Late rupture of knitted Dacron graft.

An 87-year-old man underwent aorto-bifemoral bypass using a bifurcated Bionit II knitted Dacron graft for high aortic occlusion in 1987 at another hospital. In November, 2004, he was admitted to our institution because of difficulty in walking due to swelling and tenderness in the right groin. Computed tomography (CT) scan indicated bilateral aneurysms of the grafts in the groins. The size of the right and left aneurysms were 73 mm and 52 mm, respectively. Angiography showed some extravasation in the right thigh. We performed surgical replacement of all the dilated parts with new ringed-Dacron grafts. We report a rare case of late rupture of bifurcated Sauvage Bionit II Dacron graft.

A surgical case for severe hemolytic anemia after mitral valve repair.

We report a rare case of severe hemolytic anemia accompanied by moderate renal insufficiency after mitral valve repair. Although the degree of the residual mitral regurgitation was less than 1+ during the first three weeks after the operation, the maximum lactate dehydrogenase (LDH) was up to 7,430 U/l and the minimum hemoglobin was 4.9 g/dl. The mitral valve replacement successfully resolved the hemolysis, but the renal function did not completely recover.

[Surgical treatment of ventricular and pericardial perforation by a permanent pacing lead: a case report].

An 83-year-old woman was transferred to our hospital because of pacing failure and suspected ventricular perforation by a permanent pacing lead. She had undergone permanent pacemaker implantation 5 months previously. Chest radiography showed the pacing lead running out of the cardiac shadow. Computed tomography and echocardiography confirmed the diagnosis of ventricular perforation by the pacing lead. No evidence of cardiac tamponade was found. The lead was surgically removed through a median sternotomy. Intraoperatively, the lead was found perforating the ventricle and the pericardium, and reaching into the left pleural cavity but not injuring the left lung. A pacing lead may potentially injure the heart or the lung. Regular check-up of lead position and pacing status is recommended.

Effect of pump flow mode of novel left ventricular assist device upon end organ perfusion in dogs with doxorubicin induced heart failure.

End organ effects of nonpulsatile (NP) and pulsatile (P) left ventricular assist device (LVAD) flow were compared in a canine model of doxorubicin-induced heart failure. After heart failure induction, a prototype bimodal LVAD was implanted. Hemodynamics, cardiac dimensions, and myocardial metabolism were monitored with the LVAD off (baseline) and on (in NP and P modes at 70% or 100% power). End organ perfusion was assessed by colored microsphere analysis. Seven dogs were used: two died before pump implantation and were excluded from analysis, and the remaining five survived to study termination. At 70% NP, ascending aortic flow and myocardial oxygen consumption (MVO2) decreased significantly. At 100% NP, LV dimensions decreased, aortic systolic, pulse, and LV pressures decreased but not significantly, and ascending aorta flow reversed. At 100% NP, coronary blood flow, MVO2, and LV free wall subepicardial and subendocardial blood flows decreased significantly. However, as NP support increased, the subepicardial/subendocardial blood flow ratio remained near baseline. At 100% NP, right ventricular perfusion decreased but not significantly, cerebral perfusion decreased significantly, and renal perfusion stayed constant. P mode results were similar, except that ascending aorta flow decreased significantly at 100% P instead of reversing as at 100% NP. These results suggest that end organ perfusion is not differentially affected by LVAD flow mode during chronic heart failure.

A surgical case for hemolytic anemia after ascending and total arch replacement.

A 61-year-old man presented with consistent hemolytic anemia 15 months after ascending and total arch replacement for DeBakey I type acute aortic dissection. The cause of hemolysis turned out to be mechanical damage of red blood cells at the inverted felt of the proximal anastomosis. Reoperation of resection of the felt and repair of the proximal anastomosis successfully resolved this problem. We report a rare case of hemolytic anemia at the site of inverted felt strip after total arch replacement.

Thrombogenicity of mechanical aortic valves in an animal model: site specific testing is crucial.

We evaluated a new trileaflet prosthesis and a control bileaflet prosthesis in the mitral and aortic positions in 27 calves. The prototype trileaflet valve (TV1) functioned satisfactorily in the mitral position (TV1m, n = 7) but later yielded thrombogenic complications in the aortic position (TV1a, n = 4). The valve was redesigned (TV2) and retested in the mitral (TV2m n = 4) and aortic (TV2a, n = 5) positions, along with control valves (Cm, n = 4; Ca, n = 3). At necropsy, the valves were graded on a scale of 0 (no visible thrombi) to 4 (thrombi greater than 5 mm and/or obstructed leaflets). The TV1m, TV2m, and Cm animals, respectively, had implant durations of 215+/-112, 140+/-63, and 159+/-89 days and thrombus grades of 0.71+/-0.76, 0.33+/-0.58, and 1.50+/-0.58. The TV1a, TV2a, and Ca animals had implant durations of 18+/-12, 159+/-61, and 108+/-62 days and thrombus grades of 2.75+/-1.00, 0.50+/-0.58, and 0.67+/-0.58 (p < .005; TV2a vs. TV1a). Three TV1a calves died early of valve related complications. A design irregularity, undetected in the mitral position but revealed in the aortic position, caused a high early mortality in the TV1a animals. Redesigning the prosthesis eliminated valve related mortality and significantly reduced the thrombus grade. Because satisfactory performance in the mitral position does not guarantee safety or efficacy in the aortic position, site specific preclinical testing is crucial for mechanical heart valves.

Baseline hemodynamic and echocardiographic indices in anesthetized calves.

The experimental calf model is used to assess mechanical circulatory support devices and prosthetic heart valves. Baseline indices of cardiac function have been established for the normal awake calf but not for the anesthetized calf. Therefore, we gathered hemodynamic and echocardiographic data from 16 healthy anesthetized calves (mean age, 189.0 +/- 87.0 days; mean body weight, 106.9 +/- 32.3 kg) by cardiac catheterization and noninvasive echocardiography, respectively. Baseline hemodynamic data included heart rate (65 +/- 12 beats per minute), mean aortic pressure (113.5 +/- 17.4 mm Hg), left ventricular end-diastolic pressure (16.3 +/- 38.9 mm Hg), and mean pulmonary artery pressure (21.7 +/- 8.3 mm Hg). Baseline two-dimensional echocardiographic data included left ventricular systolic dimension (3.5 +/- 0.7 cm), left ventricular diastolic dimension (5.6 +/- 0.8 cm), end-systolic intraventricular septal thickness (1.7 +/- 0.2 cm), end-diastolic intraventricular septal thickness (1.2 +/- 0.2 cm), ejection fraction (63 +/- 10%), and fractional shortening (37 +/- 10%). Doppler echocardiography revealed a maximum aortic valve velocity of 0.9 +/- 0.5 m/s and a cardiac index of 3.7 +/- 1.1 L/minute/m2. The collected baseline data will be useful in assessing prosthetic heart valves, cardiac assist pumps, new cannulation techniques, and robotics applications in the anesthetized calf model and in developing calf models of various cardiovascular diseases.

Preclinical hemodynamic assessment of a new trileaflet mechanical valve in the aortic position in a bovine model.

BACKGROUND AND AIM OF THE STUDY: The hemodynamic characteristics of a new trileaflet mechanical heart valve (TTV) (TriFlo Inc., Costa Mesa, CA, USA) in the aortic position were evaluated in a bovine model. The TTV was designed to combine the durability of mechanical heart valves with the central flow characteristics of a bioprosthesis. METHODS: Using nine calves, the native aortic valve was replaced with a 21-mm TTV (n = 6) or a St. Jude Medical (SJM) valve (n = 3). Hemodynamic values were assessed with echocardiography at implantation and with catheterization at explantation. All calves underwent a necropsy, followed by gross pathology and light microscopy studies. RESULTS: The mean implant duration was 159 +/- 55 days for the TTV and 102 +/- 67 days for the SJM valve. Immediately before euthanasia, the peak and mean pressure gradients were respectively 35 +/- 14 and 24 +/- 9 mmHg for the TTV, and 100 +/- 72 and 59 +/- 38 mmHg for the SJM valve (p = 0.03). Two of the SJM-valve animals were electively sacrificed after showing symptoms of aortic stenosis. At necropsy, all nine valves were free from thrombi, pannus, occlusive tissue, or mechanical impairment of leaflet motion. The prematurely sacrificed SJM-valve animals had concentric myocardial hypertrophy consistent with severe functional aortic stenosis. CONCLUSION: The significantly higher gradients and left ventricular hypertrophy in the SJM-valve animals were related to a smaller effective orifice area, which precluded adaptation to increasing transvalvular volumes in the growing animal. This problem was not seen with the TTV, which performed hemodynamically as well as the SJM valve. The high transvalvular gradients seen with the SJM valve at study end may suggest that the hemodynamic characteristics of the TTV may be superior, though additional studies are needed to confirm this.

Outcome of the perioperative use of percutaneous cardiopulmonary support for adult cardiac surgery: factors affecting hospital mortality.

Percutaneous cardiopulmonary bypass support (PCPS) has become a widespread standard modality for the treatment of circulatory collapse; however, its clinical use for postcardiotomy low cardiac output syndrome (LOS) has been reported to be unsatisfactory. We reviewed the clinical outcomes of twenty-three patients undergoing cardiac surgery and treated with PCPS. Solitary coronary artery grafting was undertaken for nine patients, while three had concomitant procedures. The remaining patients underwent valvular surgery. The indications for PCPS were preoperative shock in two patients and postcardiotomy LOS or shock in twenty-one patients. All patients except one underwent an intraaortic balloon pump. Sixteen of the twenty-three patients (69.6%) were weaned from PCPS and twelve patients (52.2%) reached hospital discharge. A univariate analysis revealed that risk factors for hospital mortality were age older than seventy years (P = 0.05), PCPS running time (P = 0.017), low cardiac function at the institution of PCPS (P = 0.004), and urine output within the initial 24 h (P = 0.041). The cardiac index (CI) in survivors was improved within 24 h, and eleven of the twelve survivors were weaned off PCPS within 48 h, whereas ten of the twelve nonsurvivors required PCPS for more than 48 h (P = 0.0006). There is little possibility of weaning patients from PCPS who do not show any signs of hemodynamic recovery within 48 h after its institution. Limited use of PCPS within 48 h may be applicable for postcardiotomy patients, but other cardiopulmonary support, such as a left ventricular assist device, may be required when hemodynamic recovery is not obtained within 48 h.

Myocardial hemodynamics, physiology, and perfusion with an axial flow left ventricular assist device in the calf.

The Jarvik 2000 axial flow left ventricular assist device (LVAD) is used clinically as a bridge to transplantation or as destination therapy in end-stage heart disease. The effect of the pump's continuous flow output on myocardial and end-organ blood flow has not been studied experimentally. To address this, the Jarvik 2000 pump was implanted in eight calves and then operated at speeds ranging from 8,000 to 12,000 rpm. Micromanometry, echocardiography, and blood oxygenation measurements were used to assess changes in hemodynamics, cardiac dimensions, and myocardial metabolism, respectively, at different speeds as compared with baseline (pump off, 0 rpm) in this experimental model. Microsphere studies were performed to assess the effects on heart, kidney, and brain perfusion at different speeds. The Jarvik 2000 pump unloaded the left ventricle and reduced end-diastolic pressures and left ventricular dimensions, particularly at higher pump speeds. The ratio of myocardial oxygen consumption to coronary blood flow and the ratio of subendocardial to subepicardial blood flow remained constant. Optimal adjustment of pump speed and volume status allowed opening of the aortic valve and contribution of the native left ventricle to cardiac output, even at the maximum pump speed. Neither brain nor kidney microcirculation was adversely affected at any pump speed. We conclude that the Jarvik 2000 pump adequately unloads the left ventricle without compromising myocardial metabolism or end-organ perfusion.

Preclinical assessment of a trileaflet mechanical valve in the mitral position in a calf model.

BACKGROUND: The bileaflet valve is currently the mechanical replacement valve of choice. Though durable, it does not closely mimic native valve hemodynamics and remains potentially thrombogenic. METHODS: Prototype trileaflet valves (T1 and T2) were implanted in the mitral position in calves. Group I calves received either a T1 valve (n = 12) or a control bileaflet valve (n = 5); Group II, either a T2 valve (n = 7) or a control bileaflet valve (n = 5). Valve function, perivalvular leakage, and transvalvular pressure gradients were evaluated. Also, long-term prototype leaflet wear was evaluated in vivo in one Group I calf (502 days) and two Group II calves (385 and 366 days). Calves were euthanized and necropsied at study termination, and major organs weighed and examined. RESULTS: Valve function was excellent and hematologic parameters remained normal in all calves that survived to study termination. Mean peak transvalvular pressure gradients were 10 +/- 7 mm Hg for T1 valves, 6 +/- 3 mm Hg for T2 valves, and 12 +/- 4 mm Hg for bileaflet control valves. Clinically insignificant valvular regurgitation was observed in both prototypes. Explanted valves showed no thrombus-impaired leaflet motion, except in two T1-fitted calves and one T2-fitted calf. Major organs showed no evidence of clinically significant thromboembolic events. There were no other significant differences between the results of experimental and control groups. CONCLUSIONS: Prototype trileaflet valves performed safely and effectively in the mitral position in calves, even without long-term anticoagulation. This warrants their evaluation as an equivalent alternative to bileaflet valves.

Evaluation of a new cardiac recovery system in a bovine model of volume overload heart failure.

We evaluated the short-term hemodynamic efficacy of the Cancion cardiac recovery system (CRS) in a bovine model of volume overload heart failure. We created severe mitral regurgitation (MR) by disrupting the mitral chordae tendineae of two calves, which were allowed to survive for 13 and 11 months. Four hours before we killed the calves, we introduced the CRS, which maintained flows of 1.2 L/min. Hemodynamic data were recorded before and after MR creation and CRS initiation. Left ventriculography was performed at those same intervals and 4 hours after CRS initiation. After chordal disruption, the left ventricular end-diastolic pressure (LVEDP) increased from 14 to 23 mm Hg in calf 1 and 15 to 27 mm Hg in calf 2. After 4 hours of CRS support, the LVEDP decreased from 23 to 8 mm Hg (calf 1) and 27 to 14 mm Hg (calf 2); dP/dt increased from 1,373 to 2,900 mm Hg/s (calf 1) and 1,068 to 2,384 mm Hg/s (calf 2). MR decreased from 3+ to 1 in calf 2 but could not be determined in calf 1. In this bovine model of volume overload heart failure, the CRS unloaded the left ventricle and reduced the afterload. Future trials will determine the pump's ability to treat congestive heart failure.

Prolonged controlled hemorrhagic shock in a swine model: is there a role for mechanical circulatory assistance?

Outcomes of mechanical circulatory assistance during hemorrhagic shock were evaluated in a swine model. Pigs were bled to a mean arterial pressure of 35 mm Hg (group I, n = 3) or 40 mm Hg (group II, n = 5; group III, n = 5), maintained there for 30 minutes, and then resuscitated with fluids alone (groups I and II) or fluids plus mechanical circulatory assistance (group III). Mean blood loss was greater in group I than in groups II or III (1,037 +/- 212 vs. 862 +/- 387 ml vs. 681 +/- 117 ml, respectively; I vs. III, p < 0.05) and survival was shorter (230 +/- 25.5 min vs. 709 +/- 251 min vs. 662 +/- 428 min, respectively; I vs. II or III, p < 0.05). Cardiac arrhythmia caused death in most cases. Mean biochemical parameters increased progressively in all cases. Left anterior descending coronary artery flow stayed relatively constant in group II but increased in group III. Superior mesenteric artery flow returned to baseline in group II but increased in group III. Cardiac output was similar in groups II and III, but SGOT levels significantly differed (750 +/- 135 U/L vs. 359 +/- 157 U/L; p < 0.005). These results suggest that the swine model will be useful for studying ways to improve outcomes after prolonged hemorrhagic shock.

Ex vivo resuscitation of adult pig hearts.

One possible way to expand the human heart donor pool is to include non-heart-beating human donors. To begin validating this approach, we developed an ex vivo cardiac perfusion circuit to support large mammalian hearts in Langendorff mode and beating-ejecting mode and to assess and improve their ischemic tolerance. In vivo hemodynamic data and heparinized blood (4.0 +/- 0.5 L) were collected from 6 anesthetized pigs. Hearts were isolated and connected to a recirculating perfusion circuit primed with autologous buffered blood (pH, 7.40). After retrograde aortic perfusion in Langendorff mode, the left atrium was gravity-filled at 10-20 mmHg, and the left ventricle began to eject against a compliance chamber in series with a systemic reservoir set to a hydraulic afterload of 100-120 mmHg. Left ventricular function was restored and maintained in all 6 hearts for 30 min. Cardiac output, myocardial oxygen consumption, stroke work, aortic pressure, left atrial pressure, and heart rate were measured. The mean myocardial oxygen consumption was 4.8 +/- 2.7 mL/min/100 g (95.8% of in vivo value); and mean stroke work, 5.3 +/- 1.1 g x m/100 g (58.95% of in vivo value). One resuscitated heart was exposed to 30 min of normothermic ischemic arrest, then flushed with Celsior and re-resuscitated. The ex vivo perfusion method described herein restored left ventricular ejection function and allowed assessment of ischemic tolerance in large mammalian hearts, potentially a 1st step toward including non-heart-beating human donors in the human donor pool.

Use of autologous auricular chondrocytes for lining artificial surfaces: a feasibility study.

BACKGROUND: Auricular elastic cartilage is a potential source of autologous cells for lining the luminal surfaces of cardiovascular prostheses. We tested this potential in vitro and in vivo using a left ventricular assist device (LVAD) and a calf model. METHODS: In vitro, auricular cartilage was harvested from the anesthetized ear of a calf, isolated, and cultured on tissue culture dishes. Primary chondrocytes were typed by immunocytochemistry, transferred into culture media, passaged twice, and seeded onto the blood-contacting luminal surfaces of four LVADs (HeartMate; Thoratec Corporation, Woburn, MA). Seeded cell linings were preconditioned under simulated flow conditions to promote cell adhesion to luminal surfaces. Seeding efficiency and cumulative cell loss under flow conditions were quantitated. In vivo, one of the four autologous chondrocyte-lined and preconditioned LVADs was implanted into the tissue-donor calf; run for 7 days; explanted; and evaluated grossly, by scanning electron microscopy, and by transmission electron microscopy. RESULTS: The efficiency of seeding chondrocytes onto the luminal surfaces of the four LVADs was 95.11% +/- 4.23% (n = 4). Cumulative cell loss during preconditioning under flow conditions in vitro did not exceed 12% (n = 4). After 7 days of in vivo implantation, the luminal surfaces of the implanted LVAD demonstrated an intact, strongly adherent cellular lining. CONCLUSIONS: Auricular elastic cartilage is a ready and easily accessible source of chondrocytes whose ability to produce collagen II and other important extracellular matrix constituents allows them to adhere strongly to the luminal surfaces of LVADs. The simple method of isolating and expanding auricular chondrocytes presented here could be used to provide strongly adherent autologous cell linings for LVADs and other cardiovascular devices. If and when chondrocytes can be genetically engineered to produce antithrombogenic factors and then used to line the luminal surfaces of LVADs or other cardiovascular prostheses, they may be able to improve the hemocompatibility of the blood-biomaterial interface in such devices. Our successful feasibility study in a calf model warrants further studies of this concept in vivo.

Development of a Centrifugal Pump with Improved Antithrombogenicity and Hemolytic Property for Chronic Circulatory Support.

A centrifugal pump with a unique structure has been developed for chronic support. The pump is driven by a magnetic coupling and has no rotating shaft, no seal around the rotating part, and a balancing hole at the center of the impeller and the thrust bearing. The pump was improved in stepwise fashion to realize good antithrombogenicity and low hemolysis. The first pump, the National Cardiovascular Center (NCVC)-O, had an impeller with 4 rectangular and curved vanes; 6 triangularly shaped curved vanes were employed in the second model, the NCVC-1, to reduce trauma to the blood. In the third design, the NCVC-2, the central hole was enlarged, and the thrust bearing shoulder was rounded so that blood washing was enhanced around the impeller; stream lines also were smoothed for improved antithrombogenicity. The hemolytic property of the device was evaluated in vitro with heparinized fresh goat blood; hemolysis indexes of the NCVC-0, -1, and -2 were 0.05, 0.01, and 0.006 g per 100 L, respectively. Antithrombogenicity of the pumps was examined in animal experiments as a left heart bypass device in goats weighing 52-75 kg. Six NCVC-0 pumps were driven for 14 to 33 (22.0 ± 7.6) days in goats receiving the antiplatelet drug cilostazol orally. Four NCVC-I pumps ran for 1 to 80 (28.5 ± 30.6) days with the same drug regimen in 2 cases and with no anticoagulation therapy in 2 cases. After 3 preliminary 1-week tests of NCVC-2 pumps in animals, the pump was installed in 3 goats; 2 pumps were still running on the 182nd and 58th pumping day. Intracorporeal implantation also was attempted successfully. The results indicate that this pump has promising features for chronic support although longer term and additional evaluations are necessary.