CLINICAL APPLICATION OF END SYSTOLIC P-V RELATIONS

我们正在研究心脏，以收集关于心脏如何作为泵起作用的新信息。我们希望了解心脏的泵送能力是如何在健康和疾病中维持的。被选中的患者被安排进行常规心导管检查，以确定其心脏瓣膜问题的严重程度。参与研究的患者将在完成常规心导管检查后接受额外的研究，以证明冠状动脉没有阻塞。这些额外的研究将包括：1)放置一个临时心脏起搏器，2)在心脏内放置一个特殊的压力感应导管，3)在冠状窦内放置一个导管，4)输注3h -去甲肾上腺素，5)多个血液样本（总共不超过150毫升，或3汤匙），6)用药物（甲氧基胺或硝普塞）向静脉注射锝-99m，以增加或降低你的血压（甲氧基胺或硝普塞），7)多巴酚丁胺超声心动图，8)验血，测量血液中细胞因子和儿茶酚胺的水平；9)心肌活组织检查。下面是更完整的解释。在研究期间，将使用临时起搏导线来保持您的心率恒定。一根特殊的导管将被插入心脏的主要泵腔中，以精确测量其中的压力。导管也将通过一个小的，灵活的导管插入静脉（冠状静脉窦），从心脏排出血液，以测量血液流向心脏。研究过程包括静脉输注放射性同位素（3h -去甲肾上腺素），并维持60分钟。在输注过程中的特定时间和输注完成后的20分钟内，将从您的腿部动脉鞘和静脉导管中抽取多个血液样本，以测量全身和心脏交感神经系统的活动。然后，你的心脏将以每分钟100次的速度跳动。在静息状态下，通过静脉注射另一种放射性同位素（锝-99m）和在白天可能正常变化的范围内增加或降低血压的药物（甲氧苄胺或硝普塞），可以获得泵腔和心脏片的精确压力测量。估计需要150分钟才能完成心导管插入术的额外部分。另一天，将做多巴酚丁胺超声心动图。这个测试使用声波来创造心脏的运动图像。心脏的照片将在休息时拍摄，同时将多巴酚丁胺药物注入静脉。这个测试可以让我们看到心脏肌肉和心脏瓣膜在休息和压力或用力时是如何工作的。所有有生育潜力的妇女在任何研究诊所访问之前都将进行妊娠试验。如果有严重的二尖瓣泄漏，需要进行心脏瓣膜手术，患者将接受手术修复二尖瓣。这是治疗心脏瓣膜问题的最佳手术方法。在手术过程中，将对心肌进行小的活检，以确定心肌是否因心脏问题而发生了结构变化或损伤。我们想跟踪那些接受手术修复二尖瓣的患者在康复的第一年。这将包括在手术后大约3个月和12个月进行超声心动图和MUGA扫描，并进行门诊检查，以评估每位患者的健康状况。

We are studying the heart to gather new information regarding how the heart functions as a pump. We hope to learn how the pumping ability of the heart is maintained in health and disease. Patients selected are scheduled for a routine heart catheterization to determine the severity of their heart valve problem. Patients who participate will undergo additional studies after the completion of the routine heart catheterization which demonstrated no blockages in the coronary arteries. These additional studies will include: 1) placement of a temporary heart pacemaker, 2) placement of a special pressure sensing catheter into the heart, 3) placement of a catheter into the coronary sinus, 4) infusion of 3H-norepinephrine, 5) multiple blood samples (a total of not more than 150 ccs, or 3 tablespoons), 6) an injection into your vein of technetium-99m with drugs to increase or decrease your blood pressure (methoxamine or nitroprusside), 7) a dobutamine echocardiogram, 8) a blood test to measure the cytokine and catecholamine levels in your blood, and 9) heart muscle biopsies. A more complete explanation follows.A temporary pacing wire will be used to keep your heart rate constant during the study. A special catheter will be inserted into the major pumping chamber of your heart to measure precise pressure in it. A catheter will also be inserted through a small, flexible catheter into the vein (coronary sinus) that drains blood from your heart to measure the blood flow to your heart. The study procedure will involve infusion by vein of a radioisotope (3H-norepinephrine) that will be maintained for 60 minutes.Multiple blood samples will be drawn from the sheath in the artery in your leg and from the catheter in the vein that drains the blood from your heart at specific times during the infusion and for 20 minutes following completion of the infusion to measure the activity of the sympathetic nervous system both in the whole body and the heart. Then, your heart will be paced at 100 beats per minute. Measurement of precise pressures in the pumping chamber and movies of your heart will be acquired using another radioisotope (technetium-99m) injected by vein both at rest and with drugs to increase or decrease your blood pressure (methoxamine or nitroprusside) within a range that it might vary normally during the day. It is estimated that 150 minutes will be required for the additional portion of the heart catheterization to be completed. On a separate day, a dobutamine echocardiogram will be done. This test uses sound waves to create moving pictures of the heart. Pictures of the heart will be taken at rest and while a medication, dobutamine, is infused into a vein. This test allows us to see how the heart muscle and heart valves are working at rest and under periods of stress or exertion. All women of child bearing potential will have a pregnancy test before any study clinic visits. If there is a severe leak of the mitral valve and heart valve surgery is needed, patients will be referred for surgical procedure to repair the mitral valve. This is the optimal surgical procedure for this heart valve problem. During the operation, small biopsy specimens of the heart muscle will be taken to determine whether any structural change or damage to the heart muscle has occurred as a result of the heart problem. We would like to follow the patients who do undergo surgery to repair their mitral valve during the first year of recovery. This would involve an echocardiogram and MUGA scan approximately three and twelve months after surgery and clinic visits to assess each patients health status.