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Computer-enhanced "robotic" cardiac surgery: experience in 148 patients.

OBJECTIVE: A computer-enhanced instrumentation system was used in 148 patients to minimize access in cardiac surgical procedures. METHODS: The da Vinci telemanipulation system (Intuitive Surgical, Mountain View, Calif) provides a high-resolution 3-dimensional videoscopic image and allows remote, tremor-free, and scaled control of endoscopic surgical instruments with 6 degrees of freedom. By April 2000, the system had been used in 131 patients for coronary artery bypass grafting and 17 patients for mitral valve repair. In the coronary bypass group, the system was used in one of three ways: (1) to take down the internal thoracic artery followed by a minimally invasive direct coronary bypass procedure (n = 81); (2) to perform the anastomosis between the internal thoracic artery and the left anterior descending coronary artery in standard-sternotomy coronary bypass (n = 15); or (3) for total endoscopic coronary artery bypass grafting to anastomose the left internal thoracic artery to the left anterior descending on the arrested heart (n = 27) or the beating heart (n = 8). In 17 patients with nonischemic mitral valve insufficiency the mitral valve was repaired. Closed-chest cardiopulmonary bypass with cardioplegic arrest (Port-Access technique; Heartport, Inc, Redwood City, Calif) was used for arrested-heart total endoscopic coronary bypass and mitral valve repair. RESULTS: The da Vinci system allows for precise tissue handling and enables the endoscopic performance of cardiac surgical tasks that require a high degree of dexterity (coronary anastomosis, mitral valve repair). No technical mishaps have occurred. The internal thoracic artery was successfully taken down in 79 of 81 patients in the group undergoing minimally invasive coronary bypass and, after a steep learning curve, is currently performed in less than 40 minutes. The postoperative patency rate is 96.3%. Total endoscopic coronary bypass was completed in 22 of 27 cases with 95.4% patency as demonstrated by angiography at 3 months' follow-up. Closed-chest endoscopic beating-heart bypass grafting was successfully performed in 2 out of 8 patients with the use of a new endoscopic stabilizer. In the group having mitral valve repair, primary endoscopic computer-enhanced repair was successfully completed in 14 of 17 patients; three others had to be changed to a standard endoscopic technique, including 1 who required valve replacement. At 3 months' follow-up, 1 additional patient underwent early reoperation for recurrent mitral insufficiency. Overall early and late mortality in this cohort of 148 patients was 2.0% and was not related to the use of the system. CONCLUSION: In conclusion, computer-enhanced endoscopic cardiac surgery can be performed safely in selected patients. Internal thoracic artery takedown is now routinely performed with good results. Total endoscopic coronary bypass is feasible on the arrested heart but does not offer a major benefit over the minimally invasive direct approach because cardiopulmonary bypass is still required. The early clinical experience with closed-chest beating-heart bypass grafting outlines the limitations of this approach despite some procedural success.

Animals↗

Effect of pressure on myocardial function after 6-hour preservation with blood cardioplegia.

BACKGROUND: This study examined the return of cardiac function in pig hearts after 6 hours' preservation by continuous perfusion with blood cardioplegia at two perfusion pressures compared with preservation with crystalloid solutions. METHODS: Isolated pig hearts were randomly divided into five groups (n = 8 per group) according to the following treatments: group 1 = fresh hearts (control); group 2 = hearts arrested with Queen's cocktail cardioplegia and then immersion in 0 degrees C saline solution (QS group); group 3 = hearts arrested with (5 degrees C) and simple immersion in 0 degrees C University of Wisconsin solution (UW group); and groups 4 and 5 = hearts arrested with blood cardioplegia at 10 degrees C and then continuously perfused at a pressure of 80 cm H2O or 40 cm H2O, respectively (groups BC80 and BC40). After preservation for 6 hours, donor hearts were reperfused by a cross-circulation support pig. Thereafter, cardiac function and metabolism were examined every half hour for 2 hours. A three-way mixed general linear model was used to analyze data with repeated measures. Bonferroni test was used to determine differences (p < or = 0.05) between groups. RESULTS: Only 4 hearts recovered electric activity in the BC80 group (p < or = 0.05 versus other groups). There was poor recovery of left ventricular work in the BC80 group compared with the other groups (p < 0.001). Left ventricular work in the QS and UW groups was also lower than in the control and BC40 groups. Left ventricular work in the BC40 group fully recovered. Maximum elastance did not differ between groups. Compliance was reduced in the QS, BC80, and BC40 groups versus controls after preservation (p < 0.006). Coronary flow decreased and coronary vascular resistance increased in the BC80 group versus the other groups (p < or = 0.001). Coronary flow in the QS, UW, and BC40 groups was lower than in the control group (p < 0.001). The magnitude of lactate release was much higher in the BC80 group than in the other groups (p < or = 0.001). CONCLUSIONS: Continuous perfusion with 10 degrees C blood cardioplegia at 40 cm H2O pressure for 6 hours provided adequate preservation of systolic function in this model. University of Wisconsin solution provided the best protection of diastolic function.

Adenosine↗

Transplantation of hearts after arrest and resuscitation. Early and long-term results.

Transplant surgeons are reluctant to use hearts that have undergone cardiopulmonary resuscitation for cardiac arrest because of the fear of poor early and late cardiac function. A policy of minimizing contraindications to use of donor hearts has led to the unique opportunity of assessing the effects of donor arrest and successful cardiopulmonary resuscitation on early and late cardiac function in pediatric heart transplantation. A number of 140 infants and children undergoing transplantation from birth to 17 years of age were studied retrospectively and divided into two groups on the basis of cardiopulmonary resuscitation status. Group 1 (72 patients) received donor hearts that were not subjected to cardiopulmonary resuscitation; group 2 (68 patients) received donor hearts that had cardiopulmonary resuscitation for a mean of 18.8 +/- 14.6 minutes, the longest period of time being 60 minutes. Mean ischemic times were almost identical in the two groups: 4.43 +/- 2.0 hours (cardiopulmonary resuscitation) versus 4.5 +/- 2.1 hours (no cardiopulmonary resuscitation). Early cardiac function was assessed on the basis of the number of days the recipient was supported by the ventilator, days receiving dopamine, days receiving isoproterenol, and the amount of inotropic agents required after the operation. The groups did not differ. Parameters of systolic function included fractional shortening, posterior wall thickening, and maximum velocity of change in left ventricular posterior wall dimension during systole. Diastolic function was measured on the basis of left ventricular end-diastolic volume, left ventricular mass, and maximum velocity of change in left ventricular posterior wall dimension during diastole. Both systolic and diastolic function were measured and analyzed from M-mode echocardiography at 1 week, 1 month, 6 months, 1 year, and 2 years after the operation. There were no statistically significant differences in graft function between the two groups in any of the echocardiographic parameters studied, even at 2 years. No group differed from ranges of normal. Our results suggest that hearts undergoing cardiopulmonary resuscitation for periods of up to 60 minutes can be used safely without evidence of deterioration of early or late cardiac function.

Adolescent↗

Amelioration of the effects of ischemic cardiac arrest by the intracoronary administration of cardioplegic solutions.

Interruption of coronary flow during cardiac surgical procedures provides a bloodless flaccid heart and allows precise and rapid correction of complex cardiac defects. However, myocardial damage occurs in direct proportion to the duration of the ischemia. As the induction of cardioplegia simulataneous with the initiation of cardiac ischemia helps to preserve cardiac energy reserves and thus myocardial integrity, the identification of a consistently reliable cardioplegic technique is desirable. Isolated perfused working rat hearts were made ischemic for one hour by aortic cross-clamping and were compared with hearts rendered cardioplegic at the onset of ischemia by the intracoronary administration of 5 ml of a hypothermic solution: 1) Krebs-Henseleit buffer, 2) Ringer's lactate, 3) tetrodotoxin, 4) potassium chloride, or 5) potassium citrate. Cardiac output, heart rate, aortic pressure and coronary flow were determined pre and post-ischemia. When compared to time-matched controls and hearts arrested with potassium or tetrodotoxin, the ischemia and ischemia-Ringer's lactate groups showed significant post cross-clamp depression of all measured parameters. Intracoronary Ringer's lactate, although often used as an adjunct to ischemic arrest, was not of significant value. In contrast, hearts arrested with tetrodotoxin, potassium chloride or potassium citrate showed no significant post-ischemic functional or histologic deficit. Perfusion with hypothermic Krebs-Henseleit buffer protected the myocardium better than did Ringer's lactate but less well than the tetrodotoxin or isotonic high potassium solutions. The induction of hypothermic metabolic arrest of the heart by briefly perfusing the coronary arteries via the aortic root with isotonic buffered solutions results in markedly improved myocardial tolerance to one hour of ischemia and avoids the problems of low cardiac output and ventricular irritability previously reported with hypertonic potassium citrate arrest.

Animals↗

Experimental evaluation of myocardial preservation techniques: V. A. membrane-stabilizing agent, procaine hydrochloride.

The protective effects of procaine hydrochloride on the anoxic heart were investigated using the papillary muscle contractility of an isolated, blood-perfused rabbit heart as an index of myocardial function. Fifty-four experiments were divided into nine groups of six experiments each, in which anoxic periods (30, 45, 60 minutes) and concentration of procaine (solution 3, 0.3%) were the variables. The hearts arrested significantly faster with solution 3 compared with solution 2 or 1 (p < 0.01). After 30 minutes of anoxia, the recovery of the contractility was 81.1 +/- 4.2% with solution 1, 90.7 +/- 3.4% with solution 2, and 90.6 +/- 3.3% with solution 3. After 45 minutes of anoxia, the recovery was 31.8 +/- 19.0% with control, 67.5 +/- 15.8% with 0.03% procaine, and 58.1 +/- 22.8% with 0.3% procaine. After 60 minutes of anoxia, the recovery was 2.2 +/- 2.7% with control, 18.7 +/- 14.1% with 0.03% procaine, and 5.0 +/- 7.3% with 0.3% procaine. After each anoxic period, the best recovery occurred with those hearts arrested by solution 2. Although the difference in recovery between the procaine groups was not statistically significant, a longer time was required for the hearts arrested with solution 3 to reach full functional recovery. This study indicated that procaine per se has a protective effect on the anoxic hearts and that although high concentration (0.3%) of procaine arrests the heart rapidly, it delays the recovery of contractions. We recommend the use of 0.03% procaine in cardioplegic solution.

Animals↗

A new hydroxyl radical scavenger "EPC" on cadaver heart transplantation in a canine model.

This study was performed to determine if an "arrested" heart, resuscitated with cardiopulmonary bypass (CPB) after the cessation of beating, can be successfully transplanted, and whether a hydroxyl radical scavenger EPC can reduce ischemic and reperfusion injury during resuscitation of the arrested heart and following orthotopic heart transplantation. A total of 16 pairs of canines were divided into a control group of eight pairs and an EPC-treated group of eight pairs. Cardiac arrest of the donor heart was induced by the discontinuation of respiratory support after the induction of brain death. The cadaver heart was then resuscitated and core-cooled to myocardial temperature of 15 degrees C using CPB. The donor heart was harvested using cold cardioplegia and orthotopically transplanted. All of the transplanted hearts in the EPC group were weaned from CPB without any inotropic support after 60 min of bypass support, whereas all the animals in the control group required 5 micrograms/kg/min dopamine (P = 0.001). Moreover, cardiac function (Emax) 1 h after orthotopic heart transplantation was better preserved in the EPC group than in the control group, at 110 +/- 36% vs. 70 +/- 21% of the post brain death values (P = 0.02) These findings demonstrate that EPC reduces posttransplant reperfusion injury, and thus it may prove to be a valuable adjunct in this challenging model.

Animals↗

Temperature threshold and modulation of energy metabolism in the cardioplegic arrested rabbit heart.

Hypothermia protects ischemic tissues by reducing ATP utilization and accumulation of harmful metabolites. However, it also reduces ATP production, which might cause deterioration in the energy supply/demand ratio. Modulation of energy supply/demand according to temperature has not been previously studied in detail. In this study, isolated, perfused rabbit hearts (n = 60) were used to determine the effects of various temperatures on myocardial energy metabolism and function during cardioplegic arrest. Ischemia was induced by crystalloid cardioplegic solution at 4, 18, 30, and 34 degrees C for 120 min, respectively. At each temperature, the hearts were divided into a glucose-treated group which contained 22 mM glucose in cardioplegic solution as the only substrate and a control group which contained 22 mM mannitol to keep same osmolarity. Following 15 min reperfusion, recovery of left ventricular developed pressure (DP), +/- dP/dtmax, and the product of heart rate and DP were significantly higher in 30, 18, and 4 degrees C groups than those in 34 degrees C control group. The functional recovery was also significantly higher in the 34 degrees C glucose-treated group than that in the 34 degrees C control group, but there was no difference between those groups at 30 degrees C and the temperature below 30 degrees C. Myocardial ATP concentration was significantly lower in 34 degrees C control group than those in other groups. There is a close relationship between myocardial ATP concentration and functional recovery (R2 = 0.90). The accumulations of lactate and CO2 were significantly higher at 34 degrees C in glucose-treated group than those in the control group. However, there was no significant difference between these two groups at 30 degrees C and the temperature below 30 degrees C. These results indicate that under these study conditions: (1) a marked decrease in energy supply/demand occurs above 30 degrees C, implying that a temperature threshold exists; and (2) this can be ameliorated by provision of glucose as substrate in cardioplegia solution.

Adenosine Triphosphate↗

[Effects of Young's solution (YNG solution) on cardiac function and mitochondrial function during one hour ischemia at 30 degrees C and after reperfusion].

In a previous paper from this laboratory, protective effects of YNG solution on the myocardial mechanical function and metabolism of the heart arrested at 10 degrees C ascribable to the presence of Mg2+ were demonstrated. In order to further clarify the role played by Mg2+ in the protection, the present experiment was conducted using the isolated perfused guinea pig heart arrested at 30 degrees C. While the time to arrest of the contraction was equally short both with YNG (K+ + Mg2+) and K (K+) solutions, the time to resumption of contraction was significantly longer with K solution than with YNG solution, and the regular contraction was not resumed with the former solution. The recovery of the coronary flow, left ventricular pressure and dp/dt after reperfusion was around 100% with YNG solution, while the recovery was significantly poorer with K solution. Although the mitochondrial function was well maintained during the arrest both with YNG and K solution, the recovery of the mitochondrial function after reperfusion was observed only with YNG solution; severe damage was noted in mitochondria of the hearts arrested with K solution. There was a good correlation between the changes in mitochondrial function and those in cardiac function.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗