Efficiency of different hollow-fiber hemofilters in continuous arteriovenous hemodiafiltration.

Low dialysate to blood flow rate ratios are a unique characteristic of continuous arteriovenous hemodiafiltration (CAVHDF) that should allow complete saturation of dialysis fluid with small-molecular-weight blood solutes. The aim of the investigation was to evaluate the performance of different hemofilters in CAVHDF. In 10 critically ill patients with acute renal failure, the efficiency of four hollow-fiber hemofilters, polyamide 0.6 m(2), polyacrylonitrile (PAN) 0.3 and 0.6 m(2), acrylonitrile sodium methallylsulfonate (AN69HF) 0.6 m(2), has been evaluated. For comparison, dialysate flow rates (Q(di)) were standardized to 16.6 and 25 ml/min. Samples for urea nitrogen were obtained from the arterial blood line (C(bi)) and from the dialysate exit port (C(do)) within 24-hour running time. Outflowing dialysate (Q(do)) was also measured at the same time. Blood flow (Q(b)) was calculated by the bubble transit time technique. Diffusive and total urea clearances were determined. AN69HF and PAN hemofilters provided higher clearances than the polyamide hemofilter. Despite the smaller surface area, PAN 0.3 m(2) had a total urea clearance comparable to that of PAN 0.6 m(2) and AN69HF at Q(di) = 16.6 ml/min. While at Q(di) = 16.6 ml/min equilibrium between blood and dialysate (C(do)/C(bi) congruent with 1) occurred with the AN69HF and PAN hemofilters, at Q(di) = 25 ml/min the equilibrium was obtained only with the AN69HF hemofilter. In conclusion, almost complete urea saturation of dialysis fluid has not been obtained with all hemofilters tested here. In our experience, membrane characteristics play an important role in determining diffusive efficiency in CAVHDF.

Repair of intramural hematoma of the ascending aorta without graft interposition.

A 68-year-old woman was admitted to hospital with a one-hour history of chest pain and syncopal episode. Transesophageal echocardiography showed an intramural aortic hematoma with cardiac tamponade. The patient underwent repair of the ascending aorta without graft interposition (resection and end-to-end anastomosis). The patient had an uneventful postoperative course and the 38-month follow-up was event-free. This case report shows that end-to-end anastomosis in patients with intramural hematoma and absence of intimal tearing, may provide good long-term results.

[Weaning in cardiopulmonary bypass patients with compromised cardiac function. Comparison of enoximone and dopamine]. / Weaning dal bypass cardiopolmonare di pazienti coronaropatici a funzionalità cardiaca compromessa. Confronto tra enoximone e dopamina.

OBJECTIVE: Evaluate the effects of enoximone and dopamine in patients with impaired left ventricular function after cardiopulmonary bypass (CPB). DESIGN: Prospective study on a consecutive series of patients subdivided into two groups: enoximone (Group E) and dopamine (Group D). SETTING: Policlinico Umberto I, University La Sapienza of Rome. PATIENTS AND METHODS: Thirty patients undergoing elective myocardial revascularization. Before weaning from CPB the patients received inotropic drugs as follows: Group E: enoximone: bolus: 1 mg/kg in 10 min, and continuous infusion of 5 mcg/kg/min; Gruppo D: dopamine: continuous infusion of 5 mcg/kg/min. Hemodynamic measurements were made using a Swan-Ganz catheter inserted before the induction of anaesthesia. RESULTS: Enoximone has proved to be effective in decreasing pre-load and after-load of both right and left ventricle by a positive lusitropic effect and a reduction of systolic stress, thereby increasing the cardiac index. In group D patients maintenance of cardiac output has been demonstrated to be dependent on a chronotropic effect. As a consequence in group D the increase in rate-pressure product has reached potentially dangerous values, reflecting a marked increase in myocardial oxygen consumption. On the contrary in Group E the increase in rate-pressure product has been much more limited. Finally both drugs have proven effective, since all patients have been easily weaned from CPB. CONCLUSIONS: Enoximone is a useful and easily-handled drug to facilitate weaning from CPB of patients with preoperative impaired ventricular function.

The shape of human atrial action potential accounts for different frequency-related changes in vitro.

We aimed at investigating frequency-related changes of human atrial action potential (AP) in vitro to see whether baseline AP shape might account for different responses to increasing stimulation rates. Human right atrial trabeculae (n = 48) obtained from adult (n = 38, mean age 59 +/- 8, range 45-72 years) consecutive patients (approximately equal to 30% of those operated upon by a single surgeon; 1.26 preparations per patient, range 1-2) were superfused in an organ bath with oxygenated (O2 content 16 ml/l) and modified (NaHCO3 25.7 mmol/l) Tyrode's solution at 31 degrees C. Baseline electrophysiology (pacing: 1 ms duration, 2-4 mA current intensity) at cycle length (CL) of 1000 ms was recorded in 90% (43 out of 48) of the preparations. The frequency-related protocol (CL from 1600 to 300 ms) was, however, undertaken in 23 (48%) preparations because 20 (42%) became pacing unresponsive immediately after baseline recordings. No statistical differences were seen when baseline electrophysiological parameters (mean +/- SD) were grouped according to late pacing responsiveness (n = 43 vs. n = 23): respectively, resting membrane potential (RMP) was -74 +/- 6 vs. -75 +/- 4 mV, maximal upstroke velocity (Vmax) 172 +/- 60 vs. 173 +/- 39 V/s, AP amplitude (APA) 89 +/- 11 vs. 91 +/- 8 mV and AP durations were at 30% (APD30%) 10 +/- 13 vs. 13 +/- 18 ms, 50% (APD50%) 45 +/- 79 vs. 62 +/- 91 ms and 90% (APD90%) 383 +/- 103 vs. 407 +/- 108 ms. To classify baseline AP shape, two criteria were adopted: criterion 1 ("objective"), based on APA (cut-off 90 mV) and APD90% (cut-off 500 ms) computed values and criterion 2 ("visual") derived from the literature. These criteria enabled us to differentiate three AP shape types: type 1 (spike and dome), type 3 (no dome) and type 4 (extremely prolonged). At baseline, the two criteria diagnosed different proportions of AP shape types. There were, however, no intra-type statistical differences among electrophysiological parameters. By criterion 1, analysis of variance (ANOVA) showed significant inter-type differences of RMP,Vmax, APA, APD50 and 90% and by criterion 2 of APA, APD30, 50 and 90%, respectively. To facilitate comparisons with previous published data, criterion 2 was selected to analyse frequency-related changes of AP shape types. At low stimulation rate, ANOVA for repeated measures (with Greenhouse-Geisser epsilon correction) showed inter-type differences for APD30, 50 and 90% (P = 0.00005). RMP, Vmax, APA and APD90% were overall frequency-related (P = 0.00005). Inter-type frequency-related differences were however seen only for APD90%. Human atrial AP durations (30, 50 and 90%) enable differentiation among AP shape types (1, 3 and 4). By a standardized use-dependent protocol overall RMP, Vmax, APA and APD90% are frequency-related. AP shape accounts for frequency-related changes of APD90% only. A type 4 AP shape with much prolonged AP duration had a flat frequency dependence. At high stimulation rates, adult type 1 and 3 AP shapes are indistinguishable. Use-dependent and pharmacological investigations in human atrial myocytes need to take AP shape into account.

Activation or block of adenosine triphosphate-sensitive potassium channel have opposite effects on postcardioplegic myocardial dysfunction, "stunning". A multivariate prediction based on relative operating characteristic curve.

The relative effects of nicotinic acid (NA) and nitroglycerin (NT) added to cold high K+ cardioplegia were studied, to represent the two moieties of the adenosine triphosphate-sensitive potassium channel (KATP) activator nicorandil (N). In addition, we made a pooled analysis of a large series of experiments performed in our Laboratory to investigate the effects of KATP activation by N, or block (by glibenclamide, G), on postcardioplegic myocardial dysfunction. In both studies, reversibility from myocardial dysfunction (stunning) was assessed by the positive inotropic agent dobutamine. Guinea pig papillary muscle preparations were immersed in Tyrode's solution (O2 content 16 ml/l, 37 degrees C), then hypoxic (O2 content 5 ml/l) superfusion with hypothermic (20 degrees C) cardioplegic Saint Thomas' Hospital solution (STHS) was performed for 120 min. We investigated: A) 5 groups based on treatments added to STHS: 1) saline (Control (C)); 2) N = 1 mmol/L; 3) G = 1 mumol/L (also given for 15 min in Tyrode's solution); 4) NA = 1 mmol/L; 5) NT = 100 mumol/L; B) 76 consecutive experiments and we defined, independent of whether just before or during STHS: 1) KATP activation (by N, in the concentration range 1 mumol/L to 1 mmol/L, n = 36); 2) KATP block (by G 1 mumol/L, either alone or just before N, n = 20); 3) controls (n = 20) (either saline, n = 12, or saline plus dimethyl sulfoxide, as vehicle, at the ratio 100 to 1, n = 8). Absolute isometric contractility variables were evaluated along with percent changes of baseline values: 1) at 30 s of STHS, 2) after 60 min of reoxygenation with Tyrode's solution and 3) following further 15 min of dobutamine 10 mumol/L. In all preparations, developed tension (DT), time to peak tension (TPT), DT/TPT and time to arrest (TTA) were measured. In study A): TTA was significantly abbreviated (intergroup F = 5.79, p < 0.001) in N (49 +/- 11 s, mean +/- SD) p < 0.01 vs C and NA). At 30 s of STHS %DT/TPT was unchanged among groups. By contrast, after 60 min of reoxygenation %DT/TPT in N (118 +/- 35%, p < 0.05 vs C, p < 0.01 vs G) was improved (intergroup F = 5.48, p < 0.002). G, NA and NT showed recovery of contractility similar to C. However, after dobutamine the poorest %DT/TPT were seen in G (p < 0.01 vs C, p < 0.05 vs N). In study B): using the multivariate logistic model, with KATP activation, the odds of normal contractile response, respectively at 60 min of reoxygenation (t = 2.81) and after dobutamine (t = 3.22), were 29.8 and 8.86 of controls, whereas TTA (t = -1.59) was inversely related. Moreover, with KATP block the odds after dobutamine was 0.204 of controls. The relative operating characteristic plots showed areas under the curve greater than 0.7, which is evidence for accurate assessment of the predictive rules adopted. This is the first report where a probabilistic approach to cardioplegia-related experiments showed high accuracy in predicting the recovery of post-hypoxic contractile function (stunning). The results indicate that on postcardioplegic stunning: 1) KATP activation by N and KATP block by G (both given prior to or contemporary with hypoxia) have opposite effects; 2) the favorable effects of nicorandil seem unrelated to its nicotinamide or nitrose moieties.

In-vitro effects of cardioplegic solutions on human saphenous vein endothelium--a scanning electron microscopy study.

In order to evaluate the effects of potassium cristalloid cardioplegic solutions (CPS) on the endothelial morphology, human saphenous veins were studied by scanning electron microscopy after exposure to three CPS named MKP (magnesium-potassium-procaine cardioplegia), LK (low-potassium cardioplegia), and HKA (high-potassium-albumin cardioplegia) and to their main components. Vein rings, selected from the saphenous veins sampled for graft harvesting in 63 patients undergoing aorto-coronary bypass surgery, were exposed for 30, 60, and 120 minutes to the following buffered solutions: Krebs bicarbonate (as control); MKP cardioplegia; KCl (16.0 mmol/L); MgCl2(2).6H2O (16.0 mmol/L); Procaine (0.05 mmol/L); NaCl (92.5 mmol/L); LK cardioplegia; KCl (10.0 mmol/L); Mannitol (74.3 mmol/L); Glucose (27.7 mmol/L); HKA cardioplegia; KCl (30 mmol/L). Severe endothelial lesions, consisting of diffuse disendothelialization and diffuse signs of endothelial suffering, were induced by KCl (30 and 16 mmol/L) after 60-120 min, and by MKP cardioplegia and KCl (10 mmol/L) after 120 min. Moderate endothelial lesions, characterised by diffuse endothelial surface changes and focal cellular loss, were induced by KCl (30 and 16 mmol/L) after 30 min, MKP cardioplegia and KCl (10 mmol) 30-60 min, LK cardioplegia, HKA cardioplegia, and MgCl2.6H2O after 120 min. Slight endothelial lesions, consisting of diffuse endothelial bulging, or absence of significant endothelial changes, were found in samples otherwise treated. Our findings showed a significant damaging effect of CPS on the human saphenous vein endothelium in-vitro. The endothelial lesions seemed related to the presence of potassium and magnesium, and to prolongation of the time of exposure to the cardioplegic solutions.(ABSTRACT TRUNCATED AT 250 WORDS)

Evidence for sympathetic neurotransmission through presynaptic N-type calcium channels in human saphenous vein.

1. The specific type(s) of voltage-sensitive calcium channels (VSCCs) involved in sympathetic neurotransmission have not yet been characterized in human vascular tissues. We therefore examined the functional role of the N- and L-type VSCCs in human saphenous veins. 2. Contractile response curves for transmural nerve stimulation (TNS) and for exogenously administered noradrenaline (NA) were obtained in superfused saphenous vein rings. The contractions induced by TNS, but not by NA, were inhibited by 1 microM tetrodotoxin and by 10 microM guanethidine. Both responses were substantially reduced by 1 microM phentolamine, indicating that the contractions evoked by TNS were mediated by endogenous NA released from noradrenergic nerves. 3. In the presence of 2 microM omega-conotoxin GVIA (omega Conus Geographus toxin, fraction VI A; omega-CgTx), a polypeptide with specific inhibitory activity on N- and L-type calcium channels, the neurally evoked contractions were almost completely abolished. In contrast, the responses induced by exogenous NA were not affected by the neurotoxin, thus providing evidence of the exclusive presynaptic action of omega-CgTx. 4. In the presence of the calcium antagonist verapamil (10 microM), which selectively blocks L-type VSCCs, the contractions induced by both TNS and NA were diminished to the same extent, suggesting that the organic calcium blocker is active only at the postjunctional level. 5. It is concluded that N-type calcium channels are the main pathway of calcium entry controlling the functional responses induced by activating sympathetic nerves; the role of L-type channels appears to be limited to the postjunctional level, modulating smooth muscle contractions.

Immunodetection of human atherosclerotic plaque with 125I-labeled monoclonal antifibrin antibodies.

To test the affinity of a new F(ab')2 monoclonal antibody (TRF1) against human fragment D dimer of cross-linked fibrin for atherosclerotic plaques free of detectable thrombi, 6 atherosclerotic segments of carotid and femoral artery, and as a control 5 segments of atherosclerosis-free internal mammary artery, were drawn from 11 male patients undergoing bypass surgery. All segments were carefully washed in order to remove possible endoluminal thrombi, and cut to obtain pairs of intimal fragments of similar weight, containing either plaques (n = 16), or fatty streaks (n = 12), or normal endothelium (n = 20). Each fragment underwent a direct binding test to TRF1, or to a non-specific antibody, both labeled with 125I. The activity in each fragment was measured after 3 h of incubation at 37 degrees C, and after washing the fragments every hour for 3 h. TRF1 binding (as percentage of initial activity) was significantly higher (P < 0.001) in atherosclerotic than in normal fragments (26% +/- 11.5%, vs. 9.2% +/- 3.9% in fatty streaks, and 1.9% +/- 0.6% in normal endothelium), and indirect immunofluorescence confirmed TRF1 uptake within the plaque wall. By contrast, the non-specific antibody did not show any significant binding. These preliminary results demonstrate the high specific affinity of TRF1 for atherosclerotic plaques, probably due to the hemorheologic phenomena that activate platelets and provoke the formation of fragment D dimers of cross-linked fibrin on the plaque surface.

Renal function in patients undergoing cardiopulmonary bypass operations.

We evaluate short- and long-term effects on renal functional reserve of cardiopulmonary bypass in 11 patients. A selected group (persistence of renal functional reserve before operation) of 11 adult patients undergoing cardiopulmonary bypass for aorta-coronary bypass were studied. Renal functional reserve tests were performed in all patients before the operation, at postoperative day 9, and at 6 months after operation. Basal glomerular filtration rate did not show significant changes at 9 days and at 6 months after operation. On the contrary, renal functional reserve was absent at 9 days, but it was restored to preoperative levels at 6 months after operation. In conclusion, our data indicate that cardiopulmonary bypass probably causes renal damage that is not sufficient to influence routine renal function parameters.

Effects of cardioplegic solutions and their components on human saphenous vein contractility.

Cardioplegic solution administration into the vein graft is an established method to ensure cardioplegic distribution beyond coronary artery stenoses. The ultrastructural demonstration of severe endothelial damage after cardioplegic exposure suggests that intravenous cardioplegic administration can contribute to early and late graft thrombosis. The direct effect on human saphenous vein contractility of three cardioplegic solutions and their components was compared. A solution with 30 mmol/L K+ and 82 mmol/L Na+ produced intense venoconstriction. Lowering the potassium level to 10 mmol/L and increasing the sodium level to 92 mmol/L reduced its vasoconstricting action. A third solution with 16 mmol/L K+, 16 mmol/L Mg2+, and lidocaine caused venodilatation. Analysis of the single component effects showed that high potassium level, low sodium level, and the addition of lidocaine produced concentration-dependent vasoconstriction. High magnesium concentration resulted in vasodilatation. The present data suggest that cardioplegic solution composition may cause marked vasomotor effects on saphenous vein and thus influence its endothelial integrity. In the search for an "ideal solution" to the cardioplegic controversy, a venoconstrictor infusate should be avoided to improve patency rates of coronary artery bypass grafts.

[THe surgical treatment of aneurysmatic lesions of the ascending aorta: the immediate and long-term results in 40 patients]. / Trattamento chirurgico delle lesioni aneurismatiche dell'aorta ascendente: risultati immediati e a distanza in 40 pazienti.

From January 1981 to January 1991, 40 patients underwent operation for acute ascending aorta dissection (AAD, 14 patients), chronic ascending aorta dissection (CAD, 9 patients) or aortic ectasia (AE, 17 patients), with simultaneous aortic valve replacement in 30 cases (75%). Average age was 54 years with a 3:1 M/F ratio. In 20 cases (50%) a composite graft bearing a mechanical bileaflet valve was inserted with coronary artery reattachment (Bentall operation). In 16 cases (40%) the ascending aorta was replaced by a woven dacron graft alone (7 cases) or associated with aortic valve substitution (7 cases) or resuspension (2 cases). In 1 case (2.5%) a sutureless ring graft replacement of ascending aorta was carried out and 3 patients (7.5%) underwent aortoplasty with aortic valve substitution. Postoperative mortality rate was 21% for AAD group, 11% for CAD group and 6% for AE group. Non-fatal postoperative complications developed in 36% of AAD patients and in 78% and 29% of CAD and AE patients respectively. These complications occurred in 45% of patients who underwent Bentall operation, in 44% of those who underwent ascending aorta replacement associated with aortic substitution or resuspension, and in 14% of those operated of simple ascending aorta replacement. Average follow-up was 41.6 months (range 1.7-107.4 months). During this period 5 deaths occurred for a long-term mortality rate of 14.2%. Out of 30 survivors 21 (70%) underwent CT-study to evaluate the natural course of the false channel and the risk of redissection or late aneurysm formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Ultrastructural changes of coronary artery endothelium induced by cardioplegic solutions.

Coronary artery endothelial and myocardial ultrastructure was studied in guinea-pig heart-lung preparations (HLP) subjected to ischemic cardiac arrest induced by three hypothermic solutions. Two of the solutions used had high potassium chloride concentration ("Alabama" and "St. Thomas") while the third, instead, was a bicarbonate buffer (Kreb's solution). Five experimental groups were studied. In group 1 (control) the HLP were not subjected to cardiac arrest. Groups 2, 3, and 4 were subjected to a period of cardiac arrest of 30, 60, and 120 minutes respectively. In group 5, HLP were reperfused with blood for 30 minutes after 60 minutes of cardiac arrest. A thin ring of the left anterior descending coronary artery and myocardial fragments were obtained at the end of each experiment and were analyzed by means of transmission electron microscopy (TEM). Functional parameters were recorded in group 5. HLP perfused with Alabama solution showed a well-preserved endothelium and myocardium. HLP perfused with Krebs solution showed slight changes of the endothelial glycocalix only in group 4. Further, HLP perfused with Krebs solution showed extensive myocardial lesions (groups 3 and 4). These ischemic changes were not completely reversed after reperfusion (group 5). HLP perfused with St. Thomas solution showed only endothelial changes. These lesions were mainly characterized by: disappearance of the glycocalix and pynocytotic vesicles, endothelial cell bulging (group 2), and loss of the endothelial continuity (groups 3, 4, and 5). Hemodynamic parameters were significantly changed only in the Krebs-perfused HLP which showed a deterioration of the cardiac function related to the ischemic damage.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of uncomplicated coronary artery bypass graft surgery on global and regional left ventricular function at rest. Study by equilibrium radionuclide angiocardiography.

To evaluate the effects of uncomplicated revascularization surgery on resting global and regional left ventricular function we studied 34 patients, enrolled consecutively, by radionuclide angiocardiography. After surgery, we found no significant change in global left ventricular ejection fraction; this was true even in the subgroup of 14 patients who developed paradoxical septal motion. This finding indicates that the development of paradoxical septal motion after uncomplicated cardiac surgery does not compromise global left ventricular function. Both in the subgroup of patients with paradoxical septal motion and in the subgroup without paradoxical septal motion regional ejection fraction calculations showed the same postoperative pattern consisting of increase of the proximal and distal posterolateral regional ejection fraction, increase in the inferoapical regional ejection fraction and unchanged proximal and distal septal regional ejection fraction. In our patients paradoxical septal motion is not due to pericardial effusion, conduction disturbance, septal ischemia or infarction. Our data suggest that the anteromedial translation of the entire heart during systole, due to surgical removal of constraints, may account for both the false improvement of posterolateral and inferoapical regional wall motion and the development of paradoxical septal motion.

Calcium entry blockers and cardioplegia: interaction between nifedipine, potassium, and hypothermia.

The potential additive protective effect provided by nifedipine to the University of Alabama Hospitals cardioplegia solution (ACS) was assessed with the use of a guinea pig heart-lung model of cardiopulmonary bypass and ischemic arrest. The addition of nifedipine consistently enhanced the protective properties of ACS infused at 37 degrees C; functional recovery was similar to that observed with cold ACS. Despite the additional protection under normothermic conditions, nifedipine did not improve recovery after infusion at 4 degrees C. The abolition by hypothermia of the protective effects of nifedipine suggests a similarity in action between nifedipine and hypothermic protection. The interaction between ACS and nifedipine was studied on bovine coronary arteries in vitro. Nifedipine caused a marked reduction in the coronary vasoconstricting effect of ACS, both under normothermic and hypothermic conditions. The use of nifedipine in cardioplegia may provide additional protection when uneven distribution of the cardioplegic solution is expected and hypothermic protection is unreliable.

Interactions between pharmacological cardioplegia and hypothermia for intraoperative myocardial protection.

Cold cardioplegia is currently the method of choice for providing myocardial protection during open-heart surgical procedures. Two components of protection, perfusion cooling and pharmacological cardiac arrest, were investigated in the guinea pig heart-lung model. The effects of two cardioplegic solutions, the University of Alabama Hospital solution and the St. Thomas' Hospital solution, and a control perfusate were compared. The results confirmed the efficacy of hypothermia as a protective agent and the additional protection afforded by pharmacological cardioplegia. Infusion temperature critically influenced the cardioprotective action of the Alabama solution: Striking protection was afforded only under hypothermic conditions, whereas myocardial damage was exacerbated by the infusion at 37 degrees C. The St. Thomas' Hospital solution provided substantial protection independent of infusion temperature. Thus, the safety margin of the Alabama solution was narrower than that of the St. Thomas' solution. It is suggested that the difference between the two cardioplegic solutions partially depends on their coronary vasoactivity, since the administration of the Alabama solution at 37 degrees C increased coronary perfusion pressure. It would seem worthwhile to use a temperature-independent cardioplegic solution devoid of coronary vasoconstricting action.

[Effects of cardioplegic solutions on coronary and myocardial ultrastructure. Preliminary note]. / Effetti delle soluzioni cardioplegiche sull'ultrastruttura coronarica e miocardica. Nota preliminare.

Ultrastructural changes of the myocardium and the coronary arterial endothelium were studied following cold perfusion with two different cardioplegic solutions (CPS) (the University of Alabama and the St. Thomas Hospital solutions), and with Krebs' solution as a control (CS). Guinea pig heart-lung preparations (HLP) were subjected to cardiac arrest by perfusion under CPS or CS (4 ml/Kg/min. X 4 min.). The duration of the cardiac arrest was 60 minutes, and additional amounts of cold solution were perfused after the first 30 minutes. In a second experimental group, HLP were reperfused with blood following 60 minutes of cardioplegic arrest, and maintained under full activity for the next 30 minutes. At the end of the study, specimens of coronary artery and myocardium were obtained and observed by Scanning (SEM) and Trasmission (TEM) electron microscopy. All the specimens were compared with additional specimens obtained from control hearts not subjected to cardiac arrest. The myocardial ultrastructure of hearts arrested with CPS was well preserved, whereas severe myocardial damage, consisting in the absence of glycogen granules, intracellular edema and myofibrillar contraction, was following CS-induced cardiac arrest. In contrast, perfusion with the St. Thomas CPS produced severe vascular damage, characterized by interruption of the endothelial layer, and bulging of endothelial cells into the lumen; no vascular changes were observed following cardiac arrest with CS or Alabama CPS. We conclude that the damage to the coronary arterial endothelium is not related to cardiac arrest, or to perfusion with cristalloid solution, or to myocardial damage, but appears to depend on the composition of the CPS.

Management of massive air embolism during open-heart surgery with retrograde perfusion of the cerebral vessels and hyperbaric oxygenation.

Retrograde perfusion through the superior vena cava was used in 2 patients who were injured by massive air embolism occurring during open-heart surgery. They underwent hyperbaric treatment immediately following completion of the intracardiac repair. Both patients made complete recovery and were discharged, with no defects attributable to the incident.