Korean J Vasc Endovasc Surg 2011;27(4):145-150 http://dx.doi.org/10.5758/kjves.2011.27.4.145 복부대동맥의비틀림과동맥경화성변화와의상관관계 충북대학교의과대학외과학교실 이진영ㆍ장이찬ㆍ선우영ㆍ박진우ㆍ최재운 Relationship between Tortuosity and Atherosclerotic Changes of the Abdominal Aorta Jin Young Lee, M.D., Lee Chan Jang, M.D., Woo Young Sun, M.D., Jin Woo Park, M.D. and Jae Woon Choi, M.D. Department of Surgery, Chungbuk National University School of Medicine, Cheongju, Korea Purpose: Tortuosity and atherosclerosis of the abdominal aorta are commonly observed in the elderly. Few studies about aortic tortuous changes have been performed. This study was carried out to investigate the relationship between aortic tortuous and atherosclerotic changes. Methods: We included 2,920 patients by reviewing computerized tomography scans in Chungbuk National University Hospital during 2007. We classified the abdominal aorta into straight (I form) and tortuous forms (T form), defined as a deviation involving more than half the aortic diameter. The T form was further subdivided into 2 types (C type, 1 curve; T type, >2 curves). The calcification index (CI) was also measured. The tortuosity index (TI) was measured in 60 patients each with the I form and the C and S types. We analyzed relationships between tortuosity and clinical variables. Results: The incidence of tortuosity was 56.2%, and in the 7th, 8th, 9th decades of life it was 61.7%, 77.3%, and 91.0%, respectively. In univariate analysis, age, female sex, hypertension, and CI were statistically significant. In multivariate analysis, CI was not statistically significant between the I and T forms but significant between the I form and the S type. TI in the T form was lower than in the I form. However, no difference was seen between the I form and C type. Conclusion: A tortuous change of the abdominal aorta was seen earlier and more frequently than an atherosclerotic change and were associated with aging, calcification, and hypertension. Aortic calcification was associated with more complex tortuous changes. Key Words: Artery, Abnormalities, Tortuosity 중심단어 : 복부대동맥, 죽상동맥경화증, 비틀림 서 복부대동맥은나이가들면서여러가지의형태적변화가생긴다. 대동맥은휘고, 콜레스테롤이침착하고, 동맥 접수일 : 2011년 2월 4일, 수정일 : 2011년 3월 8일 (1차), 2011 년 4월 25일 (2차), 승인일 : 2011년 5월 16일책임저자 : 장이찬, 청주시흥덕구분평동우 361-764, 충북대학교의과대학외과학교실 Tel: 043-269-6337, Fax: 043-266-6037 E-mail: lcjang@chungbuk.ac.kr 론 벽이석회화되어혈관내벽이단단해지고, 울퉁불퉁해진다 (1). 또한, 동맥이길어지면서비틀어지고, 탄성섬유의변성으로동맥류가발생한다 (2). 이러한변화는임상적으로고혈압, 동맥경화증, 동맥류라는질환을유발한다. 동맥경화증은 40세이후부터점점증가한다. 복부대동맥류는신장동맥하부에서주로발생하며고령에서많이생긴다 (3). 대동맥의비틀어지는현상은나이가증가하면서흔히발견되고다른병적변화이전에시작되는것으로추정되지만, 임상적으로문제를일으키지않기때문에별로주목을받지못하여비틀림에대한연구는별로없다. 최근혈관내치료가발전하면서동맥의비틀림변 145
146 Korean J Vasc Endovasc Surg Vol. 27, No. 4, 2011 Fig. 1. The examples of I form and T form (C, S type). (A) I form. (B) C type. (C) S type. 화는혈관접근을어렵게하고혈관내치료후이차적변화로말미암아관내누출, 혈관폐색과관련이있을것으로추정하고있다 (4). 동맥의비틀림변화는나이, 혈압, 체형, 척추의변화, 다리의활동정도, 동맥경화증의발생요인등여러요인에의해영향을받을것으로추정되지만이에대한연구는거의없는실정이다. 이에저자들은복부대동맥의비틀림변화와복부대동맥에서흔히발견되는동맥경화성변화와의상관관계에대해알아보고자하였다. 방법 1) 연구대상본연구는 2007년 1월 1일부터 12월 31일까지충북대학교병원을내원하여복부및골반컴퓨터단층촬영을시행한 40세이상부터 90세미만의환자 3,293명의컴퓨터단층촬영의영상을조사하였다. 다중검출기컴퓨터단층촬영 (multidetector row computed tomography, Brillance 64, Philips, Best, the Netherland) 으로촬영된 3,293명의복부및골반영상과축면, 단면으로영상을재구성 (multiplanar reformation, MPR) 하여분석하였다. 이중 2명의조사자가대동맥의비틀림의변화를조사하여결과가일치하는 2,920명을연구대상으로하였다. 2) 연구방법비틀림이없는직선형 (I form) 과비틀림이있는만곡형 (T form) 으로나누었다. 만곡형은컴퓨터단층촬영의단면상에서신장동맥하방과양측총장골동맥의분지부위까지의연결선상에서동맥의한부위가동맥지름의반이상이이동하여곡선을이루는경우로정의하였다. 만곡형은 1개의곡선을이루는 C형 (C type) 과 2개이상의 곡선을이루는 S형 (S type) 으로구분하였다 (Fig. 1). 두사람이영상을조사하여결과가일치하는환자 2,920명의영상을연구대상으로하였다. 직선형, C형과 S형영상을각각 60예를무작위로선택하여비틀림지수 (tortuosity index) 를측정하였다. 비틀림지수는삼차원영상재구성소프트웨어 (Lucion ver. 1.1, MeviSYS, Seoul, Korea) 를이용하여 1 mm 영상으로 3차원재구성을하여관상단면상에서우측신장동맥이기시하는대동맥에서대동맥이장골동맥으로분지하는지점까지혈관의중심을잇는곡선의길이와두점을연결하는직선의길이비를계산하였다. 복부대동맥과총장골동맥에서석회화지수 (0-20) 를조사하였다 (5). 복부대동맥을신장동맥상부, 신장동맥하부를반씩두부위로나누고, 총장골동맥을포함하여총 4부위에서석회화정도 (0-5) 로조사하여 4부위석회화정도의합을석회화지수로하였다. 비틀림과관련된인자중질병들, 즉고혈압, 당뇨, 관상동맥질환, 뇌혈관질환, 척추질환, 신부전은환자의병원질환코드를찾아서확인하였다. 이들질병과기본적인인적사항, 동맥의변화특성들과비틀림변화와의상관관계를조사하였다 (Table 1). 3) 통계학적분석방법수치는평균 ± 표준편차로표시하였다. 단변량분석에서나이와석회화지수에따른비틀림의유무와정도의차이는선형회귀분석으로분석하였다. 성별, 질환유무, 대동맥확장여부와비틀림상관관계는교차분석을이용하였다. 대동맥의비틀림에영향을미치는인자는다변량분석은로지스틱다중회귀분석을이용하였다. 비틀림지수의비교는 T-검정을이용하였다. 모든통계학적분석은 SPSS ver. 12.0 (SPSS Inc., Chicago, IL, USA) 을이용하였다.
Jin Young Lee, et al: Relationship between Tortuosity and Atherosclerotic Changes of the Abdominal Aorta 147 Table 1. Demographics of study groups I form T form Subtotal I form (n=1,280) C type (n=1,032) S type (n=608) T form (n=1,640) Total (n=2,920) Age 56.4±11.0 66±10.5 67.1±10.6 66.5±10.6 62±11.9 Sex (ratio of female, %) 39.3 42.7 51.3 45.9 43 Calcification index 3.45±4.0 5.6±4.2 5.4±4.2 5.5±4.2 4.6±4.2 Chronic renal failure (%) 2.0 1.0 3.0 1.8 1.8 Diabetes mellitus (%) 8.0 9.0 9.0 9.0 8.6 Cerebrovascular disease (%) 4.9 5.3 5.3 5.3 5.1 Coronary artery disease (%) 2.0 3.0 5.0 3.7 3.1 Hypertension (%) 6.9 11.9 12.7 12.2 9.9 Aneurysm (%) 0.5 1.1 1.0 1.0 0.8 Spinal disease (%) 2.0 1.0 1.0 1.2 1.7 Table 2. The incidence of tortuosity according to associated factors Fig. 2. The incidence of tortuosity (T form, C and S type) according to age (P<0.0001). 결 1) 대상선정의일치율 3,293명중두조사자의결과가일치는경우는 2,920명으로 kappa 값이 0.88이었다. 2) 연구대상의특성 (Table 1) 평균나이는 62±11.9세이며여자가 43% 였다. 평균석회화지수는 4.6±4.2였다. 만성신부전, 당뇨, 뇌혈관질환, 관상동맥질환, 고혈압, 복부대동맥류, 척추질환은각각 1.8%, 8.6%, 5.1%, 3.1%, 9.9%, 0.8%, 1.7% 를나타내었다. 과 3) 복부대동맥의비틀림변화의빈도 복부대동맥의형태는직선형이 43.8%, 만곡형이 56.2% 로나타났다 (Table 1). 복부대동맥에서만곡형의빈도는나이별로통계적으로유의하게 (P<0.0001) 점차증가하였다 Tortuosity (%) Odds ratio 95% confidence interval P-value Sex (female/male) 60.0 (53.3) 0.756 0.637-0.896 0.001 Disease (-/+) Chronic renal 56.1 (58.8) 1.102 0.539-1.899 0.971 failure Diabetes mellitus 55.9 (59.1) 1.018 0.758-1.367 0.906 Cerebrovascular 56.0 (58.0) 0.757 0.521-1.101 0.145 disease Coronary artery 55.8 (65.9) 0.709 0.437-1.150 0.163 disease Hypertension 54.7 (69.4) 1.448 1.077-1.947 0.014 Aneurysm 56.0 (73.9) 1.030 0.392-2.704 0.952 Spinal disease 56.4 (38.8) 1.211 0.627-2.339 0.568 (Fig. 2). 나이별평균빈도를보면 60대, 70대, 80대에서각각 61.7%, 77.3%, 91% 로나타났다. 4) 비틀림변화와관련된인자들의단변량분석 나이가증가할수록비틀림의빈도도증가하였다. 여자가남자보다만곡형의빈도가 (60% vs. 53.3%) 높았다. 고혈압 (69.4% vs. 54.7%) 에서통계적으로유의하게높았다. 당뇨 (59.1% vs. 55.9%), 신부전 (58.8% vs. 56.1%), 관상동맥질환 (65.9% vs. 55.8%), 뇌혈관질환 (58.0% vs. 56.0%) 이있으면만곡형의빈도가증가하였지만, 통계적으로유의하지않았다. 척추질환 (56.4% vs. 38.8%) 이있으면만곡형이높게나타났지만, 통계적으로유의하지않았다 (Table 2). 복부대동맥의석회화지수와비틀림은단변량분석에서통계적으로유의하였다 (Fig. 3). 대동맥류 (56% vs. 73.9%)
148 Korean J Vasc Endovasc Surg Vol. 27, No. 4, 2011 Fig. 3. The incidence of tortuosity (T form, C and S type) according to calcification index (CI) (P<0.05). Fig. 4. The mean calcification index (CI) of I and T form according to age (P<0.05). Table 3. Multivariate analysis of factors associated with tortuosity (I form vs. T form, C and S type) I form vs. T form I form vs. C type I form vs. S type Age <0.0001 <0.0001 <0.0001 Sex (female) 0.002 NS <0.0001 Calcification index NS NS 0.023 Chronic renal failure NS NS NS Diabetes mellitus NS NS NS Cerebrovascular disease NS NS NS Coronary artery disease NS NS NS Hypertension 0.014 NS NS Aneurysm NS NS NS Spinal disease NS NS NS NS = statistically not significant. 가있으면만곡의빈도가높았지만, 통계적으로유의하지않았다. 5) 비틀림변화와관련된인자의다변량분석 다변량분석에서 I form과 T form의비교에서는나이, 성별 ( 여자 ), 고혈압이통계적으로유의한상관인자였다 (Table 3). 또한, I form과 C형의비교에서는나이만이유일하게의미있는인자였으며, I form과 S형의비교에서는나이, 성별, 석회화지수가통계적으로유의한인자였다. 6) 비틀림지수 비틀림지수는직선형 (I form) 은 0.99±0.05, C형에서평균이 0.95±0.03, S형의평균은 0.93±0.05이었다. I form과 T form, I form과 S형과는통계적으로유의한차이가있 지만, I form과 C형, C형과 S형간의차이는없었다. 7) 나이에따른석회화지수석회화지수는나이가증가할수록증가하는데 40세에평균 0.3으로거의석회화가없으며 50세에서는 1.3으로미미하다가 60세에 4.5, 70세에 5.7을나타내었다. 70세후반에서더이상의지수의증가없이평행선을나타내었다 (Fig. 4). 고찰비틀림과관련된임상질환은 arterial tortuosity syndrome 이외는거의알려진것이없다. Arterial tortuosity syndrome은유전적결체조직이상으로얼굴, 피부, 관절등에서주요탄력혈관들이늘어나고비틀어진다. 상행대동맥의동맥류나폐혈관의협착등이생길수있는데, 수술적치료나혈관내치료가필요하다 (6,7). 비틀림은흔히관찰되지만, 임상적으로문제를일으키지않기때문에별로주목을받지못하여이에대한연구는별로없다. 그러나최근복부대동맥류의치료에서혈관내치료가발전하면서동맥의비틀림변화가주목받기시작하였다. 비틀림변화가심할수록혈관접근을어렵게하고 (8,9), 혈관내치료후비틀림현상으로말미암아이차적인변화로관내누출이나혈관폐색이생길수있는것으로추정된다 (10,11). 하지만, 아직은대동맥류의혈관내치료후에발생하는이들합병증과비틀림과직접적인상관관계가있다는보고는없다. 비틀림을측정하는방법은여러가지가제시되어있다. 크게네가지로나누어볼수있는데, 관찰자의판단에의한임상적인방법, 3차원재구성영상에서혈관의중심선을 1 mm 간격으로측정한곡선반지름의역인
Jin Young Lee, et al: Relationship between Tortuosity and Atherosclerotic Changes of the Abdominal Aorta 149 비틀림지수 (tortuosity index) 를구하는방법, 혈관두점사이의중심선의길이와직선길이의비, 그리고 3차원재구성영상을이용하여직접측정하는방법이다 (11,12). 동맥조영영상에서동맥만 3차원으로구성하여길이를측정하는방법이비틀림을측정하는데가장정확하다. 본연구에서는임상적방법과비틀림지수를사용하였다. 임상적비틀림의기준에대해서는일정한기준이없지만, 대동맥의직경의반이상이휘어지면비틀림이있다고하였다. 비틀림지수는타연구에서는신장동맥기시부의대동맥과총장골동맥분기까지의측정하였지만본연구에서는복부대동맥의신장동맥기시부부터대동맥의분기까지 3차원재구성을통해일부에서만측정하였다. 비틀림지수를통해비틀림의심한정도를알아보고자하였으나, 연구에이용된영상들은동맥조영시기의영상으로 3차원재구성을할수있는영상들은별로없어지연영상 (delayed image) 으로단면영상을재구성 (MPR) 하여관상면에서비틀림지수를측정함으로다른단면으로동맥이휘어지면정확하게비틀림지수를측정하지못하는경우가발생하여비틀림지수로비틀림의정도를비교하는데는한계가있었다. 따라서비틀림의정도의비교는임상적인방법으로비틀림곡선의개수가한개인경우 (C type) 와두개이상 (S type) 인경우로나누어비교하였다. 즉곡선의개수가많을수록비틀림이심한것으로가정하였는데곡선의만곡이두개이상인경우가한개보다비틀림지수가작게나오는경우도발생할수있다. 하지만, 비틀림지수를측정해보면곡선이한개인경우와직선형 (I form) 과는비틀림지수의차이가없었지만곡선이 2개이상인경우 (S type) 가직선형보다통계적으로유의하게비틀림지수가작았다. 비틀림여부와정도는일차적으로임상적분류를기준으로하여두관찰자의결과가일치하는환자만을대상으로하였다. 두관찰자의일치율인 kappa score는 0.88로상당히높게나타났다. 일반적으로척추질환즉척추협착, 골절, 척추후만증등과대동맥의만곡과관련이있을것으로추측되지만비틀림의빈도에서는별다른차이를보이지않았다. 동맥경화증과관련이있는당뇨, 뇌혈관질환, 심혈관질환과비틀림의빈도와는상관관계를보이지않았고, 대동맥의석회화와관련이있을것으로생각하는당뇨, 신부전과도무관하였다. 복부동맥류가있으면다소비틀림이많이생길것으로추정되지만, 통계적으로유의한차이를보이지는않았다. 여성에서많이비틀어지는것은대동맥의유연성이여성에서좋기때문으로추측되며, 여성에서에스트로젠의영향으로탄력섬유가남성보다많아서대동맥의경직도가남자보다떨어지는데동맥이유연하다. 대동맥류의발생률이낮은것과유연성은관련이있을것으로 생각한다 (13,14). 혈압이높아지면비틀림이증가하는것은혈관내의압력증가로말미암아생기는것으로생각하며예상된결과였다. 당뇨에서는대동맥류의발생이오히려감소하는데 (14), 이는대동맥벽이석회화되어동맥류의발생이줄어드는것으로알려졌다. 비틀림변화의발생과석회화는상관이없는것으로생각하지만, 석회화지수가높은혈관에서비틀림의곡선의개수가증가하기때문에여러각도로복잡하게비틀어지는데는석회화가관련이있는것으로생각한다. 동맥경화증과관련된질환들은비틀림과상관관계를보이지않기때문에동맥경화증과비틀림은무관한것으로추정된다. 비틀림은 40대에 40% 까지관찰되는데석회화지수는 40세에 0.5, 50세에 1.3으로석회화지수가낮게나타났다. 이런결과로추정해볼때비틀림은동맥경화증보다는시기적으로먼저시작되는현상으로생각된다. 한편, 비틀림이진행되면동맥경화증이발생할수있다는가정을할수있는데동맥경화증관련질환과아무런상관관계가없어비틀림이동맥경화증을유발하는것으로생각하지는않는다. 결 대동맥의비틀림과석회화는나이가증가할수록증가하며, 시기적으로비틀림은석회화보다더일찍나타나는것으로생각한다. 대동맥의비틀림은나이가증가할수록, 대동맥의석회화로말미암아혈관의유연성이감소할수록, 고혈압으로혈관내압력이증가할수록비틀림의빈도는증가한다. 석회화가있으면복부대동맥은더욱복잡하게비틀어지는것으로추정된다. 론 REFERENCES 1) Dixon AK, Lawrence JP, Mitchell JR. Age-related changes in the abdominal aorta shown by computed tomography. Clin Radiol 1984;35:33-37. 2) Dobrin PB, Schwarcz TH, Baker WH. Mechanisms of arterial and aneurysmal tortuosity. Surgery 1988;104:568-571. 3) Dobrin PB, Mrkvicka R. Failure of elastin or collagen as possible critical connective tissue alterations underlying aneurysmal dilatation. Cardiovasc Surg 1994;2:484-488. 4) Wolf YG, Tillich M, Lee WA, Rubin GD, Fogarty TJ, Zarins CK. Impact of aortoiliac tortuosity on endovascular repair of abdominal aortic aneurysms: evaluation of 3D computer-based assessment. J Vasc Surg 2001;34:594-599. 5) Sun WY, Jang LC. Calcification in the abdominal aorta and common iliac artery. J Korean Soc Vasc Surg 2008;24:94-100. 6) Ritelli M, Drera B, Vicchio M, Puppini G, Biban P, Pilati M,
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