Biomedical subjects
Publications and source records attributed to T Tkebuchava.
Isolated anomalous origin of the right coronary artery (RCA) is a very rare congenital malformation. The case of a 15-month-old boy with anomalous origin of the RCA from the pulmonary artery is presented. The RCA was reimplanted into the aorta. The anatomical correction was uneventful and its success demonstrates that diagnosis and surgical correction are possible at a very young age.
Recurrent aortic aneurysms, persistent or new dissection, new onset of valvular and coronary artery disease, graft infection, and prosthetic endocarditis are not rare after thoracic aortic operations; they can be difficult to diagnose and represent a formidable surgical challenge. Between 1977 and 1991, 876 operations were performed on the thoracic aorta in our institution: 340 in dissections, 299 in true aneurysms, 150 for aortic remodeling and external wall support during aortic valve replacement, and 87 for miscellaneous causes. During the same period, there were 193 additional reoperations. Vascular reoperations on abdominal aorta and peripheral arteries accounted for 73 cases and are not further discussed in this study. The reasons for reoperation (n = 130) in 120 patients were: failure of biologic valves (n = 23); aneurysm recurrence in a proximal or distal aortic segment (n = 21); pseudoaneurysm formation at suture lines (n = 13); new dissection or dilatation involving ascending aorta (n = 11), aortic arch (n = 13), and descending aorta (n = 10); aneurysm after aortic remodeling (n = 13); new onset of valvular disease (n = 5); and new onset of coronary disease (n = 5). Infected aortic graft and prosthetic endocarditis accounted for 10 reoperations, and a planned two-staged procedure was performed in 6 patients. Omitting the failed biologic valves, reoperations were performed on the aortic segment previously operated on in 69.3% of the cases and on other thoracic segments in 30.7%. Overall hospital mortality rate after reoperation was 5.8%. A significant decrease in operative mortality was observed in the most recent period (3.0% between 1989 and 1991). Reoperations are technically demanding, and some of them are preventable; therefore (1) graft inclusion technique should be abandoned in ascending aortic operation due to formation of false aneurysms; (2) in patients with Marfan syndrome, complete repair of the diseased aorta should be attempted during the initial operation; (3) aortic arch dissection should be repaired definitively during the first operation in low-risk patients; (4) biological valves should be avoided in aneurysm operations; and (5) homograft replacement is the treatment of choice in prosthetic endocarditis or in infected composite graft after an aortic valve or ascending aortic operation.
Two patients (one girl, one boy) with Kartagener syndrome (situs inversus, bronchiectasis, sinusitis), despite pulmonary problems and associated congenital cardiac anomalies, were operated on at the ages of 4 years and 7 years, respectively. They had had previous palliative treatment at the age of 3 months and 1.3 years, respectively. Both postoperative periods after total correction were without significant complications. Long-term follow-up was available for 9 and 19 years, respectively, with no manifestations of heart insufficiency. Both patients are physically active, and neither requires cardiac medication. Patients with Kartagener syndrome and associated congenital cardiac anomalies can successfully undergo multiple cardiac operations with good long-term outcome.
Thromboembolic events remain a significant issue in mechanical circulatory support. The aim of this study was to evaluate the potential benefit of surface modification in total artificial hearts (TAHs) using polymeric phospholipids (biomembrane mimicry). For this purpose, pneumatic TAHs (vacuum formed pellethane housing, hard double flap hinged inflow valves, soft trileaflet polyurethane outflow valves) had their blood-exposed surfaces either modified with polymeric phospholipids or unmodified before evaluation in bovine experiments. Orthotopic implantation of the TAHs was performed with cardiopulmonary bypass (CPB) using tip-to-tip heparin surface coated perfusion equipment and very low systemic heparinization (50 IU/kg bodyweight). After weaning from CPB and stabilizing hemodynamics, circulating heparin was neutralized with protamine (1:1). All animals were totally supported for 24 hours before elective sacrifice. No heparin was added at any time during support. Mean activated coagulation time (ACT) was 167+/-24 s at baseline before heparinization for CPB, 330+/-45 s at the end of CPB, 181+/-25 s after 1 hour of support, 180+/-31 s after 6 hours, and 185+/-28 s after 18 hours. After explantation, the TAHs perfused without anticoagulation were carefully analyzed. Atrial cuff coverage with red clot was 30+/-21% for artificial surfaces modified by biomembrane mimicry versus 100+/-0% for standard control surfaces (p<0.01). The number of macroscopic deposits found on the inflow valves was 1.33+/-0.47 for surfaces modified by biomembrane mimicry versus 3.83+/-1.86 for standard control surfaces (p<0.05). Likewise, on the outflow valves the number of macroscopic deposits was 0.00+/-0.00 for surfaces modified by biomembrane mimicry versus 1.00+/-0.81 for standard control surfaces (p<0.05). We conclude that presence and distribution of red clots and other macroscopic deposits are significantly different for artificial surfaces with biomembrane mimicry versus standard control surfaces. Application of the biomembrane mimicry concept has the potential to provide improved TAHs.
Coronary artery fistula is a very rare congenital malformation with an abnormal coronary-cameral communication that may involve any chamber and any or all coronary artery branches. We present our experience with 11 consecutive patients (mean age 16.6 years, ranging from 4 to 64 years); 9 of them were treated surgically, spontaneous closure of the fistula was observed in 1 patient and 1 patient is still under observation. Nine patients were under 17 years of age at the time of operation whereas only 2 patients were older (56 and 64 years). Fistulas originated from the right coronary artery in 4 patients and drained either into the right (n = 3) or into the left system (n = 1). In 8 patients, the origin of the coronary artery from the aorta was normal and the fistulous communications developed with the right cardiac structures only. In 2 patients, both coronary arteries were involved in the pathological drainage and 2 patients were demonstrated to have multiple drainage from the left coronary artery. Additional congenital cardiac malformations were found in 2 patients: severe tricuspid valve regurgitation in 1 and ventricular septal defect in another patient. Surgical closure of the fistula was successful in all operated patients (in 1 case treatment was possible without cardiopulmonary bypass). Simple ligation of the fistula was performed in 1 patient, intracardiac closure of the fistula was combined with different reconstructive procedures in the other patients. No hospital mortality nor severe complications occurred in this small group of patients. The mean follow-up interval was 39.4 months and all patients were in NYHA functional class I, except 1 with moderate tricuspid and mitral valve regurgitation. In the presence of symptoms of congestive heart failure, significant left-to-right shunt and arrhythmias, elective closure of coronary fistula is generally accepted, whereas the indication is more controversial in asymptomatic patients. Considering the low perioperative morbidity, we recommend surgical closure of coronary fistulas with significant shunt and/or increased coronary artery diameter.
An anomalous origin of the left coronary artery from the pulmonary artery is a very rare congenital malformation. We examined the early and late results of 9 patients (4 males and 5 females, mean age at operation: 6.5 years +/- 6 years). Eleven operations were performed in these 9 patients. The following types of operation were performed: ligation of the left coronary artery close to the pulmonary artery in one case, coronary artery bypass grafting in 3 patients, reimplantation of the LCA into the aorta in 3 patients and interpulmonary artery tunnel repair ("tunnel operation") in 4 instances. These operations were combined with plastic reconstruction of the mitral valve (1 patient) or aneurysmectomy of the left ventricle (3 patients). There was no intra- or early operative mortality. After a mean follow-up of 7.3 years, all patients are alive and in New York Heart Association functional class I, except one patient suffering from dyspnoea during moderate exercise. In two patients complications requiring reoperations occurred after 4 and 100 months respectively: stenosis of the distal anastomosis after coronary artery bypass grafting using saphenous vein and thrombosis of the intrapulmonary tunnel. We conclude that an anomalous origin of the left coronary artery from the pulmonary artery is best operated by reimplantation of the vessel into the aorta at any age of life. Concomitant pathology may be corrected simultaneously, without increasing operative mortality.
Single and double hollow fiber intravascular gas exchangers were evaluated in an extracorporeal veno-venous bypass circuit (right atrium to pulmonary artery) including a tubular blood chamber (mimicking caval veins with an inner diameter of 26 mm) for evaluation of the membrane surface area/host vessel diameter gas transfer relationships. Six bovine experiments (body wt: 68 +/- 4 kg) with staged ex vivo blood flows of 1, 2, 3, and 4 L/min and a device oxygen inflow of 0, 3, and 6 L/min (0 or 3 L/min/device) were performed. Total oxygen transfer at a blood flow of 1 L/min was 33 +/- 4 ml/ min for a gas flow of 3 L/min (one device) vs 60 +/- 25 ml/ min for a gas flow of 6 L/min (two devices); at a blood flow of 2 L/min, the corresponding oxygen transfer was 46 +/- 16 ml/min for a gas flow of 3 L/min vs 95 +/- 44 ml/min for a gas flow of 6 L/min; at a blood flow of 3 L/min, the corresponding oxygen transfer was 48 +/- 24 ml/min for a gas flow of 3 L/ min vs 92 +/- 37 ml/min for a gas flow of 6 L/min (p < 0.01 for comparison of areas under the curves). Total carbon dioxide transfer at a blood flow of 1 L/min was 47 +/- 18 ml/min for a gas flow of 3 L/min vs 104 +/- 26 ml/min for a gas flow of 6 L/min; at a blood flow of 2 L/min, the corresponding carbon dioxide transfer was 59 +/- 19 ml/min for a gas flow of 3 L/ min vs 129 +/- 39 ml/min for a gas flow of 6 L/min; at a blood flow of 3 L/min, the corresponding carbon dioxide transfer was 60 +/- 22 ml/min for a gas flow of 3 L/min vs 116 +/- 49 ml/min for a gas flow of 6 L/min (p < 0.01). For the given setup, the blood flow/gas transfer relationship is non linear, and a plateau is achieved at a blood flow of 2.5 L/min for O2 and CO2. Doubling membrane surface area and consecutively sweeping gas flows result in doubling of gas transfers at all tested blood flows. However, increased membrane surface area and blood flow produce a higher pressure drop that in turn limits the fiber density that can be used clinically.