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Biomedical subjects

A T Kawaguchi

Publications and source records attributed to A T Kawaguchi.

At least 19 recordsLinked to original sources
PubMed1996

Risks and benefits of combined maze procedure for atrial fibrillation associated with organic heart disease.

OBJECTIVES: This study sought to identify the risks and benefits of adding the maze procedure in patients with atrial fibrillation (AF) undergoing operation for underlying organic cardiac disorders. BACKGROUND: Persistent AF often leaves patients symptomatic even after otherwise successful cardiac surgery. METHODS: Fifty-one patients undergoing valvular operation and the maze procedure (n = 43) or repair of congenital anomalies (n = 8) combined with the maze procedure were compared with 51 patients (control group) matched for underlying diseases and procedures except for the maze operation. Each group, including 31 patients with a concomitant tricuspid annuloplasty and 12 undergoing reoperation, were similar in age, duration of arrhythmia, degree of cardiomegaly and New York Heart Association functional class. RESULTS: Patients undergoing the maze procedure had longer cardiopulmonary bypass time (213 vs. 144 min, p < 0.0001), longer cardiac arrest (134 vs. 93 min, p < 0.0001) and greater blood loss with longer respiratory care (39 vs. 18 h p = 0.021) and intensive care unit stay but no mortality. No significant differences were found in catecholamine or transfusion requirements immediately after operation. Sustained AF was much less frequent in the maze group (12% at 1 year) than the control group (86%, p < 0.0001), with an average follow-up period of 32 months (range 25 to 42). Atrial contraction was documented in 41 (80%) and 40 (78%) patients for right and left ventricular filling, respectively, after the maze procedure, resulting in a significantly smaller cardiac size and improved functional capacity. Medication was discontinued in seven patients in the maze group compared with two in the control group. CONCLUSIONS: Improved restoration of atrial rhythm and contraction with combined maze operation appeared to justify the increased operative time and complexity and postoperative care.

Atrial Fibrillation↗
PubMed1996

Inhaled nitric oxide: diameter response patterns in feline small pulmonary arteries and veins.

Using an X-ray television system on the in vivo cat lung, we directly measured internal diameter (ID) changes in the small pulmonary arteries and veins (100-1,100 microns ID) in response to 5, 15, and 40 ppm nitric oxide (NO) inhalations. We also measured to what extent 40 ppm NO inhalation can attenuate large ID constrictions at the different serial segments of the small vessels due to unilobar anoxic (0% O2) exposure. Under normoxic conditions, 5-40 ppm NO inhalations significantly increased the ID of both arteries and veins less than approximately 900 microns dose dependently but caused no significant, or only slight, ID increases in the vessels larger than this, if any at all. The ID increase in the serially connected arteries was nonuniform (4-18, 8-28, and 7-35% with 5, 15, and 40 ppm NO inhalations, respectively), whereas that for the veins was relatively uniform (4-9, 6-17, and 7-18% with 5, 15, and 40 ppm NO, respectively). The maximum ID increase occurred in the 200- to 500- and 200- to 700-microns arteries in response to 5-15 and 40 ppm NO, respectively. Unilobar anoxic exposure significantly decreased the ID of the 100- to 700-microns arteries and veins, but not the ID of the other-sized vessels. The ID decrease in the serially connected arteries was nonuniform (13-29%) but relatively uniform in the veins (8-12%). The maximum ID decrease occurred in the 200- to 300-microns arteries. However, adding 40 ppm NO to the lobe completely eradicated the ID decreases at all segments of the arteries and veins and, instead, caused significant ID increase (11-21%) in the arteries and (10-12%) in the veins. The data indicate that, according to dosage, 5-40 ppm NO inhalations cause selective dilation of approximately 100- to 900-microns pulmonary arteries and veins, particularly the 200- to 700-microns arteries. During anoxic exposure, the vasodilator effect of NO is preserved and can completely reverse the marked pulmonary vasoconstriction.

Administration, Inhalation↗
PubMed1995

Modified maze procedure for patients with atrial fibrillation undergoing simultaneous open heart surgery.

BACKGROUND: Persistent atrial fibrillation (AF) leaves patients symptomatic and at increased risk of thromboembolism even after otherwise successful cardiac surgery. METHODS AND RESULTS: To treat AF secondary to cardiac lesions requiring surgery, we combined a modified maze procedure in 101 patients simultaneously undergoing valvular procedures (87), repair of congenital anomalies (12), and other procedures (2), including 24 repeat operations. Duration of AF varied from 0.1 to 30 years (average +/- SD, 8.8 +/- 7.0 years); the f-wave voltage ranged from 0 to 0.45 mV (0.15 +/- 0.09 mV); and cardiothoracic ratio varied from 40% to 99% (63 +/- 9%). Aortic cross-clamp time varied from 75 to 229 minutes (138 +/- 31 minutes), with bypass time ranging from 119 to 326 minutes (217 +/- 42 minutes). There were two early deaths (2%), no late deaths, and one episode of transient neurological ischemic attack in follow-up ranging from 1.0 to 3.1 years, for a total of 190 patient-years. Postoperative rhythms were sinus in 83 patients (82%), junctional in 4 (4%), and persistent AF in 14 (14%), each of whom had mitral valve disease. Patients with other underlying pathology had complete recovery of atrial rhythm. A normal-sized A wave was detected in 88% for transtricuspid flow and in 73% for transmitral flow, suggesting concomitant recovery of atrial contraction. Among 36 patients without mechanical valves, 30 (83%) with atrial rhythm and contraction have been taken off anticoagulation therapy, including 10 who are free of all medication. CONCLUSIONS: The results suggest that the combined approach is safe, effective, and indicated in patients who are judged capable of tolerating the procedure and likely to regain atrial rhythm.

Aged↗
PubMed1995

Changes in efferent pulmonary sympathetic nerve activity during systemic hypoxia in anesthetized cats.

Changes in efferent sympathetic nerve activity to the pulmonary vessels during systemic hypoxia have yet to be elucidated. The purpose of this study was to determine the pulmonary sympathetic nerve activity (PSNA) changes in response to acute systemic hypoxia before and after sinoaortic denervation plus vagotomy in anesthetized cats. The denervation was performed to estimate the central nervous system-mediated peripheral chemoreceptor- and baroreceptor-independent PSNA change. PSNA was recorded from the central end of the cut nerve bundle, which was isolated from the lobar artery supplying the diaphragmatic lobe. Renal sympathetic nerve activity (RSNA) and systemic and pulmonary arterial pressures were also measured simultaneously. The animals were submitted to approximately 3-min periods of graded hypoxia (16, 12, 8, 5, and 3% O2 inhalations). PSNA did not change from normoxia down to an arterial O2 partial pressure (PaO2) of approximately 45 Torr (with 12-21% O2 inhalations). Below this level, PSNA began to increase, and markedly so (approximately 2.5-fold) at a PaO2 of approximately 15 Torr (with 3% O2). The hypoxic PSNA increase was significantly larger than that for RSNA, with a PaO2 of less than approximately 30 Torr (with 3-8% O2). Particularly at a PaO2 of approximately 15 Torr, the magnitude of the PSNA increase was two times greater than that for RSNA. After denervation, the hypoxic PSNA increase was significantly attenuated at a PaO2 of approximately 25 to approximately 45 Torr (with 5-12% O2), but the attenuation was very small; therefore most of the PSNA increase persisted. The hypoxic RSNA increase, in contrast, was mostly abolished after denervation. The data indicate that the neural reflex effect of systemic hypoxia on PSNA is significantly greater than that on RSNA and suggest that the hypoxic PSNA increase is mostly mediated by central mechanisms, whereas that for RSNA is chiefly caused by peripheral chemoreceptors.

Animals↗
PubMed1994

Cox maze procedure for chronic atrial fibrillation associated with mitral valve disease.

Between April 1992 and October 1993, we combined a modified maze procedure with mitral valve repair (n = 26) or replacement (n = 36) in 62 patients with atrial fibrillation, including 16 patients undergoing reoperation. Associated procedures included aortic valve operation (n = 22), tricuspid annuloplasty (n = 28), atrial plication (n = 10), and others (n = 3). Duration of atrial fibrillation varied from 0.1 to 23 years (average 8.3 +/- 6.4 years), the f-wave voltage ranged from 0 to 0.45 mV (0.16 +/- 0.09 mV), and cardiothoracic ratio varied from 46% to 85% (64% +/- 9%). We modified the maze atriotomies to preserve the sinus node artery and used cryoablation to simplify procedures. Aortic crossclamp time was 142 +/- 25 minutes and cardiopulmonary bypass time 226 +/- 34 minutes. No early or late deaths occurred in a total of 783 patient-months of follow-up. In 52 patients (84%) who regained atrial rhythm, an atrial A-wave was detected in 84% for transtricuspid flow and in 71% for transmitral flow. One patient with sinus rhythm had an episode of transient neurologic ischemia 4 months after mechanical valve implantation. The 10 patients who remained in atrial fibrillation had preoperative fibrillation for a significantly longer time than the rest of the patients with atrial rhythm (14.8 versus 7.2 years p < 0.001) and a larger left atrial dimension (70 versus 58 mm, p < 0.01). Nonetheless, no variable alone could have predicted postoperative rhythm for individual patients. The results suggest that the maze procedure is safe and effective and therefore should be considered for patients with chronic atrial fibrillation undergoing mitral valve operations.

Adult↗
PubMed1993

Right-to-left interatrial shunt in rats with progressive pulmonary hypertension.

A right-to-left interatrial shunt may prolong survival in patients with pulmonary hypertension presumably because of decompression of the right side of the heart. To test this hypothesis, 74 rats with monocrotaline-induced pulmonary hypertension were followed up weekly with cardiopulmonary exercise testing with a metabolic treadmill system for exercise tolerance, heart rate, oxygen uptake, carbon dioxide production, and survival until subsequent or induced death 8 weeks after monocrotaline treatment. In rats with an interatrial shunt, oxygen uptake and carbon dioxide production were higher and survival was better (n = 22, 27%) than those in rats without a shunt (n = 52, 0%; p < 0.05). For the prospective assessment of the effects of a reversed shunt, 24 other rats underwent a left superior vena cava-to-left atrial appendage anastomosis as a functional interatrial shunt (atrial septal defect group) 4 weeks after monocrotaline treatment when severe pulmonary hypertension had developed and were compared with an additional 25 rats receiving a sham operation. Both groups had exercise capacity depressed to the resting levels by 2 weeks after operation. Although transcutaneous oxygen levels decreased in response to exercise in the atrial septal defect group, uptake and carbon dioxide production stayed higher than those in the sham operation group with significantly better survival 4 weeks after operation (atrial septal defect 30% versus sham operation, 0%; p < 0.05), at which time a reversed shunt was determined with systemic embolization of intravenously infused microspheres. A right-to-left interatrial shunt, anatomic or functional, preserved basal metabolism and prolonged survival in rats with progressive pulmonary hypertension.

Animals↗
PubMed1993

Long-term results of entry closure and aneurysmal wall plication with axillofemoral bypass: a new procedure for repair of DeBakey type 3 dissecting aneurysm.

To prevent aneurysm rupture, avoid pseudoaneurysm formation, and preserve intercostal arteries, a new procedure for repair of DeBakey type 3 dissecting aneurysm was developed. Since January 1977, 28 patients have undergone repair of type 3 dissecting aneurysm. Fifteen patients with type 3b underwent this new procedure (group 1) and 13 patients with type 3a dissecting aneurysm underwent segmental graft replacement (group 2). In group 1 a permanent axillofemoral bypass was placed on the right side. Next the intrathoracic false lumen was opened longitudinally, the entry was closed, and the aneurysmal wall was sutured around the true lumen as tightly as possible. The operative mortality rate was 20% in group 1 and 31% in group 2. One of 15 patients in group 1 died of operation-related causes, whereas three patients in group 2 died. There were six late deaths: three in group 1 and three in group 2. Paraplegia occurred in neither group 1 nor group 2. The mean diameter of the plicated descending aorta was 24.0 +/- 2.7 mm 3 months after surgery. No recurrence was detected in group 1. These results suggested that this new surgical technique for repair of type 3 dissection reduces the incidence of paraplegia and pseudoaneurysm formation.

Adult↗
PubMed1992

Single lung transplantation in rats with fatal pulmonary hypertension.

Effects of single lung transplantation on fatal pulmonary hypertension were evaluated in rats receiving a lethal dose of monocrotaline. Inbred rats treated with monocrotaline (80 mg/kg) received a left lung isograft at 4 weeks (n = 9) and at 6 weeks (n = 6), when moderate and severe pulmonary hypertension, respectively, had developed. Medicated (n = 12) and nonmedicated rats (n = 12) served as control animals. Each rat was tested weekly with treadmill for exercise tolerance and oxygen consumption during a 10-week period after medication and after they were killed. Medicated control rats lost exercise tolerance and highest oxygen consumption per unit time consistently to the range of resting value (or 45% of nonmedicated control rats), and all died from severe pulmonary vascular occlusive disease with right ventricular hypertrophy before 10 weeks (right ventricular/left ventricular weight ratio of 1.16). All rats receiving a left lung isograft at 4 weeks survived and regained highest oxygen consumption per unit time (87% of nonmedicated control rats), with the lung transplant receiving 65% (nonmedicated control rats, 39%) of cardiac output and milder right ventricular hypertrophy (right ventricular/left ventricular weight ratio of 0.46). Except for one, all rats that received a left lung isograft at 6 weeks tolerated single lung transplantation, but they died soon after reperfusion because of pulmonary edema in the graft that received 58% of cardiac output with right ventricular/left ventricular weight ratio of 0.79. Results of single lung transplantation in rats were dependent on severity of pulmonary hypertension. In rats with moderate pulmonary hypertension, single lung transplantation was successful in reversing exercise intolerance and right ventricular hypertrophy. Single lung transplantation was unsuccessful when pulmonary hypertension was severe in the rat model because increased flow toward the lung transplant resulted in graft pulmonary edema.

Animals↗
PubMed1992

Survival prediction in staged heart transplantation using Jarvik-7 artificial heart.

BACKGROUND: Because mechanical circulatory assist as a bridge to heart transplantation places a further strain on current donor shortage as well as on medical cost containment, safe and effective use of the device is essential. METHODS AND RESULTS: To predict survival before undertaking staged heart transplantation with the Jarvik-7 artificial heart, our 58 attempts were reviewed retrospectively. Scores of 1-4 were given for six preoperative factors based on results obtained by univariate and multivariate analyses between survivors and nonsurvivors of staged heart transplantation: transplant rejection (scored 4: S4) or postoperative heart failure (S3) as the indication, recipient height < 175 cm (S3), body surface area < 1.8 m2 (S3), hyperbilirubinemia > 24 microM/l (S2), weight < 60 kg (S2), and age > 40 years (S1). Of 14 survivors, 13 had a total score < 4 (sensitivity, 93%), with an average score of 1.6 in contrast to 5.5 for 44 nonsurvivors (p < 0.001). Among 26 patients scored < 4, 21 had heart transplantation, of whom 13 left the hospital. Of 32 patients scored > or = 4, only four could be discharged after transplantation (specificity, 70%). CONCLUSIONS: Multiple preoperative factors successfully predicted transplantability and survival in staged heart transplantation. The results underscore the importance of preoperative condition and patient selection to achieve successful and effective use of Jarvik-7 as a bridge to heart transplantation.

Actuarial Analysis↗
PubMed1992

Single lung transplantation in rats with chemically induced pulmonary hypertension.

Physiologic effects of single lung transplantation on pulmonary hypertension were studied in rats with monocrotaline-induced pulmonary hypertension. Inbred rats treated with monocrotaline (40 mg/kg) received a left lung isograft from a normal donor 2 weeks later, when pulmonary hypertension became significant (transplant group; n = 6). These rats and control rats treated with monocrotaline (mediated control group; n = 11) or vehicle alone (normal control group; n = 9) were followed up weekly by metabolic treadmill testing for exercise tolerance and oxygen consumption up to 6 weeks after monocrotaline (4 weeks after transplantation), when all rats underwent hemodynamic and histologic examinations. Whereas maximal oxygen consumption and exercise tolerance consistently deteriorated in the medicated control group of rats, indices in the transplant group stopped deteriorating 2 weeks after lung transplantation and remained at levels similar to those of normal control rats. Severe pulmonary hypertension (68 +/- 19 mm Hg) and right ventricular hypertrophy (right ventricular/left ventricular weight ratio, 0.95 +/- 0.19) were confirmed in medicated control rats in contrast to transplant animals, in which these two indices remained at normal control levels. Whereas left-to-right lung perfusion ratio was constant among rats not receiving transplants (0.69 +/- 0.16), it was significantly elevated (2.27 +/- 0.65; p less than 0.001) in those receiving transplants, suggesting preferential flow through the lung isograft. The results suggest that, in the early phase of pulmonary hypertension, single lung transplantation shifts pulmonary perfusion to the grafted lung, avoiding right ventricular pressure overload and thereby preserving exercise tolerance at a nearly normal level in rats with monocrotaline-induced pulmonary hypertension.

Animals↗
PubMed1991

Preoperative risk analysis in patients receiving Jarvik-7 artificial heart as a bridge to transplantation.

To distinguish high-risk patients prior to implantation of a Jarvik-7 artificial heart as a bridge to transplantation, our 37 attempts were reviewed retrospectively. Arbitrary scores of 1 to 4 were given for nine preoperative factors on the basis of results obtained by uni- and multivariate analyses between successful cases and failed attempts; transplant rejection (scored 4: S4) or postoperative heart failure (S3) as the indication, recipient height less than 175 cm (S3), body surface area less than 1.8 m2 (S3), hyperbilirubinemia greater than 24 microM/l (S2), preoperative renal failure requiring dialysis (S2), weight less than 60 kg (S2), and age greater than 40 years (S1). All except one of the 16 patients with successful bridge had a total score of less than 4, with an average score of 1.3 in contrast to 6.6 in the 21 failed cases (p less than 0.001). Among the 17 patients who scored less than 4, 15 received transplants (specificity 90%), while only one qualified for transplantation among 20 patients who scored 4 or more (sensitivity 94%). The two unpredicted failures resulted from mediastinitis and pulmonary infarction, both attributable to postoperative management. Multiple preoperative factors in combination could have successfully predicted the outcome of mechanical support in our experience. These results underscore the importance of patient selection to achieve successful and effective use of the Jarvik-7 as a bridge to heart transplantation.

Adolescent↗
PubMed1990

Factors affecting survival in total artificial heart recipients before transplantation.

To identify factors affecting the successful bridge to transplantation, experience with 32 recipients of the Jarvik-7 artificial heart was reviewed. Between patients with and without a successful bridge, there were no significant differences in preoperative hepatorenal function or postoperative hemodynamics, but there were significant differences in body size. When recipients were divided according to body surface areas of less than or greater than 1.8 m2, the smaller patients more frequently developed respirator dependence (73% vs. 18%, p less than 0.01), renal failure (53% vs. 18%, p less than 0.05), and hepatic failure and sepsis, resulting in less frequent qualification for transplantation (20% vs. 65%, p less than 0.05). There were no successful bridge operations in seven patients with body surface areas of less than 1.7 m2, and only one success in nine patients who were less than 170 cm in height, despite use of a smaller stroke volume model. The smaller patients had poorer ventricular filling, which was largely compensated for by the drive controls set for significantly longer diastole and higher vacuum, resulting in similar hemodynamics between the groups. The results suggest that device fitting as manifested by body size is an important factor affecting major organ recovery and subsequent transplantation in recipients of the Jarvik-7 artificial heart. A paracorporeal device may be advisable for patients with body surface areas of less than 1.8 m2 or who were less than 175 cm in height until an even smaller model with a better fit in the thorax becomes available.

Adult↗
PubMedDate not supplied

Liver and kidney function in patients undergoing mechanical circulatory support with Jarvik-7 artificial heart as a bridge to transplantation.

Changes in liver and kidney function were reviewed in 32 patients who received a Jarvik-7 total artificial heart (TAH) as a bridge to transplantation. Preoperatively, seven (22%) had significant isolated kidney dysfunction, five (15%) had isolated liver impairment, and 13 (41%) had combined disorder, affecting 25 (78%) of the 32 recipients. Immediately after TAH implantation, vigorous diuresis occurred, and biochemical indices improved in 17 patients: 71% of isolated kidney, 60% of isolated liver, and 38% of combined organ disorder were reversed irrespective of severity in preoperative dysfunction. In contrast, urine output remained poor, and biochemical indices continued to deteriorate in 15 patients regardless of preoperative status; as a result, kidney (28%), liver (17%), and combined organ failure (33%) accounted for a total of 78% of failure in this series. Although preoperative liver and kidney dysfunction were frequent and severe, they did not correlate with postoperative functional recovery and later transplantation. Recipient body size and initial postoperative urine output were found to be the variables discriminating patients with or without subsequent transplantation. Because liver/kidney failure remained as the leading cause of death, knowledge of the underlying cause of the organ failure would increase the success of TAH as a bridge to transplantation.

Acute Kidney Injury↗