End Notes

The Politics of Intraoperative Transesophageal Echocardiography

World Journal for Pediatric and Congenital Heart Surgery 2014, Vol. 5(2) 352-354 ª The Author(s) 2014 Reprints and permission: sagepub.com/journalsPermissions.nav DOI: 10.1177/2150135114521843 pch.sagepub.com

Richard A. Jonas, MD1 Keywords intraoperative transesophageal echocardiography, early myocardial ischemia, early post-bypass period, echocardiographer Submitted January 07, 2014; Accepted January 08, 2014.

The ‘‘Roast’’: A True Story One of the intriguing American cultural traditions that the foreign medical graduate experiences while settling into the United States is ‘‘the roast.’’ Wikipedia defines a roast as ‘‘an event, almost exclusively in the United States in which an individual is subjected to a public presentation of comedic insults, praise, outlandish true and untrue stories and heartwarming tributes as a mock counter to a toast, the implication being that that the roastee is able to take the jokes in good humor and not as serious criticism or insult and it is seen by some as a great honor to be roasted.’’ I had the opportunity to be a roastee at a surgical conference not too long ago where I was one of the guest speakers. One of my ‘‘roasters’’ was a good friend of many years who is an echocardiographer. He and I worked together closely on many cases including patients in the operating room in which he undertook transesophageal echocardiography. The theme of his roasting was that in case after case the roaster had been able to describe to me an excellent outcome with beautiful surgical results and being taciturn by nature my response was always ‘‘thank you, please give the protamine.’’ The twist to the story was that one day the result was not particularly good and the roaster was concerned that there were significant residual problems. After a comprehensive presentation to me in the operating room my response was ‘‘thank you, please give the protamine.’’ In the tradition of a good roasting, this was meant in a good-hearted way but nevertheless as the roastee the experience crystallized for me the complexities surrounding the interpretation of echocardiographic outcomes in the operating room. Although the comment was designed to be humorous, there was also an important kernel of information here, namely, that the echocardiographer was in a subtle way disrespected by the surgical team because they ‘‘did not take any notice’’ of the interpretation of the surgical outcome. The following thoughts are offered by the surgical team to the echo team in a spirit of open communication to assist the echo team to have a better understanding of the reason why the response by the surgical team to an imperfect result may often be ‘‘thank you, please give the protamine.’’

The Dynamic Nature of the Early Postbypass Period Many excellent echocardiographers pride themselves on providing an anatomical and physiological diagnosis in the absence of any information from other diagnostic modalities. While this may make sense in the preoperative patient who may have undergone previous cardiac catheterization or magnetic resonance image scanning, and the rationale for performing an echocardiogram is to obtain completely independent diagnostic information, the principle can be overextended in the operating room where at a minimum it is important to know whether the patient is still on cardiopulmonary bypass. It is not uncommon at all for the novice echocardiography trainee to come to the operating room and to begin to provide a commentary of diagnostic findings including statements such as ‘‘the right ventricle is very underfilled, the gradient across the mitral valve has gone from 12 mm preoperatively to 2 mm now . . . ’’ without any reference to the patient’s status with respect to cardiopulmonary bypass. Often, if the patient is on full cardiopulmonary bypass, there is no antegrade blood flow through the ventricle and the only blood flow returning to the left atrium is from bronchial collateral or true collateral flow to the lungs. When the patient is on partial cardiopulmonary bypass some of the systemic venous return coming to the right atrium is no longer taken by the venous cannulas and is being pumped by the right heart through the lungs to the left heart. This is under the control of the perfusion team. The perfusionist may choose at the direction of the surgical team to ‘‘fill the heart’’ by lowering the venous reservoir level and effectively transfusing blood from the venous reservoir to the patient while at the same time maintaining a high level of pump flow. Thus, the level of 1

Children’s National Heart Institute, Children’s National Medical Center, Washington, DC, USA Corresponding Author: Richard A. Jonas, Children’s National Heart Institute, Children’s National Medical Center, 111 Michigan Ave NW, Washington, DC 20010, USA. Email: [email protected]

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venous filling of the patient as well as the pump flow rate must be factored into any echo assessment if the patient is still on partial cardiopulmonary bypass.

The Early Postbypass Period In the first minutes after weaning from cardiopulmonary bypass, the physiology of the patient is changing dramatically. Much of this is under the control of the surgical team, the anesthesia team, and the perfusion team. Factors to be taken into consideration are the patient’s body temperature, which will impact myocardial contractility and peripheral resistance, the level of inotropic support, the level of afterload reduction, the patient’s hematocrit, and the filling status of the patient. Although a transfusion of 100 cm3 to a newborn would probably never be given over less than one minute in the intensive care unit, this is something that is quite routine in the operating room and can have a considerable impact on the patient’s physiology. If transfusion is being made purely from the reservoir of the heart and lung machine, there is not likely to be a drastic change in calcium level. On the other hand, if transfusion is being undertaken by the anesthesia team using citrated blood or blood products, then there will be major shifts in the calcium level that will also impact myocardial contractility. The bottom line is that the first 15 to 30 minutes after weaning from bypass is an extremely labile period which in no way is analogous to the stable status of the patient preoperatively or a few days postoperatively. There is also the ‘‘Heisenberg uncertainty principle’’ factor to take into consideration, namely, that in the neonate or small infant, even the smallest probes can affect the size of the left atrium, particularly if the probe is curved to achieve a different angle of insonation. The angle of insonation of course will also have an important impact on Doppler gradients that are being read.

The Role of Myocardial Ischemia When the aortic cross-clamp is applied intraoperatively, the heart is made totally ischemic. The surgical team will attempt to optimize the heart’s tolerance of myocardial ischemia by infusing a cardioplegia solution. This is generally a very cold solution with a high potassium level as well as numerous other constituents that vary from center to center. Cardioplegia infusion results in diastolic arrest of the myocardium. Retraction of the infant and neonatal myocardium will also have an impact on the contractility of the myocardium in the early postbypass period. When the aortic cross-clamp is released, the cardioplegia solution is washed out and the warm oxygenated blood rewarms the myocardium and begins to supply substrate once again. Electrical and mechanical activity are gradually restored over the next 15 to 30 minutes. The residual effects of the myocardial ischemic period will be experienced for at least the next 24 hours during which time thermodilution studies have documented a consistent fall in cardiac output that is often at its worst about 9 to 12 hours postoperatively. During the early reperfusion period, there may be an extended period of

asystole, there may be several episodes of ventricular fibrillation, and there are quite commonly periods of transient heart block. Rhythm abnormalities in the early post-bypass period can have an important impact on valve function, particularly the atrioventricular valves. The residual effects on contractility of the ischemic period may also impact the function of papillary muscles and result in a transient worsening of valvar regurgitation. This problem can be exacerbated if air emboli to the coronary arteries are experienced, which may be apparent to the surgical team if bubbles are actually seen in the coronary system or may be inferred from a focal reduction in contractility, ST changes, or arrhythmias.

Putting the Whole Picture Together The highly experienced surgical team is very familiar with the usual sequence of recovery of the myocardium from myocardial ischemia as well as the transition from full bypass to partial bypass to off bypass. In addition to information from echocardiography, the surgical team will be monitoring the patient’s filling pressures as well as the arterial blood pressure. Under some circumstances, they may also be monitoring pulmonary artery pressure in addition to right atrial and left atrial pressure. In effect, it is possible to have a complete real-time right heart and left heart catheterization, with catheters effectively measuring pressures in all chambers of the heart. Saturation data can also be obtained if there is concern regarding a potential residual septal defect. Atrial pressure tracings can be carefully examined in the context of the patient’s rhythm with information regarding the height of A waves and V waves in addition to the mean atrial pressure. In the same way that the preoperative diagnostic exercise must seek the best unifying solution for the various diagnostic tests that have been undertaken and will on occasion have to exclude data that are inconsistent with the majority, likewise transesophageal echocardiography data on occasion may be inconsistent with the catheterization data as well as the patient’s consistency with a usual pattern of recovery from myocardial ischemia and the off bypass transition. However under some circumstances, it is not so much the inconsistency of the echo data with other data as much as it is a judgment by the surgical team of ‘‘just how good a result can we achieve here.’’

Perfect Is the Enemy of Good One of the favorite aphorisms of the great pioneer congenital heart surgeon Dr John Kirklin was: ‘‘perfect is the enemy of good.’’ One of the most difficult judgments for the junior congenital heart surgeon and at times even for the senior congenital heart surgeon is ‘‘what will be the trade-off in terms of longer bypass time and longer myocardial ischemic time versus a potential improvement in the anatomical result of a second attempt at repair.’’ One of the reasons that neonatal and young infant surgery is so much more challenging for the surgical team is that tissues are fragile and the deleterious effects of bypass are less well tolerated in the neonate and young infant.

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World Journal for Pediatric and Congenital Heart Surgery 5(2)

Neonates are particularly susceptible to the increased vascular permeability that results from the whole-body inflammatory response to bypass that is still ubiquitous with all heart lung machines. The edematous bloated appearance of the newborn who has been on bypass for several hours is the inevitable response to an extended period of bypass, particularly if there has been an interim period off bypass with a poor physiological result. There is also a limit to the amount of myocardial ischemic time that can be tolerated back to back with a previous period of myocardial ischemia. The surgical team also has to factor in the degree of anatomical severity of the problem with which they were originally confronted. Unlike the classical descriptions of congenital cardiac anomalies and operative procedures to repair them, the reality is that there is an extremely wide spectrum of complexity and severity that does not fit into traditional descriptions in real life. The common atrioventricular (AV) valve of complete AV canal, for example, rarely falls exactly into the Rastelli classification of types A, B, and C. The surgical team may have to be quite creative as to how a valve reconstruction is undertaken. The patient with double outlet right ventricle and a ventricular septal defect that is not immediately subarterial may require a relatively long baffle pathway that will inevitably have turbulence and perhaps a Doppler gradient. Thus, the surgical team will be factoring in (1) how much myocardial ischemic team has already been consumed, (2) how much bypass time has been experienced, (3) just how complex was the initial anatomy, and (4) how well is the patient tolerating the combination of factors 1 through 3. There are times in which the judgment of the surgical team will be that although the result is suboptimal, it is well tolerated and it may be necessary to return on another day to tune up the result.

Communication in the Early Post-Bypass Period The first 15 to 30 minutes after weaning from cardiopulmonary bypass is an extremely busy time for the surgical team. Not only is a careful assessment being made of the patient’s recovery from myocardial ischemia and the deleterious effects of bypass including the status of the patient’s coagulation system but in addition there may be surgical hemostasis challenges that require suturing in a very inaccessible area. Hemostatic suturing may require considerable heart retraction and add further insult to the patient who is recovering from the myocardial ischemia of the cross-clamp period. It is difficult for the surgical team to admit it but yes, perhaps after five or six hours of surgery with no more than a few seconds of break, the surgical team is actually tired and not as sharp as they were five or six hours earlier. Nevertheless, the challenges of hemostasis still

lie ahead, perhaps for the next hour or two. With a lot to think about the surgical team may not be in a position to have an extended discussion with the echo team regarding all of the various points described earlier. Perhaps, it would be a preferable routine to allow the patient to stabilize for an hour or so and for hemostasis to be achieved and then at that point when there is greater stability to complete the transesophageal echocardiogram. However, this in some ways defeats the point of an intraoperative transesophageal echocardiogram in that if there is a completely unexpected and unacceptable anatomical finding then it should be dealt with before the protamine is given and hemostasis has been achieved. Thus, there is a challenge in obtaining good anatomical information at a time when the patient is in a very unstable and labile state. Experienced echocardiographers understand all of this but nevertheless they can still feel disrespected when their dire warnings of serious problems are disregarded and ‘‘give the protamine’’ is announced.

The Special Problem of the Junior Surgeon and the Senior Echocardiographer The difficulty encountered in communication between echocardiographer and surgeon is usually minimal when the surgeon is highly experienced and has a very good understanding of how a particular patient should be behaving after a period of myocardial ischemia and cardiopulmonary bypass. If the patient is behaving in a completely anticipated fashion and the numbers from the monitoring catheters are all reassuring and minimal inotropic support is required, it is likely that echo information will be reviewed but not necessarily acted upon. However, when the surgeon is quite junior and the echocardiographer is senior and experienced, there may be a tendency for the echocardiographer to ‘‘instruct’’ the surgeon that he must redo the procedure. This has led to a number of stories of conflicts in the operating room that have unfortunately led to either the echocardiographer or the surgeon leaving a program. Hopefully this opinion piece will help to reduce the tension by contributing to a better understanding on both sides of the ether screen about the challenges of assessing the early post-bypass patient. Declaration of Conflicting Interests The author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Funding The author(s) received no financial support for the research, authorship, and/or publication of this article.

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The politics of intraoperative transesophageal echocardiography.

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