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Biomedical subjects

A Piwnica

Publications and source records attributed to A Piwnica.

At least 19 recordsLinked to original sources
PubMed1992

[Towards an integrated protection of heart grafts].

In an attempt to provide a consistent protection of cardiac allografts during the sequence of events inherent in transplantation procedures, we developed two preservation solutions of which one is used for initial arrest, storage and cardioplegia during graft implantation, whereas the other serves as initial reperfusate. The formulations of these solutions are closely interrelated and their design has integrated the basic principles of organ preservation with those of myocardium-specific metabolism. Based upon experimental studies in the isolated rat heart model, this integrated approach has yielded better functional recoveries than conventional preservation protocols.

Animals↗
PubMed1992

Left ventricular pseudoaneurysm associated with mitral regurgitation.

A patient with a large posterolateral left ventricular pseudoaneurysm flush with the posterior papillary muscle and associated with mitral regurgitation was successfully treated surgically. The operation consisted of opening the sac of the aneurysm, dissecting the wall of the left ventricle from the fibrous wall of the sac, leaving a cuff of fibrous tissue suitable to hold sutures, and closing the defect with a Dacron patch.

Echocardiography↗
PubMed1992

Normothermic cardioplegia: is aortic cross-clamping still synonymous with myocardial ischemia?

The enthusiastic clinical reports on normothermic blood cardioplegia contrast with the paucity of data on the myocardial metabolic effects of this technique. The present study was therefore designed to assess whether normothermic blood cardioplegia really provides an aerobic environment during aortic cross-clamping. Thirty-one patients undergoing coronary (16 patients), valve (13 patients), and transplantation (2 patients) procedures were given continuous normothermic blood cardioplegia through the coronary sinus. Myocardial metabolism was assessed either immediately before aortic unclamping (16 patients) by collecting blood simultaneously from the cardioplegia infusion line and the aortic effluent or during reperfusion (15 patients) by collecting blood simultaneously from the radial artery and the coronary sinus. All samples were assayed for markers of anaerobiosis (blood gases, lactates), leukocyte activation (elastase), and lipid peroxidation (malondialdehyde, vitamin E). At the end of arrest, oxygen extraction was low, whereas the production of lactates was small, thereby suggesting the efficacy of normothermic blood cardioplegia in maintaining a predominantly aerobic metabolism. This was confirmed by postarrest data, as oxygen extraction measured immediately after cross-clamp removal was unchanged from prearrest values, whereas lactate metabolism yielded transient and limited production followed by prompt recovery of normal extraction patterns. There was no release of elastase from the myocardium, which suggests adequate protection of the coronary endothelium from ischemic injury and the related increase in leukocyte activation. Likewise, postarrest coronary sinus concentrations of malondialdehyde and vitamin E were identical to the respective arterial concentrations, thereby ruling out the occurrence of intramyocardial lipid peroxidation at the time of reperfusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMed1992

Is the internal mammary artery an acceptable graft in the elderly patients with left main coronary artery disease?

Age over 70 years and critical stenosis of the left main coronary artery trunk are two situations in which the use of the internal mammary artery has been questioned. Because the coexistence of these two conditions is increasingly seen, we reviewed our experience with 53 patients 70 years of age or older that underwent myocardial revascularization for left main disease. In 17 patients, the left anterior descending coronary artery was grafted with the left internal mammary artery whereas the 36 remaining patients were exclusively revascularized by means of saphenous vein conduits. There was no significant difference in postoperative mortality or morbidity between the two patient groups. We conclude that elderly patients with left main disease should be offered the benefits of a mammary artery graft provided they are hemodynamically stable.

Age Factors↗
PubMed1992

Pretreatment with captopril improves myocardial recovery after cardioplegic arrest.

Among the interventions designed to limit postischemic oxidative injury, those that enhance the myocardial content of thiol groups are attractive because thiols are powerful antioxidant. Indeed, part of the protection afforded by the angiotensin-converting enzyme (ACE) inhibitor captopril in regional myocardial ischemia is attributed to its thiol group. This study assesses the effects of captopril in a surgically relevant model of global ischemic arrest. Thirty rats were implanted subcutaneously (s.c.) with osmotic pumps that allowed continuous delivery of captopril (total dose 75 mg), enalapril (a nonthiol-containing ACE inhibitor, total dose 7.5 mg) or saline in 48 h. Drug concentrations were equipotent in their effect on angiotensin I (ANGI) pressor response. Hearts were then excised, perfused under isovolumic conditions, and subjected to 90-min cardioplegic arrest at 30 degrees C followed by 1-h reperfusion. Pre- and postischemic coronary flows were significantly higher to a similar extent in the two drug-pretreated groups than in controls. However, captopril-pretreated hearts had the best recovery of contractility (dP/dtmax; 3,590 +/- 74 versus 2915 +/- 64 mm Hg s-1 in the enalapril group, p less than 0.001), and diastolic pressure (13.7 +/- 0.9 mm Hg vs. 20.0 +/- 1.6 mm Hg in the enalapril group, p less than 0.05). We conclude that pretreatment with ACE inhibitors improves myocardial recovery after cardioplegic arrest and that captopril is more effective than enalapril. The additional protection afforded by captopril was not flow mediated, suggesting that the cardioprotective effects of this drug not only involve an ACE inhibition-dependent coronary vasodilation but could be related to a thiol-dependent limitation of oxidative injury.

Animals↗
PubMed1992

[Current role of reconstructive surgery in the treatment of acute mediastinitis after cardiac surgery].

Infected median sternotomy often requires wide debridement. A large thoracic defect usually results with subsequent exposition of heart, great vessels, aortocoronary bypass grafting, vascular prosthesis. Coverage with muscles transplantation was the standard procedure carried out in this series of 150 cases observed between 1983 and 1991. Details of technique are presented as well as a review of our reconstructive options. Rewarding results were observed even in the most challenging circumstances, suggesting that pursuing this aggressive approach was warranted.

Acute Disease↗
PubMed1992

Maintenance of the myocardial thiol pool by N-acetylcysteine. An effective means of improving cardioplegic protection.

The reduced thiol pool of myocardial tissue represents an important defense mechanism against oxygen toxicity. Since the ischemia-induced depletion of this pool might favor the cytotoxicity of oxygen-derived free radicals produced during reperfusion, we assessed the effects of the thiol group donor N-acetylcysteine in an isolated buffer-perfused rat heart model of ischemia/reperfusion. Fifty hearts were studied. A first series of experiments that consisted of two groups (n = 10) was designed to simulate the conditions of standard cardioplegic arrest. Hearts were subjected to 180 minutes of cold (15 degrees to 18 degrees C) global ischemia and 1 hour of reperfusion. The control group received crystalloid hyperkalemic cardioplegic solution given every 30 minutes during arrest, and the treated group received the same solution supplemented with N-acetylcysteine (0.04 mol/L). On the basis of comparisons of postreperfusion left ventricular developed pressure, maximal dP/dt, and diastolic pressure, N-acetylcysteine-containing cardioplegic solution afforded significantly better protection. A second series of experiments was then undertaken to assess the effects of N-acetylcysteine in hearts subjected to the sequence of ischemic events that is inherent in transplantation procedures. Hearts were cardioplegically arrested, stored for 5 hours at 2 degrees C, subjected to 1 additional hour of ischemic arrest at 15 degrees to 18 degrees C, and reperfused for 60 minutes. Three groups (n = 10) were studied that differed by the modalities of cardioplegic preservation used during the poststorage ischemic interval. One group received multidose unmodified cardioplegic solution. A second group received multidose cardioplegic solution supplemented with N-acetylcysteine (0.04 mol/L), and the third group was given only a single dose of N-acetylcysteine-enriched (0.07 mol/L) cardioplegic reperfusate at the end of arrest. Multidose N-acetylcysteine-containing cardioplegic solution resulted in a significantly better hemodynamic recovery than unmodified cardioplegic solution. The protection afforded by N-acetylcysteine was lost when the drug was given only at the time of reperfusion. We conclude that supplementation of cardioplegic solution with N-acetylcysteine markedly improves postarrest recovery of function, presumably through an enhancement of the reduced thiol pool, which increases the capacity of reperfused myocardium to handle the postischemic burst of free radical production. The clinical relevance of these findings stems from the fact that thiol-containing drugs are available for human use.

Acetylcysteine↗
PubMed1991

Hemostasis in patients undergoing extracorporeal circulation: the effect of aprotinin (Trasylol).

The administration of aprotinin during extracorporeal circulation (ECC) reduces blood loss. To explore the mechanism of this effect, a placebo-controlled double-blind study was performed in 20 patients (10 were administered with a high dose of aprotinin, 10 with placebo) undergoing a primary, elective operation of coronary artery bypass grafting (CABG) with ECC. Biological tests were performed at 4 different time points during the operation. A marked reduction in the placebo group of ristocetin-induced platelet agglutination (binding of von Willebrand factor [vWF] to platelet glycoprotein [GP] Ib) was shown during ECC and at the end of surgery, but not in the aprotinin group. This abnormality is not related to the hydrolysis of vWF or GP Ib, since washed platelets were resuspended in pooled normal plasma which provided a constant amount of vWF in this test and since the plasma concentration of the fragment of GP Ib (glycocalicin) did not correlate with this abnormality. Despite a high concentration of heparin (5-7 IU/ml) in patient's plasma during bypass, activation of blood coagulation in both groups was evidenced by an increase in ATm (thrombin-modified antithrombin III) level. The level of ATm in the placebo group reached a maximum at the end of ECC during rewarming, while in the aprotinin group, ATm level at this time point was significantly lower than in the control group. In comparison to the placebo group, the generation of the fibrin degradation products (DDE complexes) was inhibited by aprotinin during ECC, but the level of DDE complexes in the aprotinin group was slightly elevated after ECC, although much less than in the placebo group.(ABSTRACT TRUNCATED AT 250 WORDS)

Antithrombin III↗
PubMed1991

Efficacy of coronary sinus cardioplegia in patients with complete coronary artery occlusions.

Myocardial areas distal to complete coronary artery occlusions are poorly protected by antegrade cardioplegia. We assessed the effects of coronary sinus cardioplegia in 30 patients undergoing bypass operations and at high risk of cardioplegic maldistribution because of the following anatomical patterns of coronary artery disease: critical (greater than or equal to 50%) stenosis of the left main trunk with total occlusion of the right coronary artery (16 patients) or critical (greater than or equal to 70%) stenosis of the right coronary artery with total occlusion of the left anterior descending (11 patients) or circumflex artery (3 patients). After induction of arrest through the aorta, coronary sinus cardioplegia was given intermittently during the cross-clamp period at a flow rate of 100 mL/min. Intraoperatively, occluded arteries were consistently found to be filled with the retrogradely infused solution. One patient died early postoperatively of low cardiac output and a second patient died later during his hospital stay, presumably of an arrhythmia. At autopsy, none of them had pathological evidence of inadequate myocardial protection. One patient sustained a myocardial infarction and 3 others required inotropes for more than 24 hours postoperatively. Postoperative values for right and left stroke volume indices were not significantly different from prebypass levels. Overall, these results are consistent with the occurrence of limited intraoperative ischemic damage and, by inference, suggest the efficacy of the coronary sinus route in preserving myocardial areas supplied by completely occluded coronary arteries and, hence, in jeopardy of inadequate cardioplegia delivery.

Aged↗
PubMed1991

Cardioplegia by way of the coronary sinus for valvular and coronary surgery.

Retrograde coronary sinus perfusion has recently reemerged as an attractive means of delivering cardioplegic solutions during open heart procedures. In patients undergoing aortic valve or aortic root surgery, there is no evidence that coronary sinus cardioplegia results in a better myocardial protection than that achieved with the use of standard methods of anterograde cardioplegia delivery. However, the retrograde approach provides distinct technical advantages that might favor its use as an alternative to direct coronary ostial cannulation. In select subgroups of patients undergoing coronary bypass procedures, there is a growing body of evidence that the coronary sinus route may be more effective than the anterograde route because of its superior capacity to ensure homogeneous distribution of cooling and cardioplegia in myocardial areas supplied occluded arteries. The well established safety of coronary sinus cardioplegia in the clinical setting further justifies its inclusion among techniques for ensuring adequate myocardial preservation during surgically induced ischemic arrest.

Animals↗
PubMed1991

[Retrograde cardioplegia through the coronary sinus in the surgery of the aortic valve. A clinical study of 500 patients].

Over the last few years there has been a renewal of interest in retrograde administration of cardioplegic solutions but this method has not been validated by a large scale clinical trial. From 1980 to 1989 our group used retrograde coronary sinus perfusion as the only means of administering cardioplegia in 500 consecutive patients undergoing isolated aortic valve replacement (AVR) (359 cases) or associated with another valvular or myocardial revascularization procedure (141 cases). Using this method, there were 31 hospital deaths (6.2%) of which 20 were of cardiac origin (4%). During the last 5 years, hospital mortality for isolated AVR decreased to 1.5%. With an incidence of low cardiac output of 12%, of arrhythmias and atrioventricular block of 7.4% and 1.2% respectively, and of myocardial infarction of 1.4%, this method of cardioplegia compares favourably with anterograde perfusion. There were only 3 traumatic lesions of the coronary sinus, all occurring at the beginning of the series and all of which were successfully repaired. Retrograde coronary sinus perfusion is therefore a safe and effective method of cardioplegia during aortic valve surgery: the cardioplegic solution is distributed uniformly in patients with coronary artery disease and therefore, this could become the technique of choice for myocardial protection in coronary artery or mixed coronary and valvular surgery.

Aged↗
PubMed1990

Retrograde coronary sinus cardioplegia for aortic valve operations: a clinical report on 500 patients.

Retrograde delivery of cardioplegic solutions has recently been the subject of renewed interest, but the reliability of this technique has not been assessed in large clinical series. From 1980 to 1989, we used retrograde coronary sinus perfusion as the exclusive means of cardioplegia delivery in 500 consecutive patients undergoing aortic valve replacement, either isolated (359 patients) or combined with another valve or coronary procedure (141 patients). The coronary sinus was always cannulated under direct vision after bicaval cannulation with snaring. Cold crystalloid cardioplegia was delivered retrogradely at an average flow rate of 100 mL/min in conjunction with topical and systemic (25 degrees C) hypothermia. The mean cross-clamp time was 83 +/- 23 minutes (+/- the standard deviation). There were 31 hospital deaths (6.2%), 20 of which were cardiac related. Transient hemodynamic instability (defined as a need for inotropic agents for less than 24 hours postoperatively) occurred in 16 patients (3.2%), whereas a true low-output syndrome developed in 60 patients (12%). The incidence of clinically significant supraventricular arrhythmias and of permanent conduction defects was 7.4% and 1.2%, respectively. There were three nonfatal coronary venous injuries during our early experience. We conclude that coronary sinus perfusion is a safe and effective means of delivering cardioplegia in aortic valve operations. While providing a degree of myocardial protection similar to that reported with anterograde cardioplegia, the coronary sinus technique offers distinct advantages, in particular, the avoidance of perfusion-related coronary artery complications and the opportunity to repeat cardioplegia administration without interrupting the procedure.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1990

Determinants of systolic and diastolic flow in coronary bypass grafts with inotropic stimulation.

Using implanted pulsed Doppler microprobes sutured on saphenous bypass grafts in ten patients we studied, 6 h after cardiac surgery, the effects of 5 and 10 micrograms.kg-1.min-1 of dobutamine on mean (Qm), systolic (Qs), and diastolic (Qd) coronary bypass graft flows, as well as on coronary systolic (integral of Qs) and diastolic (integral of Qd) blood volumes entering the myocardium per cardiac beat. Qm increased during the inotropic stimulation from 61.8 +/- 19.2 to 81.1 +/- 21.8 ml.min-1 (P less than 0.001) and resulted from an unchanged Qs and from a large increase in Qd (P less than 0.01). Qd increased more than did diastolic arterial pressure and was related to rate pressure product taken as an index of myocardial oxygen consumption (r = 0.76, P less than 0.001). Despite the dobutamine-induced increase in heart rate (P less than 0.01), integral of Qs, and integral of Qd, the systolic and diastolic inflow volumes per cardiac beat were unchanged. We conclude that increased myocardial blood supply through the saphenous vein bypass graft during inotropic stimulation by dobutamine resulted from different systolic and diastolic events. The oxygenated blood volume entering the coronary vascular bed per beat was unchanged despite tachycardia.

Coronary Artery Bypass↗
PubMed1990

[Floating left atrial thrombus in 2 cases of severe mitral stenosis].

The authors report two operated cases of floating left atrial thrombus. Both patients had severe mitral stenosis, atrial fibrillation and dilatation of the left atrium. In the first case, the patient had no anticoagulant therapy; in the second case, the observance of anticoagulant therapy was irregular. Neither patient complained of syncope. The diagnosis was made in both cases by two-dimensional echocardiography which, in addition to confirming the severe mitral stenosis, showed a round, free-floating intra-atrial mass, rebounding from wall to wall and repeatedly engaging itself into the mitral orifice. The risk of prolonged engagement of the thrombus in the mitral orifice, causing syncope or sudden death, justifies urgent surgery associating thrombectomy and treatment of mitral stenosis every time this problem is encountered.

Adult↗
PubMed1990

Iron chelation by deferoxamine inhibits lipid peroxidation during cardiopulmonary bypass in humans.

Iron catalysis is involved in oxygen-derived free radical generation and subsequent lipid peroxidation, which have been reported to occur during cardiopulmonary bypass in humans. We assessed the effects of the iron chelator deferoxamine on the susceptibility of circulating low density lipoproteins (LDLs) to induced peroxidation in 20 adult patients (10 controls and 10 treated) undergoing cardiopulmonary bypass for coronary or valve procedures. Deferoxamine was given both intravenously (30 mg/kg body wt, starting 30 minutes before bypass and extending for the next 4 hours) and as an additive to the cardioplegic solution (250 mg/l). Blood samples were taken from both atria before and immediately after the end of cardiopulmonary bypass. Plasma lipid peroxidation was assessed by measuring spectrophotometrically the thiobarbituric acid reactive substances (TBARS) content of selectively isolated LDLs after their exposure to a peroxidizing agent. Before cardiopulmonary bypass, the right and left atrial blood values of LDL-TBARS were not significantly different between the two groups. Cardiopulmonary bypass resulted in a lipid peroxidation of significantly greater magnitude in control than in treated patients. Postbypass right atrial values for LDL-TBARS (expressed in mumol/mmol LDL-phospholipids) were 45.7 +/- 17.2 (mean +/- SEM) in control patients and 6.9 +/- 2.9 in treated patients (p less than 0.02), whereas in the left atrial blood, LDL-TBARS yielded values of 62.7 +/- 20.5 and 10.3 +/- 3.9, respectively (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Cardiopulmonary Bypass↗