PubMed Health⌕ Search

Biomedical subjects

Z C Weng

Publications and source records attributed to Z C Weng.

14 recordsLinked to original sources
PubMed1994

Effects of perfusion-induced edema on diastolic stress-strain relations in intact swine papillary muscle.

The mechanism through which edema reduces left ventricular compliance has not been defined. Accordingly, diastolic properties of in situ left ventricular swine papillary muscles were studied in three groups: control (n = 6, 4 degrees to 6 degrees C), edematous (150 mOsm/L coronary perfusion, n = 6, 4 degrees to 6 degrees C), and ischemic contracture (n = 8, 28 degrees C). Lagrangian stress (sigma) and strain (epsilon) were calculated from slow stretch data and approximated by sigma = alpha(e beta epsilon-1). The natural logarithm of stress versus strain was linear over the physiologic range of 0.05 < strain < 0.40. Hypotonic perfusions (1 L x 3) progressively shifted the stress-strain relationship upward and to the left. Compared to baseline, alpha increased significantly (p < 0.05) after perfusion 3 (6.7 +/- 2.1 baseline, 12.2 +/- 6.6 perfusion 1, 12.7 +/- 3.5 perfusion 2, and 42.9 +/- 16.3 gm/cm2 perfusion 3). The constant beta did not change significantly (13.0 +/- 1.5 baseline, 13.1 +/- 1.6 perfusion 1, 13.2 +/- 1.6 perfusion 2, and 14.1 +/- 1.4 perfusion 3). Right ventricular water content increased after each perfusion (77.1% +/- 1.4% baseline, 81.6% +/- 1.3%, 84.7% +/- 1.5%, and 86.9% +/- 1.7%, p < 0.05). With ischemic contracture, alpha increased from 61.9 +/- 17.8 to 173.1 +/- 61.5 gm/cm2 (p > 0.05) and beta increased insignificantly from 6.5 +/- 0.6 to 10.6 +/- 1.8 (p = NS). In the control group all variables were unchanged after 210 minutes. We conclude that myocardial stiffness increases with myocardial edema. This may explain decreased compliance in the edematous left ventricle.

Animals↗
PubMed1994

Synchronous carotid endarterectomy and myocardial revascularization.

BACKGROUND: The management of the coexisting extracranial carotid and coronary disease is still controversial. We reviewed our experience in synchronous operation for both diseases in Veterans General Hospital-Taipei. METHODS: From Jan. 1988 to Nov. 1992, the synchronous carotid endarterectomy and myocardial revascularization were performed in nine patients with the mean age of 66.6 +/- 11 years. Five had symptomatic extracranial vascular disease or stabilized neurological deficits, and four had asymptomatic carotid bruits. Four had bilateral hemodynamically significant carotid stenosis. NYHA functional class III-IV was noted in three patients. Triple-vessel coronary disease was documented in 6 patients including one with left main lesion more than 50%. Eight had previous or recent myocardial infarction and four had moderate to severe left ventricular dysfunction noted on left ventriculography. RESULTS: All nine patients received unilateral carotid endarterectomy and a mean number of 2.8 distal anastomosis. Operative number of 2.8 distal anastomosis. Operative mortality within 30 days was zero and morbidity was noted in two patients. One patient was CVA and the other one was perioperative myocardial infarction. Late mortality occurred in previous two patients with morbidity. Late morbidity was mainly due to cardiac rather than neurological problems. CONCLUSIONS: If long-term natural history of coronary or carotid artery disease could be actually altered by surgery, a systemic evaluation for possible multifocal atherosclerosis is mandatory. By following a proposed guideline, synchronous operation is appropriate for a subgroup of patients with coexisting carotid and coronary artery disease.

Aged↗
PubMed1993

Quantitative effects of myocardial edema on the left ventricular pressure-volume relation. Influence of cardioplegia osmolarity over two hours of ischemic arrest.

We previously studied edema and left ventricular pressure-volume relations in a porcine heart model in which edema occurred even with hyperosmolar crystalloid cardioplegia. This susceptibility to edema was attributed to venous occlusion and an initial 20-minute period of ischemia. Results did not demonstrate reversal of edema by hyperosmolar perfusates. Accordingly, in the present study, heart weight, myocardial water content, and left ventricular pressure-volume curves were measured before and after perfusion-induced edema in eight isolated, arrested, hypothermic porcine hearts. Cardioplegic solution was infused 2.1 +/- 0.8 minutes after the onset of ischemia, and the atrioventricular ring was not clamped during the administration of cardioplegic solution. Cardioplegic solution (1 L) was infused at intervals of 33 +/- 6 minutes at 4 degrees C. Solution osmolarity was 380 (Stanford solution) or 294 mOsm/L (Plegisol solution). The perfusion sequence was 380-1, 380-2, 294-1, 380-3. Pressure-volume relations were assessed with the use of left ventricular volume at a pressure of 10 mm Hg and the ventricular chamber stiffness constant, beta, derived from P = alpha e beta V. Perfusions 380-1 and 380-2 did not affect the pressure-volume curve. Perfusion 294-1 increased heart weight and water content (p < 0.05) and decreased left ventricular volume at 10 mm Hg compared with perfusions 380-1, 380-2, and 380-3. In addition, beta increased (0.023 +/- 0.005 versus 0.029 +/- 0.006, p < 0.05) after perfusion 294-1, compared with 380-1. Correlation coefficients for linear regressions between left ventricular volume at 10 mm Hg and heart weight and water content were r = 0.84 and r = 0.70, respectively. We conclude that under conditions similar to those used clinically, the left ventricle of the pig does not develop edema with Stanford solution (380 mOsm/L). Edema does follow Plegisol solution (294 mOsm/L) cardioplegia. Edema and reduced compliance are incompletely reversed by hypertonic cardioplegia. The porcine left ventricle can usefully replicate the clinical model.

Animals↗
PubMed1992

A new autoperfusion technique for aortic reconstruction of suprarenal aortic aneurysm.

Visceral ischemia is a serious factor in the postoperative morbidity and mortality of suprarenal aortic reconstruction. We reported two patients of suprarenal aortic aneurysm involving visceral arteries, who received successful Dacron graft replacement by using Pruitt-Inahara balloon catheters as an autoperfusion for preservation of the visceral organs. No visceral organ ischemia occurred postoperatively except in patient 2 who had preoperative chronic renal failure and persistent renal failure after the operation. The renal function recovered gradually during the follow-up period. Both patients are doing well at the present time. The new autoperfusion technique can directly deliver normothermic blood from the arterial cannula at proximal aorta to the individual visceral arteries by using the balloon perfusion catheters. It is simple, safe, easily instituted and the used products are readily obtainable. It allows the surgeon to provide an effective protection of visceral organs for the suprarenal aortic reconstruction.

Aged↗
PubMed1992

Effects of crystalloid, blood, and University of Wisconsin perfusates on weight, water content, and left ventricular compliance in an edema-prone, isolated porcine heart model.

Coronary perfusion with blood and cardioplegic solutions was examined in isolated, arrested, hypothermic porcine hearts. Myocardial water content, heart weight, and left ventricular diastolic pressure-volume curves were measured before and after coronary perfusion. Statistics were based on exponential curve fitting to pressure-volume data and analysis of variance. Thirty-two pig hearts were divided into five experimental groups and a control group; after control measurements, each experimental group underwent three successive coronary perfusions with 1 L of unmodified blood or a solution of controlled osmolarity, 150 mOsm/L (diluted Plegisol solution), 280 mOsm/L (Plegisol solution and albumin), 334 mOsm/L (University of Wisconsin solution), or 380 mOsm/L (Stanford solution). After each perfusion, measurements were repeated. All experiments were completed within 90 minutes. The first perfusion was delayed 20 minutes after excision of the heart to allow for instrumentation. Each experimental group demonstrated a statistically significant increase in heart weight and myocardial water content and a significant decrease in left ventricular compliance after perfusion. Changes were less pronounced with blood than crystalloids. Edema effects were minimized but not prevented by hyperosmolarity. University of Wisconsin solution appeared unique in minimizing progressive edema after the first perfusion. Over the 81 perfusions studied, changes in left ventricular compliance were linearly related to heart weight and water content. We conclude that in this model, in which edema sensitivity is increased by delayed perfusion and venous occlusion, edema is minimized but not eliminated by whole blood and University of Wisconsin solution. The model appears useful in assessing properties of cardioplegia vehicles intended for use in the injured myocardium.

Adenosine↗
PubMed1991

[Double aortic arch associated with severe left ventricular dysfunction--a case report].

A case of a 3-month-old male infant with severe LV dysfunction and a complete double aortic arch (both arches patient) is reported. The right dominant aortic arch runs retroesophageally to the right and joins with the left smaller arch to form the descending thoracic aorta on the right side while the ligamentum arteriosum was located in its normal position (the left side). Through a left thoracotomy, the smaller left arch and the ligamentum were divided to relieve the obstruction of the trachea from compression of the vascular ring. Postoperative convalescence was good. Further follow up of this patient after 9 months showed that there was neither any respiratory failure nor any heart failure sign present, though severe LV dysfunction persisted.

Aorta, Thoracic↗
PubMed1991

The influence of myocardial edema after coronary perfusion on left ventricular compliance of isolated ischemic porcine hearts.

The effects of myocardial edema on left ventricular (LV) compliance were studied in the isolated, arrested, hypothermic porcine heart. Myocardial water content, heart weight, and diastolic pressure-volume curves were measured before and after coronary perfusion with different coronary perfusates used to induce edema. Five control hearts without coronary perfusion showed no significant changes in LV compliance after 90 minutes of ischemia as assessed by the exponential ventricular stiffness constants, beta, (0.016 +/- 0.003 vs 0.018 +/- 0.007) and by corresponding volume at 15 mmHg LV filling pressure (LVV-15, 77 +/- 15 ml vs 77 +/- 14 ml). Sixteen pig hearts were divided into three experimental groups; after control measurements, each group underwent coronary perfusion with one liter of a solution of graded osmolarity, 380 (n = 6), 280 (n = 5), or 150 (n = 5) mOsm/L. Following perfusion, measurements were repeated. Each group demonstrated increasing heart weight (233 +/- 16 g vs 259 +/- 24 g, 380 group; 186 +/- 23 g vs 228 = +/- 24 g, 280 group; 190 +/- 20 g vs 254 +/- 34g, 150 group; p less than 0.05) and decreasing LVV-15 (81 +/- 13 mL vs 67 +/- 10 mL, 81 +/- 11 mL vs 57 +/- 16 mL, 77 +/- 14 mL vs 21 +/- 11 mL, respectively, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1990

Experimental implantation of human umbilical vein grafts in dogs.

Locally produced human umbilical vein grafts (HUVG), using glutaraldehyde as a stabilizing agent, were implanted into 24 mongrel dogs. Different arterial bypass procedures, using HUVG, were carried out in three experimental groups. In Group I, 2 dogs underwent femorofemoral crossover bypass procedures and 6 dogs received aortoiliac bypass procedures. Thrombus formation was found in all HUVG implants of Group I. In Group II, 8 dogs received abdominal aorta HUVG interposition. In Group III, 8 dogs received abdominal aorta HUVG bypass procedures. Patent HUVG implants without thrombus formation, demonstrated by postoperative angiogram, were found in 6 dogs of Group II and 5 dogs of Group III. Morphological and histological studies of the patent HUVG implants retrieved after sacrifice showed on sign of rejection, biodegeneration, or aneurysmal formation. Our preliminary experience with this cost-effective locally produced human umbilical vein graft material was promising and may pave the way to further clinical applications.

Animals↗
PubMed1990

[Humoral factors in the modulation of sustained discharges of polymodal nociceptors].

By using a model of sustained discharges of polymodal nociceptors (PMN) due to injection of a compound algogenic substance into the skin in anesthetized rats, it was found that stimulation of the sciatic nerve inhibited or facilitated at first and then inhibited the PMN sustained discharges markedly. In a crossperfused preparation, stimulation of the sciatic nerve of donor rat caused the similar effects on sustained discharges of PMN of the recipient rat. Injection of the animal serum after stimulation of the sciatic nerve affected PMN activity obviously. The inhibitory course of most units could not be reversed by naloxone. In the animal tolerance to morphine, the effects of stimulation of the sciatic nerve could still be obtained. Preadministration of reserpine almost completely abolished the facilitatory effect. The results indicate that sustained activity of PMN could be modulated by some humoral factors due to somatic afferents. The inhibitory substances in the humoral factor seem to be both opioid and nonopioid in nature. The facilitatory substance seem to be a catecholamine.

Acupuncture Analgesia↗
PubMed1990

Simulated left ventricular aneurysm and aneurysm repair in swine.

Patch reconstruction of left ventricular aneurysm may be superior to linear closure, but this hypothesis has not been tested experimentally. Accordingly, six anesthetized domestic pigs were instrumented to measure regional left ventricular wall thickening, stroke volume, systolic left ventricular pressure, and myocardial oxygen consumption. With total bypass and cardioplegia, a 6 by 8 cm Dacron patch was inserted into the anteroapical left ventricle. Simulations were as follows: left ventricular aneurysm, patch open; patch reconstruction, 50% patch plication; standard repair, ventriculotomy edges approximated. Global function, from stroke work (stroke volume x integral of left ventricular pressure)-left ventricular end-diastolic pressure curves, was depressed in all three simulations compared with control. A tendency for stroke work to be greater for standard repair than for left ventricular aneurysm and patch reconstruction at higher preloads was not statistically significant. Mechanical efficiency, from stroke work/myocardial oxygen consumption (joules per milliliter oxygen per beat), was 2.43 +/- 0.52 (mean +/- standard error of the mean) (control), 2.22 +/- 0.94 (standard repair), 1.27 +/- 0.39 (patch reconstruction), and 1.09 +/- 0.37 (left ventricular aneurysm) (no significant differences). Regional work was calculated as regional left ventricular wall thickening x integral of left ventricular pressure. The slope of the regional work-end-diastolic wall thickness relation decreased in the posterior wall 14.0 +/- 2.9 (control) versus 8.4 +/- 2.0 (left ventricular aneurysm), 6.9 +/- 1.4 (patch reconstruction), and 7.4 +/- 1.4 (standard repair) (p less than 0.05). In the anterior wall, contractility did not change significantly (7.4 +/- 1.2, control; 7.8 +/- 2.7, left ventricular aneurysm; 5.0 +/- 0.4, patch reconstruction; and 5.3 +/- 0.4, standard repair). Decreased end-diastolic wall thinning anteriorly suggested tethering. These results in the normal left ventricle suggest that patch ventriculoplasty is of no greater benefit than linear repair. Either repair may impede function of adjacent myocardium through restriction of regional diastolic lengthening.

Animals↗
PubMed1990

[Results of vascular reconstruction in lower limbs ischemia: a six-year clinical experience].

During the period between Dec. 1982 to Nov. 1988, a total of 412 patients with 471 limbs at risk of peripheral arterial occlusive disease underwent vascular surgical treatment at the Veterans General Hospital. There were 382 men and 30 women, who ranged in age from 20 to 84 years (mean 63.17 +/- 11.85 years). 95 cases were isolated aortoiliac occlusive disease, 94 cases were combined aortoiliac and femoropopliteal disease, 169 cases were femoropopliteal occlusive disease and 54 cases were femorotibialperoneal occlusive disease. Various reconstructive procedures were performed in the these patients. The cumulative limb salvage rate (LSR) exceeded cumulative patency rate (CPR) in all categories and the result of LSR and CPR were 97.6% and 91% for aortoiliac reconstructive surgery in six years, 96% and 77% for above-knee femoropopliteal saphenous vein bypass (SVB) in six years, 79% and 74% for below-knee femoropopliteal SBV and 63% and 34% for femoro-distal SVB in five years. 88% and 76% for above-knee femoropopliteal human umbilical vein (HUV) bypass in four years. 67% and 45% for femoro-distal HUV bypass in three years follow-up period individually. The immediate good symptomatic results of the vascular reconstruction was 88% encountered in isolated aortoiliac disease, 63% in combined aortoiliac and femoropopliteal disease, 70.4% in isolated femoropopliteal disease and only 26% in femorotibial-peroneal disease (FTP). No change symptoms was still higher (33%) in FTP than the other vascular reconstruction due to poor distal runoff in this series. The early postoperative mortality rate was 1.6%, the late mortality rate was 2.7%, the incidence of postoperative complication rate was 13.6%. The major lower limb amputation rate was low as 7% in our series.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗