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Biomedical subjects

T J Gardner

Publications and source records attributed to T J Gardner.

At least 127 records · Page 7Linked to original sources
PubMed1983

Coronary heart disease and bypass surgery in urban blacks.

Myocardial revascularization was reviewed in 56 urban black patients (41 men, 15 women). The age range was 33 to 70 with a mean of 53. Fifty percent presented with class III angina and 50 percent had progressed to severe unstable angina. Cardiac catheterization revealed severe triple-vessel disease in 75 percent of the patients while 15 percent had double-vessel disease and only 9 percent had single-vessel disease.At surgery the average number of bypass grafts performed was 2.3. The operative mortality was 3.4 percent for the group with stable angina and 15 percent for the unstable group.At follow-up, 73 percent of the patients had no angina. Sixteen percent were improved and 11 percent continued to have angina. In spite of the presence of advanced coronary artery disease, myocardial revascularization can be accomplished with acceptable operative risks and good results in symptomatic urban blacks. The risk, however, is higher in patients who have already progressed to unstable angina. It is therefore imperative that operative intervention be carried out at an earlier stage of the disease if satisfactory results are to be realized in this group.

Adult↗
PubMed1983

Improved myocardial preservation during global ischemia by continuous retrograde coronary sinus perfusion.

To investigate whether retrograde continuous low-pressure perfusion of the coronary sinus could deliver cardioplegic solutions with oxygen and substrate beyond stenoses and result in improved myocardial preservation, we subjected 41 canine hearts to 90 minutes of ischemia with an occlusion on the circumflex coronary artery. There were four groups: Group I, antegrade (aortic root) crystalloid cardioplegia every 30 minutes during ischemia; Group II, antegrade plus topical cooling; Group III, continuous retrograde perfusion; Group IV, same as Group III, with an oxygenated perfluorocarbon. All solutions had a PO2 of 400 to 500 mm Hg. Intramyocardial oxygen and carbon dioxide tensions (PO2 and PCO2) and mean myocardial temperatures were monitored during ischemia, and left ventricular (LV) function was assessed before ischemia and after reperfusion. After global ischemia, the circumflex occlusion was released and the hearts reperfused. Following 60 minutes of reperfusion, isovolumic developed pressure returned to 36% +/- 4% and 41% +/- 5% of preischemic levels, respectively, in Groups I and II. By contrast, Groups III and IV (retrograde perfusion) had a significantly greater percent of recovery (78% +/- 5% and 73% +/- 5%). Circumflex area intramyocardial PO2 fell 20 and 25 mm Hg below preischemic levels in Groups I and II during ischemia, whereas in Group III, intramyocardial PO2 in the circumflex region remained near preischemic levels, and in Group IV, it rose 19 mm Hg. Mean myocardial temperature during ischemia in the circumflex area was significantly higher in Group I than in Groups II, III, and IV. Peak intramyocardial PCO2 in the circumflex region was significantly less in the retrogradely perfused hearts. Retrograde coronary sinus perfusion resulted in significant improvement in recovery of LV function, uniform myocardial cooling, normal intramyocardial PO2, and less intramyocardial PCO2 accumulation, despite the presence of a total circumflex coronary artery occlusion.

Animals↗
PubMed1983

Left ventricular aneurysmectomy. Factors influencing postoperative results.

One hundred consecutive patients who underwent resection of aneurysms of the left ventricle were reviewed. Eighty-four of these patients had resection or plication of an aneurysm of the anterior left ventricular wall either alone or in combination with coronary artery bypass grafting. In 27 patients who had little or no congestive heart failure, the primary indication for operation was disabling angina pectoris. In them the early mortality was 4% and late mortality, 4%. In nine other patients the primary indication for operation was life-threatening ventricular arrhythmias. In this group the early mortality was 56% and late mortality, 0%. Severe congestive heart failure was the primary indication for aneurysmectomy in 48 patients. In these patients the early mortality was 21% and late mortality, 34%. When the primary indication for operation was severe congestive heart failure, overall survival and postoperative results were best in patients in whom the nonaneurysmal left ventricle had good function preoperatively and was supplied by coronary arteries either unobstructed or favorable for bypass grafting; results were poorest in those patients with three-vessel coronary artery disease who had impaired motion of the lateral left ventricular wall and distal lateral wall vessels that were unfavorable for bypass grafting. It is concluded that patients with left ventricular aneurysms form a heterogeneous group in which the prognosis varies markedly. The probability of a good postoperative result can be predicted by careful preoperative analysis of a patient's symptoms, ventricular function, and coronary artery anatomy.

Adult↗
PubMed1983

Improved myocardial protection with perfluorocarbon cardioplegia.

An oxygenated perfluorocarbon solution containing 25 mEq/L potassium has been investigated as a potentially useful cardioplegic solution to be administered to patients undergoing prolonged induced global myocardial ischemia during open-heart surgical procedures. Experimental studies have demonstrated that, compared to simply crystalloid and cold-blood cardioplegic solutions, an oxygenated perfluorocarbon cardioplegic solution administered at low temperatures can deliver oxygen to the ischemic heart and that this available oxygen is utilized by the heart. In an experimental study in which a Fluosol-43 solution was compared to both crystalloid and oxygenated-blood cardioplegia, Fluosol-43-treated hearts demonstrated better recovery of left ventricular function following postischemic reperfusion.

Animals↗
PubMed1983

Enhanced myocardial protection with verapamil prior to postischemic reflow.

Reperfusion of the heart after induced myocardial ischemia may be associated with severe myocardial damage, characterized by massive calcium influx and accumulation in the heart cells. The present study was undertaken to investigate whether verapamil, a slow channel calcium blocker, administered prior to reperfusion, might reduce this reflow injury without causing depression of heart function. Thirty-two isolated, perfused rabbit hearts were subjected either to 45 minutes of normothermic or 150 minutes of hypothermic global ischemia. Half of the heart in each group received verapaMil immediately prior to reperfusion, while the remaining hearts received no verapamil. Following ischemia and 60 minutes of reperfusion, left ventricular (LV) contractivity was superior in both groups of verapamil-treated hearts, compared to control hearts (LV developed pressure [DP] in normothermic hearts 63 +/- 6% of preischemic DP for verapamil-treated hearts versus 46 +/- 6% of preischemic DP for control hearts; in the hypothermic group, 65 +/- 8% of preischemic DP for verapamil-treated hearts versus 33 +/- 10% DP for control hearts). Postischemic LV compliance also was significantly improved in the verapamil-treated hearts through the period of reperfusion, compared to control hearts. No differences were noted in coronary flow, myocardial water content, or the onset of electromechanical activity between the verapamil and control hearts, but there was significantly improved ultrastructural preservation in both verapamil groups. These data demonstrate that verapamil, when administered just prior to reperfusion, results in improved recovery of myocardial function and excellent cellular preservation, presumably for reducing calcium influx into myocardial cells.

Animals↗
PubMed1982

Use of an isolated heart model to test the utilization of substrates for inclusion in cardioplegic solutions.

Previous studies from our laboratory utilized an isolated isovolumic Langendorff heart preparation to study myocardial metabolism and preservation of left ventricular function following global ischemia and reperfusion. The present study employed a similar preparation to assess the utilization of various glycolytic substrates by monitoring the level of left ventricular developed pressure. Twenty-one rabbit hearts were perfused with an oxygenated but substrate-free Krebs-Ringer-bicarbonate solution in order to deplete the hearts of endogeneous substrate stores. Following a brief period of anoxic, substrate-free perfusion, hearts were perfused with one of seven test substrates under anaerobic, then aerobic conditions. Under anaerobic conditions only perfusion of glucose resulted in a measurable increase in ventricular function which was still less than 20% of control. Under aerobic conditions, provision of glucose, pyruvate, or the combination of alpha-glycerol phosphate and pyruvate resulted in significant increases in contractile function which were 40-70% of control. These results obtained in normal hearts will provide a base line for future studies of the metabolism of postischemic hearts which may have altered cell membrane permeability and/or enzymatic activity.

Animals↗
PubMed1982

Optimal myocardial protection with fluosol cardioplegia.

An oxygenated perfluorocarbon cardioplegic solution was examined, utilizing a blood-perfused canine model. Twenty-one animals were divided into three equal groups, and each animal received Fluosol cardioplegia at one of three infusion temperatures: 20 degrees C, or 4 degrees C. All hearts underwent 90 minutes of ischemia, during which time 150 ml of the cardioplegic solution was infused every 30 minutes. Myocardial oxygen and carbon dioxide tensions (PmO2 and PmCO2) were monitored continually using mass spectrometry, and myocardial oxygen consumption was calculated with each cardioplegic injection. The mean increase in PmO2 was 7.1 +/- 0.9 mm Hg with 20 degrees C Fluosol infusions, 31.1 +/- 4.7 mm Hg with 10 degrees C Fluosol injections, and 22.2 +/- 4.7 mm Hg with infusions of 4 degrees C Fluosol. Average myocardial oxygen consumptioN, expressed as cubic centimeters of oxygen per 100 gm of left ventricle (wet weight), was 21.2 +/- 0.5 with 20 degrees C Fluosol, 22.8 +/- 1.3 for 10 degrees C Fluosol, and 19.6 +/- 1.0 for 4 degrees C Fluosol. Mean myocardial temperatures with infusions of 20 degrees C, 10 degrees C, and 4 degrees C solutions were 21.4 +/- 0.1 degree C, 16.9 +/- 0.4 degree C, and 15.9 +/- 0.5 degree C, respectively. After 45 minutes of reperfusion, maximum rate of rise of left ventricular pressure, expressed as percentage of preischemic control, was 70.9 +/- 3.9% for 20 degrees C Fluosol, 90.9 +/- 3.2% for 10 degrees C Fluosol, and 90.4 +/- 2.3% for 4 degrees C Fluosol (p less than 0.005, 20 degrees C versus 10 degrees C, 4 degrees C Fluosol). In addition, the 10 degrees C and 4 degrees C Fluosol hearts had essentially normal structure by light and electron microscopy. These data demonstrate tht Fluosol cardioplegia results in near optimal myocardial protection when infused at cold temperatures (4 degrees C to 10 degree C). The increases intramyocardial oxygen and myocardial oxygen consumption with each injection demonstrate that there is enhanced oxygen delivery and utilization, which may account for the improved functional recovery observed in these hearts.

Animals↗
PubMed1982

St. Jude Medical cardiac valve prosthesis in infants and children: early and intermediate experience.

The St. Jude Medical valve prosthesis has been used for valve replacement in 14 children. Ages ranged from 14 months to 17 years (average 8.5 years). Preoperative diagnosis included mitral regurgitation in five patients, aortic stenosis in one patient, aortic regurgitation in one, mitral stenosis in one, combined aortic stenosis and aortic regurgitation in five patients, and other in one patient. Seven patients required mitral valve replacement and seven aortic valve replacement. All patients survived operation and there have been no late deaths. Ten patients have been maintained on warfarin anticoagulation and four on aspirin alone. During a follow-up period of two months to three years (average 20.5 months) there have been no complications related to the valve, no thromboemboli, and no incidence of hemolysis. Three patients have had postoperative cardiac catheterization, and satisfactory pressure and angiographic studies have been recorded. The St. Jude Medical valve prosthesis initially appears to be a satisfactory device for valve replacement in children.

Adolescent↗
PubMed1982

Mechanisms of ischemic myocardial cell damage assessed by phosphorus-31 nuclear magnetic resonance.

Phosphorus-31 nuclear magnetic resonance (31P NMR) can estimate tissue intracellular pH as well as the content of high-energy phosphate metabolites in isolated perfused hearts. We used 31P NMR to examine mechanisms associated with the recovery of ventricular function in hearts subjected to global ischemia and reperfusion, with special emphasis on intracellular pH, a previously unreported variable. Single-dose and multiple-dose administration of a hyperkalemic cardioplegic solution were compared with hypothermia alone in 18 isolated perfused rabbit hearts. Hearts in group 1 were subjected to 24 degrees C hypothermia during 60 minutes of global ischemia; group 2 hearts received a single injection of 37-mM KCL cardioplegic solution at 10 degrees C at the onset of ischemia; and group 3 hearts received a similar initial cardioplegic injection followed by two subsequent 24 degrees C injections at 20-minute intervals during the ischemic period. Using an intraventricular balloon, maximal dP/dt provided a quantitative index of left ventricular performance before and after ischemia. Return of ventricular function expressed as a percentage of control was 54 +/- 11% for group 1, 84 +/- 6% for group 2, and 101 +/- 18% for group 3. Differences in the rate of development of intracellular acidosis were noted during the 60-minute ischemic period. Intracellular pH fell to 6.09 +/- 0.12 in group 1, 6.31 +/- 0.09 in group 2, an 6.79 +/- 0.03 in group 3. In all three groups intracellular pH returned to control (pH 7.20) within 10 minutes of reflow. The metabolic correlates of functional recovery appeared to be the tissue content of ATP at the end of ischemia and after reflow. ATP content at the end of ischemia was 22 +/- 2% of control in group 1 hearts, 31 +/- 4% in group 2 and 64 +/- 2% in group 3. After 45 minutes of reperfusion, ATP levels recovered to 33 +/- 9% of control in group 1, to 71 +/- 9% in group 2 and to 86 +/- 6% in group 3. Although there were no differences between groups in the content of creatine phosphate after 60 minutes of ischemia, the rates of creatine phosphate decline were dissimilar. Further, during the early reflow period, a marked overshoot in tissue creatine phosphate was detected, especially in groups 1 and 2. Histologic damage assessed by light microscopy correlated with the metabolic data, confirming that multidose cardioplegia provided the best preservation of cellular morphology. These results demonstrate that the magnitude of intracellular acidosis and the associated increase in inorganic phosphate correlate inversely with recovery of postischemic ventricular structure and function. ATP, but not creatine phosphate, content correlates with return of contractile performance after reperfusion. The overshoot in creatine phosphate during early reperfusion might impede optimal restoration of ATP content and, as a result, optimal recovery of cell functions.

Adenosine Triphosphate↗
PubMed1982

Failure of blood cardioplegia to protect myocardium at lower temperatures.

To assess the effect of temperature, oxygenated blood and crystalloid cardioplegic solutions (CPs) at infusion temperatures of 20 degrees C, 10 degrees C and 4 degrees C were compared. The amount of potassium in each CP was 25 mEq/l. There were six study groups with seven canine hearts in each group, all of which were subjected to 90 minutes of global ischemia at 20 degrees C, 10 degrees C or 4 degrees C, followed by 45 minutes of normothermic reperfusion. During ischemia, either blood or crystalloid CP was given every 30 minutes. With each infusion, any change in myocardial oxygen tension was recorded using mass spectrometry, and oxygen consumption (MVO2) was calculated. Left ventricular (LV) function was assessed before and after ischemia in all hearts by measuring isovolumic developed pressure using an intraventricular balloon. Injection of 20 degrees C blood CP resulted in a mean increase in intramyocardial oxygen tension (PO2) of 7 mm Hg. At 10 degrees C or 4 degrees C, blood CP infusions did not cause a significant increase in intramyocardial PO2, while with crystalloid CP, intramyocardial PO2 did not increase at any of the three infusion temperatures. The mean MVO2 with each blood CP injection, expressed as ml O2/100 g LV wet weight, was 16.5 +/- 0.8 for 20 degrees C blood, 4.1 +/- 0.3 for 10 degrees C blood and 3.5 +/- 0.4 for 4 degrees C blood (p less than 0.001, 20 degrees C blood vs 10 degrees C and 4 degrees C blood). MVO2 with each crystalloid CP injection was 0.9 +/- 0.1 for 20 degrees C CP, 0.8 +/- 0.1 for 10 degrees C CP, and 0.7 +/- 0.1 for 4 degrees C CP. Recovery of developed pressure after 45 minutes of reperfusion, expressed as a percentage of preischemic control, was 76.0 +/- 3.4% or 20 degrees C blood CP, 65.6 +/- 2.3% for 10 degrees C blood CP, and 54.0 +/- 2.7% for 4 degrees C blood CP (p less than 0.05, 20 degrees C blood CP vs 10 degrees C and 4 degrees C blood CP). Recovery of developed pressure, also expressed as a percentage of preischemic control, was 56.6 +/- 1.4% for 20 degrees C crystalloid CP, 72.9 +/- 3.0% for 10 degrees C crystalloid CP, and 72.0 +/- 2.3% for 4 degrees C crystalloid CP (p less than 0.05, 20 degrees C crystalloid CP vs 10 degrees C and 4 degrees C crystalloid CP). These data show that blood CP is most effective when infused at 20 degrees C. The use of 10 degrees C blood CP enhanced myocardial cooling, but was of no additional benefit, presumably because there was little oxygen delivery. Blood CP at 4 degrees C resulted in significantly poorer preservation of LV function. Crystalloid CP infused at either 4 degrees C or 10 degrees C was as effective as 20 degrees C blood CP, despite the absence of oxygen use by hearts treated with crystalloid CP.

Animals↗
PubMed1982

Assessment of myocardial protection during global ischemia with myocardial gas tension monitoring.

Intramyocardial gas tension monitoring with mass spectrometry allows for the continuous assessment of myocardial metabolic activity during prolonged global ischemia. With aortic cross-clamping there is a rapid decrease in intramyocardial oxygen tension (PmO2) and a steady increase in carbon dioxide tension (PmCO2). In laboratory studies the extent to which myocardial metabolic activity is reduced has correlated with the degree of myocardial protection being afforded. In the present study the metabolic consequences of single-dose versus multiple-dose infusions of a hyperkalemic cardioplegic solution were compared in 23 patients undergoing aortic valve replacement (AVR) for severe aortic stenosis. Group I (n = 13) had single-dose cardioplegia during AVR, while group II (n = 10) had multiple-dose cardioplegia. The preoperative status and the surgical procedures were identical except for two multiple-dose patients who also underwent single coronary bypass grafting. In group I the PmCO2 rose steadily and at cross-clamp release was 182 +/- 20 mm Hg, while in group II the PmCO2 rose only to 77 +/- 8 mm Hg (P less than 0.01). During reperfusion the peak PmCO2 in group I was 219 +/- 22 mm Hg versus 111 +/- 5 mm Hg in group II (P less than 0.01). After operation six patients in group I required pharmacologic support, and two other patients died of low cardiac output. In contrast, only one patient in group II required inotropic support, and there were no deaths. The significantly lower PmCO2 values with multiple-dose cardioplegia suggest both reduced metabolic activity and washout of metabolic end products, with resultant improved myocardial protection, evidenced by less postoperative left ventricular dysfunction.

Adult↗
PubMed1982

Constrictive epicarditis as a cause of delayed or absent response to pericardiectomy: a clinicopathological study.

It is widely held that constrictive pericarditis is curable by pericardiectomy, and failure to respond reflects an underlying myocardial disease. Fibrous epicarditis could account for residual cardiac constriction, and delayed hemodynamic response in some patients is an alternative explanation. To examine this, we studied the 12 consecutive patients with otherwise normal hearts treated with extensive pericardiectomy for constrictive pericarditis over the past 7 years. Three hemodynamic responses to pericardiectomy were observed: (1) rapid response, where central venous pressure (CVP) fell below 10 cm H2O by 24 hours in two patients; (2) delayed response, where CVP fell below 10 cm H2O by 48 hours in six patients; and (3) no response of CVP in four patients. The CVPs remained critically elevated (greater than 25 cm H2O) in three patients with delayed response until a sclerotic epicardial peel was resected. Another patient whose CVP of 30 cm H2O showed no change after parietal pericardiectomy was thought to have amyloid cardiomyopathy but instead at autopsy had constrictive epicardial sclerosis not recognized at parietal pericardiectomy. Histologic features of parietal pericardium had no correlation with hemodynamic response, whereas epicardial histology did correlate with hemodynamic response in four patients. The data showed a spectrum of postpericardiectomy delayed hemodynamic responses, which in some patients may be due to a slowly resolving or fixed component of fibrous epicarditis that may be clinically misconstrued as a cardiomyopathy. Interruption of visceral pericardial tissue may be as important as resection of the parietal pericardium in patients with epicardial sclerosis.

Adolescent↗
PubMed1982

Valve replacement in children. A fifteen-year perspective.

Between 1965 and 1980, 64 children form 1 to 19 years of age have undergone replacement of the aortic, mitral, or tricuspid valve at The Johns Hopkins Hospital. Three of these patients have had successful second valve replacements 4 to 12 years after the initial operation. During the first 5 year period of this review, the hospital mortality was 31%, whereas only one of 33 children having valve replacement during the most recent 5 year period died early after operation (hospital mortality, 1976 to 1980, 3%). Thromboembolic complications have been seen in only two patients in this group, for an incidence of 0.8% per patient-year. Among patients receiving long-term warfarin anticoagulation, there has been only one major bleeding episode in 133 patient-years of follow-up. The type of valve prosthesis implanted during this 15 year period has changed greatly. Ninety-four percent of the prostheses placed during the initial 5 year period were the caged-poppet type of valve, whereas tilting disc, central flow, and tissue valve substitutes have been implanted more recently. Eight of the 10 patients most recently undergoing valve replacement have received St. Jude Medical prostheses, and postoperative catheterization studies have confirmed the excellent hemodynamic performance of these valves, even in patients with prostheses of very small annular diameter. Despite the disappointing occurrence of premature tissue valve failure in the young population, valve replacement in children currently is safer and there is a wider variety of technically satisfactory valve substitutes available for implantation today.

Age Factors↗
PubMed1982

Reduced oxygen consumption with effective left ventricular venting during postischemic reperfusion.

The effect of left ventricular (LV) venting on myocardial oxygen consumption (MVO2) during reperfusion after hypothermic cardioplegic arrest was tested using 29 dogs placed on cardiopulmonary bypass (CPB). During the first 20 minutes of reperfusion after 45 minutes of 20 degrees C arrest, group 1 (n = 10) had total venting with the LV systolic pressure (LVSP) maintained at 0 mm Hg. Group 2 (n = 10) had partial venting with the LVSP at 41.6 +/- 1.4 mm Hg (one-half perfusion pressure), while in group 3 (n = 9), the LVSP was kept just below CPB perfusion pressure (76.6 +/- 3.1 mm Hg) by occlusion of the LV vent. Next, there were 10 minutes of partial bypass (CPB flow reduced by 50%) followed by cessation of CPB. MVO2 expressed as ml O2/100 g LV/min (wet weight) during the first 20 minutes of reperfusion was 2.66 +/- 0.33 for group 1, 2.40 +/- 0.36 for group 2 and 4.62 +/- 0.53 for group 3 (p less than 0.05 vs groups 1 and 2). There were no significant differences in MVO2 in any of the groups during partial CPB compared with the period without CPB. These results demonstrate that effective LV venting reduces MVO2 during reperfusion after hypothermic ischemic arrest. However, there was no reduction in MVO2 during partial CPB compared with the initial period without CPB. Thus, volume loading of the left ventricle during reperfusion by failing to vent leads to increased myocardial oxygen demand, which may be detrimental in hearts that have sustained significant ischemia or when revascularization is incomplete.

Animals↗
PubMed1981

Association of postoperative delirium with raised serum levels of anticholinergic drugs.

Drugs with anticholinegic effects are often used in surgical procedures and may impair higher cognitive functions and produce delirious states. This prospective study examined the relation between serum levels of anticholinergic drugs, measured by a radioreceptor assay, and the development of delirium in patients undergoing cardiac surgery. Most patients who had postoperative delirium had high serum levels of anticholinergic drugs, whereas those who remained cognitively intact had low levels; and impairment in cortical function correlated with serum levels of anticholinergic drugs (p less than 0.001). Raised serum levels of drugs with anticholinergic effects may contribute to the development of delirium, and to the increase in risk of morbidity following cardiac surgery.

Adult↗
PubMed1981

Diagnosis and management of postoperative pericardial effusions and late cardiac tamponade following open-heart surgery.

The clinical and laboratory findings of 28 patients identified as having late pericardial effusions were examined. Eleven of these patients were asymptomatic; 9 patients had moderate symptoms including fatigue, malaise, weight gain, and dyspnea on exertion, and 8 patients with similar symptoms had evidence of cardiac tamponade. Ten patients underwent right heart catheterization in the intensive care unit; normal hemodynamics were confirmed in 4 and cardiac tamponade in 6 patients. Pericardiocentesis was effective in decompressing cardiac tamponade in 7 of 8 patients. One patient required operative subxiphoid drainage after unsuccessful pericardiocentesis. In addition, 5 patients with moderate clinical symptoms and pericardial effusions, who did not have cardiac tamponade, underwent pericardiocentesis because of a need for chronic anticoagulant therapy. The remaining patients were managed successfully by observation, discontinuation of warfarin when possible, fluid restriction, and diuretic therapy. All but 1 patient was symptomatically improved. A diagnostic and therapeutic schema is presented as an aid to early recognition of this troublesome and potentially lethal complication.

Adult↗