Use of internal mammary artery in myocardial revascularization after mediastinal irradiation

Duplex Imaging Assessment of the Internal Mammary Arteries in Women after Unilateral Mastectomy and Radiotherapy for Breast Cancer

BACKGROUND

The effects of incidental radiation exposure on internal mammary arteries remain unclear. The present study was designed to test the hypothesis by comparing diameter and blood flow of the irradiated and nonirradiated internal mammary arteries, using Duplex ultrasound imaging.

METHODS

The study was designed as a single-center, transversal, comparative study. The main outcomes were diameter and volumetric blood flow of the internal mammary arteries. The Wilcoxon rank-sum test was used to assess the differences between the irradiated and nonirradiated internal mammary arteries with regard to the diameter and volumetric blood flow.

RESULTS

The diameter (median [interquartile range]) of the irradiated internal mammary arteries (0.170 mm [0.160, 0.180]) was smaller than that of the contralateral nonirradiated ones (0.180 mm [0.170, 0.200], P < 0.0001) and that of the internal mammary arteries in the control group (0.180 mm [0.170, 0.190], P < 0.0001). Similarly, blood flow (median [interquartile range]) of the irradiated internal mammary arteries (52.4 ml/min [37.78, 65.57]) was smaller than that of the contralateral nonirradiated ones (62.7 ml/min [46.87, 84.17], P < 0.0001), as well as of the left (56.7 ml/min [46.88, 72.58], P = 0.02) and the right internal mammary arteries in the control group (61.0 ml/min [47.47, 74.52], P = 0 0.0009).

CONCLUSIONS

The data indicate that the irradiated internal mammary arteries in patients with a history of total mastectomy followed by radiotherapy for breast cancer had significantly smaller diameter and blood flow compared to the nonirradiated internal mammary arteries.

Radiation-Associated Cardiac Disease: A Practical Approach to Diagnosis and Management

Radiation-associated cardiac disease (RACD) results in complex clinical presentations, unique management issues, and increased morbidity and mortality. Patients typically present years or even decades after radiation exposure, with delayed-onset cardiac damage sustained from high cumulative doses. Multimodality imaging is crucial to determine the manifestations and severity of disease because symptoms are often nonspecific. Comprehensive screening using a coordinated approach may enable early detection. However, timing of intervention should be carefully considered in these patients because surgery is often complex and high-risk second surgeries should be minimized in the long-term. This review aims to provide treating physicians with a comprehensive and clinically focused overview of RACD, including clinical/imaging manifestations, multi-modality screening recommendations, and management options.

Percutaneous revascularization in patients treated with thoracic radiation for cancer

OBJECTIVES

To assess coronary revascularization outcomes in patients with previous thoracic radiation therapy (XRT).

BACKGROUND

Previous chest radiation has been reported to adversely affect long term survival in patients with coronary disease treated with percutaneous coronary interventions (PCI).

METHODS

Retrospective, single center cohort study of patients previously treated with thoracic radiation and PCI. Patients were propensity matched against control patients without radiation undergoing revascularization during the same time period.

RESULTS

We identified 116 patients with radiation followed by PCI (XRT-PCI group) and 408 controls. Acute procedural complications were similar between groups. There were no differences in all-cause and cardiac mortality between groups (all-cause mortality HR 1.31, P=.078; cardiac mortality 0.78, P=.49).

CONCLUSION

Patients with prior thoracic radiation and coronary disease treated with PCI have similar procedural complications and long term mortality when compared to control subjects.

Bilateral Isolated Coronary Ostial Stenosis following Mediastinal Irradiation

Isolated coronary ostial narrowing is rare and may represent a separate disease entity from atherosclerotic coronary artery disease. The case of a 41-year-old female with no coronary risk factors who developed severe bilateral isolated coronary ostial stenosis following mantle radiotherapy for Hodgkin's disease is described. She underwent urgent coronary artery bypass grafting and has remained well for 3 years.

Radiation-induced heart disease: an under-recognized entity?

OPINION STATEMENT

Radiation-induced heart disease (RIHD) represents a spectrum of cardiovascular disease in patients who have undergone mediastinal, thoracic, or breast radiotherapy (RT). RIHD may involve any cardiac structure and is a major cause of morbidity and mortality in cancer survivors. While large cohort studies have demonstrated that symptomatic RIHD is a common late finding in this population, the incidence of asymptomatic disease is likely to be even higher. Long-term follow-up with regular screening for RIHD plays an important role in the management of cancer survivors who have undergone RT. Aggressive modification of traditional cardiovascular risk factors such as hypertension, dyslipidemia, and cigarette smoking is essential in patients at risk for RIHD, as these have been shown to potentiate the risks of radiation. In patients with symptomatic RIHD, medical and/or percutaneous therapies are often preferable to surgical interventions in view of the increased surgical risk associated with radiation damage to surrounding tissues. Percutaneous revascularization should generally be favored over surgical revascularization. Transcatheter valve replacements have not been widely used in this population but may offer an alternative to high-risk surgical valve procedures. Pericardiectomy is usually associated with extremely poor short-term and long-term outcomes in patients with RIHD and should be avoided in most cases. Heart transplantation is also higher risk in patients with RIHD than in patients with other etiologies of heart failure, but may be considered in young patients without other comorbidities.

Cardiovascular complications of radiation therapy for thoracic malignancies: the role for non-invasive imaging for detection of cardiovascular disease

Radiation exposure to the thorax is associated with substantial risk for the subsequent development of cardiovascular disease. Thus, the increasing role of radiation therapy in the contemporary treatment of cancer, combined with improving survival rates of patients undergoing this therapy, contributes to a growing population at risk of cardiovascular morbidity and mortality. Associated cardiovascular injuries include pericardial disease, coronary artery disease, valvular disease, conduction disease, cardiomyopathy, and medium and large vessel vasculopathy-any of which can occur at varying intervals following irradiation. Higher radiation doses, younger age at the time of irradiation, longer intervals from the time of radiation, and coexisting cardiovascular risk factors all predispose to these injuries. The true incidence of radiation-related cardiovascular disease remains uncertain due to lack of large multicentre studies with a sufficient duration of cardiovascular follow-up. There are currently no consensus guidelines available to inform the optimal approach to cardiovascular surveillance of recipients of thoracic radiation. Therefore, we review the cardiovascular consequences of radiation therapy and focus on the potential role of non-invasive cardiovascular imaging in the assessment and management of radiation-related cardiovascular disease. In doing so, we highlight characteristics that can be used to identify individuals at risk for developing post-radiation cardiovascular disease and propose an imaging-based algorithm for their clinical surveillance.

Cardiac complications of thoracic irradiation

Adjuvant radiation therapy in the management of early stage breast cancer, Hodgkin's disease, and to a lesser extent other thoracic malignancies has led to a significant improvement in disease-specific survival. Cardiovascular disease is now the most common nonmalignancy cause of death in radiation-treated cancer survivors, most often occurring decades after treatment. The spectrum of radiation-induced cardiac disease is broad, potentially involving any component of the heart. The relative risk of coronary artery disease, congestive heart failure, valvular heart disease, pericardial disease, conduction abnormalities, and sudden cardiac death is particularly increased. Over the years contemporary techniques have been introduced to reduce cardiac morbidity and mortality in radiation-treated cancer survivors; however, the long-term effects on the heart still remain unclear, mandating longer follow-up. Awareness and early identification of potential cardiac complications is crucial in cancer survivors, with the management often being quite complex. This review examines the epidemiology of radiation-induced cardiac disease together with its pathophysiology and explores the available treatment strategies and the potential utility of various screening strategies for affected cancer survivors.

Long-term cardiac and pulmonary complications of cancer therapy

Cardiac complications resulting from chemotherapy and radiation pose a significant risk for morbidity and mortality to the cancer survivor. Cardiac side effects may progress over time and are a concern for patients treated during childhood. Long-term pulmonary complications are relatively infrequent, and acute respiratory effects of drugs (mostly bleomycin) or radiation normally resolve early after therapy. Although most cardiovascular risk statistics and clinical experience are derived from patients treated before 1985, the modern radiation approach that limits the exposure of the heart and reduces the total dose seems to attenuate the previously observed cardiovascular risk. Potential preventive measures for high-risk patients are of increasing interest but remain experimental.

Cardiac toxicity in association with chemotherapy and radiation therapy in a large cohort of older patients with non-small-cell lung cancer

BACKGROUND

The study's objective was to investigate the risks of developing cardiac disorders following the administration of chemotherapy and radiation therapy in patients with non-small-cell lung cancer (NSCLC).

METHODS

The study consisted of 34 209 patients aged > or =65 years with American Joint Committee on Cancer stages I-IV NSCLC identified from the Surveillance, Epidemiology, and End Result-Medicare linked database (1991-2002) who were free of cardiac disorders at NSCLC diagnosis.

RESULTS

There were significant associations between the use of chemotherapy/radiation and the risks of developing ischemic heart disease, conduction disorders, cardiac dysfunction, and heart failure. The absolute risks for cardiac dysfunction increased with the administration of chemotherapy-only and radiation-only, and incrementally with chemoradiation. Men, blacks, older patients, those with higher comorbidity scores, and advanced disease were at higher risk. The risk for ischemic heart disease increased when radiation/chemoradiation were rendered to the left lung and both lungs and for cardiac dysfunction, radiation administered to the left lung.

CONCLUSIONS

There were significant associations especially for cardiac dysfunction with use of chemotherapy/radiation therapy and risks of developing cardiac toxicity in NSCLC patients. The risks of treatment-associated cardiac toxicity, specifically ischemic heart disease and cardiac dysfunction, were greatest among those with left-sided lung tumors.

Conduit choice for coronary artery bypass grafting after mediastinal radiation

OBJECTIVE

Patients who have undergone prior mediastinal radiation might require coronary artery bypass grafting. However, there is some concern regarding potential radiation damage to the internal thoracic artery. Our objective was to assess the late patency of the internal thoracic artery and venous grafts in patients with prior mediastinal radiation.

METHODS

Patients undergoing coronary artery bypass grafting at our clinic after prior mediastinal radiation were identified, and medical records, including operative reports, clinical notes, and coronary angiography, were reviewed.

RESULTS

Between 1985 and 2005, 138 patients had coronary artery bypass grafting after mediastinal radiation. Of these, 25 underwent clinically indicated postoperative angiography. The mean patient age was 56.1 +/- 13.8 years, and 24% were female. All patients received between 3000 and 6000 rads in fractionated doses. Seventy-two percent of patients had 3-vessel coronary artery disease. At late angiography (mean, 2.2 years), 6 (32%) of 19 internal thoracic arteries and 13 (27%) of 48 venous or radial arterial conduits showed stenosis of 70% or greater (P = .72). Assessing only grafts that were anastomosed to the left anterior descending coronary artery, 35% (6 of 17) of internal thoracic artery grafts and 60% (3 of 5) of non-internal thoracic artery grafts showed narrowing of 70% or greater (P = .61). Among patients who received a graft to the left anterior descending coronary artery (n = 113), however, age-adjusted survival at 5 years was superior among those receiving an internal thoracic artery graft to the left anterior descending coronary artery.

CONCLUSIONS

Internal thoracic artery graft patency among patients with prior radiation was less than expected and similar to that for venous grafts, although the effect of conduit disease versus distal target vessel runoff is unknown. Despite this, late survival was superior among those receiving an internal thoracic artery graft to the left anterior descending coronary artery. These data support use of an internal thoracic artery graft to the left anterior descending coronary artery when it appears grossly to be an acceptable conduit.

Cardiovascular effects of breast cancer radiotherapy

Cardiac toxicity has been implicated as the primary reason for excess non-breast cancer mortality in early breast cancer radiotherapy studies. Refinements in radiotherapy techniques have allowed for a considerable reduction of this risk in the majority of breast cancer patients. Recent large population-based studies confirmed an increase of cardiovascular death risk in patients irradiated for cancer of the left breast and in individuals exposed to relatively low (hitherto believed to be of no cardiovascular disease risk) doses of radiation, such as atomic bomb survivors or patients treated for various benign conditions. The issue of potential radiation-related cardiac damage may also be assuming a new significance due to the widespread use of other cardiotoxic agents, such as anthracyclines, paclitaxel and trastuzumab. The aim of this review is to summarize and critically analyze the available evidence on the impact of ionizing radiation on the cardiovascular system, with special attention to recent data demonstrating previously unrecognized adverse effects. This review discusses the pathology of radiation-related cardiovascular disease, its clinical presentation, risk factors and methods of assessment, as well as technical developments minimizing cardiac exposure. Epidemiological data are presented on the incidence of radiation-induced heart disease and cardiovascular mortality in various populations of patients irradiated for breast cancer and in individuals exposed to low radiation doses. Additionally, non-cardiac radiation-related vascular morbidity and mortality in breast cancer patients are addressed.

Radiation-Induced Bilateral Coronary Ostial Stenosis in a 17-Year-Old Patient

Mediastinal irradiation can induce coronary artery disease characterized by the localization of lesions at the proximal segment of the arteries. We report the case of a 17-year-old patient who underwent a mediastinal irradiation for pulmonary sarcoma and developed 15 years later an asymptomatic ischemic cardiopathy. Bilateral coronary ostial stenosis was discovered by a transthoracic echography and coronary angiography showed isolated bilateral ostial stenosis. Coronary bypass grafting was performed with internal thoracic arteries. We recommend testing exercise and echocardiography during follow-up of patients who have received more than 30 Gy of mediastinal radiation. Surgery is the treatment of choice in bilateral ostial stenosis using internal thoracic arteries in young patients if preoperative assessment shows patency.

Report of simultaneous off-pump CABG and modified mastectomy

The patient was a 75-year-old female who had received medical treatment for effort angina. Recently, she noticed a left breast tumor, which was diagnosed as breast cancer with axillary lymph node swelling. Coronary angiography performed prior to the surgery for the breast cancer showed 90% stenosis in segment 6 of the left anterior descending artery (LAD). Coronary intervention was not possible due to anatomical reasons, so she was admitted for simultaneous surgery for the breast cancer and angina. The chest was opened through a median sternotomy and the full-skeletonized right internal thoracic artery was grafted on the LAD without cardiopulmonary bypass. A transverse elliptical incision was made after the median sternotomy was closed, and the breast tumor and lymph nodes around the subclavian and axillary vessels were completely dissected. Even in the case of multiple vessel coronary disease, simultaneous surgery may be possible, but indications should be carefully assessed considering the cardiac function and general condition of the patient.

Thoracic Radiation Therapy and Suitability of Internal Thoracic Arteries for Myocardial Revascularization

INTRODUCTION AND BACKGROUND

Myocardial revascularization using internal thoracic arteries (ITAs) has been associated with superior clinical outcome. This study addresses the question of whether internal mammary arteries are unsuitable for grafting due to radiation-based damage in patients with history of thoracic radiation therapy. We review our experience in this subset of surgical candidates.

PATIENTS AND METHODS

Forty-nine patients undergoing elective coronary artery bypass grafting with use of at least one ITA were enrolled and matched to 49 comparable nonirradiated individuals by propensity scoring system. Preoperative and postoperative data were collected and compared. A 18-month clinical follow-up was performed.

RESULTS

Intraoperative mammary artery flow was assessed by transthoracic Doppler echocardiography probe, and there was no significant difference between irradiated and nonirradiated individuals (36 +/- 8.3 mL/min vs 39 +/- 7.2 mL/min, p = 0.15). The two study groups were also comparable in terms of survival (overall mortality, 2%) and recurrence of angina and perfusion defect at control stress perfusion nuclear scan (p = 0.99 and p = 0.77, respectively). One arterial graft showed stenosis at postoperative angiography. The dose of radiation therapy administered did not correlate with graft flow values after anastomosis.

CONCLUSION

Our data suggest that the use of a monolateral or bilateral ITA is not associated with early graft failure in patients with history of chest/mediastinal irradiation. Skeletonization harvesting technique might be recommended because of the frequent presence of fibrous tissue around the in situ vessel. Arterial graft stenosis in thorax-irradiated patients should be attributed to the primary atherosclerotic disease rather than to irradiation itself.

Radiation-associated cardiovascular disease

As the number of cancer survivors grows because of advances in therapy, it has become more important to understand the long-term complications of these treatments. This article presents the current knowledge of adverse cardiovascular effects of radiotherapy to the chest. Emphasis is on clinical presentations, recommendations for follow-up, and treatment of patients previously exposed to irradiation. Medline literature searches were performed, and abstracts related to this topic from oncology and cardiology meetings were reviewed. Potential adverse effects of mediastinal irradiation are numerous and can include coronary artery disease, pericarditis, cardiomyopathy, valvular disease and conduction abnormalities. Damage appears to be related to dose, volume and technique of chest irradiation. Effects may initially present as subclinical abnormalities on screening tests or as catastrophic clinical events. Estimates of relative risk of fatal cardiovascular events after mediastinal irradiation for Hodgkin's disease ranges between 2.2 and 7.2 and after irradiation for left-sided breast cancer from 1.0 to 2.2. Risk is life long, and absolute risk appears to increase with length of time since exposure. Radiation-associated cardiovascular toxicity may in fact be progressive. Long-term cardiac follow-up of these patients is therefore essential, and the range of appropriate cardiac screening is discussed, although no specific, evidence-based screening regimen was found in the literature.

Functional comparison of the human isolated femoral artery, internal mammary artery, gastroepiploic artery, and saphenous vein

Human femoral, internal mammary, and gastroepiploic arteries and saphenous veins are used as bypass grafts for coronary surgery or for reconstruction in arterial occlusive disease. We have characterized the contractile responses of these vessels to various agents that are liberated during cardiac or vascular surgery. In organ baths, U46619 (a stable thromboxane A2 mimetic), norepinephrine, endothelin-1, angiotensin II, and KCl caused concentration-dependent contractions in all vessels tested. Leukotriene C4 did not induce any contraction in the arteries, whereas a contraction was obtained in the saphenous vein rings. U46619 induced the most powerful contraction in all vessels tested. The pD2 values for each agent did not differ among the different vessels. When responses were expressed as a percentage of KCl-induced contraction, the contraction of endothelin-1 (151 ± 5%) and leukotriene C4 (43 ± 5%) was more significant on saphenous veins than on arteries. In conclusion, thromboxane A2 appears to be the most potent endogenous constricting agent on different human vascular beds. Our second finding is that saphenous veins are more sensitive to contract to leukotriene C4 and endothelin-1 than arteries. These properties may influence early and (or) long-term vein graft patency.Key words: femoral arteries, vascular reactivity, thromboxane A2, endothelin-1, leukotrienes.

Rescue revascularization for acute coronary occlusion late after radiotherapy

Because radiation-induced coronary artery stenoses are frequently severe and located proximally, some patients are admitted in emergency. This report describes the case of a 47-year-old woman with radiation-induced stenosis of the left main coronary artery who presented with cardiac arrest during angiography. The patient was successfully treated using circulatory assistance and percutaneous transluminal coronary angioplasty as a bridge to coronary artery bypass grafting.

Coronary artery operation in patients after breast cancer therapy

OBJECTIVE

The purpose of this investigation was to retrospectively study the outcome of patients undergoing coronary artery operation who were previously treated for breast cancer.

METHODS

Between July 1992 and December 1996, 28 patients with a history of breast cancer underwent coronary artery bypass graft operation and were randomly matched against a noncancer group of similar size (n = 36) to allow for comparison of their preoperative characteristics, operative course, and postoperative outcome.

RESULTS

The incidence of sternal wound infection was significantly higher in the cancer group than in the control group (25% versus 6%; p = 0.027). Postoperative noncardiac chest pain occurred more frequently in the cancer group than in the control group (52% versus 31%; not significant). In the study group, radiotherapy and recent myocardial infarction were the only two independent factors associated with sternal wound complications. Patients with a less than 17-year interval between the breast cancer therapy and the coronary artery operation had a higher incidence of sternal wound infection (46%) as opposed to patients with a longer time interval (7%; p = 0.028; odds ratio = 12). Sternal wound complications were more frequent in patients with a history of right-sided breast cancer (50%) compared with left-sided lesions (12.5%; p = 0.068; odds ratio = 7).

CONCLUSIONS

Coronary artery operation in patients after breast cancer therapy may be associated with an increased sternal wound infection rate. To decrease this risk of infection, an approach through a right thoracotomy, minimally invasive techniques, the use of skeletonized internal mammary artery, and broad spectrum antibiotic therapy may be considered.

Exercise-induced syncope as late consequence of radiotherapy

This report describes a 34-year-old female with an exercise-induced atrioventricular block resulting from transient ischemia caused by a radiation-induced ostial stenosis of the right coronary artery. Patient first underwent coronary artery surgery with a right internal mammary artery to the right coronary artery. After 18 months she was readmitted with exercise-induced syncope due to graft occlusion. This time a successful rotablator procedure was performed on the ostial stenosis.

Use of color Doppler imaging in assessment of preoperative and postoperative flow characteristics of internal thoracic artery in myocardial revascularization

Between January 1993 and February 1993, the left internal thoracic arteries of 40 consecutive patients scheduled for aortocoronary bypass operation were examined by transthoracic B-mode imaging. Perioperative measurements correlated well with preoperative noninvasive measurements (r = 0.914). In the postoperative period, B-mode images could not be obtained in 17 (44.7%) of 38 patients. Adequate Doppler spectra of the internal thoracic artery were obtained in all patients preoperatively and in 36 (94.7%) of 38 patients postoperatively. Preoperatively a triphasic wave form was obtained with a large systolic peak followed by small reversed and diastolic components in all patients. Postoperatively this triphasic wave form had been converted into a combined systolic-diastolic wave form. In all patients peak systolic velocity of the internal thoracic artery decreased (96.4 +/- 15.3 vs 64.2 +/- 18.9 cm/sec., P < 0.05), and peak diastolic velocity increased (21.7 +/- 8.8 vs 28.3 +/- 11.2 cm/sec., P < 0.05) significantly in the postoperative period as compared with the preoperative values. A slight decrease in peak systolic and diastolic velocities was detected at twelve months postoperatively. This study indicates that transthoracic B-mode imaging and Doppler spectrum analysis are reliable techniques in the preoperative and postoperative assessment of the internal thoracic artery in myocardial revascularization.

Radiation therapy-induced cardiac injury

Radiation therapy is currently standard treatment for a number of malignancies, including Hodgkin's disease. With the advent of techniques (e.g., subcarnial blocks) that limit the dose of radiation to which the heart is exposed, the incidence of radiation-induced heart disease can be minimized. However, a small percentage of patients will eventually suffer iatrogenic effects. Most commonly seen is pericardial disease, but valvular, conduction system, and coronary artery disease are also seen. Further, because these patients are now surviving longer after therapy, those effects with a longer latent period may be seen with increasing frequency.

Noninvasive hemodynamic assessment of the internal mammary artery in myocardial revascularization

Using transthoracic B-mode imaging and Doppler spectrum analysis it was found that the luminal diameter of the internal mammary artery and its hemodynamics were not significantly different among 15 preoperative patients (64 +/- 10 years) who underwent myocardial revascularization using the left internal mammary artery and young and older control groups (25 +/- 3 years and 61 +/- 9 years, respectively). These data indicate that older age does not significantly adversely influence the degree of intimal thickening and compliance in the internal mammary artery. Doppler spectrum analysis of the internal mammary artery in the patients who were operated on revealed conversion from a triphasic systolic waveform preoperatively to a unidirectional combined systolic/diastolic waveform at 1 week and 2 and 6 months postoperatively, characterized by a significant increase in the diastolic blood flow velocity and a significant decrease in the systolic blood flow velocity and the pulsatility and resistance indices. This study indicates that transthoracic B-mode imaging and Doppler spectrum analysis are promising noninvasive techniques in the preoperative assessment of internal mammary artery morphology and physiology. In addition, Doppler spectrum analysis can also be used in the long-term serial assessment of the internal mammary artery conduit after myocardial revascularization.