The Use of Transesophageal Echocardiography for Differential Diagnosis of Poor Venous Return During Cardiopulmonary Bypass

Optimal Position of Inferior Vena Cava Cannula in Pediatric Cardiac Surgery: A Prospective, Randomized, Controlled, Double-Blind Study

OBJECTIVE

To examine the authors' hypothesis that during the cardiopulmonary bypass (CPB) in children, the inferior vena cava cannula tip placed proximal to the right hepatic vein orifice would produce a higher venous drainage compared with that placed distally.

DESIGN

A prospective, randomized, controlled, double-blind study.

SETTING

Single university hospital.

PARTICIPANTS

Thirty-two patients aged <6years, scheduled for elective cardiac surgery using CPB for congenital heart disease.

INTERVENTIONS

Participants were randomized to 2 groups: the proximal group with the cannula tip placed proximally within 1cm of the right hepatic vein orifice and the distal group with the cannula placed distally within 1cm of the right hepatic vein orifice.

MEASUREMENTS AND MAIN RESULTS

The primary outcome of this study was the perfusion flow rate at the time of establishment of total CPB with cardioplegia. The authors initially planned to enroll 60 patients, but before reaching the target sample size, the authors terminated this study owing to patient safety, and 18 patients in the proximal group and 14 patients in the distal group finally were analyzed. No significant differences in patient characteristics were observed between the 2 groups. The mean perfusion flow rate in the proximal group was significantly greater (2.55 ± 0.27 L/min/m²) than that in the distal group (2.37 ± 0.20 L/min/m², p = 0.04).

CONCLUSION

The inferior vena cava cannula tip placed in the proximal position was clinically superior, compared with a distal placement, in producing higher perfusion flow in children.

Evaluation of different types of inferior vena cava cannulae placement by transesophageal echocardiography and its impact on hepatic dysfunction

BACKGROUND

Postoperative hepatic dysfunction may occur in an otherwise uncomplicated open heart surgery. One of the reasons is malpositioning of the inferior vena cava (IVC) cannula in the hepatic vein (HV) or beyond. A straight cannula is considered more likely to be malpositioned compared to the angled cannula and a malpositioned cannula can lead to hepatic dysfunction.

METHODS

In this prospective study, forty adult patients undergoing atrial septal defect repair were randomized into two groups as: straight cannula group (n=20) and angled cannula group (n=20). The cannula position was assessed by transesophageal echocardiography (TEE) (hepatic vein view). Alanine aminotransferase levels (ALT) and bilirubin levels were measured immediately, at 6 hours and on day 1, day 2 and day 7 after surgery as a marker of hepatic injury.

RESULTS

TEE localization of the IVC cannula was achieved in all patients except one. Visualization was good in 85% of patients. A cannula in the HV or beyond the HV in the IVC was considered malpositioned. The number of cases of cannula malposition was 10 (50%) and 4 (20%) in the straight and angled cannula groups, respectively. The pattern of change in serum bilirubin and liver enzymes levels in the postoperative period was similar in both the groups (p>0.05). The mean distance between the right atrium (RA) - inferior vena cava (IVC) junction to the hepatic vein was 1.94±0.56 cm and the mean diameters of the IVC and HV were 1.95±0.5 and 1.31±0.33 cm, respectively.

CONCLUSION

TEE can be used to monitor IVC cannula position. A higher frequency of cannula malposition was observed with the straight cannula compared to the angled cannula, but was not found to be associated with hepatic dysfunction.

Spontaneous ear hemorrhage during cardiac surgery

A 79-year-old patient who underwent mitral valve replacement experienced prolonged elevated central venous pressure associated with poor venous return during a cardiopulmonary bypass. After the procedure, the patient was noted to have spontaneous bleeding from the left ear. Otolaryngologic examination in the operating room showed no trauma in the exterior auditory canal and suggested that the hemorrhage was related to a superior vena cava syndrome and anticoagulation during the cardiopulmonary bypass. Determinants and management considerations of poor venous return, including maintenance of cerebral perfusion pressure, are discussed.