Intraoperative two-dimensional echocardiography: new application of an old technique

A Modification of the Trans-Oesophageal Echocardiography Protocol can Reduce Post-Operative Dysphagia following Cardiac Surgery

Use of intra-operative trans-oesophageal echocardiography (TEE) is an independent risk factor for post-operative dysphagia. This study investigated whether modifying the TEE probe-placement protocol could reduce the incidence of post-operative dysphagia. In group I ( n = 100), the TEE probe was inserted after anaesthetic induction and remained in place until the completion of surgery. In group II ( n = 100), the TEE probe was inserted after anaesthetic induction, the heart was examined, then the probe was removed. The probe was inserted again before weaning from cardiopulmonary bypass and then immediately removed after examination. The incidence of dysphagia was significantly higher in group I than in group II patients (51.1% versus 28.6%). Multivariate regression analysis showed that the length of time that the TEE probe was in the oesophagus was an independent predictor of dysphagia. Modification of the TEE protocol in this way can reduce the incidence of post-operative dysphagia in cardiac surgery patients.

Continuous transoesophageal echocardiography monitoring during weaning from cardiopulmonary bypass in children

The purpose of this study was to evaluate the effectiveness of transoesophageal echocardiography monitoring during weaning from cardiopulmonary bypass after intracardiac repair in children. The left ventricular ejection fraction, left ventricular end-diastolic volume and left ventricle wall motion were monitored continuously by transoesophageal echocardiography in controls weaned easily from cardiopulmonary bypass (group A, n = 25), and those weaned with difficulty from cardiopulmonary bypass after mechanically assisted circulation (group B, n = 16). In group A, left ventricular ejection fraction and left ventricle wall motion were within normal range, and did not change significantly during weaning after cardiopulmonary bypass when compared with pre-bypass data. In contrast, left ventricular ejection fraction, left ventricular end-diastolic volume and left ventricle wall motion in group B during the first trial of weaning from bypass were significantly worsened. Hence, assisted circulation was performed until the data obtained via transoesophageal echocardiography improved with regard to maintenance of fluid balance, catecholamine dosage and assisted pump flow. All cases in group B were weaned safely from cardiopulmonary bypass despite their critical condition. In conclusion, continuous transoesophageal echocardiography monitoring may be a useful tool in children with severe heart failure for safe weaning from cardiopulmonary bypass after intracardiac repair.

Intraoperative prosthetic valve dysfunction: detection by transesophageal echocardiography

We describe the valuable role of intraoperative transesophageal echocardiography in the detection of immediate prosthetic valve dysfunction. Transesophageal echocardiography accurately diagnosed one leaflet of a St. Jude Medical mitral valve to be stuck. We recommend routine transesophageal echocardiography for mitral valve operations.

Benefits of intraoperative echocardiography in the surgical management of hypertrophic cardiomyopathy

OBJECTIVES

The purpose of this study was to determine the role of intraoperative echocardiography in planning the site and extent of myectomy and in ensuring adequate control of the left ventricular outflow tract gradient.

BACKGROUND

Although intraoperative echocardiography has been found to be beneficial in patients undergoing valve repair, its impact on surgical decisions in patients undergoing septal myectomy for hypertrophic cardiomyopathy has not been described.

METHODS

In 50 patients undergoing septal myectomy over a 5-year period, epicardial echocardiography was performed before cardiopulmonary bypass to establish the extent of outflow tract obstruction, locate its site and plan the myectomy. In 30 patients, transesophageal echocardiography was also used to corroborate data on outflow tract anatomy and examine the mitral valve.

RESULTS

In 40 patients (80%) the initial myectomy resulted in a reduction of the maximal outflow tract gradient from 88 +/- 45 to 24 +/- 11 mm Hg, measured by epicardial continuous wave Doppler echocardiography. Ten patients (20%) were shown by postbypass intraoperative echocardiography to have an unsatisfactory result, based on a persistent gradient > 50 mm Hg (n = 7) or persistent mitral regurgitation of greater than moderate severity (n = 3). The postbypass two-dimensional echocardiogram was then used to direct the surgeon toward the most likely site of continued obstruction, and cardiopulmonary bypass was reinstituted to permit further myectomy (n = 9) or mitral valve repair (n = 1). After the second or subsequent period of cardiopulmonary bypass, the outflow tract gradient (26 +/- 14 mm Hg) was substantially reduced and was not significantly different from the postbypass gradient (24 +/- 11 mm Hg) in the group with initial surgical success. At postoperative follow-up (20 +/- 37 weeks), the maximal measured outflow tract gradient (22 +/- 21 mm Hg) showed no difference between patients with immediate surgical success and those requiring a second period of cardiopulmonary bypass for further resection.

CONCLUSIONS

Intraoperative echocardiography proved a useful tool to guide the site and extent of septal myectomy, leading to more adequate surgical resection and to persistence of satisfactory control of the outflow tract obstruction into the early follow-up period.

Effects of prolonged transesophageal echocardiographic imaging and probe manipulation on the esophagus--an echocardiographic-pathologic study

Transesophageal echocardiography is being increasingly utilized in the operating room and intensive care and ambulatory settings. However, to date no data are available concerning possible trauma of the transesophageal echocardiographic technique to the esophagus due to probe insertion, manipulation or direct ultrasound energy transmission. To test the hypothesis that transesophageal manipulations caused no traumatic or thermal injury to the esophageal mucosa, 12 animals were studied with continuous transesophageal echocardiography for a period of variable duration (mean 4.6 h +/- 51 min). The study group consisted of four monkeys (mean weight 5.7 +/- 0.6 kg and eight mongrel dogs (mean weight 29.8 +/- 1.4 kg). The eight dogs were studied during right heart bypass with full heparinization for 6.6 +/- 0.2 h, whereas the four monkeys were studied for 60 to 90 min in the absence of cardiopulmonary bypass and anticoagulation. Immediately after completion of transesophageal echocardiography in each case, the esophagus was entirely excised. Detailed macroscopic and microscopic examination of the esophagus revealed no significant mucosal or thermal injury. This preliminary animal study suggests that transesophageal echocardiography is safe for the esophageal mucosa in animals as small as 5 kg in weight, despite prolonged use and in the presence of systemic anticoagulation.

Intraoperative epicardial echocardiography: early experience with a newly developed small surgical transducer

To test the feasibility of performing intraoperative echocardiography with a specially designed epicardial transducer, 20 adult patients were studied. All patients were undergoing coronary bypass surgery and had structurally normal intracardiac anatomy. The surgical transducer has 48 elements and a size at the tip of 10 x 12 x 5 mm. The scan plane has been set at 90 degrees to the cable axis to allow scanning from lateral positions. The terminal 10 cm of the cable has been reinforced to act as a malleable and steerable handle. Good quality images were obtained with the new transducer, and many different imaging planes were identified compared to imaging with the standard transducers. These include the right ventricular apex, the right and left lateral aspects of the heart, the aortic arch, and the pulmonary artery and its branches. The limitation of the probe was the difficulty in obtaining left ventricular apical views because of ventricular arrhythmias sustained when the transducer was placed between the left ventricular apex and the diaphragm. We conclude that this new transducer has a promising future in the application of intraoperative epicardial echocardiography.

Surgery for Ebstein's anomaly: the clinical and echocardiographic evaluation of a new technique

Ten consecutive patients (age range 4 to 44 years, mean 22) underwent surgical repair of Ebstein's anomaly by vertical plication of the right ventricle and reimplantation of the tricuspid valve leaflets. No patient died during or after operation. Intraoperative postbypass echocardiography documented a good result in nine patients but severe tricuspid regurgitation in one patient, who then underwent prosthetic valve replacement during a second period of cardiopulmonary bypass. Two of four patients who had had right ventricular papillary muscle dysfunction in the early postoperative period showed improved papillary muscle function with concomitant reduction of tricuspid regurgitation 6 months later. All patients were evaluated clinically and by echocardiography 2 to 23 months later. All patients showed clinical improvement, seven by one functional class and three by two classes. All were in sinus rhythm. The mean cardiothoracic ratio decreased by 6% (p less than 0.05). On bicycle ergometry performed in six patients, peak oxygen consumption exceeded 20 ml/kg per min in five. Tricuspid regurgitation diminished in eight patients (by three grades in two patients, by two grades in five and by one grade in one patient); it remained unchanged in two. Comparison of preoperative and postoperative pulsed Doppler flow velocities across the pulmonary valve showed an increase in the peak velocity of flow across the valve (mean 83 +/- 14 versus 97 +/- 11 cm/s, p less than 0.005) and a decrease in the time to peak velocity (mean 130 +/- 16 versus 91 +/- 23 ms, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Value of transesophageal echocardiography during repair of congenital heart defects

Two-dimensional transesophageal color Doppler echocardiography was employed intraoperatively in 30 children undergoing repair of a variety of simple and complex cardiac malformations. There were 16 female and 14 male patients, with a mean age of 9 +/- 3 years (range, 4 to 13 years) and a mean weight of 31 +/- 9 kg (range, 16 to 50 kg), 16 children weighing less than 30 kg. A standard, commercially available transesophageal echocardiography probe (5 MHz, 64 elements) was used in all patients without complications. Transesophageal echocardiography proved helpful in selecting the surgical approach, in assessing the adequacy of surgical repair, in detecting residual intracardiac shunts, and in allowing uninterrupted monitoring of ventricular performance throughout the procedure. Our initial experience suggests that transesophageal echocardiography is a valuable tool to be used in children with congenital cardiac malformations, particularly in those requiring complex intracardiac procedures. The amount of information obtained by the surgeon should favor the routine use of transesophageal echocardiography during open heart procedures and stimulate the development of probes to be safely used even in infants and newborns.

Intraoperative epicardial echocardiography: technique and imaging planes

With the recent innovations in cardiac surgical techniques, there is need for an immediate and reliable way to assess results in the operating room. Intraoperative epicardial echocardiography with Doppler color flow mapping provides an accurate and rapid imaging modality to assess the anatomical and functional results of cardiac surgery. This gives the surgeon a way to determine whether the hemodynamic abnormality has been successfully eliminated, prior to closure of the chest. After enclosure in a sterile sheath, a standard echocardiographic transducer is placed directly onto the epicardial surface. The heart is imaged in multiple tomographic planes developed specifically for intraoperative use: the parasternal equivalent; aortopulmonary sulcus; subcostal equivalent; and aorta-superior vena cava transducer positions. Two-dimensional echocardiography is useful to assess the morphology of valves and the size and function of cardiac chambers. Doppler color flow mapping provides a semi-quantitative assessment of the severity and physiological mechanism of valvular regurgitation. Continuous-wave Doppler echocardiography is used to estimate gradients across stenotic valves. This comprehensive appraisal of cardiac anatomy and flow is useful in the pre- or postcardiopulmonary bypass phase of cardiac surgery. This review focuses on the technique of intraoperative echocardiography and its applications in valve reconstruction operations with specific emphasis on the epicardial imaging planes.

Intraoperative evaluation of valvular regurgitation: comparison of echocardiographic techniques

Intraoperative echocardiography provides information on cardiac structure and function that is unobtainable from routine monitoring modalities. Intraoperative imaging can be performed from the epicardial and/or transesophageal approach, and with the addition of contrast and/or color flow Doppler mapping, blood flow characteristics within the cardiac chambers can be visualized. The relative severity of regurgitation can be assessed before and after valvular surgery, and before the patient leaves the operating room, thereby facilitating successful valve repair or replacement. Surgeon preference, equipment availability, and valvular pathology will determine which technique will be utilized.

Intraoperative Doppler color flow mapping for decision-making in valve repair for mitral regurgitation. Technique and results in 100 patients

Mitral valve repair provides substantial advantages over mitral valve replacement in patients with severe mitral regurgitation. However, because of the possibility of persistent regurgitation, an intraoperative technique is needed to provide an immediate and accurate assessment of the adequacy of the repair before closure of the chest. One hundred patients with pure mitral regurgitation were studied with intraoperative epicardial Doppler color flow mapping immediately before and after valve repair. Intraoperative assessment of the severity of mitral regurgitation showed good agreement with preoperative left ventriculography and with standard precordial Doppler echocardiography before and after surgery. Postrepair intraoperative Doppler studies showed satisfactory surgical results in 92 patients. Postrepair intraoperative Doppler studies in the remaining eight patients demonstrated unsatisfactory results: persistent significant regurgitation in four, systolic anterior motion of the mitral valve with dynamic left ventricular outflow tract obstruction in three, and a persistent flail leaflet in one. In six of the eight patients, further surgery was performed during the same thoracotomy. In two patients, the intraoperative postrepair Doppler findings of persistent regurgitation were confirmed on precordial Doppler studies within 5 days, and mitral reoperation was required. Intraoperative epicardial Doppler color flow mapping provided a "safety net" that ensured a successful outcome in all 100 patients by providing the surgeon with a direct means to assess the success of the operation and the need for further surgery.

The use of intraoperative echo with Doppler color flow imaging to predict outcome after repair of congenital cardiac defects

Surgical repair of congenital cardiac defects (CCD) has undergone a remarkable evolution in the past decade. Major defects are now often completely corrected in early infancy with continually improving rates of survival. It has become clear that the next major focus will be improvements in the long-term quality of life and this has promoted many innovations in surgical technique and approach. One advance is the use of intraoperative echo with Doppler color flow imaging (echo-DCFI) to evaluate the exactness of operative repair. Aside from anecdotal reports, very little information is available regarding the interpretation of images produced by this technology in the operating room. Furthermore there have been no studies addressing the predictive value of intraoperative echo-DCFI findings with respect to outcome for patients undergoing repair of CCD. The prospective data obtained by following the course of 273 patients receiving intraoperative echo-DCFI has been reviewed after repair of a variety of CCD (age range, 1 to 53 years; mean 5.3 years; smallest patient, 1.8 kg). Forty-seven patients (17%) had initially unacceptable results, by echo, at the completion of their repair. Eighteen of these patients (7% of entire series) had no clinical problems and the defects were discernible only by echo. Twenty-six patients with initially unacceptable results had their repairs revised in the operating room and left with an acceptable result by echo. Twenty-one patients were allowed to leave the operating room with echo-discernible defects. Follow-up of these patients demonstrated a significantly higher (p less than 0.006) rate of reoperation (42% vs. 3%) and of early death (29% vs. 10%) for those patients whose defects were left unrepaired compared to those whose problems were corrected before leaving the operating room. Sixty-eight patients (25%) had some alteration of ventricular function (compared to their prebypass evaluation) at the completion of their repair. Regardless of whether the dysfunction was limited to the right ventricle, left ventricle, or was biventricular, patients in this group had a significantly higher incidence (p less than 0.004) of early, but not late, death compared to patients without alteration of ventricular function (35% vs. 4%). Patients who left the operating room with no problems of concern by echo-DCFI had a greater than 90% likelihood of a long-term acceptable outcome compared to patients who had any problem of concern (residual defect, anatomic or technical imperfection, ventricular dysfunction, and so on) whose long-term likelihood of an acceptable outcome approached 50% (p less than 0.0125).(ABSTRACT TRUNCATED AT 400 WORDS)

Quantifying changes in regional myocardial perfusion with aortic contrast echocardiography

We developed a technique to assess regional myocardial perfusion by quantifying echocardiographic myocardial contrast appearance and intensity after aortic root injection of an agitated diatrizoate meglumine solution. The technique was validated by comparing digitized echocardiographic contrast parameters to regional perfusion in the circumflex bed determined by calibrated Doppler flow probe and antemortem monastral blue staining. Regional perfusion was altered by circumflex stenosis, occlusion, and reactive hyperemia. Contrast effects were measured in an initial subset of six dogs by peak intensity change, time to peak intensity, maximal rate of intensity rise, and mean intensity change integrated over 1, 2, or 3 seconds after contrast appearance (MI1, MI2, MI3). MI2 and MI3 best predicted regional perfusion (r = 0.93, standard error of the estimate [SEE] 0.38 ml/gm/min for each). These findings were confirmed in a second subset of six dogs (r = 0.84, SEE = 0.70 ml/gm/min). Although there was a relatively broad standard error for the prediction of absolute perfusion for the pooled data, for individual dogs data were internally consistent so that each had r greater than 0.88 for its varied flow states. The hyperemic ratio calculated by contrast echocardiography correlated well with the Doppler value (r = 0.85). Observer and study-to-study predictive variabilities were small (SEE 0.19 to 0.32 ml/gm/min). No alterations were seen in hemodynamics or reactive hyperemia after 25 consecutive injections over a 90-minute period. Contrast echocardiography with aortic root contrast injection tracks changes in regional blood flow. This approach can assess regional coronary reserve and detect changes in regional myocardial perfusion during acute ischemia and drug intervention.

Intraoperative two-dimensional echocardiography in congenital heart disease

Intraoperative epicardial two-dimensional echocardiography was used in 195 patients undergoing surgery for congenital heart disease to evaluate its potential to identify new diagnostic information immediately before and after surgical correction. In 168 patients the preoperative diagnosis was confirmed by intraoperative echocardiography. In four patients, unsuspected findings were revealed, which resulted in modification of the surgical approach. In 18 patients additional morphologic information was obtained which contributed to alteration or refinement of surgical management. The adequacy of cardiac repair was assessed before closure of the chest in all patients. In six patients this information led to immediate reoperation and in four other patients to inotropic drug therapy. During congenital heart surgery, epicardial two-dimensional echocardiography may yield important information for surgical management. The technique is an essential adjunct when preoperative diagnostic studies are not conclusive or when the initial response to repair is unsatisfactory.

Assessment of successful valve reconstruction by intraoperative transesophageal echocardiography (TEE)

In 17 patients (10 patients with mitral insufficiency, 5 patients with tricuspid regurgitation, 2 patients with mitral stenosis) the result of valve reconstruction was evaluated by intraoperative two-dimensional transesophageal contrast-echocardiography (TEE). Therefore, 1-2cc of an agitated contrast-medium (Gelifundol) were injected into the left or right ventricle. The result of reconstruction was assessed by the extent of regurgitant microbubbles into the left or right atrium. A successful valve repair could be demonstrated in 15 patients without or with only minimal regurgitation of contrast-fluid. In one patient residual severe mitral insufficiency after valve reconstruction could only be detected when valve function was examined by contrast-TEE in the beating heart. An intraoperative decision for valve replacement was made. In another patient, mild to moderate residual mitral incompetence was shown; no further surgical intervention was done. By TEE the function of reconstructed valves can be examined under physiological conditions in the beating heart. Surgeons can obtain additional intra-operatively information and certainty about the result of reconstruction and an early decision for valve replacement can be made if necessary.