쌍엽 기계 승모판막의 크기 및 심박동수 변화에 따른 확장기 승모판막 압력 구배의 변화

Abstract

[한글]

정상적인 기능을 갖고 있는 인공판막이라 할 지라도 어느 정도의 혈류에 대한 협착이 있다. 이는 인공판막의 구조상 야기되는 문제중의 하나로서 이로 인해 "인공판막-환자 부적합"의 상태를 초래한다. 개심슬 후 심장 및 인공판막의 기능을 검사하기 위하여 시행하

는 비침습적인 검사방법 중 운동부하 심초음파 검사법은 널리 행해지고 있는 진단적 방법이며, 이 중 Dopplor 초음파를 이용한 검사법은 표준화된 방법 중 하나다. 그러나 경흥부 운동부하 초음파 검사법은 운동부하방법이나 동반된 질환 혹은 환자의 상태에 따라 영상의 질이 나빠지기 때문에 10-15%이내에서는 만족할 만한 결과를 얻을 수 없다. 이러한 문제등으로 경식도심방조율 부하검사를 선택하게 되는데, 이 방법은 초음파검사와 아울러 시행함으로써 관상등맥 질환 환자의 진단적 목적, 약제의 작용기전에 대한 연구적 방법 흑은 심실기능 및 판막의 기능을 검사하는 목적으로 사용되고 있다. 본 연구에서는Carbomedics**R 기계 승모판막을 이식 받은 27명의 환자를 대상으로 하여 인공 승모판막의 크기에 따라 Ⅰ군(25 mm크기, n=6), Ⅱ군(27 mm크기, n=12), Ⅲ군(29 mm크기, n=9)으로 나누어 각 군의 나이, 체중면적, 체표면적당 판막 면적등의 기본자료와 경식도 심방조율을 이용한 박동수의 증가시 혈류학적 변화를 비교하고 정상인 대조군(n=6)과 비교하여 봄으로써 정상적으로 작동하는 인공 판막에 있어 운동부하시에 나타나는 기능이상을 찾아내고 이를 기초로 수술시 인공 판막을 선택할 수 있는 기본 조건을 추정 해보고자 하였다. 대상 환자들의 각 군 사이에는 체중과 체표면적 등 기본 조건에는 차이가 없었다. 환자군 간의 나이의 차이는 Ⅰ군과 Ⅱ군 사이에서는 없었으나 Ⅰ군이 Ⅲ군에 비해 통계적으로 유의하게 많았다(p=0.0025). 기계 판막의 계산 면적을 체표면적으로 나눈 지수 한산 판막면적(Indexed calculated orifice area)은 Ⅰ군과 Ⅱ군은 Ⅲ군과 대조군에 비해 의의있게 작았으며(p<0.05), Ⅰ군과 Ⅱ군 사이에도 의의 있는 차이를 보였다(p<0.05).Ⅲ군과 대조군 사이에는 차이를 보이지 않았다. 휴식기, 중등도 박동 증가 때까지는 Ⅰ군, Ⅱ군, Ⅲ군 사이에는 심박출량, 좌심실 확장기말 내경, 좌심실 수축기말 내경, 효과적 판막면적, 승모판막을 퉁한 정점 압력 구배(peak pressuregradient), 평균 압력 구배(mean pressure gradient)등에 차이를 보이지 않았으나 정상 대조군에 비하여는 의의 있는 차이가 있었다. 최고 박동수에서의 정점 압력구배는 Ⅰ군이 16.68 ± 1.56 mmHg, Ⅱ군은 11.27 ± 1.

44 mmHg, Ⅲ군은 10.14 ± 0.99 mmHg, 대조군은 3.33 + 0.28 mmHg서 각 군이 대조군보다 높았으며,Ⅰ군은 Ⅱ군과 Ⅲ군에 비해 의의 있게 높았으나(p<0.0001), Ⅱ군과 Ⅲ군 사이에는 차이가 없었다. 평균 압력 구배는 Ⅰ군이 9.03 ± 0.98mmHg, ll군이 6.78 ± 0.90 mmH

g,Ⅲ군은 5.29 ± 0.55 mmHg, 대조군은 1.50 ± 0.07mmHg로서 각 환자군이 대조군보다는 높았으며(p=0.0001), Ⅰ군과 Ⅱ군 사이에는 차이가 없었으나 Ⅰ군과 Ⅲ군 사이에는 의의 있는 차이를 보였다(p=0.0001). Ⅰ군, Ⅱ군, Ⅲ군에 있어서 심박출율은 박동수가 증가될수록 감소하였고(p<0.0001), 확장기말 내경과 수측기말 내경은 변화가 없었다. 대조군에서는 심박동 증가에 따라 심박출율은 차이를 보이지 않았으며, 확장기말 내경과 수측기말 내경은 박동수가 증가함에 따라 의의 있게 감소하였다(p=0.001). 환자군에서는 단게별

박동수의 변화에 따라 점차 평균 압력 구배가 증가하여 Ⅰ군은 '병적인' 협착을 일으키는 것으로 나타났고 Ⅱ군은 경계범주, Ⅲ군은 정상 협착의 범주에 속하였다. 체표면적당 판막면적과 인공판막을 통한 압력 구배의 상관관계를 살펴볼 때 운동시 평균 판막 압력 구

배가 5 mmHg이하가 되기 위해서는 최소 207.52mm**2/m**2의 지수 환산판막면적이 필요할 것으로 생각되며 이것이 판막선택의 기준으로 될 수 있을 것으로 생각된다.

Diastolic Pressure Gradient Change in Bileaflet Mechanical Valve: Influence of

Heart Rate and Prosthetic Valve Size

Dong Moon Soh

Department of medical Science Graduate school Yonsei University

(Directed by Professor Bum Koo Cho)

Various noninvasive techniques have been used to evaluate prosthetic value

function. Doppler echocardiography is increasingly used to quantitate prosthetic

valve function and pressure gradient with good correlation and reproducibility as

compared with cardiac catheterization.

Exercise Doppler echocardiography is noninvasive, effecticve, but there are some

limitations due to technical problems of echocardiography during exercise or

physical limitation such so musculo-skeletal disease or peripheral vascular disease

or cor pulmonale etc. Therefore we have used transesophageal atrial pacing in

increase cardiac output during doppler echocardiography to evaluate prosthetic

valve function during exercise. Normally functioning Prosthetic valves are mild to

moderately stenotic."normal" prosthetic stenosis or "pathologic" stenosis are

originated from the reduction of the effective valve area due to sewing ring. This

causes "prosthesis-patient mismatch". The purpose of this study is to draw a

selection criteria for suitable size of prosthetic valve implanted for cardiac

patients. In this study, 27 patients who had recieved Carbomedics**R bileaflet

mechanical mitral prosthesis were included for hemodynamic evaluation with Doppler

echocardiogrphy during interval change of the heart rate with transesophageal

pacing. They are classified into three sub-groups according to the prosthetic valve

size as group Ⅰ (25 mm, n=6), group Ⅱ (27mm, n=12) and group Ⅲ(29mm, n=9). For

control group, 6 male normal volunteers were included.

During interval change of the heart rate Induced by transesophageal pacing, study

parameters such as ejection fraction, left ventricular end diastolic dimension.

left ventricular end systolic dimension, effective valve area. peak transmitral

pressure gradient and mean transmitral pressure gradient were compared between the

sub-groups and between the control group.

Smallest sized valves(25 mm) were implanted for older patients(P=0.0025). Indexed

valve area of group Ⅰ or group Ⅱ was significantly smaller than of group Ⅲ which

was comparable with normal indexed valve area(p<0.05). In resting and moderate

increase of heart rate phase, peak and mean transmitral pressure gradients were not

different between sub-groups which were quite different from the control

group(p<0.05). During maximum heart rate phase, peak transmitral valve gradient was

significantly higher in group Ⅰ than in group Ⅱ and group Ⅲ(16.68 ± 1.56 mmHg

versus 11.27 ± 1.44 mmHg and 10.14 ± 0.99 mmHg, respectively. p<0.0001). Mean

transmitral gradient was higher in group Ⅰ than In group Ⅲ (9.03 ± 0.98 mmHg

versus 5.79 ± 0.55 mmHg, p=0.0001) and there was no difference between group Ⅲ

and control group(5.29 ± 0.55 mmHg versus 1.50 ± 0.07 mmHg).

The effect of increasing heart rate on patient group showed decrease of ejection

fraction (p<0.0001), while there was no change in the normal control. And left

ventricular end-diastolic dimension and end-systolic dimension of patient group

were not changed in contrast to the significant shortening of both dimension in

control group(p=O.001). Therefore we may conclud that the group Ⅰ Showed

"Pathologic" stenosis, the group Ⅱ "borderline" and group Ⅲ "normal" stenosis.

In conclusion, at minimum, 207.52mm**2 /m**2 of indexed calculated orifice area

could be suitable selection criteria for the purpose of getting low transmitral

pressure gradient less than 5 mmHg during exercise after mitral valve prosthesis

implantation.

[영문]

Various noninvasive techniques have been used to evaluate prosthetic value function. Doppler echocardiography is increasingly used to quantitate prosthetic valve function and pressure gradient with good correlation and reproducibility as

compared with cardiac catheterization.

Exercise Doppler echocardiography is noninvasive, effecticve, but there are some limitations due to technical problems of echocardiography during exercise or physical limitation such so musculo-skeletal disease or peripheral vascular disease or cor pulmonale etc. Therefore we have used transesophageal atrial pacing in increase cardiac output during doppler echocardiography to evaluate prosthetic valve function during exercise. Normally functioning Prosthetic valves are mild to moderately stenotic."normal" prosthetic stenosis or "pathologic" stenosis are originated from the reduction of the effective valve area due to sewing ring. This causes "prosthesis-patient mismatch". The purpose of this study is to draw a selection criteria for suitable size of prosthetic valve implanted for cardiac patients. In this study, 27 patients who had recieved Carbomedics**R bileaflet mechanical mitral prosthesis were included for hemodynamic evaluation with Doppler echocardiogrphy during interval change of the heart rate with transesophageal

pacing. They are classified into three sub-groups according to the prosthetic valve size as group Ⅰ (25 mm, n=6), group Ⅱ (27mm, n=12) and group Ⅲ(29mm, n=9). For control group, 6 male normal volunteers were included.

During interval change of the heart rate Induced by transesophageal pacing, study parameters such as ejection fraction, left ventricular end diastolic dimension.

left ventricular end systolic dimension, effective valve area. peak transmitral pressure gradient and mean transmitral pressure gradient were compared between the sub-groups and between the control group.

Smallest sized valves(25 mm) were implanted for older patients(P=0.0025). Indexed valve area of group Ⅰ or group Ⅱ was significantly smaller than of group Ⅲ which was comparable with normal indexed valve area(p<0.05). In resting and moderate

increase of heart rate phase, peak and mean transmitral pressure gradients were not different between sub-groups which were quite different from the control group(p<0.05). During maximum heart rate phase, peak transmitral valve gradient was significantly higher in group Ⅰ than in group Ⅱ and group Ⅲ(16.68 ± 1.56 mmHg versus 11.27 ± 1.44 mmHg and 10.14 ± 0.99 mmHg, respectively. p<0.0001). Mean transmitral gradient was higher in group Ⅰ than In group Ⅲ (9.03 ± 0.98 mmHg versus 5.79 ± 0.55 mmHg, p=0.0001) and there was no difference between group Ⅲ

and control group(5.29 ± 0.55 mmHg versus 1.50 ± 0.07 mmHg).

The effect of increasing heart rate on patient group showed decrease of ejection fraction (p<0.0001), while there was no change in the normal control. And left ventricular end-diastolic dimension and end-systolic dimension of patient group were not changed in contrast to the significant shortening of both dimension in control group(p=O.001). Therefore we may conclud that the group Ⅰ Showed "Pathologic" stenosis, the group Ⅱ "borderline" and group Ⅲ "normal" stenosis.

In conclusion, at minimum, 207.52mm**2 /m**2 of indexed calculated orifice area could be suitable selection criteria for the purpose of getting low transmitral pressure gradient less than 5 mmHg during exercise after mitral valve prosthesis implantation.