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Contribution of each ventricular wall to ventricular interdependence
LITERATURE REVIEW
similar or slightly worse prognosis has been reported in group 3. Calcium entry and beta-adrenergic blocking therapy reduce the incidence of silent ischemia.
Windsor JA, Hill GL: Risk factors for postoperative pneumonia. Ann Surg 208:209-214, 1988 Postoperative pneumonia occurs in about 20% of surgical patients. Reduced respiratory muscle strength, resulting from protein depletion, has been suggested to impair postoperative respiratory function. The protein index (PI), the ratio of measured-topredicted total body protein, was used to measure protein depletion. Total body protein was determined by in vitro neutron activation analysis and tritiated water dilution. This study divided 80 patients into two groups based on presence (PI _<0.77) or absence (PI _>0.77) of protein depletion. The 0.77 cutoff is 2 SD from PI of normal volunteers. Respiratory muscle strength was measured as mouth pressure during maximal static expiration (MEP) at total lung capacity, and maximal static inspiration at functional residual capacity (MIP). The respiratory muscle strength index was the average of the percent of predicted MIP and MEP. Pneumonia was defined as purulent sputum, positive blood and/or sputum culture, temperature higher than 38.5°C, and clinical or radiologic evidence of consolidation absent before surgery. Protein-depleted patients had reduced respiratory muscle strength, vital capacity, and peak expiratory flow rate. Although the postoperative incidence of atelectasis was similar in both groups, pneumonia occurred significantly more often in protein-depleted patients (20% v 7%, P = 0.05). Using multiple logistic regression analysis, protein depletion was as important as site of incision as a risk factor for postoperative pneumonia.
Clement R, Rousou JA, Engelman RM, et ah Perioperative morbidity in diabetics requiring coronary artery bypass surgery. Ann Thorac Surg 46:321-323, 1988 Diabetic patients are considered to be at increased risk for complications associated with cardiac surgery because of diffuse, severe atherosclerosis, hypertension, and decreased resistance to infection. This retrospective review of 384 diabetic patients (defined as preoperative fasting blood glucose over 145 mg/dL or history of diabetes requiring therapeutic intervention) compared with 396 randomly selected nondiabetic patients undergoing isolated coronary bypass grafting demonstrated no difference in perioperative myocardial infarction, renal failure, neurologic complications, leg wound infections, or thromboembolism. However, the incidence of hypertension and duration of hospitalization were increased in diabetic patients. When intraaortic balloon pumping was required, diabetic patients developed complications (postoperative neurologic problems, renal failure, myocardial infarction, and femoral arterial thrombosis) more frequently than if balloon support was not required. Except
241
for this subgroup, the presence of diabetes did not affect perioperative morbidity or mortality.
Santamore WP, Constantinescu M, Minezak BM, et ah Contribution of each ventricular wall to ventricular interdependence. Basic Res Cardioi 83:424-430, 1988 Pressure and volume changes in either cardiac ventricle influence those of the other through the phenomenon of ventricular interdependence. In this study, the transfer of pressure and volume between the ventricles was evaluated by changes in interventricular septal and ventricular free wall compliance. Technical limitations of the study included the use of postmortem hearts maintained by cardioplegia, removal of pericardium, and the use of an artificial means to alter ventricular compliance (injection of glutaraldehyde). Transfer of pressure from the right to the left ventricle depends upon left ventricular free wall and septal compliance, but not right ventricular compliance. When septal compliance decreased, pressure transfer from right to left ventricles decreased. However, it increased with decreased left ventricular free wall compliance. As predicted from a theoretical model, pressure transfer depends upon septal compliance divided by the sum of left ventricular free wall and septal compliance. Two clinically relevant implications of this work are the effects of infarction site on ventricular coupling and the equalization of diastolic pressures in constrictive pericarditis. Impaired right ventricular filling occurs in anterior myocardial infarction secondary to altered ventricular coupling. Likewise, in constrictive pericarditis, decreased ventricular wall compliance increases relative septal compliance, increasing the transfer of pressure between the ventricles.
Lowe JE, Hartwich T, Takla M, et al: Ultrastructure of electrophysiologically identified human sinoatrial nodes. Basic Res Cardiol 83:401-409, 1988 Freshly excised human sinoatrial nodes, identified by electrophysiologic study, were studied to confirm the myocardial cell types previously described in postmortem studies (James TN: Anatomy of the human sinus node. Anat Rec 141:109-139, 1961). Three types of cells were identified: P cells, the pacemaker or polygonal cells that have few contractile elements or mitochondria and clear cytoplasm with atrial granules; T cells or transitional cells that have slightly increased numbers of myofibrils (compared with P cells) and some atrial granules, and atrial myocardial cells with normal numbers of myofibrils. P cells occur singly or in clusters of two or three surrounded by a basement membrane closely adherent to the sarcolemma. Such cells are 5 to 20/~m in diameter and polyhedral in shape. An interesting feature of the nodes studied was an increase in lipofucsin-laden vacuoles in the transitional cells of three patients with inappropriate sinus tachycardia (ages 20, 30, and 36) requiring surgical extirpation of the sinoatrial node. Such cellular changes usually indicate cellular degeneration, an unexpected finding in cells of young adults.
similar or slightly worse prognosis has been reported in group 3. Calcium entry and beta-adrenergic blocking therapy reduce the incidence of silent ischemia.
Windsor JA, Hill GL: Risk factors for postoperative pneumonia. Ann Surg 208:209-214, 1988 Postoperative pneumonia occurs in about 20% of surgical patients. Reduced respiratory muscle strength, resulting from protein depletion, has been suggested to impair postoperative respiratory function. The protein index (PI), the ratio of measured-topredicted total body protein, was used to measure protein depletion. Total body protein was determined by in vitro neutron activation analysis and tritiated water dilution. This study divided 80 patients into two groups based on presence (PI _<0.77) or absence (PI _>0.77) of protein depletion. The 0.77 cutoff is 2 SD from PI of normal volunteers. Respiratory muscle strength was measured as mouth pressure during maximal static expiration (MEP) at total lung capacity, and maximal static inspiration at functional residual capacity (MIP). The respiratory muscle strength index was the average of the percent of predicted MIP and MEP. Pneumonia was defined as purulent sputum, positive blood and/or sputum culture, temperature higher than 38.5°C, and clinical or radiologic evidence of consolidation absent before surgery. Protein-depleted patients had reduced respiratory muscle strength, vital capacity, and peak expiratory flow rate. Although the postoperative incidence of atelectasis was similar in both groups, pneumonia occurred significantly more often in protein-depleted patients (20% v 7%, P = 0.05). Using multiple logistic regression analysis, protein depletion was as important as site of incision as a risk factor for postoperative pneumonia.
Clement R, Rousou JA, Engelman RM, et ah Perioperative morbidity in diabetics requiring coronary artery bypass surgery. Ann Thorac Surg 46:321-323, 1988 Diabetic patients are considered to be at increased risk for complications associated with cardiac surgery because of diffuse, severe atherosclerosis, hypertension, and decreased resistance to infection. This retrospective review of 384 diabetic patients (defined as preoperative fasting blood glucose over 145 mg/dL or history of diabetes requiring therapeutic intervention) compared with 396 randomly selected nondiabetic patients undergoing isolated coronary bypass grafting demonstrated no difference in perioperative myocardial infarction, renal failure, neurologic complications, leg wound infections, or thromboembolism. However, the incidence of hypertension and duration of hospitalization were increased in diabetic patients. When intraaortic balloon pumping was required, diabetic patients developed complications (postoperative neurologic problems, renal failure, myocardial infarction, and femoral arterial thrombosis) more frequently than if balloon support was not required. Except
241
for this subgroup, the presence of diabetes did not affect perioperative morbidity or mortality.
Santamore WP, Constantinescu M, Minezak BM, et ah Contribution of each ventricular wall to ventricular interdependence. Basic Res Cardioi 83:424-430, 1988 Pressure and volume changes in either cardiac ventricle influence those of the other through the phenomenon of ventricular interdependence. In this study, the transfer of pressure and volume between the ventricles was evaluated by changes in interventricular septal and ventricular free wall compliance. Technical limitations of the study included the use of postmortem hearts maintained by cardioplegia, removal of pericardium, and the use of an artificial means to alter ventricular compliance (injection of glutaraldehyde). Transfer of pressure from the right to the left ventricle depends upon left ventricular free wall and septal compliance, but not right ventricular compliance. When septal compliance decreased, pressure transfer from right to left ventricles decreased. However, it increased with decreased left ventricular free wall compliance. As predicted from a theoretical model, pressure transfer depends upon septal compliance divided by the sum of left ventricular free wall and septal compliance. Two clinically relevant implications of this work are the effects of infarction site on ventricular coupling and the equalization of diastolic pressures in constrictive pericarditis. Impaired right ventricular filling occurs in anterior myocardial infarction secondary to altered ventricular coupling. Likewise, in constrictive pericarditis, decreased ventricular wall compliance increases relative septal compliance, increasing the transfer of pressure between the ventricles.
Lowe JE, Hartwich T, Takla M, et al: Ultrastructure of electrophysiologically identified human sinoatrial nodes. Basic Res Cardiol 83:401-409, 1988 Freshly excised human sinoatrial nodes, identified by electrophysiologic study, were studied to confirm the myocardial cell types previously described in postmortem studies (James TN: Anatomy of the human sinus node. Anat Rec 141:109-139, 1961). Three types of cells were identified: P cells, the pacemaker or polygonal cells that have few contractile elements or mitochondria and clear cytoplasm with atrial granules; T cells or transitional cells that have slightly increased numbers of myofibrils (compared with P cells) and some atrial granules, and atrial myocardial cells with normal numbers of myofibrils. P cells occur singly or in clusters of two or three surrounded by a basement membrane closely adherent to the sarcolemma. Such cells are 5 to 20/~m in diameter and polyhedral in shape. An interesting feature of the nodes studied was an increase in lipofucsin-laden vacuoles in the transitional cells of three patients with inappropriate sinus tachycardia (ages 20, 30, and 36) requiring surgical extirpation of the sinoatrial node. Such cellular changes usually indicate cellular degeneration, an unexpected finding in cells of young adults.