[Natural evolution of coronary artery ectasia after coronary artery bypass grafting]

Coronary artery aneurysm and ectasia, unusual angiographic findings, are considered as variant of atherosclerotic coronary artery disease. A 49-year-old man whose right coronary artery ectasia had progressed to large aneurysm, accompanied by advanced obstructive coronary artery disease, 6 years after the initial coronary artery bypass grafting. It was treated with ligation of aneurysm and distal bypass grafting under cardiopulmonary bypass. Fragile fresh clot was formed within the aneurysm irrespective of coumadin therapy as a standard regimen for the coronary artery ectasias. We will discuss the surgical management for the dilated coronary artery with significant coronary stenosis.

Washing of the residual solution of cardiopulmonary bypass circuit after coronary artery bypass grafting in idiopathic thrombocytopenic purpura

A 76-year-old female with chronic idiopathic thrombocytopenic purpura required coronary bypass grafting. Preoperative treatment with high-dose intravenous immunoglobulin at a dose of 0.4 g/kg/day raised the platelet count from 57,000 to 110,000/microL. After termination of cardiopulmonary bypass (CPB) the residual blood in the CPB circuit was washed to reduce total immunoglobulin G (IgG) level, including platelet-associated immunoglobulin G (PA-IgG), and returned to the patient. Intraoperative platelet transfusion was used due to a drop in platelet count to the pretreatment level. The postoperative level of IgG and PA-IgG remained significantly lower than preoperatively. The postoperative course was uneventful and without bleeding complications. Perioperative management of a patient with idiopathic thrombocytopenic purpura undergoing open-heart surgery is discussed.

Mediastinal irrigation with superoxidized water after open-heart surgery: the safety and pitfalls of cardiovascular surgical application

Postoperative mediastinal infection after open-heart surgery via median sternotomy is a devastating complication. In this paper, we describe a simple method of irrigating the mediastinum using superoxidized water to prevent perioperative contamination. After mediastinal hemostasis was done, warm superoxidized water of more than 21 was uninterruptedly irrigated for 5 min immediately prior to sternal closure. We have used this method in 25 patients undergoing cardiac surgery, and noted significant perioperative electrocardiographic changes, including ST elevation, without hemodynamic compromise in 15 of these patients.

Subdivided left atrium mimicking a cardiac tumor

We describe a 25-year-old man with a subdivided left atrium. The lesion was misdiagnosed preoperatively as a cardiac tumor because echocardiographic and magnetic resonance imaging revealed a solid mass arising from the posterior wall of the left atrium. Cardiac surgery revealed a small accessory chamber draining the two left pulmonary veins. No membranous structure was evident between the chamber and the left atrium. The solid mass identified noninvasively was a hypertrophic muscle which formed a wall of the accessory chamber.

Regulation of the aortic valve opening. In vivo dynamic measurement of aortic valve orifice area

Aortic valve orifice area was dynamically measured in anesthetized dogs with a new measuring system involving electromagnetic induction. This system permits us real-time measurement of the valve orifice area in beating hearts in situ. The aortic valve was already open before aortic pressure started to increase without detectable antegrade aortic flow. Maximum opening area was achieved while flow was still accelerating at a mean of 20 to 35 msec before peak blood flow. Maximum opening area was affected by not only aortic blood flow but also aortic pressure, which produced aortic root expansion. The aortic valve orifice area's decreasing curve (corresponding to valve closure) was composed of two phases: the initial decrease and late decrease. The initial decrease in aortic valve orifice area was slower (4.1 cm2/sec) than the late decrease (28.5 cm2/sec). Aortic valve orifice area was reduced from maximum to 40% of maximum (in a triangular open position) during the initial slow closing. These measurements showed that (1) initial slow closure of the aortic valve is evoked by leaflet tension which is produced by the aortic root expansion (the leaflet tension tended to make the shape of the aortic orifice triangular) and (2) late rapid closure is induced by backflow of blood into the sinus of Valsalva. Thus, cusp expansion owing to intraaortic pressure plays an important role in the opening and closing of the aortic valve and aortic blood flow.

[Surgical treatment of double orifice mitral valve in atrioventricular septal defect]

Ten patients with double orifice mitral valve and atrioventricular septal defect (AVSD) were examined. There were four cases with incomplete type, three with intermediate type and three with complete type AVSD. All patients with incomplete type AVSD were doing well after the mitral cleft repair, Leaving the accessory orifice untouched. Various valve repair procedures and prosthetic valve replacement were performed in the patients with intermediate and complete types of AVSD with left-sided atrioventricular valve regurgitation. There were three operative deaths, which included one patient with the intermediate type and two with the complete type. All of them were one-month old babies and were operated on emergency. Their general operative findings were hypoplasia of the common atrioventricular valve leaflets, abnormal attachment of the chorda tendineae and papillary muscle dysplasia. These findings increased the difficulty of the valve plasty to control mitral regurgitation.

Role of the septal leaflet in tricuspid valve closure. Consideration for treatment of complete atrioventricular canal

A septal leaflet of the tricuspid valve is thought to work differently from other anterior and posterior leaflets. We studied its role in valve closure in dogs by means of a dynamic area meter. During the control state, the tricuspid valve orifice area increased twice in diastole coincidentally with either atrial systole or rapid ventricular filling. We observed several findings after the septal leaflet resection: (1) two peak area patterns of the tricuspid valve orifice in diastole, (2) no elevation of right atrial pressure on ventricular systole (there was no V wave), (3) no tricuspid valve regurgitation on right ventriculography. These findings suggest that a complete valve closure occurred without the septal leaflet in regular sinus rhythm. An elevation of the right ventricular pressure produced by pulmonary artery stenosis without septal leaflet, however, easily caused tricuspid valve regurgitation in contrast to the same pressure of the right ventricle with the normal tricuspid valve. The right ventricular pacing caused severe valve regurgitation without the septal leaflet. Results indicate that in the repair of the complete atrioventricular canal defect and other tricuspid valve lesions, the septal leaflet of the tricuspid valve rarely requires attention. An atrioventricular block should be avoided, however, because electrical cardiac pacing on the right ventricle causes severe valve regurgitation without the septal leaflet.

[Fontan type procedure in patient with borderline hemodynamics: using a temporary R-L shunt in early postoperative period]

Fontan type procedure was successfully performed to a 14-year-old patient with borderline hemodynamics using a temporary R-L shunt in early post operative period. Preoperative diagnosis was DORV (ILD), small RV, PS, ASD, juxtaposition of atrial appendages and post bilateral B-T shunts. Preoperative catheterization studies showed low PARI but insufficient pulmonary arterial size (PA-index 220). In the Fontan procedure, RA was partitioned obliquely with a composite patch of xenograft and Dacron velour. A 5.5 mm hole was created only in xenograft to allow a temporary R-L shunt. During rewarming period, systemic pressure hovering around 60 mmHg with 10 micrograms/kg/min of dopamine and dobutamine. Then a R-L shunt was created by a side to side anastomosis between the appendages with the orifice diameter of 10 mm, followed by a rise in the systemic pressure up to about 80 mmHg. One post operative day, a readjustable occluder was applied at the site of appendage anastomosis to control R-L shunt flow. According as CVP decreased, the occluder was tightened up step by step. Finally, the occluder was fully tightened up in 10 post operative days. This experience suggests that a temporary R-L shunt in early post operative period may be applicable in patient with borderline hemodynamics for Fontan type procedure.

An in vivo area meter for real-time measurement of cross-sectional area in the cardiovascular system

A direct real-time recording of the cross-sectional area of the heart valve is useful for the fluid dynamic study of the cardiovascular system. Electronic circuitry is described that is capable of driving the transmitter coil assembly placed outside the animal and detecting an area-related signal induced in the one-turn coil in vivo. When a piece of fine pliable metal thread encircles the area of interest (e.g. the mitral/aortic valve orifice) so as to form a single loop, the electrical potential between the ends of the loop is linearly related to the size of the area irrespective of its shape. The principle of measurement, construction of transmitter coil assembly, and simple but accurate direct calibration are also described.

[A new valved conduit with commissures using a glutaraldehyde preserved equi pericardium]

We developed a new valved conduit with commissures using a glutaraldehyde preserved equine pericardium, and implanted this prosthesis between the right ventricle and the pulmonary artery in the dog to examined the movement of the valve. Our new prosthesis consists of a conduit and three leaflets. Each leaflet is sutured to the inner surface of the conduit to form a valve. The adjacent free edges of the leaflets are sutured together by placing a mattress stitch 2 mm from their attachment to the conduit so that the leaflets form commissures. These commissures are designed to facilitate prompt coaptation of the three leaflets in diastole. A radiopaque marker is anchored to the center of the free edge of each leaflet and to the outer surface of the conduit to investigate its movement. The movement of the radiopaque markers studied by cineangiography revealed good coaptation of three leaflets in diastole and their full opening in systole. These findings demonstrated that the valve in our prosthesis might function well to prevent regurgitation across it.

Percutaneously adjustable pulmonary artery band. An experimental study

Several forms of congenital heart lesions with increased pulmonary flow can be effectively palliated by pulmonary artery banding. In addition, banding has aroused renewed interest to induce left ventricular hypertrophy in infants with simple transposition of the great arteries. Occasionally a need arises to readjust the band to obtain an optimal degree of banding after operation. For percutaneous control of the degree of constriction after pulmonary artery banding, we developed a readjustable vessel occluder. The occluder consists of a stainless steel snare coated with polyethylene, an enveloping polyvinyl catheter (5F and 8 to 12 cm in length), and a screw adjuster, which is a stainless steel cylinder, 7 by 20 mm, containing a bolt and a nut. By means of a specially designed needle driver (1.0 mm in diameter), the screw adjuster can easily be driven percutaneously without a skin incision. The maximum stroke of the screw is 14 mm by 34 revolutions. One complete revolution of this screw corresponds to a change in diameter of 0.14 mm and to a change in circumference of 0.44 mm. Six mongrel dogs ranging in weight from 5 to 10 kg underwent banding of the pulmonary artery or the ascending aorta with this device. Follow-up evaluation by cardiac catheterization and angiocardiography was performed up to 2 months after implantation of the device. This band could be effectively and finely adjusted up to 2 months after implantation and no complication was seen. This preliminary study suggests that this new device may be applicable in patients with congenital heart disease and excessive pulmonary blood flow.

[Pulmonary valve replacement using the right ventricle-pulmonary artery bypass without cardiopulmonary bypass]

We underwent pulmonary valve replacement using the right ventricule pulmonary artery bypass without cardiopulmonary bypass. This right heart bypass was consisted of the vascular graft and the polystyrene tube. The vascular graft was anastomosed to the main pulmonary artery and the polystyrene tube was inserted into the free wall of the right ventricle. These were connected with a cannulating magnetic flow probe. After the bypass was established, the pulmonary artery was clamped and divided. The pulmonary valves were excised and the pulmonary valve replacement was undergone with a pulmonary valve homograft. Hemodynamics during the pulmonary valve replacement was stable and the postoperative course was uneventful. One month later, the cardiac catheterization and cineangiography showed that the implanted homograft was effective sufficiently. We concluded that this right heart bypass was useful for the pulmonary valve replacement.

Real-time and simultaneous measurement of tricuspid orifice and tricuspid anulus areas in anesthetized dogs

Tricuspid valve orifice and tricuspid valve anulus areas were measured simultaneously in the anesthetized dog with a newly developed area-measuring system based on electromagnetic induction. This system permitted real-time monitoring of the area enclosed by the edges of valve leaflets and by the juncture of the valve leaflet and the cardiac wall in situ, without artificial constraint to the valve motion. Right atrial and right ventricular pressures were measured with two catheter-tipped micromanometers. During control state, tricuspid valve orifice area (TOA) increased up to its peak [1.38 +/- 0.26 cm2 (mean +/- SD)] coincidently with either atrial systole or rapid ventricular filling. Atrial contraction evoked distinct presystolic tricuspid anulus narrowing with concomitant slow TOA reduction. This slow TOA reduction began 30.0 +/- 16.1 msec before systolic atrioventricular pressure crossover, and the following rapid TOA decrease was completed 38.7 +/- 12.2 msec after systolic atrioventricular pressure crossover. TOA began to increase 48.4 +/- 30.4 msec before diastolic atrioventricular pressure crossover at the end portion of the isovolumic relaxation phase, opposing residual transvalvular pressure gradient (3.33 +/- 1.79 mm Hg). The slow presystolic TOA decrease was considered to be a reflection of the presystolic anulus narrowing caused by atrial systole. An isolated atrial contraction induced by administering 1 mg acetylcholine chloride into the atrioventricular node artery or by vagus nerve stimulation could produce complete valve closure. Even in an isolated atrial contraction, the inflection point that marks the boundary between slow "atriogenic" closure presumably due to anulus narrowing and rapid closure presumably due to hemodynamic force was easily identified.

[An experimental study of the use of fresh aortic valve homograft for the usage of the vena caval valve. Part 1. The evaluation of hemodynamics and cineangiographic study]

The purpose of this study is to develop a vena caval valve using the fresh aortic valve homograft. A preliminary study was performed in six dogs by interposing a cryopreserved aortic valve homograft with sinus Valsalva into SVC. After making the tricuspid regurgitation, the aortic valve homograft was closed by the regurgitant flow in the systolic phase and opened by the venous return in the diastolic phase. The preliminary study showed that the cryopreserved aortic valve homograft with sinus Valsalva was useful as a vena caval valve immediately after the implantation. Fresh aortic valve homografts were implanted in 11 dogs in the same manner. Eighteen pressure studies and cine-angiographies were performed in six dogs on 8 to 165 days after the implantation. Pressure studies showed minimal/small pressure gradients across the implanted homografts. However, cineangiography revealed appearance of regurgitation through the implanted homograft three months later. Thromboembolism was not happened in all dogs at all. Therefore, we concluded that the fresh aortic homograft with sinus Valsalva might be clinically feasible for use as a vena caval valve.

[Experimental study on the optimal size of the tricuspid valve annular area on annuloplasty]

The optimal size of tricuspid valve annular area (TVAA) by annuloplasty for tricuspid regurgitation remains controversial. Recently, we developed a new measuring system which permits to do real-time measurement of tricuspid valve annular area in anesthetized dogs. Using this system, we studied the optimal size of TVAA by annuloplasty. After the right atrial incision, a metal thread which functions as a sense loop of the electromagnetic fields was stitched along the tricuspid valve annulus (visible juncture of the valve leaflets and the cardiac wall). The drive coil assembly was placed perpendicular to the extension of the long axis of the heart and was directed toward the tricuspid valve region. During control conditions, the maximum TVAA appeared at the onset of ventricular systole. The minimum TVAA appeared during the early ventricular diastolic phase which included the ventricular isovolumic relaxation phase. The maximum TVAA varied in five dogs between 2.2 cm2 and 3.1 cm2, the minimum TVAA also varied between 1.8 cm2 and 2.5 cm2: During regular sinus rhythm, a decrease of TVAA during one cardiac cycle ranged between 11.9% and 22.4% of the maximum size. When TVAA was not decreased by annuloplasty to the minimum area which was observed during cardiac cycle in the control state, the cardiac output and the right atrial pressure remained unchanged, because the ventricular filling was not obstructed. On the other hand, when TVAA was decreased smaller than this minimum area, the cardiac output decreased and the right atrial pressure rose.(ABSTRACT TRUNCATED AT 250 WORDS)

In vitro analysis of performance of porcine xenografts with inward bending of stent posts: real-time measurement of valve orifice area using an area meter

The influence of inward bending of the stent posts on bioprosthetic valve function was assessed in a hydromechanical simulation of the left heart. A Carpentier-Edwards mitral xenograft (31 mm) and an aortic xenograft (27 mm) were used. Valve function was evaluated before and after the stent posts were bent inward 15 degrees by suture constriction of the tops of the three posts. To evaluate the effects of the stent-post deformity on valve performance, the mean transvalvular pressure drop during steady flow, the bioprosthetic valve orifice area, and the maximum valve opening and closing speeds during pulsatile flow were measured using an area meter. Steady-flow data showed identical transvalvular pressure drops, and no significant difference in valve performance was detected in the pulsatile-flow study under the two experimental conditions (i.e., normal valve and deformed valve). We conclude that a 15-degree inward bending of the stent posts does not appreciably affect valve function in vitro.

Real-time measurement of tricuspid valve annular area for annuloplasty. Experimental study

We used real-time measurement of the tricuspid valve annular area in anesthetized dogs to study the optimal size of the annular area for annuloplasty. During control conditions, the maximum tricuspid annular area appeared at the onset of ventricular systole. The minimum tricuspid annular area appeared between the ventricular isovolumic relaxation phase and the early ventricular filling phase. The maximum annular area varied in seven dogs between 2.18 and 3.10 cm2, and the minimum annular area ranged between 1.68 and 2.45 cm2. In regular sinus rhythm (heart rates 97 to 120 beats/min), the maximal decreases in tricuspid annular area during one cardiac cycle ranged from 14.3% to 23.6% of the maximum size. When the tricuspid annular area after the annuloplasty was kept larger than the minimum area that was observed during the cardiac cycle in the control study, cardiac output and right atrial pressure remained unchanged, as a result of unobstructed ventricular filling. On the other hand, when the annular area was reduced to smaller than the minimum area seen in the control study, a decrease in cardiac output and an elevation of right atrial pressure ensued. These findings suggest that the tricuspid annular area can be safely decreased by annuloplasty to the minimum area seen in the control study without causing a reduction of cardiac output or an elevation of right atrial pressure.

A new method to induce topical cooling of the right atrium for treatment of supraventricular tachyarrhythmia: an experimental study

Supraventricular tachyarrhythmia (SVT) such as sinus tachycardia and atrial dysrhythmia is a life-threatening problem in the period immediately following an open-heart operation. Because of their negative inotropic effects, antiarrhythmic agents are not recommended for patients with low cardiac output syndrome. A device was developed that topically cools the right atrial surface for antiarrhythmic treatment. In experiments, this device lowered right atrial temperature and did not affect the temperature of the right ventricle or the whole body. When right atrial temperature decreased from 37 degrees to 28 degrees C, heart rate was reduced from 146.3 to 109.7 beats per minute (p less than .001). Meanwhile, cardiac output and blood pressure remained within control levels. In the treatment of experimental SVT induced by the intravenous infusion of isoproterenol hydrochloride and by direct application of aconitine, this method worked effectively and was reproducible. The results demonstrated the beneficial effects of this method in the treatment of SVT in experimental studies and suggested its future clinical application following open-heart operations.

Principle of a noninvasive method of measuring Max(dP/dt) of the left ventricle: theory and experiments

In early systole, before the effects of reflected waves from the periphery become significant, the following equation applies: PA - PO = rho cu (1) where PA and PO are the instantaneous and end-diastolic pressures in the ascending aorta, rho the density of blood, c the velocity of the pulse wave in the aorta, and u the velocity of blood. Differentiation of Eq. (1) with respect to time t yields: dPA/dt = rho c(du/dt) (2) If there is no aortic stenosis, and if the pressure gradient due to the inertia of the blood during acceleration is neglected, the left ventricular pressure P is nearly equal to PA during the ejection period. Since both dP/dt and dPA/dt take their maximum values at times close to the time of aortic valve opening, the following equation applies: Max(dP/dt) not equal to Max(dPA/dt) (3) where Max signifies the maximum value of a derivative. Equation (2) reduces to: Max(dPA/dt) = rho c Max(du/dt) (4) Substitution of Eq. (4) into Eq. (3) yields: Max(dP/dt) not equal to rho c Max(du/dt) (5) Experiments were performed on seven dogs. Max(dP/dt), Max(du/dt), and c were measured during volume loading, pressure loading and unloading, and before and after administration of positive and negative inotropic agents. There was a good linear correlation (Y = 1.01X-2, r = 0.97) between Max(dP/dt) and rho c Max(du/dt). Therefore, Eq. (5) is a universal equation which holds, irrespective of the dogs and interventions employed to change the hemodynamic state.(ABSTRACT TRUNCATED AT 250 WORDS)

Technique with lock-in amplifier for real-time measurement of tricuspid valve annulus area

A new measuring system that permits real-time registration of the tricuspid valve annular area (TVA) using lock-in amplifier is devised and applied in open-chest anesthetized dogs. The tricuspid valve annulus was stitched with a fine, pliable, metal thread made of 10 30-micron urethane resin-coated copper wires during inflow occlusion. Both ends of the thread were guided out from the right atrium through a single pinhole in the right atrial wall. The signal intensity induced in the sense loop is linearly related to the area encircled by the thread, i.e., the area of the tricuspid annulus. During control state, TVA varied by an average of 24.5% (3.8-46.5%) of its maximum. Presystolic peak and valley of TVA due to atrial contraction and a decrease in TVA during ventricular ejection were generally observed. An increase in TVA during the initial portion of isovolumic contraction phase was prominent in dogs with filariasis, whereas in the other dogs it was not.