Biomedical subjects

Kei Aizawa

Publications and source records attributed to Kei Aizawa.

11 recordsLinked to original sources

PubMed2006

Simultaneously performed mitral valve replacement and Hartmann's operation for infectious endocarditis from Streptococcus bovis and rectal cancer.

In patients with surgical indications for both cardiac surgery and a malignant neoplasm, cardiac surgery should generally be performed first; however, in some cases simultaneous surgery is recommended. We report a case of infectious endocarditis of the mitral valve caused by Streptococcus bovis with rectal cancer. Blood cultures showed a rise in coagulase-negative S. bovis, and the source of infection was thought to be the rectal cancer. The patient presented with cerebral infarction prior to surgery, and the possibility of recurrence of an infarction was predicted. The tumor of the rectum was hemorrhagic, so to avoid hemorrhagic complications due to perioperative heparinization and anticoagulant therapy and to remove the source of infection, mitral valve replacement and a Hartmann's operation were performed simultaneously. The postoperative course was uneventful.

Colectomy↗

PubMed2005

Clinical features of third open-heart valve surgery at the same valve position.

OBJECTIVE: Recently, there has been an increase in case of repeated open-heart valve surgery and the clinical results of the second surgery are only slightly worse than those of the first surgery. However, clinical results of the third open-heart valve surgery at the same position are rarely reported. Clinical features of third open-heart valve surgery at the same position are discussed in this study. METHODS: Between 1995 and 2004, 16 patients underwent third open-heart valve surgery at the same valve position under cardiopulmonary bypass. The average age of the 16 patients, 12 females and 4 males, was 56 +/- 15 years. Clinical features of the 16 cases were retrospectively analyzed. RESULTS: Mechanical valve nonstructural dysfunction was the most common valve malady, followed by bioprosthetic valve dysfunction. The duration of surgery from skin incision to establishment of the cardiopulmonary bypass was 94 +/- 42 minutes. Myocardial ischemia time was 137 +/- 38 minutes and extracorporeal circulation time was 212 +/- 82 minutes. Early mortality was seen in 1 patient (6.25%) and late mortality was seen in 1 patient. CONCLUSION: Mechanical valve nonstructural valve dysfunction leads to repeated valve surgery. The clinical results of the third open-heart valve surgery at the same valve position are acceptable, and the mid-term survival is excellent.

Adult↗

PubMed2004

Protein kinase C-epsilon primes the cardiac sarcolemmal adenosine triphosphate-sensitive potassium channel to modulation by isoflurane.

BACKGROUND: Cardioprotection by volatile anesthetic-induced preconditioning is known to involve intracellular signaling pathways. Recent studies have shown that protein kinase C (PKC) plays an important role in anesthetic-induced preconditioning. In this study, the effects of the activation of specific isozymes of PKC, specifically PKC-epsilon and -delta, on the modulation of the sarcolemmal adenosine triphosphate-sensitive potassium (sarcKATP) channel by isoflurane were investigated. METHODS: The sarcKATP current was measured in ventricular myocytes isolated from guinea pig hearts using the whole cell configuration of the patch clamp technique. Peptides that induced the translocation of specific PKC isozymes were used to activate PKC-epsilon and PKC-delta. RESULTS: Under whole cell conditions, isoflurane alone was unable to elicit the opening of the sarcKATP channel. Pretreatment with the specific PKC-epsilon activator, PP106, primed the sarcKATP channel to open in the presence of isoflurane. The resulting sarcKATP current densities in the presence of 0.88 mm isoflurane were 6.5 +/- 6.0 pA/pF (n = 7) and 40.4 +/- 18.2 pA/pF (n = 7) after pretreatment with 100 and 200 nm PP106, respectively. The PKC-epsilon antagonist PP93 abolished this effect. A scrambled peptide of the PKC-epsilon activator PP105 did not prime the sarcKATP channel. The PKC-delta activator PP114 was significantly less effective in priming the sarcKATP channel. 5-Hydroxydecanoate significantly attenuated the effect of the PKC-epdsilon activator on the sarcKATP channel. In addition, immunohistochemical analysis showed that the PKC-epsilon isoform translocated to both the mitochondria and sarcolemma after anesthetic-induced preconditioning, whereas the PKC-delta isoform translocated to the mitochondria. CONCLUSION: The PKC-epsilon isozyme primed the sarcKATP channel to open in the presence of isoflurane. The PKC-delta isozyme was significantly less effective in modulating the isoflurane effect on this channel.

ATP-Binding Cassette Transporters↗

PubMed2004

Preconditioning of the myocardium by volatile anesthetics.

Cardiovascular disease continues to be a major health problem. Tremendous efforts have been invested in clinical and laboratory research in the hopes of decreasing the risk of patients with cardiovascular disease undergoing cardiac and non-cardiac surgeries. A powerful endogenous mechanism of cardioprotection, termed ischemic preconditioning, was reported in a laboratory setting whereby the myocardium can be preconditioned by a brief ischemic episode and protected against a subsequent prolonged ischemic attack. Since this initial observation, several pharmacological agents have been demonstrated to mimic ischemic preconditioning. These include opioids, potassium channel openers such as pinacidil and diazoxide, and adenosine agonists. Recently, volatile anesthetics were found to be powerful cardiac preconditioning agents. Infarct size reduction as the result of anesthetic-induced preconditioning paralleled that of ischemic preconditioning. The use of volatile anesthetics as preconditioning agents in high-risk patients undergoing cardiac and non-cardiac surgeries can potentially result in the reduction of morbidity and disability in this class of patients. However, to fully realize the potential use of this novel property of volatile anesthetics, the underlying mechanism of anesthetic-induced preconditioning would need to be elucidated. This review highlights the major recent findings on the cardioprotective effects of volatile anesthetics.

Anesthetics, Inhalation↗

PubMed2004

[Chest wall epithelioid sarcoma].

Two relatively rare cases of epithelioid sarcoma located in the chest wall are reported herein. The first was a tumor, 3.8 x 5.5 x 2.4 cm in size, originating in the left erector spinae muscle of a man 64 years of age. He experienced local recurrence 3 times even after wide resections, and he died of systemic metastasis 22 months after the initial surgery. The second was a tumor, 2.2 x 2.0 x 1.5 cm in size, originating in the left seventh intercostal muscle of a woman 24 years of age. A metastatic tumor occurred in the same muscle, and wide resection including the seventh and eighth intercostal muscles was performed. There has been no recurrence for 1.5 years since surgery. Metastasis of chest wall epithelioid sarcoma in the muscle in which the primary lesion resides should be considered, even if the primary lesion is small.

Adult↗

PubMed2003

Modified Bentall operation in a patient with hemophilia A.

We detail a successful modified Bentall operation in a patient with hemophilia A. A 53-year-old man with mild hemophilia A and a history of few bleeding episodes was diagnosed with annuloaortic ectasia. Surgical repair was planned. Simple bolus infusions of factor VIII concentrate were given before and after cardiopulmonary bypass to achieve 100% blood levels and postoperatively every 12 hours for 7 days to maintain 50% levels. The patient received no transfusion other than 10 units of platelet concentrate. We used routine operative and cardiopulmonary bypass techniques. The patient recovered well postoperatively with no excessive bleeding despite warfarin therapy.

Aortic Aneurysm↗

PubMed2003

When and how does nonstructural mechanical prosthetic heart valve dysfunction occur?

OBJECTIVE: We discuss the clinical aspects related to mechanical valve dysfunction based upon 20 years' experience of our cases. METHODS: Between January 1982 and December 2001, 21 patients underwent surgical interventions because of mechanical valve dysfunction. Thirteen men and 8 women (mean age 47 +/- 20, range 3-75 years-old), were included. RESULTS: Mitral valve dysfunction was observed in 12 patients. Prosthetic valve stenosis occurred in 6 patients between 2 and 224 months, and paravalvular leaks in 4 between 1 and 71 months after surgery. The other 2 patients suffered from hemolytic anemia with mild paravalvular leaks between 102 and 104 months after surgery. Aortic valve dysfunction was observed in 8 patients including 3 stenotic lesions between 48 and 97 months and 5 paravalvular leaks between 3 and 150 months after surgery. Tricuspid regurgitation was seen in 1 patient with a huge right atrium at 42 months after surgery. Early death was seen in 1 patient. Late death occurred in 1 patient, 17 years after operation. Survival, including early death, was 95.2%, at 10 and 15 years. One valve-related complication of bioprosthetic valve endocarditis at the mitral and tricuspid positions occurred 12 years after a reoperation. The freedom from complications was 95.2% at 10 years, and 76.2% at 15 years. CONCLUSIONS: Paravalvular leaks without overt endocarditis had latency periods of up to 12 years, and pannus formation was observed 20 years after surgery. Early and late clinical results after surgery for mechanical valve dysfunction were excellent.

Adolescent↗

PubMed2002

Single-center experience with the bicarbon bileaflet prosthetic heart valve in Japan.

We analyzed midterm results using the Bicarbon valve in a single center. Forty-four patients had aortic valve replacement (AVR), 48 had mitral valve replacement (MVR), and 13 had both aortic and mitral valve replacement (DVR). The mean age of the 105 patients was 61.2 +/- 11.3 years. The mean follow-up was 1.8 +/- 1.1 years with a cumulative follow-up of 188 patient-years. There were 5 early deaths (4.7%: 4 in the AVR group and 1 in the MVR group) and 5 late deaths (2.7% per patient-year: 3 malignancy, 1 cerebral hemorrhage, 1 myocardial infarction). Survival at 3 years was 91 +/- 4% in the AVR group, 92 +/- 5% in the MVR group, and 66 +/- 23% in the DVR group. The linearized incidence of thromboembolic complications, hemorrhagic complications, and paravalvular leaks in all patients was 1.06 +/- 2.34%, 1.60 +/- 2.53%, and 0.53 +/- 2.22% per patient-year, respectively. No other complications were observed. In conclusion, the Bicarbon prosthetic heart valve has shown excellent clinical results associated with a low incidence of valve-related complications.

Aged↗

PubMed2002

Biphasic effects of isoflurane on the cardiac action potential: an ionic basis for anesthetic-induced changes in cardiac electrophysiology.

BACKGROUND: The mechanism underlying isoflurane modulation of cardiac electrophysiology is not well understood. In the present study, the authors investigated the effects of isoflurane on the cardiac action potential (AP) characteristics. The results were correlated to modulation of the L-type calcium (I(Ca,L)), the delayed-rectifier potassium (I(Kdr)), and the inward-rectifier potassium (I(Kir)) currents. METHODS: Single ventricular myocytes were enzymatically isolated from guinea pig hearts. The current clamp and whole cell voltage clamp configurations of the patch clamp technique were used to monitor the cardiac AP and ionic currents, respectively. A dynamic AP voltage protocol that mimicked changes in membrane potential during an AP was used to monitor the I(Ca,L), I(Kdr) and I(Kir). RESULTS: Isoflurane produced a concentration-dependent, biphasic effect on the AP duration (APD). At 0.6 mm (1.26 vol%), isoflurane significantly increased APD50 and APD90 by 50.0 +/- 7.6% and 48.9 +/- 7.2%, respectively (P < 0.05; n = 6). At 1.0 mm (2.09 vol%), isoflurane had no significant effect on APD (n = 6). In contrast, at 1.8 mm (3.77 vol%), isoflurane decreased APD50 and APD90 by 38.3 +/- 5.4% and 32.2 +/- 5.5%, respectively (P < 0.05; n = 7). The inhibitory effects of isoflurane on I(Kdr) chord conductance were greater than those on I(Ca,L) (P < 0.05; n = 6/group). Both I(Ca,L) inactivation and I(Kdr) activation kinetics were accelerated by isoflurane. Isoflurane had no significant effects on I(Kir) chord conductance (n = 6). CONCLUSION: At the lower anesthetic concentration, the prolongation of the APD may be the result of the dominant inhibitory effects of isoflurane on I(Kdr). At the higher concentration, the shortening of the APD may be caused by the inhibitory effects on I (Ca,L) combined with the isoflurane-induced acceleration of I(Ca,L) inactivation kinetics. Because I(Kdr) is significantly inhibited by isoflurane, I(Kir) appears to be the major repolarizing current, which is minimally affected by isoflurane.

Action Potentials↗

PubMed2002

[Spinal anesthesia with 0.5% isobaric bupivacaine for a patient with alcoholic cardiomyopathy].

A 69-year-old male patient with alcoholic cardiomyopathy was scheduled for inguinal herniorrhaphy. Spinal anesthesia was performed with 1.5 ml of 0.5% isobaric bupivacaine at the L 2-3 interspace. The analgesic levels were at the eighth thoracic 15 minutes after injection and the fifth thoracic dermatome at the end of the operation, respectively. The hemodynamic status was stable during operation and his postoperative course was uneventful. This case suggests that spinal anesthesia with 0.5% isobaric bupivacaine is useful for inguinal herniorrhaphy in the patient with alcoholic cardiomyopathy.

Aged↗

PubMedDate not supplied

Twenty-two year experience with the omniscience prosthetic heart valve.

This study was designed to evaluate the long-term clinical results of the Omniscience tilting disc valve. Omniscience valves were implanted in 51 patients (mean age, 50 +/- 10 years); 18 had aortic valve, 24 had mitral valve, and 9 had both aortic and mitral valve replacements. Oral warfarin potassium and dipyridamole were prescribed as our anticoagulant therapy. Preoperatively, 42 patients were in New York Heart Association class III or IV, and 23 of 25 surviving patients were in class I or II after operation. There were 2 (3.9%) early deaths and 23 late deaths (3.5 +/- 0.7% per patient-year). Cardiac related mortality including congestive heart failure, sudden death, and thromboembolism, and hemorrhagic complications were seen in 16 patients. Overall survival at 10, 15, and 20 years was 77 +/- 6%, 62 +/- 7%, and 46 +/- 7%, respectively. Thromboembolic complications were seen in 5 patients, for a rate of 0.8 +/- 0.3% per patient-year; similarly, hemorrhagic complications were also seen in 5 patients. Nonstructural prosthetic valve dysfunction was seen in 4 patients, for a rate of 0.6 +/- 0.3% per patient-year, and sudden death was seen in 2, a rate of 0.3 +/- 0.2% per patient-year. The Omniscience prosthesis demonstrated excellent postoperative clinical status with low rates of valve related complications.

Adult↗