PubMed Health⌕ Search

Biomedical subjects

M Chikada

Publications and source records attributed to M Chikada.

At least 19 recordsLinked to original sources

Successful surgical management of a tracheopulmonary artery fistula caused by an intratracheal expandable metal stent.

We describe a boy who underwent slide tracheoplasty and relocation of the left pulmonary artery at 3 months of age to treat pulmonary artery sling with congenital tracheal stenosis. Persisting tracheal stenosis required that he have a Palmaz stent inserted on postoperative day 77. He developed massive hemoptysis after the fourth attempt to expand the stent balloon and immediate computed tomography showed a tracheopulmonary artery fistula. Using cardiopulmonary bypass, we conducted emergency surgery to successfully manage the fistula. He currently depends on mechanical ventilation.

Arterio-Arterial Fistula↗

Direct closure of ostium primum defect in the repair of atrioventricular septal defect.

BACKGROUND: Patch closure is generally performed for atrial septation of an atrioventricular septal defect. We recently developed a new surgical technique for repairing atrioventricular septal defects that avoids the use of any patch material for closing the atrial septal defect. We report our experience with this procedure. METHODS: Seven patients (complete type: 5, partial type: 2) underwent this new operation. The diameters of the atrial septal defects were measured by transesophageal echocardiography. The preoperative electrocardiograms were compared with those taken after the operations. RESULTS: Diameters of the atrial defects ranged from 3 to 10 mm. Electrocardiograms before and after the operations did not change. No significant atrioventricular valve regurgitation and no residual shunts were detected by postoperative echocardiography. CONCLUSIONS: This method simplifies the repair of atrioventricular septal defects. In the short-term results, no arrhythmia and no valve regurgitation was seen.

Blood Vessel Prosthesis Implantation↗

Quantitative analysis of hypertrophy in cardiac chambers in cyanotic tetralogy of Fallot.

Although early total corrective repair for cyanotic tetralogy of Fallot is now safely performed at many institutions, long-term complications after surgical repair have been demonstrated. Therefore, the optimal procedure and timing for surgical treatment remain controxersial. In the present study, we conducted a quantitative analysis of the hypertrophy of all four chambers of 87 autopsied hearts of cyanotic tetralogy of Fallot and 71 normal control hearts utilizing the myocardial mass index, and evaluated the progression of lesions with advancing age. In cyanotic tetralogy of Fallot, hypertrophy of the right ventricle progresses immediately after birth, with that of the right atrium developing soon after. The left side of the heart is normal or slightly atrophied which could be corrected by sufficient palliative intervention or total corrective repair. The growth curves of both ventricles were parallel to those of normal hearts for the period studied. Pulmonary atresia, palliative operation, and total corrective repair have been shown to have some influence on the morphological characteristics of hearts of cyanotic tetralogy of Fallot.

Child, Preschool↗

[Modified extended septoplasty for left ventricular outflow tract obstruction after repair of double-outlet right ventricle report of a case].

A three-year-old boy with residual VSD and LVOTO after repair of double outlet right ventricle underwent modified extended septoplasty successfully. Preoperative left ventriculography showed a residual VSD and LVOTO. The peak systolic pressure gradient between the left ventricle and aorta was 38 mmHg. Operation aimd not only at relief of the obstruction, but also at streamlining of the LVOT by removal of protrusions. We modified the extended septoplasty reported by Belli et al in 1996. The postoperative course was uneventful and patient was discharged at 15 postoperative day. The most recent echocargiogram revealed no residual LVOTO.

Cardiac Surgical Procedures↗

Study of gene delivery in a rabbit vein graft model. Improvement of the efficiency of gene transfer into vein grafts.

Gene therapy is a therapeutic strategy in treating cardiovascular disease. Vein graft failure, the major limitation on coronary artery bypass surgery, may be amenable to gene approaches. Some studies describe gene therapies using functioning genes to prevent vein graft stenosis. Gene transfer efficiency remains a major issue. In this rabbit vein graft model, we studied gene delivery using a replication-deficit recombinant adenovirus to improve gene transfer efficiency into vein grafts. The adenovirus vector that contains the E.coli lacZ gene encoding beta gal was used because this vector is widely used and thought to be effective. Gene transfer was detected by X-gal staining. We hypothesized that dimethylsulfoxide and hyaluronidase, both drug delivery enhancers, would improve efficiency and that, in transfer to adventitia, direct injection would be more effective than dwelling. We studied 3 gene delivery methods to intima and media (controls, using dimethylsulfoxide and using hyaluronidase before transfection) and 2 delivery methods to adventitia (direct injection and dwelling). We used 6 rabbits per delivery method. X-gal stained positive cell rates were counted using light microscopy. Our findings indicate that (1) dimethylsulfoxide increased the efficiency of transfection to media and intima, (2) hyaluronidase increased intimal transfection efficiency, (3) direct injection to adventitia was more effective than dwelling. These findings suggest that in vein grafting, our methods are feasible for improving gene transfer efficiency.

Adenoviridae↗

Validation of the accuracy of both right and left ventricular outflow volume determinations and semiautomated calculation of shunt volumes through atrial septal defects by digital color Doppler flow mapping in a chronic animal model.

OBJECTIVES: The aim of the present study was to quantitate shunt flow volumes through atrial septal defects (ASDs) in a chronic animal model with surgically created ASDs using a new semiautomated color Doppler flow calculation method (ACM). BACKGROUND: Because pulsed Doppler is cumbersome and often inappropriate for color flow computation, new methods such as ACM are of interest. METHODS: In this study, 13 to 25 weeks after ASDs were surgically created in eight sheep, a total of 24 hemodynamic states were studied at a separate open chest experimental session. Electromagnetic (EM) flow probes and meters were used to provide reference flow volumes as the pulmonary and aortic flow volumes (Qp and Qs) and shunt flow volumes (Qp minus Qs). Epicardial echocardiographic studies were performed to image the left and right ventricular outflow tract (LVOT and RVOT) forward flow signals. The ACM method digitally integrated spatial and temporal color flow velocity data to provide stroke volumes. RESULTS Left ventricular outflow tract and RVOT flow volumes obtained by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = 0.78 +/- 1.7 ml for LVOT and r = 0.97, mean difference = -0.35 +/- 3.6 ml for RVOT). As a result, shunt flow volumes and Qp/Qs by the ACM method agreed well with those obtained by the EM method (r = 0.96, mean difference = -1.1 +/- 3.6 ml/beat for shunt volumes and r = 0.95, mean difference = -0.11 +/- 0.22 for Qp/Qs). CONCLUSIONS: This animal study, using strictly quantified shunt flow volumes, demonstrated that the ACM method can provide Qp/Qs and shunt measurements semiautomatically and noninvasively.

Animals↗

[A case of large congenital right ventricular outflow aneurysm].

A rare case of large congenital right ventricular outflow aneurysm is reported. A 5-year-old girl had been diagnosed as having atrial septal defect and pulmonary valvular stenosis. A large cavity in front of right ventricular outflow was noticed by her follow-up echocardiography. The non-contracting cavity was confirmed as an aneurysm originating from right ventricular outflow tract by angiocardiogram. Surgical resection was performed successfully with concomitant atrial septal defect closure and pulmonary valvular commissurotomy. Histological examination revealed that the wall of the ventricular outflow aneurysm consisted of dense fibrous tissue, contained no myocardium, and the cavity was lined with endocardium. It is reported that rupture of congenital ventricular aneurysm may occur even if there is no symptom. Surgical resection will be recommended especially when increasing in size is diagnosed.

Cardiac Surgical Procedures↗

Real-time three-dimensional echocardiography for determining right ventricular stroke volume in an animal model of chronic right ventricular volume overload.

BACKGROUND: The lack of a suitable noninvasive method for assessing right ventricular (RV) volume and function has been a major deficiency of two-dimensional (2D) echocardiography. The aim of our animal study was to test a new real-time three-dimensional (3D) echo imaging system for evaluating RV stroke volumes. METHODS AND RESULTS: Three to 6 months before hemodynamic and 3D ultrasonic study, the pulmonary valve was excised from 6 sheep (31 to 59 kg) to induce RV volume overload. At the subsequent session, a total of 14 different steady-state hemodynamic conditions were studied. Electromagnetic (EM) flow probes were used for obtaining aortic and pulmonic flows. A unique phased-array volumetric 3D imaging system developed at the Duke University Center for Emerging Cardiovascular Technology was used for ultrasonic imaging. Real-time volumetric images of the RV were digitally stored, and RV stroke volumes were determined by use of parallel slices of the 3D RV data set and subtraction of end-systolic cavity volumes from end-diastolic cavity volumes. Multiple regression analyses showed a good correlation and agreement between the EM-obtained RV stroke volumes (range, 16 to 42 mL/beat) and those obtained by the new real-time 3D method (r=0.80; mean difference, -2.7+/-6.4 mL/beat). CONCLUSIONS: The real-time 3D system provided good estimation of strictly quantified reference RV stroke volumes, suggesting an important application of this new 3D method.

Animals↗

A method for estimating aortic regurgitant effective orifice area by digital Doppler color flow mapping.

BACKGROUND AND AIMS OF THE STUDY: Although non-invasive assessment of the severity of aortic regurgitation (AR) is important, quantitative evaluation of AR can be difficult in clinical settings. Most Doppler echocardiographic methods have been compared with angiographic grading of AR severity. However, while aortic angiography is used widely for grading AR severity, the method is only semi-quantitative. A computed semi-automatic digital color Doppler method has recently been described for calculating stroke volume and cardiac output. The study aim was to develop a method of evaluating AR severity by using a digital automated color Doppler method (ACM) along with continuous wave (CW) Doppler for estimating aortic regurgitant effective orifice area. METHODS: A total of 22 different hemodynamic conditions were studied in six sheep. Regurgitant volumes (RV) were determined by electromagnetic flowmetry (EM) and by ACM. AR effective orifice areas (EOAs) were determined by dividing each of the RVs by the time integrals of the AR continuous wave velocities. AR EOAs by ACM were compared with those obtained by EM and with other EM indices of regurgitant severity. ACM was accurate for quantifying AR EOAs (r = 0.96). RESULTS AND CONCLUSIONS: Calculated AR EOA correlated well with peak AR flow and regurgitant fraction by EM. The combined ACM/CW Doppler method can be useful for estimating non-invasively the aortic regurgitant EOA and for evaluating the severity of AR.

Anatomy, Cross-Sectional↗

Open-heart surgery in Jehovah's Witness patients.

Open-heart surgery has been performed since 1975 on 25 patients who are Jehovah's Witnesses by religion. The patients' ages ranged from 6-60 years, and their body weights from 18-51 kg. Surgical procedures included correction of congenital heart disease in 14 patients and valve repair or replacement in 11. Six procedures were reoperations. The lowest mean haematocrits, during perfusion and the postoperative period, were 22.7% (range 15.0-31.0%) and 27% (range 16.0-36.0%), respectively. Twenty-four patients survived and are alive and well. One patient died of low output failure before discharge. The blood return system reduced blood loss. Five of the patients who underwent cardiac surgery received recombinant erythropoietin before and after surgery, leading to higher postoperative haematocrits. In one patient, a haematocrit which fell to 16.9% after surgery was raised to 27% by administration of erythropoietin, without blood transfusion. In two recent cases, high doses of aprotinin were used during surgery, resulting in better haemostasis after cardiopulmonary bypass.

Adolescent↗

Successful conduit repair using aortic homograft in a Jehovah's Witness child.

A 10-year-old female child of the Jehovah's Witness faith presented with congenitally corrected transposition of the great arteries (S,L,L), pulmonary atresia, and a ventricular septal defect. A successful surgical correction was performed using an aortic homograft as a valved extracardiac conduit without the use of homologous blood or blood products. We used permanent splinting of the sternum with a methyl methacrylate resin plate to prevent compression of the conduit.

Aorta↗

[Successful redo-AVR with cryopreserved allograft for prosthetic valve endocarditis : report of a case].

A 20-year-old male undergoing mechanical aortic valve replacement suffered from prosthetic valve endocarditis by Coagulase negative Staphylococci 3 months postoperatively. Echocardiography revealed left ventricular distention, severe paravalvular leakage, valve detachment and large periannular abscess adjacent to the left main coronary artery. Redo-AVR was successfully performed with a cryopreserved aortic allograft by cylinder technique. The orifice of abscess was covered with the aortic wall of the graft. Postoperative echocardiography showed trivial central regurgitation and the abscess cavity went on vanishing. He discharged from hospital 2 months later without any symptom.

Abscess↗

[Echocardiographic evaluation of hemodynamic function of CarboMedics heart valve in the aortic position in patients with small aortic annuli].

Hemodynamic parameter of CarboMedics heart valve in the aortic position was evaluated using Doppler echocardiography in 46 patients with small aortic annuli. The size of prosthetic valve were 19 mm in 6 cases, 21 mm in 15 and 23 mm in 25. In patients with 19 mm valve, trans-valvular peak pressure gradient was 42.2 +/- 11.8 mmHg, mean pressure gradient was 17.3 +/- 9.3 mmHg, and left ventricular systolic pressure was 174 +/- 12 mmHg. These values were significantly larger than those of the other two groups. Effective orifice area index, discharge coefficient, doppler velocity index and stroke volume showed no significant difference among each group. After aortic valve replacement for aortic stenosis, left ventricular mass decreased to around 70% of preoperative value in all groups, but significant left ventricular hypertrophy remained at two years postoperatively. We conclude that hemodynamic performance of CarboMedics heart valve in the aortic position was satisfactory, although 19 mm valve seemed to be fairly small for adult patients and deliberate patient selection is necessary.

Adult↗

[Pulsatile total cavopulmonary shunt for hypoplastic right heart syndrome with abnormal systemic venous return--a case report].

A pulsatile total cavopulmonary shunt was successfully performed on a 5-year-old girl with hypoplastic right heart syndrome associated with abnormal systemic venous return; at the same time, modified mitral valve replacement was performed for mitral regurgitation. The right atrium, tricuspid valve and right ventricle were all extremely dimunitive. The diameter of the tricuspid valve was 50% of normal and the volume of the right ventricle was 8.6% of normal. In addition, there were severe subpumonary stenosis, a restrictive ventricular septal defect (VSD) and an atrial septal defect (ASD). The bilateral superior venae cavae (SVCs) and the hepatic vein drained to the left atrium, and the inferior vena cava was infrahepatically interrupted with a hemiazygos connection to the left superior vena cava. At the operation, each SVC was anastomosed end-to-side to each branch of the pulmonary artery (PA). The restrictive ventricular septal defect and stenotic subpulmonary lesion were left. The diameter of the ASD was reduced from 12 mm to 7 mm. The main PA was neither divided nor banded. The pulsatile blood flow from the left heart to the PA was regurated by a native restrictive VSD and stenotic subpulmonary lesion, and that from the right heart via the ASD was limited by reducing the size of the ASD. These described anatomic arrangements produced adequate antegrade pulsatile flow in the PA, which might prevent the development of pulmonary arteriovenous fistulae and, besides permit transfer of drainage of the hepatic vein from the left to the right atrium via the ASD in future.

Arteriovenous Shunt, Surgical↗

[Anticoagulation therapy after mechanical prosthetic heart valve replacement with special reference to international normalized ratio (INR)].

We compared the efficacy and complications of anticoagulation with warfarin in 98 patients after isolated mitral valve replacement (MVR 57 pts) and isolated aortic valve replacement (AVR 41 pts). Fifty Medtronic-Hall valves, 33 St. Jude Medical valves, 9 Björg-Shiley valves and 6 other valves were used. In 1991, we made our control standard of prothrombin-time (%) between 25% and 35% (INR 2.3-3.1) and in 1992, between 30% and 40% (INR 2.1-2.8), although INR recommended by ACCP in 1988 was 3 to 4.5. In 1991, mean PT (%) was 31.2% and mean INR was 2.75 in our patients. In 1992, mean PT (%) was 35.0% and mean INR was 2.53. In 1991, we experienced bleeding episodes in three patients and thromboembolism in one case. In 1992, no complication occurred. We conclude that anticoagulant therapy of mean INR 2.53 seemed to be more suitable for Japanese patients than the ACCP standard.

Aged↗

[Pulmonary root reconstruction with a cryopreserved pulmonary allograft for mechanical pulmonary valve thrombosis].

A 58-year-old woman suffering from congestive heart failure caused by a mechanical pulmonary valve thrombosis was operated on with a pulmonary allograft. She had experienced pulmonary valvotomy and resection of infundibular stenotic muscle for congenital pulmonary stenosis at the age of 23 years old. She got congestive heart failure caused by pulmonary regurgitation, and underwent pulmonary valve replacement with a St. Jude Medical (SJM) valve when she was 48 years old. She suffered from episodes of a thrombosed SJM valve in 1984 and 1993. Each time, thrombolytic treatment with urokinase or recombinant tissue-type plasminogen activator was effective. She suffered from the third episode of SJM valve thrombosis in January 1994. As thrombolytic treatment was not effective this time, the thrombosed SJM valve was resected and her pulmonary root was reconstructed with a cryopreserved pulmonary allograft. Postoperative course was uneventful, and she now enjoys her life without anticoagulant therapy.

Cryopreservation↗