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Restoration of the pulmonary valve reduces right ventricular volume overload after previous repair of tetralogy of Fallot.

BACKGROUND: Severe pulmonary regurgitation (PR) and associated right ventricular (RV) dilatation are late complications of surgical repair of tetralogy of Fallot (TOF). For the past several years, we have restored pulmonary valve competence with the exclusive use of cryopreserved allografts. METHODS AND RESULTS: Sixteen patients with symptoms of diminished exercise tolerance and echocardiographic evidence of progressive PR with severe RV dilatation underwent placement of allografts in the RV outflow tract at a median age of 12 years (10 years after TOF repair). Abnormal exercise tolerance tests were documented in 10 patients. Additional surgical procedures included pulmonary artery augmentation (n = 6), closure of residual left to right shunts (n = 3), and subendocardial resection for monomorphic ventricular tachycardia (n = 1). Six patients had either preoperative or postoperative balloon dilations of pulmonary artery stenoses. All patients had symptomatic improvement after allograft insertion. At a mean follow-up of 26.4 +/- 3.4 months, the severity of PR improved in all but one patient. In 12 patients (group 1), conduit regurgitation was either trace (n = 11) or mild (n = 1). Four patients (group 2) had moderate conduit regurgitation. In a retrospective analysis, pulmonary artery diameters and cross-sectional areas were significantly smaller in the group 2 patients compared with the group 1 patients. With the exception of one patient, RV end-diastolic diameter (RVEDD/BSA) fell after allograft insertion in each patient (P < .01). The reduction in RVEDD/BSA was significantly greater in group 1 than in group 2 (31.8 +/- 3.4% versus 21.4 +/- 11.0%, P < .05). CONCLUSIONS: Thus, restoration of the pulmonary valve with cryopreserved allografts improved exercise tolerance and diminished RV volume overload in patients with severe PR after previous repair of TOF. Optimal results were achieved in patients who did not have significant residual pulmonary artery distortion.

Child↗

Outcome of bypass surgery in patients with chronic ischemic left ventricular dysfunction. Predictive value of MR imaging.

PURPOSE: To determine the preoperative findings of MR imaging of the left ventricle (LV) that could best predict the functional outcome of the LV after surgical revascularization. MATERIAL AND METHODS: Patients with angina pectoris, previous myocardial infarction, and dysfunction of the LV, and who had a preoperative cine MR, were re-evaluated after bypass surgery with MR in a study on the effects of revascularization after mean 22 months. RESULTS: Angina pectoris was relieved in all patients except one, but the maximum workload during the exercise test was increased in only 3 patients. Coronary angiography showed that 37 of 45 (82%) of the distal anastomoses were open. The LV ejection fraction was the same before and after operation both at angiography and MR imaging. MR showed LV end-diastolic volume to be increased from 190 +/- 50 ml to 250 +/- 70 ml. Compared to angiography, MR provided additional information regarding myocardial wall thickness and function, and the size of myocardial infarction. Improvement in systolic wall thickening was seen in 65% of the segments that had had an end-diastolic wall thickness (EDWT) greater than 15 mm before operation, while only 4% of the segments with EDWT < 6 mm improved. In the wall thickness range of 6-15 mm, MR was unable to predict the functional outcome of the LV. CONCLUSION: Preoperative MR findings of thick myocardial walls with poor function seem predictive of improved function after revascularization. When the LV wall thickness is less than 6 mm, no improvement should be expected.

Aged↗

Extra-anatomic bypass: a new look (opposing view).

The criteria by which revascularizations are measured ultimately is patency, since cessation of blood flow equates with a failed graft and usually signals a return to the preoperative limb perfusion or less. An uncommonly analyzed criterion for graft function is blood flow capacity through the reconstruction which is critically important when increased blood flow demands are required with exercise. This is particularly true in the aortoiliac segment when the bypass must meet large blood flow requirements. When the extra-anatomic bypass is evaluated in this manner, it is often inadequate to meet the blood flow demands required with activity. The source of blood flow is the subclavian artery and not the aorta. The graft diameter is almost one half that used to bypass or substitute for the aorta and four times as long. It is not surprising, therefore, that increases in blood flow are limited in this remote subcutaneous bypass circuit. The axillofemoral and, to some extent, the femorfemoral bypass grafts produce hemodynamic gradients to blood flow increases above basal rates. Thus, graft patency alone does not realistically measure the functional capacity of an aortoiliac reconstruction. The conceptual design of an extra-anatomic bypass results in hemodynamic liabilities that produce an inferior performance to that observed with in-line direct aortofemoral bypass. This observation further supports our contention that extra-anatomic bypass of the aortoiliac segment should be restricted to circumvent a prosthetic graft infection in the aortoiliac segment to maintain limb perfusion following graft removal. Whether it has a role in selected patients with a short life span and critical ischemia who appear to be a prohibited risk for in-line aortofemoral reconstruction will always be debatable. Current experience does not justify expanded indications for extra-anatomic bypass in symptomatic patients with aortoiliac disease. The proven effective and durable intervention is aortofemoral revascularization.

Aorta, Abdominal↗

Thallium redistribution does not predict perioperative cardiac complications following vascular surgery.

Utility of preoperative stress thallium scintigraphy (STS) was determined in 59 patients, thought to be at increased risk, prior to major vascular surgery from July 1987 to February 1990. Forty-seven had oral dipyridamole and 12 underwent exercise STS. Thallium redistribution (TR) was present in 61% (n = 36); fixed defects were present in 59% (n = 35); and some combination of defects was present in 76% (n = 45). Perioperative cardiac complications (CC = congestive heart failure [n = 3], ventricular arrhythmia [n = 2], and MI [n = 1]) were present in 8.5% (6 CC in 5 patients). Incidence of CC was 8.3% (3/36) in those with TR, and 8.7% (2/23) without TR (relative risk = 0.95). Perioperative MI was present in 2.8% (1/36) with TR vs. 0% (0/23) without. Though mortality was 3.4%, no perioperative deaths were from cardiac disease. Utility of STS is not clearly established for prediction of perioperative cardiac risk after major vascular surgery.

Adult↗

Early neuromuscular customized training after surgery for lumbar disc herniation: a prospective controlled study.

A prospective and controlled study of training after surgery for lumbar disc herniation (LDH). The objective was to determine the effect of early neuromuscular customized training after LDH surgery. No consensus exists on the type and timing of physical rehabilitation after LDH surgery. Patients aged 15-50 years, disc prolapse at L4-L5 or L5-S1. Before surgery, at 6 weeks, 4, and 12 months postoperatively, the following evaluations were performed: low back pain and leg pain estimated on a visual analog scale, disability according to the Roland-Morris questionnaire (RMQ) and disability rating index (DRI). Clinical examination, including the SLR test, was performed using a single blind method. Consumption of analgesics was registered. Twenty-five patients started neuromuscular customized training 2 weeks after surgery (early training group = ETG). Thirty-one patients formed a control group (CG) and started traditional training after 6 weeks. There was no significant difference in pain and disability between the two training groups before surgery. Median preoperative leg pain was 63 mm in ETG and 70 mm in the CG. Preoperative median disability according to RMQ was 14 in the ETG and 14.5 in the CG. Disability according to DRI (33/56 patients) was 5.3 in the ETG vs. 4.6 in the CG. At 6 weeks, 4 months, and 12 months, pain was significantly reduced in both groups, to the same extent. Disability scores were lower in the ETG at all follow-ups, and after 12 months, the difference was significant (RMQ P=.034, DRI P=.015). The results of the present study show early neuromuscular customized training to have a superior effect on disability, with a significant difference compared to traditional training at a follow-up 12 months after surgery. No adverse effects of the early training were seen. A prospective, randomized study with a larger patient sample is warranted to ultimately demonstrate that early training as described is beneficial for patients undergoing LDH surgery.

Adolescent↗

Lumbar microdiscectomy in rats.

An operative method for lumbar microdiscectomy in rats is described in general terms so that it may be adapted to any microsurgical laboratory. The operation may be used as an advanced exercise in microsurgery, or to prepare surgeons for clinical lumbar microdiscectomy surgery.

Animals↗

Retrospective risk analysis for early heart-related death after cardiomyoplasty. The Worldwide Cardiomyoplasty Group.

BACKGROUND: Dynamic cardiomyoplasty is an evolving treatment for heart failure that uses an electrically stimulated latissimus dorsi muscle wrapped around the heart to improve cardiac function. Preoperative patient characteristics and deaths after cardiomyoplasty have been recorded during the past 5 years in a cumulative database representing worldwide experience of 42 medical centers. METHODS: Statistical models of hazards (monthly death rates) were used to identify risk factors for transiently increased risk of cardiovascular mortality within 2 months after cardiomyoplasty. RESULTS: Actuarial survival (n = 261) was 88%, 80%, and 76% at 1, 3, and 6 months after cardiomyoplasty, respectively. The peak hazard of 6% dying per month occurred during the first month after the surgical procedure. Lower ejection fraction, increased number of major coronary arteries with > or = 70% stenotic lesions, and lower chronotropic responses during exercise were independent risk factors for the transient increase in early cardiovascular mortality. Early risk of cardiovascular mortality was significantly reduced as centers gained experience with more than 3 patients. CONCLUSION: Early survival after cardiomyoplasty has improved with experience and might be reduced further by preoperative assessments that identify patients at highest risk.

Actuarial Analysis↗

The two-minute walk test as a measure of functional capacity in cardiac surgery patients.

OBJECTIVE: To examine construct validity and sensitivity of the two-minute walk test (2MWT) in cardiac surgery patients. DESIGN: Measurements were made in patients preoperatively, during the postoperative in-hospital stay, and 6 to 8 weeks after discharge from hospital. SETTING: Ambulatory and hospitalized care. PARTICIPANTS: Patients (N=122; mean age +/- standard deviation, 63+/-9 y) undergoing coronary artery bypass grafting. INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: The 2MWT, New York Heart Association (NYHA) functional classification for cardiac disease, the Nottingham Extended Activities of Daily Living scale, and the Medical Outcomes Survey 36-Item Short-Form Health Questionnaire (SF-36). RESULTS: Distance walked in 2 minutes decreased significantly postoperatively (from 138+/-26 m to 84+/-33 m, P<.001), but increased again at follow-up (151+/-31 m, P<.0001). Distance walked on the 2MWT correlated significantly to SF-36 (physical function subscale) preoperatively (r=.44) and at follow-up (r=.48) (P<.001). There was a significant difference in distance walked between those with NYHA class I and II compared with those classified as III or IV (P=.04). However, there was no significant difference in distance walked in 2 minutes between those who developed cardiac or pulmonary complications postoperatively (P> or =0.2). CONCLUSIONS: The 2MWT was sensitive to change after cardiac surgery and showed moderate correlation with measures of physical functioning in this population. However, the 2MWT could not identify those who developed complications in the postoperative period.

Activities of Daily Living↗

Prophylactic inspiratory muscle training in patients undergoing coronary artery bypass graft.

Pulmonary complications after cardiac surgery are a leading cause of postoperative morbidity and mortality. Respiratory muscle weakness may contribute to the postoperative pulmonary abnormalities. We hypothesized that: (1) there is a decrease in inspiratory muscle strength (PImax at residual volume) and endurance (Pmpeak/PImax) following coronary artery bypass graft (CABG); (2) this weakness is associated with reduced pulmonary function tests (PFTs), impaired gas exchange, and a higher rate of pulmonary complications; and (3) prophylactic inspiratory muscle training (IMT) can prevent those changes. Eighty-four candidates for CABG, with ages ranging from 33 to 82 years, were evaluated prior to operation and randomized into two groups: 42 patients underwent IMT using a threshold trainer for 30 min/day for 2 weeks, 1 month before operation (group A); 42 patients served as a control group and underwent sham training (group B). There was a significant decrease in respiratory muscle function, PFTs, and gas exchange in the control group following CABG, whereas these parameters remained similar to those before entering the study in the training group. The differences between the groups were statistically significant. In addition 11 (26%) patients in the control group but only 2 (5%) in the training group needed postsurgical mechanical ventilation longer than 24 hours, CABGs have a significant deteriorating effect on inspiratory muscle function, PFTs, and arterial blood gases. The decrease in these parameters can be prevented by prophylactic inspiratory muscle training, which may also prevent postsurgical pulmonary complications.

Adult↗

Dobutamine stress echocardiography predicts surgical outcome in patients with an aortic aneurysm and peripheral vascular disease.

OBJECTIVES: This study was conducted to assess the utility of dobutamine stress echocardiography for determining the presence of significant coronary artery disease and for predicting surgical outcome and long-term prognosis in patients scheduled to undergo peripheral vascular or aortic aneurysm surgery. BACKGROUND: Assessment of coronary artery disease in patients scheduled to undergo peripheral vascular surgery can avoid perioperative complications. METHODS: Dobutamine stress echocardiography was performed in 98 consecutive patients scheduled to undergo aortic or peripheral vascular surgery. Intravenous dobutamine was infused in a graded fashion, with two-dimensional digital echocardiographic monitoring of ventricular function and segmental wall motion. Group 1 (n = 70) consisted of patients who exhibited a normal response to dobutamine infusion (negative dobutamine study); group 2 (n = 23) comprised those patients with an abnormal response to dobutamine, characterized by the development of new or worsening wall motion abnormalities at rest, indicating the presence of myocardial ischemia (positive dobutamine study). Five patients with an inconclusive dobutamine study (because of inadequate heart rate) were excluded from analysis. RESULTS: No major adverse effects occurred with testing in any patient. Sixty-eight of 70 patients with a negative study had peripheral vascular or aortic surgery performed without perioperative cardiac events (2 patients refused surgery). Nineteen of 23 patients with a positive study underwent coronary angiography and all had > 50% lumen narrowing in one or more major coronary artery distributions; 13 underwent coronary artery bypass grafting or angioplasty before peripheral vascular or aortic surgery and all had an uneventful perioperative period. Four of the 10 patients from group 2 who did not undergo coronary revascularization had a perioperative cardiac event (myocardial infarction in 2, an ischemic episode requiring urgent coronary bypass grafting in 1 and congestive heart failure in 1). CONCLUSIONS: Positive and negative dobutamine study results are significant predictors of the presence or absence of perioperative events (20% vs. 0%, p = 0.003). A positive test warrants coronary angiography and further medical or surgical intervention, or both, but a negative test indicates a low likelihood of perioperative cardiac complications of aortic or peripheral vascular surgery. During the long-term follow-up period in this study (group 1 mean, 24 months; group 2 mean, 15 months), two patients (3%) from group 1 and three (15%) from group 2 developed cardiac complications (p = 0.038). Thus, dobutamine stress echocardiography is safe and can predict surgical outcome in patients undergoing aortic aneurysm repair or surgery for occlusive disease of the peripheral arteries. In addition, a negative test result is a strong predictor of decreased perioperative and long-term cardiac morbidity and mortality.

Aged↗

Depletion of atrial natriuretic peptide during longstanding atrial fibrillation.

This review focuses on the relation between atrial fibrillation (AF) and atrial natriuretic peptide (ANP). ANP is produced by the atria secondary to atrial stretch. By causing atrial stretch, acute AF leads to an increase in plasma ANP concentration, which serves to normalize haemodynamics through natriuresis and vasodilation. However, data have been reported suggesting that prolonged AF, by inflicting structural atrial damage, is associated with a reduced capacity by the atria to produce ANP. An inverse relation was thus demonstrated between the duration of AF and plasma ANP concentration. In addition, a reduced ANP response to exercise has been shown to be predictive of unsuccessful cardioversion of AF to sinus rhythm. Finally, ANP has also been shown to predict outcome after a maze operation. Outcome was poor when preoperative plasma ANP concentration was low. Moreover, a high atrial collagen content, as a measure of atrial degeneration, correlated with low ANP. These data indicate that ANP may serve as a marker of atrial integrity, which may help in selecting AF patients for therapeutic interventions.

Atrial Fibrillation↗

Bosentan induces clinical, exercise and hemodynamic improvement in a pre-transplant patient with plastic bronchitis after Fontan operation.

We present a 14-year-old pre-transplant boy with elevated pulmonary pressure and plastic bronchitis after Fontan operation despite stent fenestration, who improved with long-term oral administration of the endothelin antagonist, bosentan. Bosentan improved the patient's symptoms and aortic saturation, World Health Organization class, maximal and sub-maximal exercise capacity, Borg dyspnea index, invasively measured mean pulmonary pressure, pulmonary blood flow and pulmonary vascular resistance. This is the first literature report examining the effect of endothelin antagonism in failing Fontan circulation and showing clinical, exercise and hemodynamic improvement with bosentan in a pre-transplant Fontan patient with high pulmonary pressure and plastic bronchitis.

Abnormalities, Multiple↗

High-frequency QRS electrocardiogram predicts perfusion defects during myocardial perfusion imaging.

BACKGROUND: Changes in high-frequency (HF) QRS components of the electrocardiogram (ECG) (150-250 Hz) are more sensitive than changes in conventional ST segments for detecting myocardial ischemia. We investigated the accuracy of 12-lead HF QRS ECG in detecting perfusion defects during adenosine tetrofosmin myocardial perfusion imaging (MPI). METHODS AND RESULTS: 12-lead HF QRS ECG recordings were obtained from 45 patients before and during adenosine technetium Tc 99m tetrofosmin MPI tests. Before the adenosine infusions, recordings of HF QRS were analyzed according to a morphologic score that incorporated the number, type, and location of reduced amplitude zones (RAZs) present in the 12 leads. During the adenosine infusions, recordings of HF QRS were analyzed according to the maximum percentage changes (in both the positive and negative directions) that occurred in root mean square voltage amplitudes within the 12 leads. The best set of prospective HF QRS criteria had a sensitivity of 94% and a specificity of 83% for correctly identifying the MPI result. The sensitivity of simultaneous ST-segment changes (18%) was significantly lower than that of any individual HF QRS criterion (P < .001). CONCLUSIONS: Analysis of 12-lead HF QRS ECG is highly sensitive and reasonably specific for detecting perfusion defects during adenosine MPI stress tests and significantly more sensitive than analysis of conventional ST segments.

Adenosine↗

Early assessment of rest and exercise left ventricular function following coronary artery surgery.

Radionuclide assessment of rest and exercise left ventricular function was performed in 14 patients before, eight days after, and three months after coronary artery bypass grafting (CABG). Resting function was unaltered after operation, although mild increases in heart rate and end-diastolic volume were observed on the eighth postoperative day. In contrast, exercise function was significantly improved at both postoperative time periods. Exercise ejection fraction was 0.54 +/- 0.10 before operation, 0.73 +/- 0.12 at eight days, and 0.64 +/- 0.13 at three months. Before CABG, the exercise-induced increase in stroke volume was achieved by an increase in end-diastolic volume, whereas eight days after CABG this increase was achieved by an increase in contractility (systolic blood pressure/end-systolic volume). By three months, both contractility and end-diastolic volume increased with exercise. Thus, improvement in left ventricular function during exercise can be documented as early as eight days after coronary revascularization. This change may be less pronounced after three months of convalescence, but considerable improvement in ventricular function persists compared to preoperative assessment.

Aged↗

Selection and preparation of high-risk patients for repair of abdominal aortic aneurysms.

OBJECTIVE: To discuss the most important risk factors in patients who undergo surgical repair of an abdominal aortic aneurysm (AAA). DESIGN: This update in vascular surgical repair highlights the criteria that identify high-risk patients, the useful preoperative tests, and the perioperative measures that can aid surgical recovery. MATERIAL AND METHODS: In elective repair of AAAs, high-risk patients are those with severe coronary or valvular heart disease, decompensated chronic obstructive pulmonary disease, severe cerebrovascular disease, chronic renal failure, hepatic cirrhosis with portal hypertension, and chronic hematologic disorders associated with bleeding dysfunction. Patients with unstable or severely symptomatic heart disease should undergo preoperative coronary angiography and ventriculography. Pharmacologic stress testing is recommended for patients with clinical markers of serious coronary artery disease and other medical or physical factors that prevent any type of standard exercise stress testing. RESULTS: Our experience with high-risk patients supports conventional repair of AAAs. Our preference for the midline abdominal incision in high-risk patients is substantiated by an operative mortality rate of 5.7% in comparison with a reported 7% mortality rate for nonresective therapy. Approximately one in three high-risk patients will have a serious postoperative complication, the most common of which is a cardiac event. Most patients recover after a slightly prolonged hospital stay. CONCLUSION: Despite an increased operative risk, patients with a stable medical condition and an AAA larger than 6 cm in diameter should be considered for elective repair. High-risk patients with smaller aneurysms (5 to 6 cm in diameter) should undergo efforts to stabilize or to improve their general medical condition before elective operation.

Aged↗

Intermittent claudication in athletes.

All reported cases have occurred in the anterior tibial or rarely peroneal compartments. Case I and V in this series follow this same pattern. Case II and III are unusual in that they are the first recorded cases of this syndrome occuring in the calf of a leg. In Case IV the syndrome was present both in the anterior compartment as well as in the calf. Case III in addition, demonstrated arteriographic evidence of impairment of blood flow preoperatively which was relieved by fasciotomy. It is this author's opinion that this syndrome develops due to obstruction of venous drainage by a rise in pressure in the myofascial compartment with exercise. Perhaps it occurs in athletes because the muscle hypertrophy in these patients in greater than that in the general public and the margin of safety is reduced. It is not necessary to perform complicated or painful investigative studies to make the diagnosis. Kennelly and Blumberg state that "a convincing history is all that is necessary," and the author is in complete agreement with this statement. Fasciotomy gives complete relief and is earnestly recommended both to relieve symptoms and to prevent the catastrophic consequences of muscle necrosis. In fact, in severe cases it is best to advise cessation of physical exercise until the operation can be done in order that this severe complication does not develop.

Adult↗