Experimental myocardial infarction. XIII. Sequential changes in left ventricular pressure-length relationships in the acute phase.

Pirzada, Farouk A.; Ekong, Enobong A; Vokonas, Pantel; Apstein, Carl S.; Hood, William B.

doi:10.1161/01.cir.53.6.970

Cited by 69 publications

(13 citation statements)

References 26 publications

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“…[1][2][3][4][5][6][7][8][9][10][11] Previous studies have clearly shown that with the loss of active shortening during ischemia, regional systolic stress increases, contributing to regional ischemic dysfunction and facilitating passive elongation of ischemic myocardium. 6,7 These regional myocardial geometric changes characterized by progressive increases in end-diastolic segment length and decreased end-diastolic wall thickness occur as a time-and load-dependent change identified as creep.…”

Section: Discussionmentioning

confidence: 99%

“…This method generally uses local coronary occlusion, resulting in a brief period of myocardial ischemia. Although the effects of ischemia on regional myocardial function have been studied extensively in animal models, [1][2][3][4][5][6][7][8][9][10] the significance of limited periods of ischemia on human heart function is not well defined. The development of regional ultrasonic dimension analysis by Theroux and associates 2,3 allowed accurate determination of changes in regional myocardial function.…”

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confidence: 99%

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Regional Left Ventricular Systolic Function in Humans During Off-Pump Coronary Bypass Surgery

Brown

Kim²,

Boyer³

et al. 1999

Circulation

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Background-Controversy exists as to whether off-pump CABG with local occlusion results in clinically significant myocardial ischemia during the occlusion period. This study was undertaken to delineate the effects of transient local coronary artery occlusion on regional systolic function. Methods and Results-Eight consenting patients undergoing left internal mammary to left anterior descending coronary artery (LAD) bypass were instrumented with a left ventricular pressure catheter and 2 subepicardial cylindrical ultrasonic dimension transducers placed in the minor axis dimension in the region served by the LAD. A digital sonomicrometer was used to collect data before, during, and after coronary occlusion from which percent systolic shortening and pressure-dimension loops were derived. Measuring devices were removed immediately after the final time point. All patients tolerated the procedure well, and there were no complications. Average duration of local occlusion needed for CABG was 15.9Ϯ4.4 minutes (range, 12 to 26 minutes). Local occlusion was associated with a decrease in peak systolic shortening from 5.8Ϯ0.8% to 1.8Ϯ0.8%. In all cases, function returned to baseline after restoration of flow. Pressure-dimension loops confirmed these findings and no evidence of diastolic creep. Linear repression analysis of degree of stenosis versus change in segmental shortening revealed a significant inverse correlation. Conclusions-Local occlusion of the LAD resulted in a transient decrease in myocardial function during occlusion with complete recovery during reperfusion. This change was less significant with increasing degrees of coronary stenosis. These data suggest that local occlusion is not associated with permanent myocardial injury but that ischemic changes do occur that may be clinically significant, especially in patients with lesser degrees of coronary stenosis. Key Words: coronary disease Ⅲ revascularization Ⅲ surgery C oronary artery bypass grafting without cardiopulmonary bypass has become an increasingly practiced technique for myocardial revascularization. This method generally uses local coronary occlusion, resulting in a brief period of myocardial ischemia. Although the effects of ischemia on regional myocardial function have been studied extensively in animal models, 1-10 the significance of limited periods of ischemia on human heart function is not well defined. The development of regional ultrasonic dimension analysis by Theroux and associates 2,3 allowed accurate determination of changes in regional myocardial function. Using this technology, Edwards et al 4 characterized the geometric alterations in myocardium during ischemia as a time-dependent stretch of myocardial segments called "creep." Glower and associates 5 showed that the reversal of diastolic creep correlated with recovery of systolic function after reversible ischemic injury.The purpose of this investigation is to define the effects of acute transient myocardial ischemia on regional systolic function in the face of chronic ischemia caused by...

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Section: Discussionmentioning

confidence: 99%

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confidence: 99%

Regional Left Ventricular Systolic Function in Humans During Off-Pump Coronary Bypass Surgery

Brown

Kim²,

Boyer³

et al. 1999

Circulation

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“…Fifteen mongrel dogs that weighed [19][20][21][22][23][24][25][26][27][28][29][30][31][32] vard infusion pump at a rate of 0.6 ml/min. Based on a flow of approximately 25 ml/min, this infusion rate would raise serum potassium concentration and presumably the extracellular potassium concentration in the myocardium perfused by the LAD to approximately 30 mEq/ 1, which would make this region electrically inexcitable.…”

Section: Methods Experimental Preparationmentioning

confidence: 99%

Contractile reserve and left ventricular function in regional myocardial ischemia in the dog.

Yoran¹,

Sonnenblick²,

Kirk³

1982

Circulation

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SUMMARY Contractile activity remaining in a region made ischemic by acute occlusion of the left anterior descending coronary artery (LAD) was assessed in dogs relative to its role in maintaining left ventricular (LV) function. Compensatory increases in contractility of normal myocardium were eliminated by treating all dogs with reserpine (3 mg/kg) to deplete their catecholamine stores. LV function was determined by measuring stroke volume while increasing the LV filling pressure with a shunt from the aorta to left atrium. Heart rate and mean aortic pressure were kept constant. LV function was studied after occlusion of the LAD alone and after the selective infusion of potassium chloride (1 mEq/ml) into the LAD to raise the regiotal extracellular potassium concentration to 30 mEq/mi. The reduction in LV function induced by LAD ligation was less than the reduction caused by abolishing contraction in the entire zone supplied by the LAD with infusion of potassium. The WHEN a coronary artery is occluded abruptly, loss of segmental shortening in the region of myocardium fed by this artery is generally observed. However, some collateral coronary blood flow remains and residual contractile function may remain in the region. The role of such contractile activity remaining in a region made ischemic by occlusion of a coronary artery on the overall function of the left ventricle has not been defined. Further, the relation between the size of the ischemic area and the extent of reduction in overall left ventricular (LV) function has not been precisely determined. When regional myocardial ischemia is induced, LV function is affected by the lateral dimensions of the ischemic region, the distribution of contractile activity transmurally in this region as determined by the remaining collateral coronary blood flow, the compliance of the ischemic zone, and compensatory increases in contractility in nonischemic zones of myocardium resulting from augmented sympathetic tone. This may explain the marked variation in the reported observations on this subject. '-9 We studied the effects of regional myocardial ischemia and total cardioplegia. The effects of involving varying amounts of the ventricle on overall LV function were also examined. stores.'0 This was done to abolish the compensatory increase in contractility that may occur in the nonischemic myocardium after coronary artery ligation.Dogs were anesthetized with sodium pentobarbital (30 mg/kg i.v.). Additional pentobarbital was administered as required to maintain anesthesia. After intubation with a cuffed endotracheal tube, dogs were ventilated with an intermittent positive pressure respiratory with 100% oxygen. A thoracotomy was performed in the fifth intercostal space and the heart was exposed by incising the pericardium. The left anterior descending coronary artery (LAD) was isolated and ligated 3-20 mm from its origin to vary the size of the ischemic region.After ligation of the LAD, a cannula was inserted distal to the occlusion and perfusion was continued through a pol...

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“…Beyond 6 h, cell death (necrotic phase) begins and at this point the tissue is considered infarcted. In the days that follow, inflammatory processes govern the mechanical behavior of the tissue with tissue stiffening being the primary manifestation [3][4][5][6]. This phase is highly dynamic making it extremely difficult to model as the material properties of the tissue are in a state of change.…”

Section: Introductionmentioning

confidence: 99%

“…The material properties stabilize (>7 weeks), with the gradual decrease in the amount of collagen being introduced into the lesion area [3][4][5][6]; however, the infarcted region does continue to change with remodeling in the form of lesion extension, expansion, and thinning. For the purposes of the following work, the remodeling aspects of the process have not been included in the analysis and the infarct material properties having been stabilized [3][4][5][6]. The underlying assumption being that the application of the technology described below will be applied to images that document the remodeled LV.…”

Section: Introductionmentioning

confidence: 99%

The Direct Incorporation of Perfusion Defect Information to Define Ischemia and Infarction in a Finite Element Model of the Left Ventricle

Veress

Fung

Lee

et al. 2015

Journal of Biomechanical Engineering

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This paper describes the process in which complex lesion geometries (specified by computer generated perfusion defects) are incorporated in the description of nonlinear finite element (FE) mechanical models used for specifying the motion of the left ventricle (LV) in the 4D extended cardiac torso (XCAT) phantom to simulate gated cardiac image data. An image interrogation process was developed to define the elements in the LV mesh as ischemic or infarcted based upon the values of sampled intensity levels of the perfusion maps. The intensity values were determined for each of the interior integration points of every element of the FE mesh. The average element intensity levels were then determined. The elements with average intensity values below a user-controlled threshold were defined as ischemic or infarcted depending upon the model being defined. For the infarction model cases, the thresholding and interrogation process were repeated in order to define a border zone (BZ) surrounding the infarction. This methodology was evaluated using perfusion maps created by the perfusion cardiac-torso (PCAT) phantom an extension of the 4D XCAT phantom. The PCAT was used to create 3D perfusion maps representing 90% occlusions at four locations (left anterior descending (LAD) segments 6 and 9, left circumflex (LCX) segment 11, right coronary artery (RCA) segment 1) in the coronary tree. The volumes and shapes of the defects defined in the FE mechanical models were compared with perfusion maps produced by the PCAT. The models were incorporated into the XCAT phantom. The ischemia models had reduced stroke volume (SV) by 18-59 ml. and ejection fraction (EF) values by 14-50% points compared to the normal models. The infarction models, had less reductions in SV and EF, 17-54 ml. and 14-45% points, respectively. The volumes of the ischemic/infarcted regions of the models were nearly identical to those volumes obtained from the perfusion images and were highly correlated (R 2 ¼ 0.99).

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Experimental myocardial infarction. XIII. Sequential changes in left ventricular pressure-length relationships in the acute phase.

Cited by 69 publications

References 26 publications

Regional Left Ventricular Systolic Function in Humans During Off-Pump Coronary Bypass Surgery

Regional Left Ventricular Systolic Function in Humans During Off-Pump Coronary Bypass Surgery

Contractile reserve and left ventricular function in regional myocardial ischemia in the dog.

The Direct Incorporation of Perfusion Defect Information to Define Ischemia and Infarction in a Finite Element Model of the Left Ventricle

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