[Banks of vascular homografts]. / Banking degli omoinnesti vascolari.

We define as Banking of the tissues all the procedures that include the finding, preparation, conservation and distribution of the homograft. The vascular homografts are taken and put into a solution of transportation at +4 degrees C and kept at this temperature till their arrival at the Bank. The following step is the dissection of the homograft which will have to be performed as quickly as possible at most 24 hours after the taking in conditions of maximum sterility. At the Italian Homograft Bank at Centro Cardiologico, the vascular homografts are kept at +4 degrees C for 96 hours on average with antibiotics. After a phase of sterilization at +4 degrees C the tissue is frozen according to a homogeneous and controlled thermic decrease and stored at -150 degrees C/-180 degrees C in fumes of liquid nitrogen till the moment of their employment allowing a long term conservation. The aim of all these procedures of cryopreservation is to keep the structural and functional integrity of cells and tissues. The thermic decrease of the tissues must occur so that to avoid all the damages of the cellular vitality and functionality and especially of the tissue structure in toto. In order to limitate these events some cryoprotector agents are employed because they reduce the concentration of the solutes, the cellular dehydration, the formation of micro-macro crystals. Another step to establish if the homograft is proper is the study of bacteriological and viral aspects. The viral screenings are performed on the donor's blood and the bacteriological tests are performed on the tissue and on the liquids. For each phase of the banking a series of information about the donor and about the tissues are recorded and filed both on paper and database so that to grant always a right conduct of the material.

[Myocarcial revascularisation without extracorporeal circulation: current indications, surgical technique and results]. / La rivascolarizzazione coronarica senza circolazione extracorporea. Indicazioni attuali, tecnica chirurgica e risultati.

BACKGROUND: This study was undertaken to assess our experience of the evolution, over time, of beating heart surgery in the Cardiologic Center Foundation Monzino. METHODS: From March 1995 to June 2000, 506 patients underwent myocardial revascularization on beating heart: 313 until May 1999, and 193 between June 1999 and June 2000, after the advent of coronary artery stabilizers and shunts, to keep the surgical field bloodless, with minimal motion and continuous myocardial perfusion. Surgical accesss was via a median sternotomy for 408 cases and via a left anterior thoracotomy for 98 cases. RESULTS: The indications by choice increased, from I to II period, from 61% to 83% with special situations in which patients had three-vessel coronary artery disease raised from 33% to 50%, concerning also bypass grafts performed on circumflex artery and right coronary increased. Postoperative mortality in hospital decreased from 1.3% to 0.5% and perioperative IMA (acute myocardial infarction) from 3.8% to 0.5% in patients undertaken to median thoracotomy. Hospital stay decreased from 8 to 7 days about [no significant differences with patients who underwent CPB (cardiopulmonary bypass)]; in patients who underwent to MTS (left anterior minithoracotomy) there was no deaths, IMA decreased from 3.9% to 0% and hospital stay from 6 to 5 days. Grafts patency increased from 92.3% to 100%. CONCLUSIONS: To perform completed revascularisations is possible now even on the beating heart, and also to make precise anastomosis as on pump CABG, in a reproducible and easy way. The beating heart procedure, that is also more economical, might be expanded to all patients, not only high risk patients.

The radial artery: which place in coronary operation?

Previous long-term studies have shown unsatisfactory patency of saphenous vein grafts, compared with internal mammary artery grafts. Recently, the use of the radial artery as a coronary artery bypass graft has enjoyed a revival, on the basis of the belief that it will help improving long-term results of coronary operations. The recent report of encouraging 5-year patency rates, supports its continued use as a bypass graft. In this paper, we review the current knowledge about the radial artery as a bypass graft, with special emphasis on the clinical results.

Protectant activity of hexarelin or growth hormone against postischemic ventricular dysfunction in hearts from aged rats.

The ability of hexarelin, a recently synthesized hexapeptide with a strong growth hormone (GH)-releasing activity, or of GH itself to display a protectant activity against postischemic ventricular dysfunction in senescent hearts was studied in 24-month-old male rats. Heart preparations from control (saline-treated) senescent rats, subjected to moderate ischemia, showed at reperfusion: (a) a low recovery of postischemic left ventricular developed pressure (LVDP; 37% of the preischemic values; from 90 +/- 5.7 to 33.5 +/- 3.8 mm Hg; p < 0.01; n = 10) coupled to a substantial increase in coronary perfusion pressure (CPP; 71% over baseline; from 68.3 +/- 5.2 to 116.8 +/- 4.6 mm Hg; p < 0.01; n = 10); (b) a marked increase of creatine kinase (CK) released in the perfusates (6.6-fold increase over preischemic values; from 45 +/- 4 to 298 +/- 25 mU/min/g wet tissue; p < 0.001; n = 10). In vivo administration of hexarelin (80 microg/kg, b.i.d., s.c.) for 21 days resulted in a striking heart protection against reperfusion stunning. In fact, the recovery of LVDP at reperfusion was almost complete (90% of the preischemic values; from 93 +/- 5.8 to 83.7 +/- 5.9 mm Hg; p > 0.05; n = 9), and the increase in coronary resistance was minimal (from 67 +/- 5.8 to 79.7 +/- 6.9 mm Hg; p > 0.05; n = 9). Furthermore, the concentration of CK in the perfusates was increased only twofold (from 45.8 +/- 5.5 to 90 +/- 7.2 mU/min/g wet tissue; p < 0.05; n = 9), with a gradual return toward basal values at the end of reperfusion. The protectant activity of hexarelin was divorced from any detectable alteration of the somatotropic function, as assessed by pituitary GH messenger RNA (mRNA) and plasma insulin-like growth factor I levels. In vivo administration of GH (400 microg/kg b.i.d., s.c.) for the same time lapse resulted in only a partial protectant activity: 55% of LVDP recovery (from 91.5 +/- 6.2 to 50 +/- 3.5 mm Hg; p < 0.01; n = 6); 65% increase of coronary resistance (from 68 +/- 4.3 to 112.2 +/- 5.2 mm Hg; p < 0.01; n = 6); 5.3-fold increase of CK concentrations in heart perfusates on reperfusion (from 43.8 +/- 3.8 to 232 +/- 16 mU/min/g wet tissue; p < 0.001; n = 6). Evaluation of the rate of release of 6-keto-prostaglandin F1alpha (PGF1alpha), the stable metabolite of prostacyclin, in heart perfusates, and assessment of the vasopressor activity of angiotensin II on the coronary vasculature, did not show any change in these parameters among the three experimental groups. Collectively these data indicate that hexarelin displays a strong heart-protectant activity against myocardial stunning in senescent rats. The protection afforded by the peptide is likely due to a direct cardiotropic action and is far greater than that of GH. Neither compound appears able to interfere with the endothelium-dependent relaxant mechanism.

Endothelial-dependent dynamic and antithrombotic properties of porcine aortic and pulmonary valves.

BACKGROUND: In the present study, the endothelium-dependent antithrombotic and dynamic properties of porcine aortic (AoV) and pulmonary valves (PuV) were investigated. METHODS: Fifteen fresh AoV and 15 fresh PuV were obtained from 25 9-month-old swines. The valves were examined for endothelial function by pharmacologic evaluation (with and without endothelium) of both the endothelial-releasing capacity of prostacyclin and the endothelial-dependent dynamic response to relaxing (acetylcholine from 10[-10] mol/L to 10[-4] mol/L in AoV and PuV segments precontracted with norepinephrine [3 x 10(-6) mol/L]) and contracting (endothelin-1, from 10[-11] mol/L to 10[-5] mol/L; and NG-monomethyl-L-arginine, 10[-4] mol/L) drugs. The ultrastructural integrity of the endothelial valve layer was also examined with transmission electron microscopy. RESULTS: Acetylcholine caused potent relaxation in both AoV and PuV specimens with, but not in those without, endothelium. Endothelin-1 produced a concentration-dependent tension increase in AoV and PuV with and without endothelium. However, the intrinsic activity of the peptide significantly increased in tissues without endothelium. NG-monomethyl-L-arginine evoked a progressive increase in resting tension of the preparations, but the AoV and PuV without endothelium were less sensitive to the inhibition of the nitric oxide generation. Aortic and pulmonary valves with an intact endothelium showed a spontaneous ability to release prostacyclin. The basal release of this lipidic autacoid significantly decreased in cardiac valves without endothelium. This phenomenon was observed in both basal conditions, and under stimulation with the aforementioned drugs. Transmission electron microscopy showed the perfect preservation of endothelial cells in all the preparations examined. CONCLUSIONS: Valvular endothelium of AoV and PuV seems to have similar antithrombotic and dynamic functions of vascular endothelium, actively participating in valvular homeostasis.

Flexible posterior mitral annuloplasty: five-year clinical and Doppler echocardiographic results.

BACKGROUND: Stabilization of the posterior annulus seems to be a critical factor to achieve a stable mitral valve repair. To assess the benefit of softer mural annuloplasty, we analyzed results obtained with the flexible linear reducer. METHODS: From 1985 to 1993, 120 patients, with pure mitral regurgitation, mainly degenerative, had a mitral reconstruction. Mean age was 64+/-11 years and 74% of the patients were in New York Heart Association functional class III or IV. RESULTS: Hospital mortality was 3.3%. Mean follow-up was 56+/-24 months. There were 23 late deaths; 10 valve-related including 7 sudden deaths. Two patients (1.7%) required a reoperation. Doppler echocardiographic studies revealed excellent valve function; 5-year freedom from significant regurgitation was 85.8%+/-5.4%. Mean mitral valve area was 2.76+/-0.77 cm2. Although 105 patients were in class I or II, 23 patients were not functionally improved. Previous myocardial infarction and shorter deceleration time of early filling were risk factors for worsening functional disability. CONCLUSIONS: This support provides stable repair with excellent clinical and echographic results. Previous myocardial infarction and noncompliant left ventricle negatively influence outcome.

[Cellular viability and immune response in homologous cryopreserved cardiac valves]. / Vitalità cellulare e risposta immunologica negli omoinnesti valvolari cardiaci criopreservati. Una revisione critica.

BACKGROUND: Long-term durability of homograft valves is related to cellular viability and immunological compatibility. In this paper, we carry out a critical update of the relationship between cellular viability and immunology of cryopreserved homograft valves. BIOLOGICAL ISSUE: In the first section, we review the theoretical background of the superior durability of cryopreserved valves with high cellular viability, with respect to the "fresh" antibiotic-stored valves, with lower viability rates. Afterwards, a brief review of the principal factors influencing the homograft valve viability rate during harvesting, preparation, sterilization and cryopreservation phases, is performed. CELLULAR VIABILITY: In the second paragraph, we analyze the problem of cellular viability in cryopreserved valves, both for matrix cells--fibroblast--and for endothelium. In particular, we report the current methods of quantifications of viability and more recent biological researches. Correlations between biological and clinical data are also discussed. IMMUNOLOGICAL ISSUE: Finally, the immunological issue and its relationships with cellular viability is analyzed, with particular regard to experimental evidence and clinical implications. Moreover, we have described the recent hypothesis on the influence of cryopreservation on the antigenicity of tissues, and the laboratory researches on the long-term antibody response in humans after homograft valve implantation.

Effects of warm ischemia on valve endothelium.

BACKGROUND: This study investigates the time-dependent resistance of the endothelium of porcine aortic and pulmonary valves to different periods of warm ischemia (WIT). METHODS: Twenty-five 9-month-old swine were divided after death into five groups of WIT (0, 6, 12, 24, and 36 hours). Aortic and pulmonary valves were removed and a total of 15 aortic and 15 pulmonary valve specimens were obtained for each WIT interval. Valves were then examined for (1) their viability rate by the trypan blue dye exclusion method at light microscopy (percent of viability compared with 0 hours of WIT); (2) ultrastructural signs of irreversible or reversible ischemic damage by transmission electron microscopy (cell disruption, dilation of endoplasmic reticulum, cytoplasmic edema, nuclear and mitochondrial changes); (3) endothelial function by pharmacologic evaluation of both the endothelial-releasing capacity of prostacyclin and the endothelial-dependent dynamic responses to relaxing (acetylcholine from 1 x 10(-10) mol/L to 1 x 10(-4) mol/L) in aortic and pulmonary valve segments precontracted with norepinephrine (1 x 10(-6) mol/L) and contracting (NG-monomethyl-L-arginine, 1 x 10(-4) mol/L) drugs. RESULTS: Our results showed an endothelial progressive time-dependent ischemic injury, which reached significance after 12 hours of exposure. Viability and functional data indicated that 6 hours of WIT only provoked slight endothelial damage (p > 0.05 respect to time 0 hours), with signs at transmission electron microscopy consistent with a reversible injury. At 12 hours of exposure, we observed a significant reduction (p < 0.05) with respect to time 0 of the viability rate of prostacyclin production and of the endothelium-dependent dynamic responses to acetylcholine and NG-monomethyl-L-arginine. These functional impairments, although significant, were not consistent, however, with a complete loss of viability. Transmission electron microscopic observations confirmed the appearance of signs of irreversible injury; nevertheless, some elements were found to be well preserved or presented reversible damage. After 24 hours of WIT, ultrastructural and functional data were consistent with a dramatic decrease compared with controls in endothelial viability and functions (p < 0.01). Finally, after 36 hours of WIT, there was a subtotal loss of viability, of functions (p < 0.001) and, at transmission electron microscopic observations, of the endothelial layer of the valves. CONCLUSIONS: Our data show that the endothelial cells are resistant to short periods of WIT (up to 6 hours), and suggest that these cells can endure longer exposures, up to 12 hours of warm ischemia. Periods of 24 and 36 hours of WIT provoke progressive irreversible damage.

Retention of endothelium-dependent properties in human mammary arteries after cryopreservation.

BACKGROUND: We investigated the effects of cryopreservation and antibiotic treatment on endothelium-dependent vasomotor properties of human internal mammary arteries (IMAs). METHODS: Sixty IMA specimens from routine coronary artery bypass grafting procedures were randomly assigned to six groups. Group I (controls) were immediately tested after harvest. Remaining groups were prepared according to a stepwise design: group II, 6 hours of warm ischemia; group III, 6 hours of warm ischemia + 24 hours at 4 degrees C (without antibiotics); group IV, 6 hours of warm ischemia + 24 hours of 4 degrees C antibiotic disinfection; group V, 6 hours of warm ischemia + 24 hours at 4 degrees C (without antibiotics) + cryopreservation; and group VI, 6 hours of warm ischemia + 24 hours of 4 degrees C disinfection+cryopreservation. The IMA specimens were cut into rings and the tension of vascular smooth muscle was recorded. The IMA rings were contracted with norepinephrine (3 x 10(-6) mol/L) and tested with cumulative concentrations of acetylcholine (from 1 x 10(-9) to 1 x 10(-5) mol/L), contracted with endothelin-1 (from 1 x 10(-11) to 1 x 10(-6) mol/L), and contracted with the nitric oxide-synthase inhibitor NG-monomethyl-L-arginine (1 x 10(-4) mol/L). Rings were also tested for their capacity to generate 6-keto-prostaglandin F1 (the stable metabolite of prostacyclin), and endothelial cell viability rate was finally evaluated with the trypan blue dye exclusion method. RESULTS: Our results show that a complete cryopreservation protocol does not significantly modify (p > 0.05) the relaxant activity to acetylcholine in norepinephrine-precontracted IMA rings (controls; 90.2% +/- 4.2% vs group VI, 77.1% +/- 6.2%) or the vasoconstrictor response induced by endothelin-1 (controls, 62.6% +/- 2.8% versus group VI, 73.7% +/- 4.8%) and NG-monomethyl-L-arginine (controls, 22.4% +/- 1.5% versus group VI, 18.9% +/- 1.9%). Furthermore, IMA cryopreservation does not significantly modify (p > 0.05) the endothelial release of prostacyclin either in basal conditions (-20% versus controls) or during pharmacologic intervention with acetylcholine (-18% versus controls), endothelin-1 (-17% versus controls), and NG-monomethyl-L-arginine (-18% versus controls). CONCLUSIONS: We conclude that the IMA endothelial function does not seem significantly injured by any of the current steps of disinfection and cryopreservation.

Preoperative management and surgical therapy in complicated acute infective endocarditis: a 5-year experience.

Twenty-five patients underwent early and elective valve replacement for infective endocarditis during a 5-year period between April 1985 and March 1991. Indications for urgent surgical intervention performed at a mean 32 (range 6-47) days after admission were intractable heart failure, systemic emboli, septic multiorgan failure and the presence of vegetations. Indication for elective surgery was persistent (mean 42 (range 17-56) days) infection after appropriate antibiotic therapy. Twenty patients (80%) had a native valve endocarditis; five (20%) had prosthetic valve involvement. A total of 30 valvular prostheses were implanted: 22 (73.3%) were aortic (21 mechanical and one biological); eight (26.7%) were mitral (all mechanical). All unstable patients referred were treated before surgery in the intensive care unit and subjected to blood ultrafiltration to restore satisfactory circulatory parameters. No patient underwent cardiac catheterization; all patients were operated upon on the basis of echocardiographic data alone. One patient (4%) died during hospitalization; two (8%) died later at 48 and 12 months after the first intervention. The reoperation rate was 12%. After a mean follow-up of 49 (range 1-71) months, 21 of the survivors (95%) were in New York Heart Association functional class I or II; the actuarial 5-year survival rate was 87%. Precise preoperative assessment of early operative indications and timely association of medical therapy in unstable patients could represent a step forward in the treatment of acute infective endocarditis.

Intracardiac ectopic thyroid: conservative surgical treatment.

The case of a patient with an intracardiac ectopic thyroid is reported. A cardiac tumor was found in a 66-year-old woman and was diagnosed by two-dimensional echocardiography. An intraoperative biopsy was performed, and the mass was recognized as an ectopic thyroid and treated with a conservative surgical approach because of the size, location, and relationship to adjacent structures. The 60-month follow-up shows normal echocardiographic images and the good clinical status of the patient.

[The use of the inferior epigastric artery as alternative conduit for myocardial revascularization: our experience]. / L'uso dell'arteria epigastrica inferiore come condotto alternativo nella rivascolarizzazione miocardica: nostra esperienza.

When complete revascularization can not be obtained with the internal mammary artery and saphenous veins, the inferior epigastric artery may be an excellent alternative conduit. We describe our experience with this conduit, review the anatomy of this artery, and present the evolution of our harvesting technique through a pararettal approach. Proximal anastomoses were made first with the aid of an oval cuff of the common femoral artery (5 cases, Group A). Two patients (40%) of this group studied postoperatively revealed a graft occlusion. In the last 13 cases (Group B) we tailored the proximal anastomoses directly to the aorta. All patients studied postoperatively showed patent inferior epigastric artery grafts. There were no hernias and no deaths. Inferior epigastric artery can be considered a good alternative conduit in myocardial revascularization.

Aortic dissection type A surgery: Doppler sonography to evaluate correct carotid artery perfusion during cardiopulmonary bypass.

In the surgery of acute aortic type A dissection we have employed preoperative and intraoperative Doppler sonography, to check safe and correct perfusion of the carotid arteries by the cardiopulmonary bypass before instituting cardiac arrest. Ten patients, operated upon for acute aortic type A dissection, were evaluated by means of Doppler sonography and in two patients a very abnormal flow pattern was found in the carotid arteries at the moment of aortic cross-clamping; immediate unclamping allowed temporary antegrade carotid perfusion, while the perfusion technique was readjusted. We report our experience with preoperative and intraoperative Doppler sonography, which appears to be a valuable new method of improving the surgical management of acute aortic type A dissection.

Abdominal aortic aneurysm in chronic thoracic dissection. Report of two cases.

Two cases of lower abdominal aortic aneurysm in association with chronic thoracic dissections are reported. These infra-renal aortic aneurysms, superimposed on an abdominal extension of the dissection, always require surgical treatment because of their well known tendency to enlarge and rupture. The authors report their experience and discuss the management of this complication in chronic dissections treated surgically.

Extracranial carotid artery aneurysms. Report of two cases.

Two cases of extracranial carotid artery aneurysm are reported. Treatment of this uncommon but interesting vascular disorder is still under discussion even if the present tendency is to treat them actively, by reconstructive techniques. We present our surgical experience and discuss the diagnostic problems and management.