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PubMed1995

Effects of isoflurane on regional pulmonary blood flow during one-lung ventilation.

Isoflurane has been reported to inhibit hypoxic pulmonary vasoconstriction. However, the effects of one-lung ventilation and isoflurane on regional pulmonary blood flow (Qr) have not been investigated in detail. Therefore, using radionuclide labelled microspheres we measured Qr in rabbits (n = 8) in the left lateral decubitus position during two- and one-lung ventilation under i.v. baseline anaesthesia and during additional administration of 1.5% isoflurane. Macrohaemodynamic variables were recorded continuously. Isoflurane increased non-dependent lung blood flow during two-lung ventilation. One-lung ventilation caused a homogeneous decrease in Qr throughout the hypoxic lung, irrespective of isoflurane administration (P < 0.001). However, isoflurane significantly augmented Qr of the hypoxic lung during one-lung ventilation (P < 0.05). During all phases, Qr of the upper lobe was higher compared with that in the lower lobe in isogravitational slices of both lungs; a ventrodorsal perfusion gradient was found in the left upper lobe. We conclude that 1.5% isoflurane increased perfusion of the non-dependent lung, inhibited hypoxic pulmonary vasoconstriction-induced redistribution of pulmonary blood flow and did not influence isogravitational perfusion gradients.

Anesthesia, Intravenous↗

PubMed1992

Myocardial dysfunction in ankylosing spondylitis.

Echocardiographic evidence has suggested abnormalities of the myocardial function in patients with ankylosing spondylitis. In this work the cardiac function in patients with ankylosing spondylitis and in normal volunteers was evaluated. Twenty four normal volunteers and 21 patients with ankylosing spondylitis aged 18-45 were studied. None had overt cardiac disease. Cardiac function was assessed at rest with echocardiography, at rest and during supine bicycle exercise using radionuclide angiography in the left anterior oblique position following equilibration with 740 MBq of technetium-99. The subjects undertook supine bicycle exercise with 30 W increments every three minutes to the point of fatigue. Comparison of data from normal volunteers and patients with ankylosing spondylitis were made using Student's t test for independent samples or the Mann-Whitney non-parametric technique, as appropriate. Subjects were matched for age, sex, height, and weight. There were no echocardiographic differences; however, global nuclide left ventricular function showed several differences between normal volunteers and patients with ankylosing spondylitis. The peak filling rate during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 6.5 (SD 1.2); patients with ankylosing spondylitis 5.7 (1.2). The time to reach peak filling during exercise was significantly lower in patients with ankylosing spondylitis: normal volunteers 102 (22); patients with ankylosing spondylitis 120 (23). Regional analysis also showed differences between patients with ankylosing spondylitis and normal volunteers both at rest and during exercise. In the anteroseptal region the filling fraction and peak filling rate were significantly lower in patients with ankylosing spondylitis. Most of the differences (although not all) were in the variables of diastolic function. This study shows that there are subtle abnormalities in cardiac function in patients with ankylosing spondylitis. The major abnormalities are in the diastolic function, suggesting a decrease in left ventricular compliance.

Adult↗

PubMed2006

Association between major depressive symptoms in heart failure and impaired regional cerebral blood flow in the medial temporal region: a study using 99m Tc-HMPAO single photon emission computerized tomography (SPECT).

BACKGROUND AND PURPOSE: Depressive symptoms are frequently associated with heart failure (HF), but the brain mechanisms underlying such association are unclear. We hypothesized that the presence of major depressive disorder (MDD) emerging after the onset of HF would be associated with regional cerebral blood flow (rCBF) abnormalities in medial temporal regions previously implicated in primary MDD, namely the hippocampus and parahippocampal gyrus. METHOD: Using 99mTc-SPECT, we measured rCBF in 17 elderly MDD-HF patients, 17 non-depressed HF patients, and 18 healthy controls, matched for demographic variables. Group differences were investigated with Statistical Parametric Mapping. RESULTS: Significant rCBF reductions in MDD-HF patients relative to both non-depressed HF patients and healthy controls were detected in the left anterior parahippocampal gyrus and hippocampus (ANOVA, p=0.008 corrected for multiple comparisons) and the right posterior hippocampus and parahippocampal gyrus (p=0.005 corrected). In the overall HF group, there was a negative correlation between the severity of depressive symptoms and rCBF in the right posterior hippocampal/parahippocampal region (p=0.045 corrected). CONCLUSIONS: These findings are consistent with the notion that the medial temporal region is vulnerable to brain perfusion deficits associated with HF, and provide evidence that such functional deficits may be specifically implicated in the pathophysiology of MDD associated with HF.

Aged↗

PubMed1995

Solid aneurysmal bone cyst with pathologic bone fracture.

A patient is presented with solid aneurysmal bone cyst of the left proximal femur and a pathologic bone fracture in this region. The radiological and histological features of this lesion are described. While a conventional aneurysmal bone cyst is an expanding osteolytic lesion consisting of blood-filled spaces of variable size, separated by connective tissue containing bone trabeculae or osteoid tissue and many osteoclastic giant cells, a solid aneurysmal bone cyst is an unusual solid bone lesion with fibroblastic, osteoclastic, osteoblastic, aneurysmal, and fibromyoxid elements. The differential diagnosis includes giant cell tumor and fibroblastic osteosarcoma as well as specific bone reactions (bone fracture, reparative giant cell granuloma in hyperparathyroidism, giant cell reaction of short tubular bones). Solid aneurysmal bone cyst is a tumor-like lesion and probably a special bone reaction to damage; it has a good prognosis. Usually curettage is curative.

Bone Cysts, Aneurysmal↗

PubMed1992

Effects of the serotonin-antagonist ketanserin on the function of ischaemic and normally perfused myocardium and modification by beta-1-blockade in anaesthetized normotensive dogs.

The 5-HT-2 antagonist ketanserin (KAS) has been successfully used to treat acute hypertension in coronary bypass surgery. The present study was performed to investigate the effect of KAS on ischaemic myocardium. In 11 anaesthetized (piritramide) dogs, systolic contraction (sdL) and end-diastolic length (edL) of myocardium supplied by the left descending coronary artery (LAD) and the left circumflex coronary artery (LCX) were measured by sonomicrometry simultaneously with aortic pressure (AoP), left ventricular dP/dtmax and end-diastolic pressure (LVedP), heart rate (HR), stroke volume, and LAD flow (QLAD). Regional ischaemia to decrease sdLLAD (-48%) was achieved by LAD stenosis (QLAD -47%). Concomitantly, edLLAD increased by 8%. However, the other variables did not change. Then KAS was given i.v. (0.15 + 0.15 + 0.30 + 0.6 mg/kg) at 15-min intervals. Following KAS, prestenotic sdLLAD recovered in a dose-dependent manner. LVedP and edLLAD decreased, sdLLCX increased, and the other variables were not affected. This functional recovery of ischaemic myocardium was attenuated by pretreatment with metoprolol (MET, 1 mg/kg) prior to LAD stenosis. The ischaemic area was not irreversibly damaged, however, as proven by the recovery of prestenotic sdLLAD values after release of the stenosis. The improved systolic shortening of ischaemic myocardium following KAS did not result from restored QLAD due to post-stenotic vasodilation or break up of platelet aggregates (QLAD did not increase) or from reduced afterload (AoP did not decrease). Obviously, it was mediated by beta-1-receptors, as shown by the attenuation of the beneficial effect of KAS by pretreatment with MET.

Adrenergic beta-Antagonists↗

PubMed1990

Pretrial EEG coherence as a predictor of semantic priming effects.

Twenty subjects were presented 240 randomized trials of a lexical decision task (LDT) while connected to a 16-electrode EEG montage. EEG data were acquired for 2 sec prior to the onset of each LDT trial. Alpha (9-13 Hz) coherence, alpha power, and 3- to 30-Hz power from five different combinations of EEG electrodes were used to predict semantic effects in the LDT trials. High pretrial coherence in the Right Hemisphere and Left Posterior-Parietal regions was associated with greater semantic facilitation (faster reaction times) in related-prime trials and greater semantic inhibition (slower reaction times) in unrelated-prime trials, relative to neutral-prime trials. No power variables were associated with semantic effects. Results support an information flow model of the functional significance of EEG coherence to cognitive processing.

Adult↗

PubMed1984

Neurologic deficit and cerebral ATP depletion after temporary focal ischemia in cats.

Focal ischemia was induced in 23 cats by occluding the left middle cerebral artery for 2 h. The animals were then divided into groups for unforced reperfusion of variable duration ranging from 2 to 48 h. Neurological ratings were obtained during both ischemia and reperfusion. Following planned sacrifice the regional ATP content was assessed by means of a bioluminescence method showing spatial distribution and degree of ATP depletion. All the animals developed a neurologic deficit, with a median of 6 points on a disability scale of 0-10. After reopening of the middle cerebral artery, neurologic recovery was quite variable depending on the initial neurologic deficit (partial phi = 0.67, p1 less than 0.05): Animals with mild initial functional impairment improved and those with severe neurologic disturbances either died early or developed a more severe neurologic deficit, irrespective of the duration of reperfusion. The degree of ATP depletion and the amount of brain tissue involved exhibited a significant correlation with the neurological outcome (tau = 0.50, p1 less than 0.05), but they were even more closely related to the initial neurologic deficit (partial phi = 1.00, p1 less than 0.001), suggesting an early definitive manifestation of deficiencies in regional energy metabolism.

Adenosine Triphosphate↗

PubMed1985

Neuroectodermal neoplasms arising in congenital nevi.

Congenital giant nevi of neuroectodermal origin are composed predominantly of melanocytes and occasional neural elements. Neoplasms arising in such nevi may be morphologically heterogeneous with variable clinical behavior. We report the case of a female infant born with multiple pigmented nevi, including a giant hairy nevus of bathing trunk distribution in which arose a large pedunculated mass involving the sacral region, buttocks, perineum, and left thigh. Within this neoplasm, mixtures of neural crest-derived tissues having both melanocytic (nevus) cell and neural supportive (neuroid of Schwannian) cell differentiation were identified. The neural differentiation, which was seen in the dermis and subcutaneous tissue, had a neurofibromatous appearance and demonstrated multiple pseudomeissnerian corpuscles. In addition, at 16 months of age the child developed a malignant melanoma in the flank region of this congenital giant nevus. The morphologic pluripotentiality of the primitive neural crest derivatives in congenital nevi has only recently been elucidated. These lesions should be regarded as neuroectodermal neoplasms and subclassified according to their differentiating histologic characteristics because prognosis and management are influenced by morphologic determinants.

Buttocks↗

PubMed1990

Effect of thromboxane receptor blockade on oxygen supply/consumption variables during reperfusion in the anesthetized dog.

The thromboxane A2/PGH2 receptor antagonist SQ 30,741 has been previously shown to reduce infarct size and to improve subendocardial reflow. The purpose of this study was to determine the effect of SQ 30,741 on reperfusion O2 supply/consumption variables. Anesthetized open-chest dogs treated with vehicle or 1 mg/kg + 1 mg/kg/hr SQ 30,741, i.v. (starting 10 min after the onset of ischemia) were subjected to 90 min left circumflex coronary occlusion and 3 hr reperfusion. Regional myocardial blood flow (radioactive microspheres) and arterial and venous O2 saturations (microspectrophotometry) were determined. Animals treated with SQ 30,741 had significantly higher subendocardial reflow at 3 hr (48 +/- 6 ml/min/100 g) compared with vehicle (27 +/- 10 ml/min/100 g). At 3 hr postreperfusion, O2 extraction was significantly higher in the reperfused region compared with the nonischemic region, although extraction was not at maximal values. O2 extraction was similar in vehicle- and SQ 30,741-treated animals despite the near doubling of reflow into the subendocardial region with SQ 30,741. O2 consumption was significantly reduced in the reperfused subendocardial region (1.65 +/- 0.9 ml O2/min/100 g) in vehicle controls compared with the nonischemic subendocardial region (10.2 +/- 2.6 ml O2/min/100 g). SQ 30,741 significantly improved subendocardial reperfused regional O2 consumption (4.03 +/- 0.41 ml O2/min/100 g) compared with vehicle and this increase was proportional to the flow increment (no change in the O2 supply/consumption ratio). SQ 30,741 is thus increasing subendocardial reflow secondary to an increase in O2 consumption and the increased O2 consumption may be due to preservation of myocardial tissue.

Animals↗

PubMed1990

Comparison of fixed and variable temporal resolution methods for creating gated cardiac blood-pool image sequences.

In each of 50 resting subjects, two gated blood-pool image sequences were created from the same LIST mode data set. One sequence was created using a sorting method that spans each individual cardiac cycle with the same number of images (the "variable temporal" or VT method), while the other (the "fixed temporal" or FT method) spans the average cardiac cycle with images of fixed temporal duration. Left ventricular time-activity curves were extracted from each sequence using identical regions-of-interest and analyzed with identical methods to obtain estimates of ejection fraction, peak ejection rate, peak filling rate, and the times of occurrence of these peak rates. Differences among certain of these parameters in kind and amount support the hypothesis that estimates of resting cardiac function are more accurately portrayed by the FT method. The magnitudes of these differences are small for systolic parameters but large for early diastolic parameters. Thus, although both methods might be used for measuring systolic function, the FT method will yield a more accurate estimate of peak filling rate in resting subjects.

Gated Blood-Pool Imaging↗

PubMed1989

Genetic variation of African swine fever virus: variable regions near the ends of the viral DNA.

Restriction endonuclease maps of the variable DNA regions of African swine fever virus field isolates from the Iberian peninsula showed that the changes in length are located in the terminal-inverted repetitions and in unique sequences close to the DNA ends. Analysis of nine clones derived from the spleen of an infected pig revealed the existence of frequent length changes within the inverted terminal repetitions. In each clone, changes occurred symmetrically at both terminal-inverted repetitions, suggesting the existence of a terminal-inverted repetition transposition or correction mechanism. Large deletions in unique sequences were detected more frequently in the region located from 8 to 20 kb from the left DNA end. The analysis of this DNA segment from a virulent African swine fever virus isolated in Lisbon (LIS57) showed that this virus strain contains about 8 kb more DNA sequence than the prototype avirulent virus strain (BA71). Hybridization of the additional sequences from LIS57 virus with DNA from different virus field isolates revealed that this DNA region is highly variable in vivo and that it contains several repeated sequences. DNA sequences present around the deletion end points in the variable regions indicate that the deletion process may take place by both homologous and nonhomologous recombination.

African Swine Fever Virus↗

PubMed2006

Regional low-flow perfusion versus circulatory arrest in neonates: one-year neurodevelopmental outcome.

BACKGROUND: Regional low-flow perfusion of the brain is a bypass technique commonly used during stage 1 reconstruction in neonates with hypoplastic left heart syndrome and related variants. The neurodevelopmental outcome of these children is unknown. METHODS: Twenty-nine infants (22 boys, 7 girls) with hypoplastic left heart syndrome or variant requiring single ventricle palliation and aortic arch reconstruction were studied between 1999 and 2004. Mental Developmental Index (MDI) and Psychomotor Developmental Index were assessed using Bayley Scales of Infant Development and correlated with intraoperative and perioperative variables. Results are reported as mean +/- standard deviation. RESULTS: Average age at stage 1 operation and at bidirectional Glenn was 7 +/- 8 days and 6.0 +/- 2 months, respectively. The MDI was in the low average range (87.7 +/- 13.2). The Psychomotor Developmental Index was in the mildly delayed range (75.2 +/- 14.5). Regional low-flow perfusion was used in 31% (9 of 29 patients), with an average circulatory arrest time of 23.5 +/- 13.4 minutes. Deep hypothermia and circulatory arrest was used as the primary operative strategy in 69% of patients (20 of 29 patients), with an average circulatory arrest time of 44.3 +/- 15.3 minutes (p = 0.003). No differences in MDI or Psychomotor Developmental Index scores were observed between the regional low-flow perfusion and non-regional low-flow perfusion groups (MDI, 88.0 +/- 12.1 versus 87.6 +/- 14.0; p = 0.93, respectively; Psychomotor Developmental Index, 75.5 +/- 15.1 versus 75.0 +/- 14.6; p = 0.93, respectively). Lowest operative temperature (<16 degrees C) and birth order (<2 versus >3) significantly related to MDI (89.6 versus 72.8; p = 0.047). CONCLUSIONS: At 1 year of age, neurodevelopmental outcomes of patients undergoing stage 1 using regional low-flow perfusion were similar to outcomes observed in children exposed to circulatory arrest. The association of birth order and MDI suggests that early intervention may benefit these patients.

Cardiac Surgical Procedures↗

PubMed2006

Predictors of left ventricular regional wall motion abnormalities after subarachnoid hemorrhage.

INTRODUCTION: Cardiac abnormalities that have been reported after subarachnoid hemorrhage (SAH) include the release of cardiac biomarkers, electrocardiographic changes, and left ventricular (LV) systolic dysfunction. The mechanisms of cardiac dysfunction after SAH remain controversial. The aim of this study was to determine the prevalence of LV regional wall motion abnormalities (RWMA) after SAH and to quantify the independent effects of specific demographic and clinical variables in predicting the development of RWMA. METHODS: Three hundred patients hospitalized with SAH were prospectively studied with serial echocardiography. The primary outcome measure was the presence of RWMA. The predictor variables included the admission Hunt & Hess grade, age, gender, cardiac risk factors, aneurysm location, plasma catecholamine levels, cardiac troponin I (cTi) level, heart rate (HR), blood pressure, and phenylephrine dose. Univariate and multivariate logistic regression was performed with adjustment for serial measurements, reporting odds ratios (OR) and 95% confidence intervals (CI). RESULTS: In this study, 817 echocardiograms were analysed. RWMA were detected in 18% of those studied. The prevalence of RWMA in patients with Hunt & Hess grades 3 - 5 was 35%. Among patients with a peak cTi level greater than 1.0 m g/L, 65% had RWMA. Multivariate analysis demonstrated that high Hunt & Hess grade (OR 4.22 for grade 3 - 5 versus grade 1 - 2, p = 0.046), a cTi level greater than 1.0 microg/L (OR 10.47, p = 0.001), a history of prior cocaine or amphetamine use (OR 5.50, p = 0.037), and higher HR (OR 1.34 per 10 bpm increase, p = 0.024) were predictive of RWMA. CONCLUSIONS: RWMA were frequent after SAH. High-grade SAH, an elevation in cTi levels, a history of prior stimulant drug use, and tachycardia are independent predictors of RWMA.

Adolescent↗

PubMed1995

Uneven hepatic iron and phosphorus distribution in beta-thalassemia.

BACKGROUND/AIMS: Determination of hepatic iron concentration is crucial in the evaluation of iron-storage disease. Iron content is normally determined in a part of a needle liver biopsy and the value obtained is considered to be representative of the iron concentration in the whole liver. To evaluate the reliability of this procedure, we studied iron distribution in the liver of two beta-thalassemic patients. Since the transport of intracellular iron is mediated by phosphates, we also studied the hepatic phosphorus distribution. METHODS: At autopsy, a liver slice extending from the left to the right lobe was divided into 51 and 49 samples, respectively. Each specimen was subdivided into two parts: one of them was paraffin-embedded and utilized for the histochemical detection of iron; the second part was analyzed for iron and phosphorus content by induced coupled plasma atomic emission spectroscopy. RESULTS: The histological picture of both livers was characterized by portal and periportal fibrosis associated with iron storage of different degree, without cirrhosis. The mean iron concentration of the liver was 20,631 +/- 4903 micrograms per g of dry tissue (micrograms/g dt) and 13,901 +/- 1976 micrograms/g dt, respectively. A striking variability in iron content between samples was also found: iron concentration ranged from 11,537 to 32,347 micrograms/g dt in the first case and from 6257 to 16,493 in the second case. We even observed regional differences in iron concentration, with a preferential peripheral accumulation in both cases and a tendency of the left compartment of the liver to accumulate more iron in the first case. Histochemical analyses confirmed the uneven iron distribution even at the acinar level, showing iron mainly being stored in hepatocytes and Kupffer cells of zone 1 of the acinus, with decreasing amounts of iron in zones 2 and 3. The mean hepatic phosphorus concentration was 6662 +/- 1300 micrograms/g dt (range: 4348-9947) and 7502 +/- 986 micrograms/g dt (range: 5844-90,282), respectively. The regional distribution of phosphorus was similar to that observed for iron. A strict correlation between iron and phosphorus content was also observed. CONCLUSIONS: Our data show that: 1) iron and phosphorus are unevenly distributed in the beta-thalassemic liver, even in the non-cirrhotic stages; 2) a regional pattern of iron and phosphorus distribution is evident, characterized by higher concentrations at the periphery of the liver; 3) the observed uneven distribution of iron and phosphorus implies that their content determined in a small liver sample cannot be considered as absolutely representative of the mean hepatic iron concentration. Therefore, iron concentrations determined in a part of a needle liver biopsy should be interpreted with caution in monitoring the efficacy of the iron-chelating therapy in beta-thalassemic patients.

Adult↗

PubMedDate not supplied

Variability of human coronary artery geometry: an angiographic study of the left anterior descending arteries of 30 autopsy hearts.

A computer-based system is described to measure objectively the geometric parameters of arteries from pairs of projection angiograms. This technique, which employs back-projection to define the vessel axes in 3-D space, was used to obtain selected parameters of coronary artery geometry from radiographic images of autopsy hearts. Results of the first 30 cases are presented, focussing on the distribution of the geometric parameters of the left anterior descending coronary artery (LAD) and its first two major branches. The derived parameters include the angle between the left circumflex artery and the LAD; the angles between the LAD and its early diagonal and septal perforator branches; distances between branch points; and tortuosity. The geometric parameters vary considerably, presumably contributing to a corresponding variability in local hemodynamic and mechanical stresses. Most parameters are uncorrelated. One exception is the angle at the origin of the second diagonal branch, which is positively correlated (p < 0.01) with the distance between the ostia of the first two diagonal vessels; this correlation could reflect the existence of "target" perfusion regions. No relation between geometric parameters and age or gender was seen. In this sample, blacks had a larger angle at the left main bifurcation than whites (p < 0.05).

Autopsy↗

PubMed1996

Selective inhibition of the alternative complement pathway by sCR1[desLHR-A] protects the rabbit isolated heart from human complement-mediated damage.

Evidence is presented that treatment with a selective inhibitor of the alternative complement pathway, sCR1[desLHR-A], protects the ex vivo perfused rabbit heart from human complement-mediated injury. Hearts from male New Zealand white rabbits were perfused in the Langendorff mode. After equilibration, normal human plasma was added to the perfusate as a source of complement. Concomitant with the addition of human plasma, vehicle (n = 13), soluble complement receptor type 1 (sCR1) (n = 10), or sCR1[desLHR-A], a truncated version of sCR1 that lacks the C4b binding region (n = 10) was included in the perfusate. Hemodynamic variables were obtained for all groups before (baseline) and after the addition of human plasma. Compared to vehicle-treated hearts, variables recorded during perfusion with human plasma including coronary perfusion pressure, left ventricular developed pressure, and left ventricular end diastolic pressure, along with a reduction of creatine kinase efflux, were improved in hearts perfused with either complement inhibitor. In addition, in vitro hemolysis assays were utilized to discriminate between the classical and alternative pathways. The addition of sCR1 to human serum prevented both the classical and alternative pathway-mediated hemolysis while sCR1[desLHR-A] prevented only the alternative pathway-mediated lysis. This study indicates that deletion of the C4b-binding site from sCR1 results in a new pharmacological moiety, sCR1[desLHR-A], that primarily inhibits the alternative pathway of human complement.

Animals↗

PubMed1989

In vivo regional diaphragm function in dogs.

A biplane videofluorographic system was used to track the position of metallic markers affixed to the abdominal surface of the left hemidiaphragm in supine anesthetized dogs. Regional shortening was determined from intermarker distances of rows of markers placed along muscle bundles in the ventral, middle, and dorsal regions of the costal diaphragm and of one row on the crural diaphragm. Considerable variability of regional shortening was seen in a given row, which was reproducible on repeat study in individual dogs but which differed between mechanical ventilation and spontaneous breathing. There were no consistent patterns among dogs. Regional shortening obtained from the change in length of rows extending from chest wall to central tendon showed no consistent differences among dogs during spontaneous breathing. At equal tidal volumes, all regions (except the ventral costal diaphragm) shortened more during spontaneous breathing than during mechanical ventilation.

Animals↗

PubMed1995

Left-sided stellate ganglion ablation or "rate-controlled" vagal nerve stimulation decreases regional myocardial metabolic impairment during acute ischemia in dogs.

This study was designed to see whether during ischemia a metabolic advantage results with left-sided ablation of the stellate ganglion (SGA), an available clinical technique. Its effects on hemodynamics and regional metabolism during myocardial ischemia were compared with those of electrical stimulation of the left vagus nerve (VS), a nonclinical technique, and those of a control condition (ischemia without intervention). The left anterior descending coronary artery (LADa) of 30 dogs was constricted to reduce blood flow by 50% and then 75% from that before constriction and after autonomic intervention (baseline). Electrocardiogram, left-ventricular (LV) first-time derivative (dP/dt), and systemic, LADa, and LV end-diastolic pressures were continuously recorded. Before and during each constriction, cardiac output and regional myocardial blood flow (by microspheres), blood gas tensions, pH, hemoglobin O2 saturation, lactate, glucose, sodium, and potassium concentrations were measured. During ischemia, SGA and VS each decreased heart rate, myocardial contractility (dP/dt), and filling pressures, the decrease in each variable being greater with VS. Also during ischemia, myocardial O2 delivery and consumption decreased to the same extent in the ischemic zone with VS, but the O2 delivery/consumption ratio was higher only with SGA. In addition, ischemic lactate production was lower with SGA and VS than with no autonomic intervention. It is concluded that left-sided SGA or VS to a heart rate of 80 to 90 beats per minute similarly mitigated metabolic impairment during myocardial ischemia. Although the study was only designed to compare modification of ischemia by two different techniques, the results suggest that ischemic zone O2 delivery/consumption ratio and hemodynamic stability were better with SGA.

Animals↗