Risk of aortic aneurysm surgery as assessed by preoperative gated heart pool scan

Vascular surgery critical care: perioperative cardiac optimization to improve survival

OBJECTIVE

To review the literature on perioperative cardiac management of patients who are scheduled to undergo vascular surgery.

DATA SOURCE

MEDLINE- and PubMed-based review of literature published from 1965 to 2005.

CONCLUSIONS

Perioperative cardiac events (myocardial infarction, heart failure) remain the leading cause of morbidity and mortality in vascular surgery patients. Existing guidelines allow physicians to cost-effectively streamline preoperative cardiac risk assessment and stratification. Perioperative optimization of volume status and cardiac function and the routine use of perioperative beta-blockers can significantly improve outcomes after major vascular surgery. Perioperative addition of statins to beta-blockers in high-risk patients undergoing vascular surgery merits further evaluation. Preoperative coronary revascularization should be restricted to patients with unstable cardiac symptoms.

Routine Measurement of Radioisotope Left Ventricular Ejection Fraction Prior to Vascular Surgery: Is it Worthwhile?

OBJECTIVE

To determine whether estimation of left ventricular (LV) ejection fraction (EF) by means of multiple gated acquisition (MUGA) scanning could reliably stratify cardiac risk prior to elective major vascular surgery.

METHODS

A review of the English-language literature.

RESULTS AND CONCLUSIONS

Twenty-two studies enrolling a total of 3096 patients were identified from 1984 to date. Selection bias, blinding of the results, different cut-off limits, and several retrospective studies were some of the problems preventing a comprehensive analysis. The resting LVEF was not found to be a consistent predictor of perioperative ischaemic cardiac events. In the perioperative phase, poor LV function was, mainly, predictive of congestive heart failure, and, in the long-term, of cardiac outcome. The presence of myocardial wall motion abnormalities was also associated with both a higher chance of postoperative cardiac complications and a worse long-term cardiac outcome. Although measurements of LV function seem to play a key role in defining a patient's long-term prognosis, the value of routinely measuring LVEF preoperatively is limited and, therefore, MUGA scanning cannot be recommended as a general screening test. Despite this, it has been widely used for cardiac risk assessment in vascular surgery, and only recently its popularity has started declining. Other tests, such as stress-echocardiography and myocardial perfusion imaging, used selectively in moderate-risk patients can refine prediction of cardiac risk. In the future, gated stress myocardial perfusion scintigraphy, perhaps combined with ANP/BNP plasma level determination, may become a first choice test in preoperative cardiac risk assessment.

A meta-analysis comparing the prognostic accuracy of six diagnostic tests for predicting perioperative cardiac risk in patients undergoing major vascular surgery

OBJECTIVE

To evaluate the discriminatory value and compare the predictive performance of six non-invasive tests used for perioperative cardiac risk stratification in patients undergoing major vascular surgery.

DESIGN

Meta-analysis of published reports.

METHODS

Eight studies on ambulatory electrocardiography, seven on exercise electrocardiography, eight on radionuclide ventriculography, 23 on myocardial perfusion scintigraphy, eight on dobutamine stress echocardiography, and four on dipyridamole stress echocardiography were selected, using a systematic review of published reports on preoperative non-invasive tests from the Medline database (January 1975 and April 2001). Random effects models were used to calculate weighted sensitivity and specificity from the published results. Summary receiver operating characteristic (SROC) curve analysis was used to evaluate and compare the prognostic accuracy of each test. The relative diagnostic odds ratio was used to study the differences in diagnostic performance of the tests.

RESULTS

In all, 8119 patients participated in the studies selected. Dobutamine stress echocardiography had the highest weighted sensitivity of 85% (95% confidence interval (CI) 74% to 97%) and a reasonable specificity of 70% (95% CI 62% to 79%) for predicting perioperative cardiac death and non-fatal myocardial infarction. On SROC analysis, there was a trend for dobutamine stress echocardiography to perform better than the other tests, but this only reached significance against myocardial perfusion scintigraphy (relative diagnostic odds ratio 5.5, 95% CI 2.0 to 14.9).

CONCLUSIONS

On meta-analysis of six non-invasive tests, dobutamine stress echocardiography showed a positive trend towards better diagnostic performance than the other tests, but this was only significant in the comparison with myocardial perfusion scintigraphy. However, dobutamine stress echocardiography may be the favoured test in situations where there is valvar or left ventricular dysfunction.

Very late survival after vascular surgery

PURPOSE

The aim of this study was to define very late survival in veterans who routinely underwent preoperative assessment of left ventricular function using radionuclide ventriculography (RNVG) before elective major vascular surgery from 7/84 to 7/88 at one Veterans Affairs Medical Center.

METHODS

RNVG defined left ventricular ejection fraction (EF) and determined the presence of ventricular wall motion abnormalities. Patients undergoing elective vascular surgery (n = 310) who had preoperative RNVG were then followed over the years using direct contact, VA administrative databases, and, most recently, the Social Security Death Index.

RESULTS

Follow-up was 6.64 +/- 4.62 years (range 0 to 16.2 years). Current survival is 10% (11/107) after carotid surgery, 12% (10/82) after aortic aneurysm repair, 15% (17/111) after extremity reconstruction, and 0% (0/10) after visceral artery reconstruction (ns). There was no statistically significant difference in mortality between the different types of vascular surgery at 30 days or at 1, 5, and 10 years after surgery (ns). Actual survival rates at 5 years after carotid surgery, aneurysm repair, extremity reconstruction, and visceral reconstruction were 55, 61, 59, and 50%, respectively. Stepwise logistic regression analysis was performed which included preoperatively defined cardiovascular risk factors, type of surgery, and results of RNVG. The final regression model indicated that age, diabetes, smoking at the time of surgery, and low EF were independently associated with overall mortality while angina, prior myocardial infarction (MI), and type of operation were not. Mean survival duration with normal EF (>50%) was 7.99 years versus 4.78 years with low EF (P < 0.001). No patient with severe left ventricular dysfunction (EF < or = 35%; n = 39) or who had postoperative cardiac complications (MI, CHF, ventricular arrhythmia; n = 38) survived to the present.

CONCLUSIONS

Very late survival after major vascular surgery was related to the presence of diabetes, active smoking at the time of surgery, left ventricular function, and postoperative cardiac complications. Since there was no association of overall mortality with angina or prior MI, an aggressive approach to coronary evaluation in such patients might not alter very late survival.

Prediction of cardiac risk before abdominal aortic reconstruction: comparison of a revised Goldman Cardiac Risk Index and radioisotope ejection fraction

BACKGROUND

A revised Goldman Cardiac Risk Index has been suggested to identify patients at higher risk for cardiac complications in patients who undergo major noncardiac surgery. The aim of this study was to test the usefulness of this model in an independent series of patients who underwent abdominal aortic surgery and to compare the index with the multiple gated acquisition (MUGA) scan in the prediction of cardiac complications.

METHODS

We studied 77 patients who underwent MUGA scan before elective abdominal aortic reconstruction. The revised index was calculated for each patient after recording the following five risk factors: history of ischemic heart disease, congestive heart failure, cerebrovascular disease, insulin-dependent diabetes, and creatinine level more than 2 mg/dL. Technetium-99m MUGA scan provided information about the resting left ventricular ejection fraction (LVEF) and the presence of regional wall motion abnormalities.

RESULTS

Fourteen patients (18%) had cardiac complications develop. The index proved to be a satisfactory predictor of postoperative cardiac events (P =.008), and an abnormal LVEF failed to do so (P =.1). The presence of wall abnormalities, with or without an abnormal LVEF, predicted cardiac complications (P =.004 and P =.006). Patients with a higher index score showed a tendency to have a lower LVEF (Spearman rank correlation, r = -0.43; P <.001). Wall abnormalities, with or without an abnormal LVEF, were more frequent in patients with higher scores (P =.03 and P =.009). Combining the index with the LVEF or the wall abnormalities or both could further stratify the cardiac risk (P =.004, P =.0003 and P =.0006, with chi(2) test for trend).

CONCLUSION

For those patients who undergo elective abdominal aortic surgery, the revised Goldman Cardiac Risk Index is a simple method of evaluating cardiac risk with minimum resource implications. MUGA scan can offer additional stratification in patients judged with the index to be at high risk.

Impact of radionuclide ventriculography prior to elective abdominal aortic reconstruction

We evaluated how preoperative radionuclide ventriculography (RNV) influences the clinical management of 96 patients referred for elective infrarenal abdominal aortic surgery. Of these, 11 had aortoiliac occlusive disease and 85 an abdominal aortic aneurysm. In 89 patients (93%), there was a known history or clinical evidence of coronary artery disease prior to RNV. The scan was abnormal in half the patients. There were 56 patients with left ventricular ejection fraction (LVEF) > 50% and 40 with LVEF < or = 50%. The LVEF ranged between 10% and 88% with a mean of 52.8+/-14.1%. There was normal wall motion in 56 patients and wall abnormalities were present in 40, including four LV aneurysms. After initial assessment, 19 patients did not proceed to surgery for a variety of reasons. Cardiology consultation was requested in 11 patients, six of which were delayed or turned down for surgery mainly on cardiac grounds. Only one of these underwent cardiac catheterization. Of the remaining 77 patients who underwent surgery, 15 were seen by a cardiologist and one was delayed in order to optimize his cardiac status. No patient underwent prophylactic coronary angioplasty/stenting or revascularization preoperatively. In addition, based on the RNV results and in conjunction with the clinical findings, six patients had pulmonary artery catheters inserted either the night prior to operation (n = 3) or after induction to anaesthesia (n = 3). This is the largest reported British series of cardiac testing using RNV prior to abdominal aortic surgery. Coronaryartery disease is very common amongst such patients. RNV influences our decision-making and patientselection. An abnormal result may alter the clinical management, lead to a cardiology referral (26/96, 27% in this series) and have anaesthetic implications.

The role of the cardiology consultant: putting it all together

Consultation represents the act of providing advice regarding diagnosis and/or management and may comprise a major component of a cardiologist's practice. A frequent cause for cardiac consultation is preoperative risk assessment. With steadily decreasing morbidity and mortality related to noncardiac surgery, cardiovascular management strategies that are known to improve long-term outcomes should guide decision making in the perioperative setting. The preoperative cardiac consultation may represent an opportunity to initiate or modify cardiac care including primary and secondary preventive measures. A stepwise approach to perioperative cardiac risk assessment, as set forth by joint American College of Cardiology and American Heart Association guidelines, should be employed. The hallmark of successful preoperative cardiology consultation is effective communication with referring physicians. A consultant's good clinical judgement will only impact a patient's care if recommendations are communicated effectively. There is no substitution for direct, verbal contact. Recommendations should be kept to less than five when possible, be brief and specific. The consultant should provide contingency plans and follow-up. Good consultative technique increases compliance with recommendations and facilitates efficient patient care.

Is preoperative cardiac evaluation for abdominal aortic aneurysm repair necessary?

PURPOSE

It is reported that 25% to 50% of patients with abdominal aortic aneurysms (AAA) have severe coronary artery disease (CAD) and should undergo an aggressive cardiac workup before AAA repair. In contrast, it has been our policy that patients referred for AAA repairs undergo no cardiac testing before surgery.

METHODS

This report reviews the last 113 consecutive patients who underwent elective AAA repair by the senior author using this policy. Seventy-four patients (group A) had only an electrocardiogram before surgery. The remaining 39 patients (group B) were referred having already had additional testing that included a thallium stress test (n = 20), echocardiogram (n = 18), multiple gated acquisition (MUGA) scan (n = 3), cardiac catheterization (n = 8), or some combination of these.

RESULTS

There was no statistical difference between group A and group B with regard to age, sex, tobacco use or history of coronary artery disease, diabetes mellitus, stroke (CVA), hypertension, peripheral vascular disease, or chronic obstructive pulmonary disease. Group B more commonly had a history of myocardial infarction (41% vs 19%, p < 0.03) and congestive heart failure (23% vs 7%, p < 0.03). During surgery there was no significant differences in blood loss, transfusion requirements, or operative times. There were no myocardial infarctions in group A and two (5.1%) in group B, which was not significantly different. Other complications, such as CVA, renal failure, pulmonary failure, pneumonia, wound infection, and hemorrhage, were not significantly different between the two groups. Postoperative hospital stay was not significantly different. There were three deaths in the entire series (2.7%), and only one in group B was cardiac-related in a patient with known end-stage cardiac disease and a symptomatic 8 cm AAA.

CONCLUSIONS

These data indicate that most patients with AAA can safely undergo repair with no cardiac workup and that cardiac workup before AAA repair contributes little information that impacts on treatment or final clinical outcome. We conclude that cardiac testing in preparation for AAA repair is not usually necessary and that intraoperative hemodynamic management may be the most important variable in determining outcome.

Minimising cardiac anaesthetic risk: the tortoise or the hare?

There is no doubt that a group of patients at increased risk of peri-operative cardiac morbidity exists and must be managed with the emphasis on the prevention of myocardial ischaemia. It is also clear that a potentially far larger group are at risk of failing to meet the increased cardiovascular and metabolic demands of surgery and therefore suffering the consequences of a relative hypoperfusion injury. Pre-operative assessment must address both groups and management regimens sought to provide optimal outcome for both. At present there is no consistent strategy for their identification, assessment or management of the high risk surgical population despite the fact that they probably consume a disproportionate share of hospital resources. The first and most important step is the recognition that this high risk group exists. Only then can this population be given similar consideration to those currently thought to be at risk of ischaemia.

Assessment of cardiac risk in noncardiac surgery

Surgical techniques have been refined so that complications directly resulting from surgical procedures are relatively small. However, with the high prevalence of coronary artery disease in the United States, many surgical patients have concomitant coronary artery disease. Anesthesia as well as the surgical procedure induce stresses on the heart and circulatory system which could result in perioperative cardiac morbidity and mortality. Assessing patients prior to surgical procedures by history, physical examination, laboratory data, and newer cardiovascular diagnostic procedures can stratify the cardiac risk and help to predict the incidence of perioperative cardiac morbidity and mortality. If great risk exists, an alternative therapy or cancellation of the surgical procedure may be considered. In certain subgroups of patients, coronary artery revascularization, valvular heart surgery, or beginning medical therapy of the underlying cardiac pathology could be performed prior to the surgical procedure. If this cannot be arranged for high-risk patients, more intensive and invasive hemodynamic monitoring and optimal medical management perioperatively might reduce cardiac complications.

Coronary artery disease in patients with peripheral vascular disease

For patients requiring peripheral vascular surgery, coronary artery disease is the major determinant of perioperative mortality and long-term survival. The management of coronary artery disease in these patients is controversial as no randomized blinded prospective studies have been conducted. Data on the prevalence, diagnosis and management are reviewed.

"Asymptomatic" ruptured aneurysm: a report of two cases of aortocaval fistula presenting with cardiac failure

Two cases of aortocaval fistula are described in patients with an otherwise asymptomatic abdominal aortic aneurysm. Both presented because of cardiac symptoms, one with chest pain and acute heart failure and electrocardiogram signs of acute coronary ischaemia, the other with a long history of chronic cardiac failure resistant to therapy. In the first case the fistula was proven by means of a CAT scan. Positive proof of a fistula or leakage is important because asymptomatic aneurysms should not be operated on in cardiac compromised patients. On the other hand, if an aortocaval fistula is present, operation is necessary to prevent fatal cardiac failure.

Cardiac risk stratification prior to vascular surgery

A cardiac etiology is the cause of death in approximately 40% to 60% of patients who die in the early postoperative period following vascular surgery. A variety of modalities has been proposed to identify the patient at risk before the surgical procedure. This article puts these modalities in perspective and discusses the increased risk of cardiac complication for the vascular surgery patient, identifies the patient at risk, and defines methods to decrease patient risk.

Preoperative and long-term cardiac risk assessment. Predictive value of 23 clinical descriptors, 7 multivariate scoring systems, and quantitative dipyridamole imaging in 360 patients

A total of 360 patients underwent preoperative cardiac risk assessment using 23 clinical parameters, seven multivariate clinical scoring systems, and quantitative dipyridamole-thallium imaging to predict postoperative and long-term myocardial infarction and cardiac death after noncardiac surgery. There were 30 postoperative and an additional 13 cumulative long-term cardiac events after an average follow-up of 15 months. Clinical descriptors were not useful in predicting the outcome of individual patients. The postoperative and long-term cardiac event rates were 1% and 3.5%, respectively, in patients with normal scans or fixed perfusion defects, and 17.5% and 22% in patients with reversible defects. Using quantitative indices reflecting the amount of jeopardized myocardium, patients could be stratified by dipyridamole imaging into multiple scintigraphic subsets, with corresponding postoperative and 1-year coronary morbidity and mortality rates ranging from 0.5% to 100% (p = 0.0001). Thus, postoperative and long-term cardiac events cannot be predicted clinically, whereas quantitative dipyridamole imaging accurately identifies high-risk patients who require preoperative coronary angiography.

Equilibrium radionuclide angiocardiography prior to elective abdominal aortic surgery

Equilibrium radionuclide angiocardiography (ERNA) was employed preoperatively in 183 patients undergoing elective abdominal aortic reconstruction to measure left ventricular ejection fraction (LVEF) and to detect abnormal regional wall movement. Abnormal ejection fractions were virtually confined to the 97 patients who had clinical, electrocardiographic or radiographic evidence of heart disease. An operative mortality of 8.7% was recorded. Major cardiac events (defined as myocardial infarction, cardiac failure or malignant ventricular arrhythmia) occurred in 15 of 86 abdominal aortic aneurysm patients (17.4%) and six of 96 (6.25%) patients with aorto-iliac occlusive disease. Patients with an abdominal aortic aneurysm and abnormal LVEF or regional wall motion abnormality were more likely to suffer a cardiac event (p less than 0.001), the event rate exceeding 60% in patients whose LVEF was less than 35%. An abnormal LVEF failed to predict a cardiac event in patients with aorto-iliac occlusive disease. While not indicated in patients lacking clinical evidence of heart disease, ERNA can refine the assessment of cardiac risk, particularly in patients with previous myocardial infarction and define a high risk group in whom aortic reconstruction should be avoided except for the most compelling of indications.

The role of central haemodynamic monitoring in abdominal aortic surgery. A prospective randomised study

To test the hypothesis that central haemodynamic monitoring is not necessary in all patients undergoing abdominal aortic surgery, a prospective randomised study in 40 consecutive patients undergoing elective abdominal aortic surgery was carried out. Patients with unstable angina, recent myocardial infarction (less than or equal to 6 months), and left ventricular ejection fraction (LVEF) less than 0.50 were excluded. Twenty-one patients had perioperative central haemodynamic monitoring while 19 patients had central venous pressure monitoring alone. Parameters studied included, perioperative haemodynamics and fluid balance, perioperative cardiac drug administration, operation time and clamp time, postoperative renal function, incidence of postoperative ventilation and line complications, duration of hospital and ICU stay, and 30 day postoperative outcome. Results obtained were compared with a high risk group of patients (LVEF less than 0.50) undergoing similar surgery. Statistical analysis failed to show any difference in outcome for any variable measured in either low risk group. All serious postoperative cardiac complications occurred in patients with LVEF less than 0.50 (P less than 0.0001). These data suggest that patients with LVEF greater than or equal to 0.50 are at low risk of developing postoperative cardiac complications and can be successfully managed perioperatively without the added potential risks and costs of central haemodynamic monitoring.