Pulmonary autograft versus aortic homograft for rereplacement of the aortic valve: results from a subset of a prospective randomized trial.

BACKGROUND: The use of a pulmonary autograft for rereplacement of the aortic valve has both potential advantages and disadvantages. This study details the early results of a subset of patients enrolled in a prospective randomized trial comparing pulmonary autografts and aortic homografts who have had previous aortic valve replacements. METHODS AND RESULTS: A total of 47 patients who had undergone >/=1 previous aortic valve replacement were randomized to receive either a pulmonary autograft (24 patients aged 40+/-11 years) or an aortic homograft (23 patients aged 37+/-11 years) for rereplacement of the aortic valve. One early death occurred in the homograft group, and 1 late (7 months) death occurred in the autograft group. One patient who received a pulmonary autograft was reoperated on for inflammatory pulmonary stenosis. One patient in each group was reopened for bleeding (both within 24 hours). Two patients in the autograft group had postoperative neurological weakness; they fully recovered over 2 months. Hospital stay, blood loss, incidence of perioperative arrhythmia, and markers of coronary ischemia were similar between the 2 groups. At 6-month follow-up (range, 1 to 12 months), left ventricular end-diastolic diameter was similar in both groups (homografts, 5.0+/-0.9 cm; autografts, 5.2+/-0.6 cm; P=NS), and no patient in either group had significant aortic valve dysfunction. CONCLUSIONS: Rereplacement of the aortic valve with a pulmonary autograft is feasible and safe in patients aged 14 to 60, regardless of their preoperative diagnosis or clinical condition.

Intraoperative cardiac troponin T release and lactate metabolism during coronary artery surgery: comparison of beating heart with conventional coronary artery surgery with cardiopulmonary bypass.

OBJECTIVE: To compare cardiac troponin T release and lactate metabolism in coronary sinus and arterial blood during uncomplicated coronary grafting on the beating heart with conventional coronary grafting using cardiopulmonary bypass. DESIGN: A prospective observational study with simultaneous sampling of coronary sinus and arterial blood: before and 1, 4, 10, and 20 minutes after reperfusion for analysis of cardiac troponin T and lactate. Cardiac troponin T was also analysed in venous samples taken 3, 6, 24, 48, and 72 hours after surgery. SETTING: Cardiac surgical unit in a tertiary referral centre. PATIENTS: 18 patients undergoing coronary grafting on the beating heart (10 single vessel and eight two-vessel grafting) and eight undergoing two-vessel grafting with cardiopulmonary bypass. RESULTS: Cardiac troponin T was detected in coronary sinus blood in all patients by 20 minutes after beating heart coronary artery surgery before arterial concentrations were consistently increased. Peak arterial and coronary sinus cardiac troponin T values on the beating heart during single (0.03 (0 to 0. 05) and 0.09 (0.07 to 0.16 microg/l, respectively) and two-vessel grafting (0.1 (0.07 to 0.11) and 0.19 (0.14 to 0.25) microg/l) were lower than the values obtained during cardiopulmonary bypass (0.64 (0.52 to 0.72) and 1.4 (0.9 to 2.0) microg/l) (p < 0.05). The area under the curve of venous cardiac troponin T over 72 hours for two-vessel grafting on the beating heart was less than with cardiopulmonary bypass (13 (10 to 16) v 68 (26 to 102) microg.h/l) (p < 0.001). Lactate extraction began within one minute of snare release during beating heart coronary surgery while lactate was still being produced 20 minutes after cross clamp release following cardiopulmonary bypass. CONCLUSIONS: Lower intraoperative and serial venous cardiac troponin T concentrations suggest a lesser degree of myocyte injury during beating heart coronary artery surgery than during cardiopulmonary bypass. Oxidative metabolism also recovers more rapidly with beating heart coronary artery surgery than with conventional coronary grafting. Coronary sinus cardiac troponin T concentrations increased earlier and were greater than arterial concentrations during beating heart surgery, suggesting that this may be a more sensitive method of intraoperative assessment of myocardial injury.

Effect of coronary occlusion on left ventricular function with and without collateral supply during beating heart coronary artery surgery.

OBJECTIVE: To study the effects of coronary occlusion and collateral supply on left ventricular (LV) function during beating heart coronary artery surgery. DESIGN: Prospective intraoperative study, performed at baseline, during wall stabilisation, coronary artery occlusion, and 2 and 10 minutes after reperfusion. Transoesophageal M mode echocardiograms, simultaneous high fidelity LV pressure, and thermodilution cardiac output were measured. LV anterior wall thickening, thinning velocities, thickening fraction, regional work, and power production were derived. Asynchrony during the isovolumic periods was quantified as cycle efficiency. SETTING: Tertiary referral cardiac centre. PATIENTS: 14 patients with stable angina, mean (SD) age 62 (7) years, undergoing left anterior descending artery grafting using the "Octopus" device. RESULTS: Collaterals were absent in nine patients and present in five. Epicardial stabilisation did not affect LV function. Results are expressed as mean (SD). Coronary occlusion (15.6 (2) minutes) depressed anterior wall thickening (1.4 (0.6) v 2.6 (0.6) cm/s) and thinning velocities (1.4 (0.5) v 3.0 (0.6) cm/s), regional work (2.2 (0.8) v 4.6 (0.6) mJ/cm2), and power (21 (4) v 33 (5) mW/cm2) in patients without collaterals (p < 0.05 for all), but only wall thinning (3.5 (0.5) v 4.8 (0.5) cm/s, p < 0.05) in patients with collaterals. All returned to baseline within 10 minutes of reperfusion. Cycle efficiency and regional work were impaired at baseline and fell during occlusion, regardless of collaterals. Within 10 minutes of reperfusion both had increased above baseline. CONCLUSIONS: Coronary occlusion for up to 15 minutes during beating heart coronary artery surgery depressed standard measurements of systolic and diastolic anterior wall function in patients without collaterals, but only those of diastolic function in patients with collaterals. Regional synchrony decreased in both groups. All disturbances regressed within 10 minutes of reperfusion.

Analysis of wave reflections in the arterial system using wave intensity: a novel method for predicting the timing and amplitude of reflected waves.

The timing and amplitude of reflected arterial waves in the ascending aorta were studied by analysis of the aortic pressure waveform and were compared with those derived using wave intensity analysis. Wave intensity analysis considers aortic pressure changes to be the result of forward and backward wavelets carrying energy. Wave intensity (dI = dPdU) is calculated from changes in pressure (dP) and flow velocity (dU), and its sign indicates the direction of travel of propagating wavelets (positive for forward-traveling waves and vice versa). We measured aortic pressure and flow velocity in 14 patients, mean age 60+/-9 years, with three-vessel coronary artery disease at the time of surgical revascularization. The travel time of the reflected wave derived from analysis of the aortic pressure waveform (tp) was measured from the foot of the aortic pressure waveform to the inflection point of the aortic pressure (derived objectively from the zero of second derivative of aortic pressure). From wave intensity analysis, the travel time of the reflected wave was measured to the onset of the wave intensity of the backward-traveling wave dI_ (t(i)), and to the onset of the separated backward pressure wave (t(b)). All patients showed an aortic pressure waveform characterized by an inflection point on the rising limb of the aortic pressure, followed by a secondary rise in pressure, representing the return of reflected waves. Wave intensity analysis consistently showed a negative peak in mid systole, the timing of its onset corresponding closely to the inflection point of the aortic pressure. The travel time of the reflected wave derived from the analysis of the aortic pressure waveform (t(p)) was 121+/-21ms and showed close agreement with ti (118+/-28 ms) and t(b) (115+/-29ms), with mean differences of 4 and 6ms, and 95% confidence intervals of difference (-2 to 7 ms) and (1 to 12ms), respectively. The augmentation index, a measure of the secondary increase in aortic pressure due to reflected waves, was significantly correlated with the magnitude of dI_ (r = 0.63, P < 0.001). Wave intensity is a quantity that indicates the rate of energy flux due to wave travel and since its value is positive for forward-traveling waves and negative for backward-traveling waves, its calculation allows the timing of reflected waves to be accurately predicted. Furthermore, the magnitude of wave intensity in backward-traveling waves (dI_) is related to the augmentation index and may provide a measure of the amplitude of the reflected wave. This analysis of the arterial system is done in the time domain and therefore can be easily applied to assess temporal changes in arterial characteristics.

Calcium requirement in elderly Japanese women.

In order to evaluate calcium requirements (RC) in Japanese elderly women, a calcium balance study was carried out in 9 osteoporotics (73.9 +/- 2.7 years old, mean +/- SE) and 9 normal elderly women (67.0 +/- 2.5 years old). Diet containing 700 mg/day of calcium were given for at least 1 week. Then, diets containing approximately 700 mg/day (722.5 +/- 91.9 mg/day) of calcium in the 1st week and 1,474 mg/day of calcium in the 2nd week were served. The amount of calcium intake to maintain zero balance, defined as daily RC, was 550.4 +/- 50.0 and 648.8 +/- 44.7 mg/day in normal and osteoporotic subjects, respectively. There was no statistically significant difference between these two groups. Although the recommended daily allowance (RDA) for the adult Japanese is 600 mg/day, our study suggests that RDA in the elderly Japanese should be 847 mg.