Highly trained, middle-aged endurance runners demonstrated a significantly greater dilating capacity of their epicardial coronary arteries in response to nitroglycerin compared with inactive men. The causes of this greater dilating capacity and its clinical significance need to be determined.

Objective-To study the time course and underlying mechanisms of right heart filling after cardiac surgery.Design-A prospective observational study of adult patients undergoing cardiac surgery.Setting-Echocardiography laboratory of the Stanford University Medical Center.Patients-Twenty six patients (mean age 54-9) undergoing cardiac surgery were studied before and two days, one week, six weeks, and six months after cardiac surgery.Main outcome measures-Flow in the hepatic veins and superior vena cava, tricuspid and mitral annulus motion, signs of tricuspid regurgitation, and right ventricular size were assessed by echocardiography.Results-Right heart filling, expressed as the ratio of systolic to diastolic forward flow Doppler velocity integrals in the superior vena cava and by tricuspid annulus motion, decreased in parallel from before surgery baseline values of 3*5 (SD 3-1) and 21-9 (3-4) mm, respectively to 02 (01) and 8-1 (2-3) mm two days after operation. A gradual increase towards baseline values was noted after six months, to 1-4 (1-3) and 15.1 (2 3) mm respectively; however, these values were still significantly less than those before operation. Similar changes were seen in the hepatic venous flow pattern. The decrease in total tricuspid annulus motion was most pronounced in its lateral segment and the atrial component of the tricuspid annulus motion showed similar changes.Conclusions-The pronounced decrease in tricuspid annulus motion during the early postoperative period suggests right atrial and right ventricular dysfunction as mechanisms responsible for the early changes-seen. The progressive return to a normal venous filling pattern and the partial recovery of annular motion six months after operation further support the influence ofthe above mechanisms, as well as their resolution with time. The persistent flow abnormalities and compromised motion of the free aspects of the tricuspid annulus, however, suggest long-term tethering of the right heart walL Right heart filling, reflected in the pattern of systemic venous return, becomes abnormal in patients who undergo cardiac surgery supported by cardiopulmonary bypass.'-' These changes were first described as an alteration in jugular venous pulse contours and flow velocities from the normal dominant systolic flow to an equal or dominant diastolic flow.45 Recently we have shown, using intraoperative transoesophageal echocardiography, that the venous flow pattern is normal before cardiopulmonary bypass even with the pericardium fully opened, but becomes abnormal immediately after termination of cardiopulmonary bypass.6 A mechanical impediment to cardiac motion and a combination of abnormalities in right heart function were suggested as possible mechanisms for these changes immediately after cardiopulmonary bypass. The present study was undertaken to further elucidate the time course and underlying mechanisms of these changes through repeated observations before and during a six month period after operation. Patients and methods PATIENT POPULATION...

Minimally invasive surgical methods have been developed to provide patients the benefits of open operations with decreased pain and suffering. We have developed a system that allows the performance of cardiopulmonary bypass and myocardial protection with cardioplegic arrest without sternotomy or thoracotomy. In a canine model, we successfully used this system to anastomose the internal thoracic artery to the left anterior descending coronary artery in nine of 10 animals. The left internal thoracic artery was dissected from the chest wall, and the pericardium was opened with the use of thoracoscopic techniques and single lung ventilation. The heart was arrested with a cold blood cardioplegic solution delivered through the central lumen of a balloon occlusion catheter (Endoaortic Clamp; Heartport, Inc., Redwood City, Calif.) in the ascending aorta, and cardiopulmonary bypass was maintained with femorofemoral bypass. An operating microscope modified to allow introduction of the 3.5x magnification objective into the chest was positioned through a 10 mm port over the site of the anastomosis. The anastomosis was performed with modified surgical instruments introduced through additional 5 mm ports. In the cadaver model (n = 7) the internal thoracic artery was harvested and the pericardium opened by means of similar techniques. A precise arteriotomy was made with microvascular thoracoscopic instruments under the modified microscope on four cadavers. In three other cadavers we assessed the exposure provided by a small anterior incision (4 to 6 cm) over the fourth intercostal space. This anterior port can assist in dissection of the distal internal thoracic artery and provides direct access to the left anterior descending, circumflex, and posterior descending arteries. We have demonstrated the potential feasibility of grafting the internal thoracic artery to coronary arteries with the heart arrested and protected, without a major thoracotomy or sternotomy.

Integrated ultrasonic backscatter (IB) is a noninvasive measure of the acoustic properties of myocardium. Previous experimental studies have indicated that altered acoustic properties of the myocardium are reflected by the magnitude of variation of IB during the cardiac cycle. In our study, cardiac cycle-dependent variation of IB was noninvasively measured using a quantitative IB imaging system in 12 patients with uncomplicated pressure-overload hypertrophy and 13 patients with hypertrophic cardiomyopathy. Sixteen normal subjects served as a control. The magnitude of cardiac cycle-dependent variation of IB for the posterior wall was 6.0± 0.9 dB in normal subjects, 5.7±+0.8 dB in the patients with uncomplicated pressureoverload hypertrophy, and 6.7+±2.1 dB in the patients with hypertrophic cardiomyopathy. There were no significant differences among any of these groups. In contrast, the magnitude of cardiac cycle-dependent variation of IB for the septum was significantly smaller in the patients with uncomplicated pressure-overload hypertrophy (2.8+1.3 dB) and in the patients with hypertrophic cardiomyopathy (3.1±2.3 dB) than in normal subjects (4.9±1.0 dB). The magnitude of cardiac cycle-dependent variation of IB was smaller as the wall-thickness index increased (r=-0.53, p<0.01, n=82 for all data). This IB measure also correlated with percent-systolic thickening of the myocardium (r=0.67,p<0.01, n=82). Thus, alteration in the magnitude of cardiac cycle-dependent variation of IB was observed in hypertrophic hearts and showed apparent regional myocardial differences. (Circulation 1989;80:925-934) L eft ventricular hypertrophy is a common adaptation mechanism in patients with pressure overload such as hypertension and aortic stenosis.1,2 Idiopathic left ventricular hypertrophy also may occur and this is usually classified as hypertrophic cardiomyopathy (HCM).3 HCM, in most cases, is characterized by asymmetric septal hypertrophy,4-8 and, thus, M-mode and twodimensional echocardiography are useful both in the quantification of hypertrophy and in the differentiation of these two forms of hypertrophy.

A strategy of routine stent implantation during mechanical reperfusion of AMI is safe and is associated with favorable event-free survival and low rates of restenosis compared with primary PTCA alone.