Internal Mammary Artery

Noninvasive functional assessment of left internal mammary artery grafts by transcutaneous Doppler echocardiography.
Rombaut E; Vantrimpont P; Gurne O; Chenu P; Schroeder E; Buche M; Louagie Y; Eucher P; Marchandise B.
J Am Soc Echocardiogr 1998 May;11(5):403-8

A noninvasive method to assess left internal mammary artery (LIMA) patency and function would be useful because this vessel is frequently used for revascularization of the left anterior descending coronary artery. The purpose of this study was to assess the feasibility of measuring changes in LIMA velocities by transcutaneous Doppler during dipyridamole-induced vasodilation. Twenty-five patients with a LIMA graft anastomosed to the left anterior descending coronary artery were studied at least 1 month a fter surgery by the use of a 5 MHz transducer placed in the left supraclavicular fossa. Doppler velocity parameters were measured at baseline and after intravenous administration of dipyridamole. Dipyridamole increased mean velocity by 127% +/- 54% (p <0.001), systolodiastolic velocity time integral by 89% +/- 31% (p0.001), and diastolic-to-systolic peak velocity ration from 0.7 +/- to 1.2 +- 0.4 (p <0.001). The dipyridamole-to-baseline mean velocity ration was 2.3 +/- 0.5. We conclude that it is possible to measure dipyridamole-induced changes in LIMA blood velocity reserve by transcutaneous Doppler echocardiography.

Internal mammary artery: 100% visualization with new ultrasound technology.
Ehrsam JE; Spittell PC; Seward JB
J Am Soc Echocardiogr 1998 Jan;11(1):10-2

We report our experience in visualizing the internal mammary artery (IMA) with new enhanced Doppler technology. Twenty-three patients without previous coronary artery bypass grafting formed the study group. Bilateral transthoracic two-dimensional and c olor flow Doppler IMA images were acquired from multiple intercostal spaces with a prototype ultrasound machine equipped with coherent beam formation technology. In all patients, the IMA was followed from its origin for an average of 15 cm. To our kn owledge, a high rate of direct visualization (100%) of the IMA has not been reported previously. Noninvasive ultrasound assessment of the IMA may reduce the need for invasive preoperative testing for patency and length and allow postoperative assessment of coronary artery flow reserve.

Noninvasive assessment of left internal mammary artery graft patency using transthoracic echocardiography
Crowley JJ; Shapiro LM
Circulation 1995 Nov 1;92 (9 Suppl):II25-30

BACKGROUND: Cardiac catheterization is the only practical method of assessing internal mammary artery graft patency. A noninvasive method would be useful in patients with recurrence of anginal symptoms after coronary artery bypass graft surgery. We h ypothesized that transthoracic echocardiography could provide information on blood velocity and anatomy and therefore has the potential to allow measurement of blood flow. METHODS AND RESULTS: High-frequency (5 MHz) transthoracic echocardiography was pe rformed on 41 consecutive patients (mean age, 67 +/- 6 years) who had had left internal mammary artery grafts to the left anterior descending coronary artery (LAD and were undergoing coronary angiography because of recurrence of anginal symptoms. The re sults were compared with those from 19 patients (mean age, 58 +/- 11 years) in whom an ungrafted left internal mammary artery was assessed and with those from 15 patients (mean age, 61 +/- 12 years) who had angiographically normal coronary arteries in who m the LAD was studied. Doppler velocity profiles of the left internal mammary graft were obtained in 35 of the 41 study patients (81%). In all cases, a biphasic pattern of blood flow was recorded that corresponded to systole and diastole. Two differ ent flow patterns were observed. In 25 patients with a normal graft or moderate (<70%) stenosis (group A), blood flow velocity was maximal during diastole. This pattern was also seen in the LAD control group. In 10 patients with severe (>70%) graft s tenosis (group B), blood velocity was maximal during systole, and low velocities were recorded during diastole. This pattern was also seen in the ungrafted internal mammary artery control group. The diastolic fraction of the velocity time integrals f or group A was 0.77 +/- 0.07 and for group B was 0.27 +/- 0.01 (P <. 05). A diastolic velocity time integral fraction < predicted severe stenosis with a sensitivity and specificity of 100%. The ratio of systolic-to-diastolic peak velocities for group was 0.54 +/- 0.26 and for group B was 3.45 +/- 0.74 (P <.05). A systolic-to-diastolic peak velocity ratio > 1 predicted severe stenosis with a sensitivity of 100% and specificity of 85%. Mean graft blood flow was 63 +/- 21 mL/min. There was no sign ificant difference in mean blood flow between any of the patient groups studied. CONCLUSION: High-frequency transthoracic echocardiography allows identification of the left internal mammary grafts and measurement of blood flow. Compared with patent gr afts or those with moderate lesions, severe stenoses demonstrated different Doppler velocity patterns. Use of this technique may allow noninvasive detection of significant stenoses of the left internal mammary artery graft.

Noninvasive assessment of left internal mammary artery graft patency using duplex Doppler echocardiography from supraclavicular fossa.
Takagi T; Yoshikawa J; Yosida K; Akasaka T.
J Am Coll Cardiol 1993 Nov 15;22(6):1647-52

OBJECTIVES: The purpose of this study was to clarify the usefulness of duplex Doppler echocardiography from the supraclavicular fossa for assessment of left internal mammary artery graft patency. BACKGROUND: A noninvasive method to assess coronary ar tery bypass graft patency would be useful for assess coronary artery bypass graft patency would be useful for clinical diagnosis and long-term follow-up of graft outcome. METHODS: Duplex Doppler echocardiography from the supraclavicular fossa was perfo rmed in 56 consecutive patients who underwent postoperative cardiac catheterization studies, including quantitative angiography. All patients underwent coronary artery bypass graft surgery using the left internal mammary artery graft to the left anterio r descending coronary artery. RESULTS: The left internal mammary artery graft and its flow were detected in 55 (98%) of the 56 patients with duplex Doppler echocardiography from the supraclavicular fossa. According to the quantitative angiographic data, the patients were assigned to three groups: group A (36 patients) with a normal left internal mammary artery graft (<50% diameter stenosis), group B (9 patients) with intermediate (50% to 75% diameter) graft stenosis and group C (10 patients) with seve re (> 75% diameter) graft stenosis. The diastolic/systolic peak velocity ration was smaller in group C than in groups A and B (p < 0.05), but there was no significant difference between groups A and B. A diastolic/systolic peak velocity ration < 0.6 predicted severe left internal mammary artery graft stenosis (> 75% diameter stenosis) with a sensitivity and specificity of 100% and 80%, respectively. The diastolic fraction of time-velocity integral was smaller in group C than in groups A and B (p < 0.05), but there was no significant difference between groups A and B. A diastolic fraction <0.5 predicted significant left internal mammary artery graft stenosis 755% diameter stenosis) with a sensitivity and specificity of 90% and 100%, respectively. CONCLUSIONS: Duplex Doppler echocardiography from the supraclavicular fossa is useful for noninvasive assessment of left internal mammary artery graft patency.

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