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Scanning electron microscopy of bovine pericardium (BP) shows anisotropic collagen fiber orientation (CFO). We studied the effect of CFO on the breaking strength of longitudinal (L) and transverse (T) strips cut from six pieces of fresh (Fr), glutaraldehyde (Glu)-, or formaldehyde (For)-fixed BP loaded at constant rate until rupture. Maximum tensile stress (Stmax) and strain (Snmax) were measured. The Stmax of L strips were larger than T ones in all groups, and Snmax was the same. Similar results were also observed in 10 pieces of Glu fixed normal canine mitral valves (MV). Maximum tensile stress is obtained when the load is parallel to CFO in both canine MV and BP.

Rapid neointima formation in fabric vascular prostheses seeded with autologous venous tissue fragments was examined. A piece of peripheral vein was minced into small fragments and stirred into 20 ml of saline. This tissue suspension was sieved through the wall of Dacron prostheses. The prostheses implanted in the descending aortae of dogs showed extremely rapid healing of the neointima. Endothelial cells lined the entire luminal surface within 14 days. There was no difference in the healing process between the area near anastomotic sites and the center.

Although significant variation in bronchial blood flow (BBF) has been reported, precise quantitation is difficult because of the small sized vessels and variable anatomy. Ventricular balance is critical to the function of the total artificial heart (TAH), and variation in BBF can alter this balance in the bovine model. Bronchial blood flow was measured in 12 calves by two methods: six by the radioactive labeled microsphere technique (MBBF), and six intraoperatively (IBBF) during cardiopulmonary bypass (CPB). In the MBBF group, BBF ranged from 1.9 ml/kg to 16.0 ml/kg, whereas IBBF varied from 2.6 ml/kg to 10 ml/kg (NS). Cardiac output (CO) was significantly higher (p less than 0.0005) in the MBBF group. Bronchial blood flow in both groups was highly variable. The higher flow in the MBBF group may be attributed to the arteriovenous shunting of microspheres, whereas lower flow in the IBBF group may be secondary to physiologic changes during CPB. This technique, described to measure IBBF, can estimate large variations in the natural right to left shunt that contributes to imbalance in the TAH.

The hemostatic effect of nafamostat mesilate (FUT-175) was evaluated in patients undergoing cardiopulmonary bypass (CPB) surgery. Thirty patients undergoing aortocoronary bypass grafting were divided into two groups. In the control group, anticoagulation was achieved with an initial dose of heparin (3 mg/kg). In the FUT-175-treated group, in addition to the ordinary treatment with heparin, FUT-175 was infused continuously into the circuit throughout the procedure at a rate of 100 mg/hr. Thrombin-antithrombin III complex (TAT), fibrinopeptide A (FPA), and fibrin degradation products (FDP-D) dimer increased in both groups as CPB proceeded. In the FUT-175-treated group, these parameters remained lower and decreased more rapidly after the end of CPB. Alpha 2 plasmin inhibitor/plasmin complex (PIC) increased progressively during CPB in the control group; no such significant increases were seen in the FUT-175-treated group. Postoperative blood loss was significantly lower in the FUT-175-treated group than in the control group. It was concluded that FUT-175 reduces postoperative blood loss by inhibiting both coagulation and fibrinolysis during CPB.

Right dominant biventricular failure often accompanies the end-stage of combined rheumatic valvular disease and some kinds of congenital heart disease. The management of right ventricular failure with conventional medical treatment, however, has encountered many difficulties. Mechanical support of the right ventricle with an RVAD (right ventricular assist device) has proved useful and effective. Seven patients who could not be weaned from cardiopulmonary bypass were subsequently transferred to an intraaortic balloon pump (IABP) and RVAD. Among these, five had severe combined rheumatic valvular disease, one had congenital heart disease and was advanced in age, and the other had a left atrial myxoma with tricuspid regurgitation. Preoperatively, all of these patients had had biventricular failure. All seven cases were successfully weaned from RVAD, and later from IABP. Five patients were discharged from the hospital and returned to normal daily life. Two patients died during their postoperative course. Long-term survival rate was 71%. Mechanical assist with RVAD and IABP seemed to be effective in the management of right dominant biventricular failure, such as that seen in combined valvular disease and some kinds of congenital heart disease.

A new technique was used to measure dynamic internal compliance of a blood vessel or vascular graft subjected to dynamic internal pressure. The internal compliance can be broken into three categories: the volumetric compliance (CV), defined as (dV/V)/dP; the longitudinal compliance (CL), defined as (dL/L)/dP; and radial compliance (CR), defined as (dR/R)/dP. It can be shown mathematically that CV = 2 CR + CL. Thus, measuring any two of the three entities will also give the value for the third. A Dynatek DCT1 dynamic compliance tester was used for measuring the compliance of DenaflexTM biologic grafts and fresh bovine internal thoracic arteries, from which the Denaflex grafts were obtained by fixation. Volumetric compliance was obtained with the test sample mounted in a loose loop that allowed the sample to move both radially and longitudinally. By mounting the sample in a straight fashion that limited longitudinal movement, the radial compliance was determined. The longitudinal compliance was then calculated from the above relationship. Test results show that the fresh bovine artery had an average volumetric compliance of 26.1%/100 mmHg, radial compliance of 9.5%/100 mmHg, and longitudinal compliance of 7.2%/100 mmHg. The Denaflex vascular graft showed a reduction in longitudinal and radial compliance, compared to the fresh raw artery, as a result of extensive fixation.

A multicenter prospective study of short hour (SH, less than or equal to 3 hr) dialysis using a high flux membrane (AN69S) plus volumetric control (VC), versus conventional (greater than or equal to 4 hr) (CNV) cellulosic non-VC dialysis, is ongoing. The study hypothesizes that SH treatment over 1 year will provide adequate dialysis, will not increase morbidity, and may improve quality of life. To date, 112 patients have been entered, and 54 have completed 6 months, 30 by SH. There were no differences in biophysiologic parameters at 6 months. Mean hospitalization was 5.24 days per patient. The SH group had a higher (p = 0.0374) hospitalization rate because of two patients. Quality of life was similar in SH and CNV groups. The study indicates that SH dialysis is feasible, safe, and as comfortable as CNV.

An orthopedic catheter for long-term access to the synovial joint is anchored by a hollow threaded tap that penetrates the capsule through a hole drilled in the surrounding bone. The proximal end of the catheter is connected to either an implantable drug infusion pump or an implantable access port for continuous or intermittent perfusion or sampling. Four catheters were evaluated in dogs. Three were attached to ports, the fourth to a pump. Water (one trial, 22 weeks) and hyaluronic acid (HA) (5 mg/ml; two trials of 8 weeks each) were administered through ports twice weekly in 1.5 ml boluses; 5 mg/ml HA was delivered by pump (1 trial of 33 weeks) at 0.31 ml/day.

Balloon inflation time during percutaneous transluminal coronary angioplasty (PTCA) is limited by the patient's tolerance to ischemia. A nonpulsatile, variable flow rate syringe pump that develops pressures up to 200 psi has been developed, along with PTCA catheters capable of delivering 0-70 cc/min of blood across a lesion at these pressures. Using this system, 110 patients have been treated with active hemoperfusion during routine PTCA. In eight cases, no preperfusion tolerated inflation time was obtained. In 96 of 102 cases, the tolerated inflation time was increased by at least 50%, for a success rate of 94%. This study demonstrated that active hemoperfusion during PTCA prolongs tolerated inflation time. The catheters and pump are capable of performing routine PTCA, supported when necessary by active hemoperfusion.

The authors analyzed the outcome of 56 episodes of cardiopulmonary resuscitation (CPR) in dialysis patients. Eleven patients (20%) left the hospital alive. Univariate analysis showed that a functional cause of cardiac arrest, absence of rib fractures, and the occurrence of cardiac arrest in the dialysis or intensive care units were associated with a favorable outcome. Logistic regression showed that the outcome of CPR was related to the presence of rib fractures, cause of arrest, degree of preexisting heart disease, and patient age. Despite the high incidence of rib fractures (77%), the outcome of CPR in dialysis patients is similar to its outcome in the general population.