effect could be explained by thoracic epidural analgesia influencing the transcapillary fluid balance, i.e. the transcapillary forces (COPpl, COPif, Pif). Interstitial fluid colloid osmotic pressure (COPif) and interstitial fluid pressure (Pif) were measured subcutaneously at heart level by the blister suction technique and the wick-in-needle technique, respectively. Simultaneously plasma colloid osmotic pressure (COPpl) was recorded. Sixteen male patients were allocated to two groups, one having general anesthesia only (controls, n = 8). The other group (TEA, n = 8) received, at the induction of anesthesia, bupivacaine 50 mg via an epidural catheter as an adjunct to general anesthesia. TEA was maintained by continuous infusion for 24 h postoperatively. Preoperatively no intergroup differences were observed in "the Starling forces" (COPpl, COPif, Pif). At the start of extracorporeal circulation COPpl was significantly lower in the TEA-group than in controls. During extracorporeal circulation the transcapillary COP-gradient (COPpl-COPif) was reversed in both groups. At the end of extracorporeal circulation Pif increased to a minor degree in the TEA-group and remained significantly lower than in controls from 3 to 24 h postoperatively. The subcutaneous interstitial tissue could be less expanded postoperatively in the TEA-group, also reflected by a lower increase in Pif.

Time-related changes in the Starling forces following extracorporeal circulation

The intra- and postoperative variations of the transcapillary forces [colloid osmotic pressure of plasma (COPpl), colloid osmotic pressure of interstitial fluid (COPif), average hydrostatic pressure in the interstitium (Pif)] were studied in the subcutaneous tissue as a function of time in 13 patients operated on for coronary artery disease using extra-corporeal circulation (ECC). The measurements were performed before operation, during ECC, and during the first 24 hours postoperatively. COPif was measured subcutaneously on the chest both by the wick method and by a noninvasive blister suction method. The latter technique allowed several consecutive measurements in the same individual during the postoperative period. Pif was measured by "wick-in-needle" technique in the same area as the COPif measurements. COPpl was measured in a blood sample collected from a cubital vein. COPpl was reduced about 50% during ECC returned to pre-ECC level within the first 6 hours postoperatively. During ECC COPif was higher than COPpl, reaching its minimum level 4 to 5 hours postoperatively. Measurements performed following ECC showed return of the transcapillary COP-gradient to the normal direction (COPpl greater than COPif). Pre-ECC level of COPif was not entirely obtained during the first postoperative day. Pif increased gradually during ECC and continued to increase the first 2 to 3 hours following ECC. Pre-ECC level was reached within 24 hours postoperatively. The present investigation has demonstrated major dynamic variations in the transcapillary forces in patients undergoing open heart surgery with ECC. There was an increased net capillary filtration (F) intraoperatively predisposing to interstitial edema formation in subcutaneous tissue until several hours following the termination of ECC.

Interstitial fluid colloid osmotic pressure of the subcutaneous tissue in controls and patients before and after open-heart surgery: a comparison between the wick technique and the blister suction technique

The purpose of this study was to compare the blister suction technique and the wick technique for measuring interstitial colloid osmotic pressure of subcutaneous tissue (COPif). Eight healthy volunteers and 14 patients undergoing aortocoronary bypass using extracorporal circulation (ECC) were included in the investigation. Colloid osmotic pressure was measured in fluid collected either from blisters (COPbl) developed by application of subatmospheric pressure to the chest skin, or from nylon wicks (COPw) implanted subcutaneously on the chest in the same area as the blisters were formed. Colloid osmotic pressure was then recorded on a colloid osmometer made for 5 microliter samples. In the patients, the measurements were performed 12-18 h pre-operatively (mean 15 h) and, on average, 4 h (range 1.5-7 h) following termination of extracorporal circulation. In the control subjects as well as in the patients, COPbl was significantly lower than COPw. However, the two types of measurements were found to change in the same direction, as a highly significant positive correlation exists between the two methods.

Transcapillary fluid balance in subcutaneous tissue of patients undergoing aortocoronary bypass with extracorporeal circulation

Colloid osmotic pressure in plasma (COPpl) from a cubital vein and in interstitial fluid (COPif) in the subcutaneous tissue at heart level, and interstitial fluid pressure (Pif) at the same level, were measured in 18 healthy subjects and in 28 patients requiring aortocoronary bypass. Interstitial fluid was collected via subcutaneously implanted double nylon wicks and Pif was measured with the 'wick-in-needle' technique. Measurements were made preoperatively and 1 1/2 to 8 hours (mean 4 hours) after termination of extracorporeal circulation. Pif rose to 2.3 mmHg above the pre-bypass level. COPpl concomitantly fell from 22.2 to 14.4 and COPif from 12.4 to 10.1 mmHg. These changes were statistically significant. Although the relatively large COPpl drop resulted in a net rise of 3.2 mmHg in filtration pressure, the incidence of pulmonary complications was low and no subcutaneous edema was discernible. The fall in COPif and rise in Pif may be regarded as important edema-preventing mechanisms.

Surgical treatment of aneurysms of the descending thoracic aorta

Six patients were operated on for aneurysm of the descending thoracic aorta in 1983-1985 by use of simple cross-clamping and interposition of a Dacron tube graft without extracorporeal circulation. The aneurysm had ruptured in three cases. The patients' mean age was 69 years. Anesthesia and muscle relaxation were obtained by drugs with only minor myocardial depressant action. There was no postoperative mortality or morbidity. Five of the patients have been followed up for at least a year. Careful pharmacologic control of the blood pressure is essential during such surgery. Despite the smallness of the series, it indicates that simple cross-clamping and Dacron graft interposition can be used for treatment of aneurysm of the descending thoracic aorta.

[Histological and bacteriological examination of uterus from the repeat breeder gilt and sow (author's transl)]

The investigation comprised sexual organs from 25 gilts and 97 sows culled because of repeat breeding. Among the gilts 24.0 per cent and among the sows 25.8 per cent had endometritis. The following germs were present in uterus from gilts and sows with signs of endometritis: Staphylococcus aureus, Corynebacterium pyogenes, alpha-hemolytiske streptococcer, Escherichia coli, Pasteurella sp., Aeromonas sp., Acinetobacter sp. and Citrobacter sp. Among gilts and sows with germs present in uterus 40.9 per cent had endometritis. The corresponding per cent among gilts and sows without germs present was 25.0.

Arsenite inhibits beta-oxidation in isolated rat liver mitochondria

A partial inhibition of acylcarnitine oxidation by arsenite in rat liver mitochondria has been studied. This inhibition is confined to the thiolase(s). The inhibition was observed also in the presence of malate, indicating no selective effect on ketogenesis. Ketogenesis from acetyl-CoA was inhibited by arsenite. Mitochondrial CoA was acylated by acylcarnitine nearly as rapidly in the presence of arsenite as in its absence. Thus, arsenite did not interfere with the availibility of CoA in the mitochondria. No effect of arsenite on enzymes of beta-oxidation other than the thiolase(s) was observed. When arsenite and acylcarnitine were added simultaneously to mitochondria, there was a delay before maximal inhibition of oxygen uptake occurred. When the mitochondria were preincubated with arsenite before addition of acylcarnitine, the inhibitory effect on oxygen utilization was initially large, but then partially repealed. Similar time delays were observed in the activity of acetoacetyl-CoA thiolase of disrupted mitochondria depending on the sequence of arsenite and acetoacetyl-CoA addition. It is suggested that substrate and arsenite complete for the reactive sulfhydryl group at the active site of the thiolase(s).