Ann Thorac Surg CORRESPONDENCE 1275 1995;59:1272-8

cant decreases in tT 4 levels, although in only 1 patient did the level fall below the normal range. The changes in serum thyroid- stimulating hormone levels are diverse and imply that different factors may be responsible for these changes.

The exact mechanism for the decrease in fT 4 levels also is not clear, but may be related to the release of cytokines as a result of operation. It is known that serum interleukin-6 levels peak postoperatively [1], and this cytokine is known to suppress thyroid function as well as to affect the release of many other hormones [2].

T. Hugh Jones, MD Steven M. Hunter, MD Alun Price, MSc Gianni D. Angelini, MD

Departments of Medicine, Cardiothoracic Surgery, and Clinical Chemistry Northern General Hospital Clinical Sciences Centre Herries Rd Sheffield $5 7AU England

References

1. Butler J, Chong GD, Baigrie RJ, et al. Cytokine responses to cardiopulmonary bypass with membrane and bubble oxygen- ation. Ann Thorac Surg 1992;53:833-8.

2. Jones TH. Interleukin-6 an endocrine cytokine. Clin Endocri- nol 1994;40:703-13.

U l t r a s o u n d of In fe r io r Epigas t r ic Ar te ry To the Editor:

Color-flow Doppler ultrasound evaluation of the inferior epigas- tric artery (IEA) has been assessed very thoroughly by Petros- sian and associates [1] with respect to location, length, internal

diameters, and presence or absence of atherosclerosis in the vessel. Not mentioned in the article is the importance of ultra- sound for determination of the flow pattern of the IEA. We report a 40-year-old male patient who underwent coronary artery bypass grafting using bilateral internal mammary arteries and the left IEA [2]. It was noted preoperatively that he had absent femoral pulses. Immediately after operation acute bilat- eral lower limb ischemia developed. There had been no postop- erative hypotension and no use of vasoconstrictive drugs. A translumbar aortogram demonstrated an occlusion of the infra- renal aorta extending to both common iliac bifurcations. This necessitated an aorto-bifemoral bypass graft.

In its vertical course along the abdominal wall, the IEA anastomoses with the superior epigastric artery, which is a terminal branch of the internal mammary artery. The normal flow pattern is caudad to cephalad. With a significant obstruc- tion of the iliac artery the lEA may become a major collateral channel and a reversal of flow then occurs (Fig 1A). Interruption of this collateral pathway in our patient caused an acute exac- erbation of lower extremity ischemia requiring an inflow proce- dure (Fig 1B).

The IEA is imaged easily by color Doppler ultrasound, and assessment of its flow pattern has been used as a screening test for aortoiliac obstruction [3]. In patients with absent femoral pulses color-flow Doppler ultrasound should be used for deter- mination of the direction of flow in the IEA before use of this artery or the internal mammary artery for coronary revascular- ization.

Michael J. Tolan, FRCS(I) Andrew J. Parry, FRCS Stephen Langley, FRCS Stephen IL Large, FRCS

Department of Cardiothoracic Surgery Papworth Hospital Cambridge, United Kingdom

Inferior epigastr ic a.

Internal mammary a.

A B

/ -~ ~\

Fig 1. (A) Collateral circulation via epigastn'c and internal mammary arteries in obstruction of the lower abdominal aorta. (B) Aorto-bifemoral graft after interruption of the collateral circulation.

© 1995 by The Society of Thoracic Surgeons 0003-4975/95/$9.50

1276 CORRESPONDENCE Ann Thorac Surg 1995;59:1272-8

References

1. Petrossian E, Menegus MA, Issenberg HJ, Brodman RF. Ultrasound evaluation of the inferior epigastric artery. Ann Thorac Surg 1994;57:895-8.

2. Mills NL, Everson CT. Technique for use of inferior epigastric artery as a coronary bypass graft. Ann Thorac Surg 1991;51: 208 -14.

3. Kwaan JHM, Connolly JE. Doppler assessment of the inferior epigastric artery flow as a screening test for aortoiliac obstruc- tion. Am J Surg 1979;137:250-1.

Reply To the Editor:

We appreciate the opportunity to respond to the important observation of Dr Tolan and his associates. We too are aware of the potential complication of lower extremity ischemia occurring in the circumstances they noted. We also are familiar with the study by Kwaan and Connolly reporting the use of Doppler assessment of the IEA as a screening test for aortoiliac obstruc- tion. It is apparent from Tolan and associates' case that the IEA system is capable of providing a good deal of collateral blood flow. Although we did not identify flow reversal in any of the subjects in our study, we agree that color Doppler ul t rasound is a useful technique for identifying patients at risk for ischemic complications when harvesting of the IEA is p lanned in patients with absent or diminished femoral pulses.

Edwin Petrossian, MD Richard F. Brodman, MD

Department of Cardiothoracic Surgery MonteJi"ore Medical Center 111 E 210th St Bronx, IVY 10467

/

A B C

Fig 1. Unsah'sfactory aortotomy and shape of the patch (A, B) in relation to the missing jigsaw puzzle piece (C).

to be extended onto the outer edge of the root of the subclavian artery.

A tubular polytetrafluoroethylene (Gore-Tex; W. L. Gore & Assoe) graft is compressed anteroposteriorly, and a piece con- forming to the missing JSPP is cut out. This piece has an anterior and posterior flap with a good convex outer edge. (A folded Gore-Tex patch can be used but does not provide a good convex edge).

The patch will vary in size and shape in each case. The middle of the posterior flap is sutured to the middle of the posterior lip of aortotomy, and the suture is carried upward and downward to the limit of the aortotomy. The anterior flap then is sutured to the anterior lip of the aortotomy (Fig 4).

I have observed that with this technique the final contour is like that of a normal aorta, avoiding eddies that could promote late aneurysm formation. The closer the final contour is to the normal aorta, the closer to normal would be the hemodynamics.

Patch Aortoplasty for Coarctation of Aorta: Technical Considerations To the Editor:

May I respond (uninvited) to Dr Moulton's call for innovations or "tricks" found useful for repair of coarctation of the aorta [1]?

Patch aortoplasty continues to evoke controversy regarding its efficacy and safety [2]. Doctor Ungerleider [2] lays stress on the use of a large generous piece of prosthetic material that extends well above and below the narrowed area of aorta. He recom- mends the patch should be usually "one and one half times the diameter of the descending aorta" (one wonders on what basis), which will eliminate any gradient and result in a good hemody- namic result and be less likely to lead to late aneurysm forma- tion. Doctor Moulton [3] is not convinced about this claim.

Dissatisfaction with patch aortoplasty may be related to the choice of aortotomy and size and shape of the patch (Fig 1A, B) usually adopted [4, 5]. What needs to be restored is the missing jigsaw puzzle piece (JSPP) (Fig 1C). I have found the missing JSPP concept useful in performing patch aortoplasty.. This JSPP will vary in size and shape (Fig 2). Of course, a kink, if any on the inner aspect, must be corrected by dividing a taut l igamentum or ductus.

To restore this missing JSPP, the aortotomy must be made on the outer convexity of the aorta (Fig 3). The aortotomy may need

Fig 2. Varying sizes and shapes of jigsaw puzzle pieces missing in the outer aspect of aorta are illustrated.

© 1995 by The Society of Thoracic Surgeons 0003-4975195/$9.50