Cross-Country Comparison of School Neighborhood Food Environments in Houston, Texas and Guadalajara, Mexico.

Studies in the U.S. and Mexico have observed the clustering of food resources around schools, which may promote the use of these resources. Our study characterized and compared school neighborhood food environments in Guadalajara, Jalisco, and Houston, Texas, and examined socioeconomic disparities in food resource availability across school neighborhoods. We used the Goods and Services Inventory to document the frequency and type of resources within each school neighborhood. School neighborhoods in Guadalajara had significantly more food resources than those in Houston. We found that convenience stores and table service restaurants were the most prevalent food resources in school neighborhoods in both cities. Guadalajara school neighborhoods had a higher prevalence of supermarkets and grocery stores than Houston. Low-income school neighborhoods in Guadalajara with poorly educated residents had significantly more food carts than high-income neighborhoods with more educated residents. In Houston, we found significantly more fast food restaurants and convenience stores in school neighborhoods with more educated residents than school neighborhoods with less educated residents. The influence of food resources within school neighborhoods on the dietary habits of schoolchildren should be further explored in both the U.S. and Mexico. The characterization of school neighborhood food environments can inform policymakers, city planners, and school officials who seek to implement policies to create healthier food environments.

Repair of posterior coronary lacerations.

Posterior lacerations of the coronary arteries that occur during arteriotomy should be repaired if significant. We describe a modification of the standard technique to repair posterior coronary artery lacerations. This technique avoids distortion and narrowing of the coronary artery.

Intraluminal milrinone for dilation of the radial artery graft.

There is renewed interest in the use of the radial artery as a conduit for coronary artery bypass surgery. The radial artery is, however, a very muscular artery, prone to vasospasm. Milrinone, a potent vasodilator, has demonstrated vasodilatory properties superior to those of papaverine. In this report, we describe our technique of radial artery harvesting and the adjunctive use of intraluminal milrinone as a vasodilator in the preparation of this conduit for coronary artery bypass grafting. We have used these techniques in 25 patients who have undergone coronary artery bypass grafting using the radial artery. No hand ischemic complications have been observed in this group. Intraluminal milrinone appears to dilate and relax the radial artery, rendering this large conduit spasm free and very easy to use. We recommend the skeletonization technique for radial artery harvesting and the use of intraluminal milrinone as a radial artery vasodilator in routine myocardial revascularization.

Left ventricular volume reduction and reconstruction in ischemic cardiomyopathy.

BACKGROUND: Ischemic cardiomyopathy can be the result of large or small myocardial infarctions or due to myocardial hibernation. Patients with an end-systolic volume index >100 mL¿m2 do not benefit from revascularization alone and require an operation that reduces ventricular volume. Various approaches to reduce ventricular volume have been described. We applied several of these techniques in patients with end-stage ischemic cardiomyopathy. METHODS: Forty eight patients with end-stage ischemic cardiomyopathy (Class III-IV) underwent left ventricular volume reduction operations with coronary revascularization and mitral valve repair or Alfieri valvoplasty. Fourteen patients underwent interpapillary resections, 22 anterior resections, 4 posterior resections, 2 anterior and posterior resections, and 6 patients reduction of left ventricular volume with endocavitary patches. RESULTS: All the techniques used improved left ventricular function. Analysis of mortality revealed that extensive resections (interpapillary, anterior, and posterior resection) had a 43% mortality. However, a limited resection or a ventricular reconstruction with an endocavitary patch had only a 12.5% mortality. When we changed our approach to a more conservative one, mortality was reduced from 26% the first 12 months to 13% in the last 15 months of the study. CONCLUSIONS: Ischemic cardiomyopathy has a poor prognosis if the end-systolic volume index exceeds 100 mL/m2. Various procedures exist to reduce left ventricular volume. Extensive ventricular resections improve ventricular function, but have a high mortality. This led us to use other methods of ventricular volume reduction such as more conservative resections combined with left ventricular reconstructions or ventricular volume reduction with endocavitary patches. Mortality was reduced significantly by this approach. The patients that survived have remained Class I-II in a follow-up that extends up to 30 months. Surgical therapy of Class III-IV ischemic cardiomyopathy is feasible, but aggressive ventricular resections have a high mortality. We advocate a more reconstructive approach with limited or no ventricular resection.

Surgical treatment of aortic dissections: initial experience with the adventitial inversion technique.

BACKGROUND: The adventitial inversion technique obliterates the false lumen and converts a dissected aorta into a conduit with tough adventitia on the inside and outside. Dacron grafts can be anastomosed to the aorta with fine sutures, which hold without tears. METHODS: From August 1995 to March 1997, we treated 6 patients with acute dissecting aneurysms. Three aneurysms were type I (A) involving the entire aorta, two type II (A) involving the ascending aorta, and one type III (B) involving the thoracoabdominal aorta. Circulatory arrest was used in 3 patients, 1 with type I aneurysm (A), 1 type II (A), and 1 type III (B). RESULTS: All Dacron-aorta anastomoses held sutures well and did not bleed intraoperatively or postoperatively. One patient (type II [A]) died of intraoperative low cardiac output. In patients with type I (A) aneurysms, the false lumen was obliterated, but 1 patient required resection of a 6-cm abdominal aortic aneurysm. CONCLUSIONS: The adventitial inversion technique is a safe technique for the treatment of acute dissecting aneurysms, which facilitates operation and solves the problem of intraoperative or postoperative bleeding due to tissue friability.

Damage control for thoracic injuries.

Some of the earliest damage control techniques were applied to the chest during emergency center thoracotomy. It provided a paradigm that was adapted to other areas. Damage control of chest injuries has a different philosophy than that of abdominal injuries. Damage control in the abdomen primarily consists of multiple staged operations with abbreviated closures. Damage control in the chest consists of different technical maneuvers to use quicker and technically less demanding operations to accomplish the same goal. The philosophy of doing only enough to restore a survivable physiology is still a common theme. The following are the major principles of damage control for thoracic injuries: 1. Emergency center thoracotomy is a damage control prototype. 2. Anterolateral thoracotomy is the empiric incision of choice in the patient in extremis. 3. Nonanatomically stapled lung resections, pulmonary tractotomy, and en masse lobectomy/pneumonectomy are pulmonary damage control procedures. 4. The unique physiology of the chest may require en masse closure of muscles or patch closure of the wound. 5. Cardiopulmonary physiology can be affected by packing. Packing thus has a limited role in thoracic damage control. 6. Prosthetic grafts, intravascular shunts, and ligation are common thoracic vascular damage control techniques. 7. With new technology, an increased role for cardiopulmonary bypass and cardiac assistance may develop. 8. New technology must not overly complicate a procedure if it is to be a valuable damage control adjunct.

Surgical management of renal cell carcinoma with inferior vena cava tumor thrombus.

BACKGROUND: The optimal management of patients with renal cell carcinoma with inferior vena cava tumor thrombus remains unresolved. Traditional approaches have included resection with or without the use of cardiopulmonary bypass. Chemotherapy has played a minor role except for biotherapeutic agents used for metastatic disease. METHODS: From January 1989 to January 1996, 37 patients with renal cell carcinoma and inferior vena cava tumor thrombus underwent surgical resection. The 27 men and 10 women had a median age of 57 years (range, 29 to 78 years). Thirty-six patients presented with symptoms; 21 had hematuria. Distant metastases were present in 12 patients. Tumor thrombi extended to the infrahepatic inferior vena cava (n = 16), the intrahepatic inferior vena cava (n = 16), the suprahepatic inferior vena cava (n = 3), and into the right atrium (n = 2). All tumors were resected by inferior vena cava isolation and, when necessary, extended hepatic mobilization and Pringle maneuver, with primary or patch closure of the vena cavotomy. Cardiopulmonary bypass was necessary in only 2 patients with intraatrial thrombus. RESULTS: Complications occurred in 11 patients, and 1 patient died 2 days postoperatively of a myocardial infarction (mortality, 2.7%). Twenty patients are alive; overall 2- and 5-year survival rates were 61.7% and 33.6%, respectively. For patients without lymph node or distant metastases (stage IIIa), 2- and 5-year survival rates were 74% and 45%, respectively. The presence of distant metastatic disease (stage IV) at the time of operation did not have a significant adverse effect on survival, as reflected by 2- and 5-year survival rates of 62.5% and 31.3%, respectively. Lymph node metastases (stage IIIc) adversely affected survival as there were no long-term survivors. CONCLUSIONS: Resection of an intracaval tumor thrombus arising from renal cell carcinoma can be performed safely and can result in prolonged survival even in the presence of metastatic disease. In our experience, extracorporeal circulatory support was required only when the tumor thrombus extended into the heart.

Hemodynamic effects of different pacing ratios in chronic dynamic double cardiomyoplasty.

BACKGROUND: Dynamic cardiomyoplasty is being used clinically worldwide, and evaluated by a clinical trial (phase III) in the United States. Some centers stimulate the skeletal muscle wrap with every heart beat (1:1 [muscle:heart]), whereas others use every other heart beat (1:2). Recent concern over the possible deleterious effects of too-frequent stimulation of the muscles motivated the attempt to evaluate, in a canine model of chronic, double cardiomyoplasty, the effects of two different pacing ratios on several hemodynamic parameters of interest. METHODS: Double cardiomyoplasty was performed using both latissimus dorsi muscles in 11 dogs. Fatigue resistance was achieved using the clinical transformation protocol. At a final experiment, acute cardiac failure was induced by administration of propranolol. Hemodynamic measurements of eight physiologic variables were averaged over complete pacing cycles, including the nonpaced beat at a 1:2 pacing ratio. RESULTS: The net effects of latissimus dorsi muscle stimulation at each of two pacing ratios were compared using nonparametric statistics. With the exception of left ventricular pressure (p = 0.0262) and its first derivative, dP/dt (p = 0.0099), there was no significant difference between hemodynamic performance at the two pacing ratios. CONCLUSIONS: In this canine model, pacing every other beat produces hemodynamic results that are statistically similar to pacing every beat. Less frequent stimulation of the latissimus dorsi muscle may preserve its function and improve clinical results without compromising hemodynamic benefit.

Vascular dynamics in isolated systolic arterial hypertension.

With a growing elderly population, the incidence of isolated systolic hypertension (ISH) has increased. This study characterizes dynamic vascular changes that occur with advanced age and with ISH. Fifty-five healthy individuals and seven with ISH were distributed in seven age groups from the second to the seventh decade. An index of aortic stiffness (delta P/delta V) was derived using a mercury sphygmomanometer to obtain pulse pressure, and ultrasonographic measurements were used to estimate aortic volumes applying the "cylinder formula." The mathematic derivation of this formula is explained in detail. Pulse pressure showed no significant change with age, but showed a significant increase with ISH. A decrease in volume change from systole to diastole was found with advanced age. Normotensive subjects aged 65 +/- 2 years had a 2.6-fold increase in aortic stiffness compared with young individuals. Elderly patients with ISH had a 7-fold increase in aortic stiffness compared with Group 1 (15 +/- 2 years) (p < 0.001) and a 2.7-fold increase compared with Group 6 (normotensive subjects aged 65 +/- 2 years). A strong correlation between systolic pressure and arterial stiffness was observed (r = 0.953) (p < 0.001). The proposed stiffness index was compared with the one described by Hirai, obtaining a high correlation, that is, r = 0.989 (p < 0.001). When compared with Stefanadis' index of distensibility, our index showed a correlation of r = 0.932 (p < 0.003). It is concluded that while systolic pressure is a main determinant of arterial stiffness, the delta P/delta V is a more sensitive method to estimate dynamic changes in elastic arteries such as the aorta.

Acute impairment of coronary blood flow by dynamic cardiomyoplasty.

The aim of this study was to quantify the effects of three different configurations of cardiomyoplasty on coronary blood flow in an acute dog model. Thirteen dogs had both latissimus dorsi muscles harvested and transposed to the chest. Coronary blood flow was measured using Doppler cuff probes on the left anterior descending and circumflex coronary arteries during each of three cardiomyoplasty configurations: left posterior, right anterior, and double. Multiple beat measures were made of systolic and diastolic flow during a control protocol and a subsequent protocol with the muscle(s) paced. Significant flow reductions during pacing were observed in the left anterior descending coronary artery during left posterior (17%, p = 0.003), right anterior (29%, p < 0.0001), and double (35%, p = 0.0001) myoplasty. Similar reductions occurred in the circumflex artery (14%, p = 0.0009; 20%, p = 0.001; 27%, p = 0.0053). The net flow over an entire pacing cycle also was reduced significantly: left anterior descending artery (11%, p = 0.0035; 23%, p = 0.0001; 23%, p = 0.0047) and circumflex artery (10%, p = 0.0025; 17%, p = 0.0018; 21%, p = 0.0091). Thus, in the acute setting cardiomyoplasty depresses coronary blood flow. A chronic setting will be needed to determine the ultimate significance of these results.

New configuration of double cardiomyoplasty based on studies of the length-tension properties of the latissimus dorsi muscle.

A new configuration of double cardiomyoplasty was designed according to studies of the length-tension properties of the linear latissimus dorsi muscle. Four dogs had both their right and left latissimus dorsi muscles dissected from the chest wall and attached to a tensiometer to measure force of contraction. The maximum active tension obtained with stimulation of the linear latissimus dorsi muscle was observed when the muscle was at its resting anatomic length and up to 5% above this length. Eight dogs had a double cardiomyoplasty in which the resting anatomic length of both muscles was maintained. Control hemodynamic parameters obtained with the muscles at rest were compared with stimulated muscle protocols. In a normal heart state, stimulation of the double cardiomyoplasty increased the cardiac output 32% (p < 0.05), the stroke volume 39% (p < 0.05), and the left ventricular pressure 42% (p < 0.05). When acute heart failure was induced with high-dose intravenous propranolol (5 mg/kg), stimulation of the double cardiomyoplasty increased the cardiac output 32% (p = 0.01), the stroke volume 32% (p < 0.05), rate of pressure rise 39% (p < 0.01), and myocardial thickening 39% (p < 0.01). The study demonstrated that this configuration of double cardiomyoplasty provides significant hemodynamic assistance in the normal and acutely failing canine heart.

Benign cystic lymphoepithelial lesion of the parotid gland an unusual presentation of the acquired immunodeficiency syndrome.

This article presents a case of a young, otherwise asymptomatic male patient with a parotid gland enlargement. The initial clinical history did not reveal any risk factors related with HIV infection. A fine needle aspiration biopsy of the lesion showed a benign cystic lymphoepithelial lesion of the parotid gland. This once unusual lesion of the salivary gland has been recently associated with infection by the human immunodeficiency virus (HIV) and is presently encountered with increased frequency in the clinical practice. The knowledge of the association between these two entities led, in this case, to the diagnosis of HIV infection in an otherwise asymptomatic patient. Early detection of HIV infection is of vital importance since it has been demonstrated that prompt treatment of these patients with AZT slows down the progression of the disease.

Cholecystectomy and right colon cancer in Puerto Rico.

A case-control study was undertaken to evaluate the possible relationship between cholecystectomy and right colon cancer. Two hundred patients with adenocarcinoma of the cecum or ascending colon (diagnosed between 1984 and 1989) were compared with 200 matched neighborhood controls. Cholecystectomy history was obtained through interviews using structured questionnaires and subsequently validated from hospital records. A statistically significant association (odds ratio = 2.14) was found between right colon cancer and a history of prior cholecystectomy. The altered bile metabolism which occurs after removal of the gallbladder may have a carcinogenic effect on the right colon. Dietary habits of the colon cancer patients in our study were consistent with prior reports in the literature, showing that this group has a lower intake of vegetables and cereal fiber than the control population.