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乳牛の心房細動症における心電図学的診断ならびに治療に関する臨床的研究
https://az.repo.nii.ac.jp/records/3207
https://az.repo.nii.ac.jp/records/320703816634-80fb-4d04-9b42-3643d3681625
| 名前 / ファイル | ライセンス | アクション |
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diss_dv_otsu0284 (8.0 MB)
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diss_dv_otsu0284_jab&rev (310.8 kB)
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diss_dv_otsu0284_jab.pdf (196.9 kB)
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| Item type | 学位論文 / Thesis or Dissertation(1) | |||||
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| 公開日 | 2013-01-29 | |||||
| タイトル | ||||||
| タイトル | 乳牛の心房細動症における心電図学的診断ならびに治療に関する臨床的研究 | |||||
| タイトル | ||||||
| タイトル | Clinical study of electrocardiographic diagnosis and treatment of atrial fibrillation in milk cattle | |||||
| 言語 | en | |||||
| 言語 | ||||||
| 言語 | jpn | |||||
| 資源タイプ | ||||||
| 資源タイプ識別子 | http://purl.org/coar/resource_type/c_46ec | |||||
| 資源タイプ | thesis | |||||
| 著者 |
相子, 正隆
× 相子, 正隆× Aiko, Masataka |
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| 抄録 | ||||||
| 内容記述タイプ | Abstract | |||||
| 内容記述 | 乳牛の生産性向上を図るために，品種の改良によって体格，消化器，乳房などの臓器が著しく発達した体型に改良されてきた。しかし，一方ではそれにともなって，従来では予想できなかった全身性または局所性の疾病が多くなり，いわゆる家畜の生産病が多発する傾向がみられる。 近年，泌乳能力の高い乳牛が，臨床的に食欲が減退し突然乳量の低下を来たす症例が多くみられる。泌乳能力の低下を来たす原因としては，さまざまな要因があるが，実際の臨床では急激な泌乳能力の低下を来たす原因の一つとして，不整脈の一種である心房細動症が重要視されている。本症は，発症してから比較的短時間で洞性調律に回復する発作性心房細動症と，細動が数カ月あるいは数年間にわたって持続する固定性心房細動症とにわけられる。 そこで著者は，乳牛の心房細動症における病態把握と，臨床的な心房細動症の診断法ならびに治療法について検討する目的で表題の研究を企図した。 1.心房細動症の心電図学的診断 聴診ならびに心電図検査を行って，臨床的に固定性心房細動症と発作性心房細動症と診断されたホルスタイン種，牝，7例(4～9歳)を用いて，心房細動症における心電図学的な変化ならびに血行動態の変化について検討を行った。 乳牛における心房細動症では，f波が不明瞭なことから，心電図誘導部位の確立のために標準肢誘導法，単極肢誘導法，A-B誘導法の他に，胸部単極誘導法によって体表面の20カ所から心電図を誘導記録して心電図学的な検討を行った。その結果，臨床心電図としては，左側第4～第6肋間の心基底部領域における胸部単極誘導法の心電図が，最も明確で確実なf波が記録されることが確認された。 心房細動症における血行動態と，心電図の先行R-R間隔との相関を観察する目的で，供試牛をOF麻酔下で開胸し，心・血管内圧を測定した。先行R-R間隔を検討するための心電図は，標準肢誘導法第II誇導またはA-B誘導法を行い，心・血管内圧と同時記録を行った。そして先行R-R間隔の割合(R-R Index)は5秒間のR-R間隔数をnとし，5秒をnで割った秒数，すなわち，平均R-R間隔値に対するそれぞれのR-R間隔の秒数の比とした。心・血管内圧の測定はカテーテル法によって左室最大収縮期圧，大動脈収縮期圧，左房圧，肺動脈収縮期圧，右室最大収縮期年，右房圧を測定した。また，心拍出量の測定は，インドシアニングリーンを用いた指示薬希釈法によって測定した。その結果，R-R Indexを指標とすれば，心房細動時における心臓内の血行動態を推定できることがわかった。すなわち，R-R Indexと左室圧の相関はr=0.721，右室圧ではr=0.699，大動脈収縮期圧ではr=0.762，肺動脈収縮期圧ではr=0.676で，R-R Indexが増大するに従って左室圧，右室圧，大動脈収縮期圧，肺動脈収縮期圧が高くなり，心拍出量は増加する。しかし，左房圧ならびに右房圧は変化がみられないか，または低下することが明らかにされた。また，心拍出量を測定した結果，心房細動を発現している場合の心拍出量は，正常牛の約1/2であり，本症における動脈系循環血液量の減少がみられたことから，泌乳量の減少は，動脈系循環血液量の減少に起因することが推測された。これらの成績は，発作性心房細動症と固定性心房細動症とではあまり大差はみられなかった。 2.心房細動症の治療 野外における乳牛の臨床例について，臨床的な聴診法ならびに心電図検査法によって抽出した固定性心房細動症24例を対象に，硫酸キニジンを用いた除細動による治療試験を行った。心不全の状態を呈していた過半数の症例に対しては，強心配糖体(ジゴキシン1000倍散)によって心機能を改善してから硫酸キニジンを投与した。また，大部分の症例で投薬前日にtest doseとして1頭当り5～10gの硫酸キニジンを投与し，副作用を観察してから治療試験を行った。硫酸キニジシによる除細動は漸減法と漸増法によって実施した。 硫酸キニジン漸減法による投薬は24時間以内の短時間で集中的に投薬する方法で，初回投薬量を1頭当り30～50gとし，次後4～6時間毎に30，25，20または10gと漸時投薬量を減量して投与する方法である。 心房細動症に対する硫酸キニジンの投薬に先だって，治療開始前にtest doseとして1頭当り5～10gの硫酸キニジンを投薬してから治療量を投薬したが，test doseの投薬量ではほとんどの例で硫酸キニジンに対する副作用はみられなかった。また，全投薬量の限度は1頭当り120gとした。 12例の症例で硫酸キニジン漸減法によって除細動された症例は10例(83.3％)で，2例は除細動されなかった。除細動された症例のうち1例では，血清レベルにおける硫酸キニジンの消退とともに心房細動症が再発した。また，除細動された10例のうち3例は硫酸キニジンの単味投与例であり，7例は事前に強心配糖体を投与した例であった。除細動されなかった2例と再発した1例は，心臓に器質的な障害があると予想された症例であった。また，硫酸キニジン漸減法では集中的な投薬と経時的な観察が必要であるうえに副作用があり，野外では実施困難であった。 硫酸キニジン漸増法による投薬は1日1回，4日間にわたって硫酸キニジンを投与する方法で，初回の投与量を1頭当り10gとし，次後，日を追って20，30，40gと漸時投薬量を増量して投薬する方法である。 12例の症例で硫酸キニジン漸増法によって除細動された症例は9例(75.0％)で，3例は除細動されなかった。除細動された9例のうち4例は硫酸キニジン単味投与例，5例は事前に強心配糖体を投与した例であった。また硫酸キニジン漸増法では，投与日数を要するが副作用が少なく，安全な投薬が可能であり，野外で容易に実施することができた。 硫酸キニジン漸増法による投薬経過中，投与開始第2日目から1日1回平地における3分間の速歩による運動負荷を実施した。また，全投薬量を投与したが，除細動されなかった例にも再度運動負荷を試みた。その結果，運動負荷によって7例中4例が投薬経過中に除細動(57.1％)され，3例は投薬終了後の運動負荷によっても除細動されなかった。非除細動例のうち1例は硫酸キニジン単味投与例で，他の2例は心臓に器質的な障害が予想された例であった。また，硫酸キニジン投与経過中に，運動負荷を加えることによって除細動効果がみられたことは，硫酸キニジンの投薬量と授薬期間の節減となり臨床的に応用価値が高かった。 硫酸キニジン漸減法では，ほとんどの症例で一過性の食欲減退または廃絶あるいは軟便や下痢便がみられ，1例では発作性頻拍，他の1例では全身性の振戦などの副作用がみられた。 しかし，漸増法では，1例にのみ一過性の下痢便がみとめられた以外は，副作用はみられなかった。血液検査，血液生化学的検査では漸増法，漸減法ともにほとんど異常は認められなかった。 硫酸キニジン投与によって除細動を行った場合，漸減法では泌乳量の減少がみられたが，除細動後には心機能が改善され投薬前より泌乳量が増加した。また，漸増法では投薬中もほとんど泌乳量に変化がなく，除細動後においては投薬前より泌乳量が増加した。 |
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| Abstract | ||||||
| 内容記述タイプ | Other | |||||
| 内容記述 | In order to improve productivity in milk cattle, the breeds have been improved with markedly developed constitution and organs such as mammary glands and digestive organs. However, on the other hand, systemic and local diseases, which have not been expected, increase in accordance with the improvement: namely, productivity diseases of domestic animals tend to increase. Recently, there are many cases of milk cattle with high secretory ability having anorexia and suddenly reduced volume of milk secretion. Various causes for reduction of the secretory ability can be supposed. One important clinical cause is atrial fibrillation, a kind of arrhythmia. The cases are divided into paroxysmal atrial fibrillation, which recovers to sinus rhythm in a relatively short time from the onset, and fixed atrial fibrillation persisting for several months or years. Therefore, the author performed a study for the purpose of comprehending the pathophysiology, diagnosis, and treatment of milk cattle with atrial fibrillation. I. Electrocardiographic diagnosis of atrial fibrillation Using 7 female Holstein cattle (ages 4 to 9 years) which were diagnosed clinically with fixed atrial fibrillation or paroxysmal atrial fibrillation, electrocardiographic and hemodynamic changes in atrial fibrillation were studied. Because the "f" wave is unclear in cattle with atrial fibrillation, electrocardiograms were reorded from 20 points of the body surface by standard limb leads, unipolar limb leads, A-B lead, and unipolar precordial chest leads in order to establish sites of electrodes. In order to observe the relationship between hemodynamics and the preceding R-R interval of the electrocardiogram in atrial fibrillation, thoracotomy was performed in a given cattle under OF anesthesia, and cardiovascular pressure was measured. For investigation of preceding R-R interval, the lead II of the standard limb leads, or A-B lead, was used to conduct simultaneous recording with the cardiovascular pressure. To obtain the R-R Index, the number of R-R interval for 5 seconds was determined as "n", into which 5 seconds were divided; that is, the index was determined as the ratio of seconds of each R--R interval against the mean R-R interval level. Measurement of cardiovascular pressure by catheterization included the left ventricular peak systolic pressure(LVSP), aortic systolic pressure(Aos), left atrial pressure(LAP), pulmonary systolic pressure(PAs), right ventricular peak systolic pressure(RVSP), and right atrial pressure(RAP). Cardiac output was measured by the dye-dilution method using indocyanine green. Clinical symptoms, electrocardiographic findings, relationship with cardiovascular pressure, and R-R Index, and changes of cardiac output were seen as follows: 1. Clinical symptoms Clinical symptoms in 5 cases of fixed atrial fibrillation included an obscure 2nd heart sound on auscultation and irregularity and deficit of heart sound. Electrocardiograms by limb lead showed absolute arrhythmia and disappearance of the P wave. For history, irregular 1st heart sound, aspiration pneumonia, and lochiometra were noted. At postmortem examination, ventricular septal defect (VSD) was recognized in one case. In 2 cases of paroxysmal atrial fibrillation, there were atrial fribrillation attacks at 30 or 60 minutes after thoracotomy during the surgery, showing the "f" wave on the epicardial electrocardiogram. 2. Electrocardiographic findings The three major electrocardiographic findings in those cases of atrial fibrillation were lack of the P wave, absolute arrhythmia of the R-R interval, and appearance of the "f" wave. However, conventional lead methods of electrocardiogram in cattle with atrial fibrillation are likely to have difficulty in confirmation of atrial fibrillation because of obscure appearance of the "f" wave. Thus, the body surface electrocardiogram was recorded in electrode sites enabling detection of the "f" wave by various lead points and methods. Consequently, the most clear "f" wave was recorded at the heart base area of the left 4th to 6th intercostals by the electrocardiogram using the unipolar chest leads. 3. Relationship between R-R Index and cardiovascular pressure From simultaneous records of electrocardiograms and cardiovascular pressure obtained by cardiac catheterization, the R-R Index was calculated and the correlation between the index and each parameter of cardiovascular pressure was compared. Consequently, it was found that R-R Index might enable speculating on the hemodynamics in the heart at atrial fibrillation. Correlation with the R-R Index was r=0.721 in LVSP, r=0.699 in RVSP, r=0.762 in Aos, and r=0.676 in PAs. In accordance with increase of the R-R Index, LVSP, RVSP, Aos, and PAs increased, and cardiac output also increased. However, no change or reduction of LAP or RAP was recognized. Cardiac output value at atrial fibrillation was about one half of normal. Because arterial blood volume in this case was reduced, reduction of the secretory milk volume was assumed to be caused by reduction of the arterial circulating volume. II. Treatment of atrial fibrillation Treatment by defibrillation using quinidine sulfate was attempted in 24 clinical cases of milk cattle in the field with atrial fibrillation detected by auscultation and electrocardiogram. For about half the cases presenting with the condition of heart failure, quinidine sulfate was administered after cardiac function was improved by cardiac glycoside (digoxin 1000 times powder). At one day prior to the administration, the majority of the cases were given quinidine sulfate of 5 to 10 g/head as a test dose in order to observe side effects before the treatment was tested. Defibrillation using quinidine sulfate was carried out by following methods. 1) Decreasing method of quinidine sulfate In this method, the administration was intensively conducted for a short time within 24 hours. The first dose was 30-50 g/head, and subsequent doses were gradually decreased every 4 to 6 hours to 30, 25, 20, or 10 g/head. 2) Increasing method of quinidine sulfate Quinidine sulfate was administered once a day for 4 days. First dose was 10 g/head and subsequent doses gradually increased to 20, 30, 40 g/head. Total dose was limited to 120 g/head in any methods. The treatment results in these methods were as follows: 1. Before administration of quinidine sulfate in treatment for atrial fibrillaiton, 5'10 g/head quinidine sulfate was administered as a test dose. Side effects due to the test administration were not seen in most cases. 2. Ten of 12 cases (83.3%) showed defibrillation by the decreaseing method. In one case among defibrillated cases atrail fibrillation recurred in accordance with disappearance of quinidine sulfate at serum level. Three of 10 defibrillated cases were administered quinidine sulfate alone, and the other 7 cases were given cardiac glycoside prior to the administration. The ineffective 2 cases and recurrent one case were speculated to have organic disorders of the heart. In the decreasing method, it was necessary to conduct intensive administration and follow-up observation, and moreover, side effects occurred, so that execution of the method was difficult in the field. Nine of 12 cases(75.0%) were demonstrated defibrillation by the increasing method. Four of the 9 cases were given quinidine sulfate alone, and the other 5 cases received pre-administration of cardiac glycoside. The increasing method of quinidine sulfate enabled conducting safe administration with only slight side effects and then conducting the field execution easily, although it took time. 3. Defibrillation effect by exercise During the administration of quinidine sulfate by the increasing method, a exercise by trot for 3 minutes was conducted once a day on a flat field from two days after initiation of the administration. Even in such cases which did not show defibrillation while the total dose was administered, the exercise was attempted again. The exercise led to defibrillation during the course of the administraion in 4 cases (57.1%), whereas 3 cases did not show defibrillation even in the exercise after the finish of the administration. Among cases without defibrillation, one case was given quinidine sulfate alone, and the other 2 cases were speculated to have organic disorders of the heart. Since addition of the exercise load during administration of quinidine sulfate led to defibrillation effect and reduction of dose of quinidine sulfate and administration period, the clinical application was considered to be highly valuable. 4. Side effects The decreasing method of quinidine sulfate led to transient anorexia, and soft feces or diarrhea, in most cases; one case showed paroxysmal tachycardia, and another case showed systemic tremor. On the other hand, in the increasing method, there was no side effect except transient diarrhea in one case. Abnormalities in the hematology and blood chemistry were hardly seen in either the increasing or the decreasing method. 5. In the defibrillation of quinidine sulfate, the secretory milk volume was reduced by decreasing method. However, cardiac function was improved after defibrillation and secretory milk volume increased to a higher level than that before the administration. The increasing method hardly changed the secretory milk volume during the administration, and the secretory milk volume after defibrillation further increased to a higher level than that before the administration. |
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| 学位名 | ||||||
| 学位名 | 獣医学博士 | |||||
| 学位授与機関 | ||||||
| 学位授与機関名 | 麻布大学 | |||||
| 学位授与年月日 | ||||||
| 学位授与年月日 | 1990-03-28 | |||||
| 学位授与番号 | ||||||
| 学位授与番号 | 乙第284号 | |||||
| 著者版フラグ | ||||||
| 出版タイプ | AM | |||||
| 出版タイプResource | http://purl.org/coar/version/c_ab4af688f83e57aa | |||||
