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From the Department of Anaesthesia and Critical Care, Northern General Hospital, Sheffield, United Kingdom.
Address correspondence to Alison D. Parnell, MBBS, FRCA, Department of Anaesthesia and Critical Care, Northern General Hospital, Sheffield, UK. Address e-mail to draliparnell{at}yahoo.co.uk.
A 24-yr-old man was referred to our cardiothoracic surgical team with worsening dyspnea on exertion. He had a systolic murmur on auscultation of the precordium and a systemic arterial oxygen saturation of 96%. Preoperative transthoracic echocardiography revealed a double-chamber right ventricle (DCRV). DCRV is an uncommon congenital abnormality, characterized by division of the right ventricular (RV) cavity into proximal and distal chambers by an anomalous muscle bundle, and often results in right ventricular outflow tract (RVOT) obstruction.1 The diagnosis was confirmed by right ventriculography, and no evidence of intracardiac shunt was found at right heart catheterization.
The patient was scheduled for surgical correction. Comprehensive perioperative transesophageal echocardiography (TEE) was performed. On the RV inflow–outflow view (Fig. 1), a muscle bundle was seen separating the body of the RV proximally from a distinct infundibular chamber distally. On the upper esophageal aortic arch short axis view, color Doppler showed turbulent flow in the proximal chamber of the RV with flow convergence and a high velocity jet in the distal chamber. The pulmonary valve opened normally. Trivial aortic incompetence was also noted (Video clips 1 and 2; please see video clips available at www.anesthesia-analgesia.org).
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Before cardiopulmonary bypass, direct needle manometry demonstrated a peak-to-peak pressure gradient of 87 mm Hg between the proximal high pressure and distal low pressure chambers of the RV (Table 1).
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On opening the heart, the thick muscle bundle and hypertrophied muscle of the anterior free wall of the RV were excised. The RV was closed with a pericardial patch. After surgical correction, and before separation from bypass, TEE clearly demonstrated a perimembranous ventriculoseptal defect (VSD) communicating with the former proximal chamber of the RV. The aortic clamp was reapplied and the heart reopened. On direct inspection, a small defect was found measuring 5 mm in diameter. It was located just below the junction of the right coronary cusp and noncoronary cusp of the aortic valve. The lesion was repaired and the patient made an uneventful postoperative recovery.
DISCUSSION
DCRV is a well-recognized congenital abnormality, most cases being described in children. The obstructing muscle bundles are probably accentuated septoparietal trabeculations.2 There are different forms of DCRV, depending on the level and angle of the muscle bundle in the RV. In this patient, it was located near the RVOT and crossed from the anterior free wall of the RV to the septum. DCRV is strongly associated with other congenital abnormalities, particularly VSD, but also pulmonary valve stenosis, atrial septal defect, and double-outlet RV.3 The VSD was the only other abnormality found in this patient. TEE is superior to transthoracic echocardiography for diagnosis of DCRV.4
TEE is useful for the detection of VSDs both as an isolated anomaly and when part of more complex structural abnormalities. Larger defects will be apparent on two-dimensional echocardiography. TEE detection of a VSD using color Doppler requires blood flow across the defect. In turn, blood flow depends on the presence of a pressure gradient, be that left to right or right to left. In this patient, the RVOT obstruction had created high pressure in the proximal chamber of the RV (120 mm Hg), which was similar to the pressure in the left ventricle (109 mm Hg) and flow across the defect would have been minimal. Retrospective examination of the prebypass TEE images suggests the possibility of reversed low velocity color flow occurring through the VSD from right to left, although this is not obvious. We believe this is why the small defect was not detected preoperatively or on the prebypass TEE. Flow restriction across the defect due to the presence of the muscle bundle is a possible alternative explanation.
Surgical correction of the DCRV resulted in normalization of right heart pressures. Higher pressure in the left ventricle (103 mm Hg) and lower pressure in the RV (48 mm Hg) then allowed high velocity blood flow from left to right through the VSD. A peak pressure gradient of 40 mm Hg was detected on continuous wave Doppler across the defect coincident with a systemic systolic pressure of 80 mm Hg. The possibility of the inadvertent, iatrogenic creation of a VSD during surgery also has to be considered. We feel this is unlikely, as when the heart was reopened and the VSD confirmed it was remote from the resection site and was smooth-walled and fibrosed, none of which suggest a surgically created interventricular communication. The strong association of VSD with DCRV is a further argument against this possibility.
Small interventricular communications, although hemodynamically insignificant, are not necessarily benign.5 In long-term follow-up during adult life, serious complications, particularly infectious endocarditis, occur in 25% of patients. To have missed this lesion would therefore have been unfortunate.
This case highlights that, in general, when using TEE for corrective adult congenital heart disease great care must be taken to search for and exclude associated congenital lesions. Specifically, given the strong association of VSD with DCRV, the absence of a VSD should be considered the exception rather than the norm in this condition.
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Footnotes
Accepted for publication December 18, 2007.
Reprints will not be available from the author.
This article has supplementary material on the Web site: www.anesthesia-analgesia.org.
REFERENCES
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