Anterior Femoral Bow and Possible Effect on the Stifle Joint: A Comparison between Humans and Dogs.

The aim of the study was to compare the anterior bow of the femur between dogs and humans in terms of the possible impact on the stifle joint. The femoral radiographs obtained retrospectively were used to determine the angles and positions of the anterior bow in both dogs (n = 135) and humans (n = 57). Descriptive statistics and Pearson's correlation analysis were used for the statistical analyses of the variables. The mean anterior bow angle (ABA) was 18.3 ± 2.02° and 4.88 ± 1.24° in dogs and humans, respectively. The bow position was at the distal shaft in dogs (64.9 ± 2.04%) and almost at the mid-shaft of the bone (46.5 ± 5.52%) in humans. The ABA was related to the bow position in both humans and dogs. Additionally, the angle correlated with age in humans, while it was correlated with weight and breed in dogs. In conclusion, it is suggested that the anterior bow should be used as a landmark on the femoral axis for the biomechanical research of stifle joint, and dog stifle could be used as a suitable model for human knee in experimental studies for clinicians, while making sure that ethical principles are fully respected.

Abnormal exercise hemodynamics in cardiac allograft recipients 1 year after cardiac transplantation. Relation to preload reserve.

The well-established elevation in left ventricular filling pressures during exercise in patients after transplantation may contribute to decreased exercise tolerance. A proposed mechanism for this increase in filling pressures is an abnormal pressure-volume homeostasis of the transplanted heart. Twenty-three patients undergoing routine 1-year evaluations performed supine bicycle exercise during right heart catheterization. Within 24 hours, these patients underwent supine bicycle exercise to the identical work load during radionuclide ventriculography. For the group, resting hemodynamics and resting left and right ventricular ejection fractions were normal. With exercise, right atrial and pulmonary wedge pressure rose markedly (from 6 +/- 2 to 14 +/- 7 mm Hg, p less than 0.0001, and from 10 +/- 3 to 20 +/- 6 mm Hg, p less than 0.0001, respectively). Left ventricular ejection fraction increased appropriately with exercise (from 0.58 +/- 0.08 to 0.63 +/- 0.07, p = 0.004). End-diastolic volume also increased mildly (from 100 +/- 31 to 117 +/- 39 ml, p = 0.001), but change in end-diastolic volume was highly variable. Patients with little or no change in end-diastolic volume with exercise had the greatest resting and exercise left ventricular filling pressures resulting in significant negative correlations between filling pressures and change in end-diastolic volume (r = -0.64, p = 0.002 and r = -0.50, p = 0.025, respectively). Negative linear relations between exercise left ventricular filling pressures or resting heart rates and donor to recipient body weight ratio (r = -0.35, p = 0.10, and r = -0.37, p = 0.06, respectively) suggested that initial donor heart size influenced subsequent cardiac function.(ABSTRACT TRUNCATED AT 250 WORDS)

Serial echocardiographic findings early after heart transplantation: evidence for reversible right ventricular dysfunction and myocardial edema.

Serial M-mode and two-dimensional echocardiograms were performed on 10 patients at 1 week, 1 month, and 3 months after heart transplantation to determine early structural and functional changes in the allograft. Standard M-mode echocardiographic measurements of at least five cardiac cycles were averaged. Right ventricular size and function were assessed by mid-ventricular diameter and the right ventricular apex to lateral tricuspid anulus shortening fraction, respectively, on the two-dimensional apical four-chamber view. There were no consistent differences in left ventricular end-diastolic dimension or fractional shortening between study periods. Left ventricular posterior wall thickness decreased from 15 +/- 2 to 11 +/- 1 mm (p = 0.001), and septal thickness decreased from 15 +/- 2 to 12 +/- 2 mm (p = 0.0006) between the 1-week and 3-month studies. Right ventricular cross-sectional dimension increased from 34 +/- 6 to 39 +/- 6 mm (p = 0.047), and right ventricular fractional shortening increased from 13% +/- 3% to 21% +/- 5% (p = 0.0051) between the 1-week and 3-month studies. There were no correlations between any of the above changes and rejection episodes. There was a weak correlation (r = 0.53) between ischemic time and change in posterior wall thickness. Right ventricular dysfunction and increased left ventricular wall thickness presumably caused by interstitial edema appear to be normal findings early after heart transplantation.

The intramyocardial pressure: a parameter of heart contractility.

A method of monitoring was developed to directly measure the intramyocardial pressure and to objectively assess the viability and contractility of a heart allograft before it is harvested, during its period of preservation and following its implantation. Intramyocardial pressure was measured in the subendocardial and subepicardial regions using implantable solid state sensors. The data demonstrated that a normally contracting in situ heart exhibits a transmural intramyocardial pressure gradient, the systolic subendocardial pressure being consistently greater than the left ventricle and subepicardial pressures. Subendocardial pressure markedly changes during inotropic stimulation or myocardial ischemia. In three canine allografts and in an isolated, perfused and vented beating heart similar responses were observed during pharmacologic and hemodynamic testing. The intramyocardial pressure measurement proved to be relatively insensitive to preload and afterload changes provided coronary perfusion remained unaltered. Ventricular fibrillation produced an elevated and oscillating intramyocardial pressure while cardioplegic arrest reduced it to near zero. Diastolic pressure measurements were most sensitive to detect myocardial contracture ("stone" heart) during which intramyocardial pressure increased significantly. The "stone" heart exhibited persistent mechanical activity despite no visible contraction. The edematous heart's response to inotropic stimulation was reduced. Ischemia induced by inadequate perfusion was detected by a rapid drop in systolic intramyocardial pressure, preferentially affecting the endocardial region. This study establishes that the change in diastolic intramyocardial pressures in response in inotropic stimulus is a reliable indicator of myocardial contractility and viability and could be used during the procurement and preservation of the heart for transplantation.

The surgical management of coronary artery disease with myocardial dysfunction.

The prognosis of patients with coronary artery disease and severe left ventricular dysfunction (ischemic cardiomyopathy) is grim and medical therapy has not significantly altered its course. To evaluate the results of aortocoronary saphenous vein bypass grafting in patients with ischemic cardiomyopathy, 51 consecutive patients with left ventricular ejection fractions under 0.35 were analyzed. The average ejection fraction was 0.24. All patients had angina pectoris. Clinical congestive heart failure was present in 43 percent of the patients. Ninety percent of the patients had one or more previous myocardial infarctions. Forty-seven patients had three vessel disease and four patients had two vessel disease. Twenty-one percent of the patients had critical left main coronary artery obstruction. Twelve percent of the patients had unstable angina pectoris. Two patients had recent myocardial infarction. Improvements in operative management and surgical techniques, particularly the use of cardioplegic solution for operative myocardial protection and the judicious use of the intra-aortic balloon, have been clearly beneficial. The period of followup was 6 to 33 months. The operative mortality rate was 2 percent (one patient). There have been no late deaths. Significant improvement in angina pectoris and congestive heart failure was found in over 90 percent of the patients postoperatively. Patients with severe preoperative congestive heart failure had remarkable relief of symptoms after operation. The aortocoronary saphenous vein bypass operation can be performed in patients with coronary artery disease and severe left ventricular dysfunction with a low operative mortality rate, with marked relief of angina pectoris, and with dramatic improvement in the symptoms of congestive heart failure.