Robotically enhanced coronary artery bypass surgery

Robotically enhanced telemanipulation surgery is a rapidly developing technique which enables totally endoscopic cardiac surgery with utmost precision and perfection on both beating heart and arrested heart. Between December 2002 and September 2006, 268 patients underwent robotically enhanced coronary artery bypass surgery using the da Vinci telemanipulation system. Fourteen patients underwent total endoscopic coronary artery bypass surgery. Of these 12 were performed on a beating heart and 2 on an arrested heart. Two-hundred and fifty-four patients had endoscopic takedown of the internal mammary artery followed by minimally invasive direct coronary artery bypass in 193 patients and left anterolateral thoracotomy in 61 patients. The internal mammary artery mobilization time was 36 min (28–76 min) and the left internal mammary artery to left anterior descending artery anastomosis time ranged from 20 to 36 min for the totally endoscopic coronary artery bypass patients. The right internal mammary artery of one patient was anastomosed to diagonal artery totally endoscopically. The mean internal mammary artery flow by Doppler measurement in patients undergoing minimally invasive direct coronary artery bypass was 58 ml min⁻¹. Seven patients required conversion to median sternotomy and coronary bypass surgery on the beating heart. The mean intensive care unit stay was 1.2 days and the mean hospital stay 4.5 days. There was one in-hospital mortality. All 14 patients who underwent total endoscopic bypass surgery had coronary angiography 3 months later which showed 100% patency in 13 patients. One patient had 50% anastomotic narrowing for which coronary angioplasty was performed in the same sitting. By using telematic technology, a complete endoscopic anastomosis is possible in both single vessels and suitable double vessel disease patients. The use of robotics is now extended to achieve complete myocardial revascularization by harvesting both the internal mammary arteries and making a small thoracotomy for direct anastomosis also.

Robotically enhanced coronary artery bypass surgery

BACKGROUND

Robotically enhanced telemanipulation surgery is a fast developing technique which allows totally endoscopic cardiac surgery with utmost precision and perfection on both beating heart as well as arrested heart.

METHODS AND RESULTS

Between December 2002 and February 2004, 125 patients underwent robotically enhanced coronary artery bypass surgery using the da Vinci telemanipulation system (Intuitive Surgical Inc., California). Eleven patients underwent totally endoscopic coronary artery bypass surgery. Of them 9 were done on beating heart while 2 were done on arrested heart. One hundred and fourteen patients had endoscopic takedown of internal mammary artery followed by minimally invasive direct coronary artery bypass in 63 patients and left anterolateral thoracotomy in 51 patients. The internal mammary artery mobilization time was 42 min (35-74 min) while the left internal mammary artery to left anterior descending artery anastomosis time ranged from 20 to 36 min for the totally endoscopic coronary artery bypass patients. In 1 patient, the right internal mammary artery was anastomosed to diagonal artery totally endoscopically. The mean internal mammary artery flow by Doppler measurement done in patients undergoing minimally invasive direct coronary artery bypass was 64 ml/min. Seven patients required conversion to median sternotomy and coronary bypass surgery on beating heart. The mean intensive care unit stay was 1.2 days and the mean hospital stay 4.5 days. There was 1 in-hospital mortality. All 11 patients who underwent totally endoscopic bypass surgery had coronary angiography done at 3 months interval which showed 100% patency in 10 patients while one patient had 50% anastomotic narrowing for which coronary angioplasty was done in the same sitting.

CONCLUSIONS

Using telematic technology, a complete endoscopic anastomosis is possible in both single vessel and suitable double vessel disease patients. The use of robotics is now extended to achieve complete myocardial revascularization by harvesting both the internal mammary arteries and making a small thoracotomy for direct anastomosis as well.

Pretreatment of human myocardium with adenosine

OBJECTIVES

While the role of adenosine pretreatment in animals has been well established, the role in humans has been controversial. We performed this prospective, randomized study to find out the usefulness of adenosine pretreatment in humans.

PATIENTS AND METHODS

Twenty patients undergoing coronary artery bypass surgery for severe triple vessel disease and left ventricular dysfunction (ejection fraction<35%) formed the study population. The adenosine group (n=10) received adenosine infusion (200 microg/kg) before aortic cross-clamp. The control group (n=10) received only normal saline injection. Cardiac function indices were assessed post-operatively.

RESULTS

In the adenosine group there was a significant increase in cardiac output in the post-operative period from 3.46+/-1.06 to 4.46+/-0.92 l/min (P<<0.05). The cardiac index increased significantly in the adenosine group from 1.97+/-0.43 to 2.54+/-0.5 l/min per m2 (P<<0.05) and even when compared with the control group this increase was significant (adenosine group vs. control group, P=0.03). Systemic vascular resistance fell from 1898.8+/-558.4 to 1134.9+/-530.7 dyne/s per cm(-5) (P<<0.05) in the adenosine group. The pulmonary artery wedge pressure fell significantly in the adenosine group from 11.1+/-5.0 to 7.2+/-2.6 mmHg (P<<0.05). Patients in the adenosine group maintained a lesser increase in resting heart rate post-operatively (96.1+/-13.4 to 114.1+/-18.7 beats/min) (P=0.7), as compared to the control group where the increase in the heart rate was significant (77.1+/-8.3 to 109.7+/-14.9 beats/min) (P<<0.05). In the adenosine group only one patient (10%) had a raised creatine phosphokinase (MB) level at 12 h post-operatively as compared to three patients (30%) in the control group (P<0.05).

CONCLUSIONS

Adenosine pretreatment appears to protect against reperfusion injury in human hearts and thus results in improved post-operative haemodynamics.

Mitral valve replacement with chordal preservation in a rheumatic population

BACKGROUND AND AIM OF THE STUDY

Mitral valve replacement (MVR) with preservation of the subvalvular apparatus may maintain postoperative left ventricular (LV) function better than conventional MVR. A prospective study was undertaken to assess the advantages of chordal preservation in rheumatic patients undergoing isolated MVR.

METHODS

Between January 1996 and January 1999, 240 patients with rheumatic etiology and normal LV ejection fraction (>50%) underwent isolated MVR using a St. Jude Medical prosthesis. Patients were allocated to two groups: in group I (n = 168), both the anterior and posterior chordae were preserved; in group II (n = 72), the entire native mitral valve apparatus was excised. Patients from both groups were evaluated postoperatively (mean 12.5 months) by echocardiography and treadmill testing.

RESULTS

Demographic and clinical profiles were comparable in both groups. There were three early deaths in group I, and one in group II. There were no late deaths. One patient in group I required reoperation for a stuck mitral prosthesis. LV function (ejection fraction >50%) was better in group I (94%) than in group II (82%) (p <0.05). No patient in either group had LV outflow tract obstruction on echocardiography. Patients in group I showed better exercise performance on treadmill (Bruce protocol): 92% of group I patients versus 88% of group II patients (p >0.05) completed stage I; 16% of group I patients, but no group II patients, were able to complete stage IV (p <0.05).

CONCLUSION

Mitral valve replacement with preservation of the subvalvular apparatus maintains LV function, and does not cause LV outflow tract obstruction.

Association between incidence of lipoprotein(a) positivity and coronary heart disease

Serum samples from 167 (109 male, 58 female) hospital based staff as controls and 760 (596 male and 164 female) clinically documented patients of coronary heart disease (CHD) were subjected to 3.75% polyacrylamide gel electrophoresis for lipoprotein profile and the presence of lipoprotein(a) [LP(a)], which is reported to be an independent risk factor for CHD. Serum total cholesterol, triglyceride and ratio of the electrophoretically separated LDL/HDL lipoprotein fractions were also evaluated. The significant observations are (i) a large proportion of both male and female CHD patients showed the presence of LP(a) as compared to controls, (ii) The incidence of LP(a) positivity was found to be independent of sex and age in controls. Female patients however showed marginal increase (p < 0.05) with age. Male patients of < 40 years demonstrated three times higher incidence of LP(a) presence as compared to their female counterparts, (iii) Comparison of LP(a)+ and LP(a)- patients for serum lipid levels did not show any significant difference. It is inferred that LP(a) positivity may be independent of these lipid variables.

Haemodynamic effects of static and dynamic exercise in males with arterial hypertension of varying severity

Sustained handgrip at 30% of the maximal strength and submaximal supine bicycle exercise elicited mean blood pressure increases of similar magnitude in healthy males and in men with essential hypertension WHO Stage 1 and 2, but with different contributions of systolic and diastolic blood pressure changes. While systolic blood pressure exceeded 22.7 kPa (170 mmHg) during static exercise in every hypertensive man, this did not occur in any of the control subjects. During dynamic exercise, the arterial blood pressure increase per litre increase in cardiac output was significantly less than during static exercise, indicating different patterns of circulatory adaptation to these two forms of stress. Combination of dynamic and static exercise tests might be of value for identifying subjects with a hypertensive pattern of circulatory regulation.

Acute haemodynamic effects of metoprolol in hypertensive patients

1. The acute haemodynamic effects of metoprolol (0.15 mg/kg body weight) intravenously were studied at rest and during exercise, in a recumbent position in five patients with arterial hypertension of WHO Stage 1 or 2. 2. Significant decreases in heart rate, cardiac output and arterial blood pressures, both at rest and during exercise, were seen. There were no changes in the calculated stroke volume or systemic vascular resistance. 3. The apparent absence of any relative preponderance of the alpha-adrenoreceptors after acute beta-adrenoreceptor blockade with metoprolol warrants further studies on metoprolol in arterial hypertension.

Systemic haemodynamics in mild arterial hypertension before and after physical training

1. Five men with borderline, latent arterial hypertension of the hyperkinetic type were studied haemodynamically at rest and during dynamic exercise before and after a 6-week period of supervised physical training.

2. Tendencies to lower heart rate, cardiac output and arterial blood pressure, both at rest and during a standardized work-load, were observed after the training period, with significant differences between paired observations for the heart rate and mean arterial blood pressure during exercise. The systemic vascular resistance being unchanged, there was a certain trend to an increased widening of the arteriovenous oxygen difference, both at rest and during exercise.

3. The present findings from a small number of subjects indicate that physical conditioning of patients with latent hypertension of the hyperkinetic type contributes to a normalization of their circulation toward a normokinetic one, thereby also normalizing their blood pressure level and achieving a more economic energy expenditure in the cardiovascular system.