Beneficial effect of balloon-induced pulsatility on brain oxygenation in hypothermic cardiopulmonary bypass

BACKGROUND

Sufficient O2 delivery to meet the demand is an important factor for protecting the brain during cardiopulmonary bypass (CPB). This study was designed to investigate the influences of temperature, pulsatility of blood flow (intra-aortic balloon pump-induced) and flow rate during CPB on the cerebral oxygenation.

METHODS

Patients were divided into five groups. Normothermia (36 degrees C): pulsatile (n=8, 2.5 L/min/m2), nonpulsatile (n=12, 2.5 L), and nonpulsatile perfusion (n=12, 2.8 L); hypothermia (30 degrees C): pulsatile (n=9, 2.5 L) and nonpulsatile perfusion (n=11, 2.5 L). The oxygen saturation (SjVO2), lactate and CPK-BB levels in the jugular venous blood were measured.

RESULTS

In all of the normothermic groups, the SjVO2 value decreased during the CPB (p<0.1-0.01). No remarkable change was observed in the hypothermic groups, with the exception during the rewarming period in the nonpulsatile group. A higher SjVO2 and a lower frequency of SjVO2 values <50% were observed in the hypothermic pulsatile group, as compared with those in the normothermic groups (p<0.05). The levels of CPK-BB were nearly the same, however the levels of lactate were higher in the normothermic pulsatile and nonpulsatile (2.5 L) groups (p<0.05).

CONCLUSIONS

We concluded that the hypothermic CPB was advantageous over normothermic CPB in regard to the SjVO2 levels and lactate production. The beneficial effect of intra-aortic balloon pump assist was only obtained in the hypothermic CPB.

Congenital mitral regurgitation from absence of the anterolateral papillary muscle

A 21-year-old woman had congenital mitral regurgitation. Echocardiography showed absence of the anterolateral papillary muscle and corresponding marginal chordae. This rare abnormality was corrected by anterolateral commissural annuloplasty and insertion of artificial chordae to prevent prolapse of the anterior leaflet. Postoperatively, there was no regurgitation, and an appropriate mitral valve area was achieved.

Right atrial myxoma complicated with pulmonary embolism

A 25-year-old woman was admitted to our hospital with chest pain and dyspnea, and was diagnosed as having a right atrial myxoma complicated with pulmonary embolism. An emergency operation was performed with cardiopulmonary bypass. A papillary pedunculated tumor was found having a narrow-based attachment to the free atrial wall. After the tumor was carefully removed together with the atrial wall around the attachment, pulmonary embolectomy was performed. Several fragments of the tumor were removed, and sufficient back-flow from the pulmonary artery was established. The postoperative course was uneventful. However, a non-perfused area was observed in the left lower lung on pulmonary hemodynamic scintigraphy at 3 months after the operation. Long-term observation is required due to the high risk for metastasis and recurrence, and further surgical treatment remains the most appropriate treatment option. A second operation may be needed to prevent progression in complications.

Superior hepatic mitochondrial oxidation-reduction state in normothermic cardiopulmonary bypass

OBJECTIVE

This study is the first comparative investigation of hepatic blood flow and oxygen metabolism during normothermic and hypothermic cardiopulmonary bypass.

METHODS

Twenty-four patients undergoing coronary bypass operations were randomly divided into 2 groups according to their perfusion temperatures, either normothermia (36 degrees C) or hypothermia (30 degrees C). The clearance of indocyanine green was measured at 3 points. Arterial and hepatic venous ketone body ratios (an index of mitochondrial redox potential) and hepatic venous saturation were measured.

RESULTS

Hepatic blood flow in both groups was identical before, during, and after cardiopulmonary bypass (normothermia, 499 +/- 111, 479 +/- 139, and 563 +/- 182 mL/min, respectively; hypothermia, 476 +/- 156, 491 +/- 147, and 560 +/- 202 mL/min, respectively). The hepatic venous saturation levels were significantly lower during cardiopulmonary bypass in the normothermic group (normothermia, 41% +/- 13%; hypothermia, 61% +/- 18%; P <.01), indicating a higher level of oxygen extraction use. The arterial ketone body ratio in the hypothermic group decreased severely after the onset of cardiopulmonary bypass (P <.01) and did not return to its subnormal value (>0.7) until the second postoperative day. However, the reduction in arterial ketone body ratio was less severe in the normothermic group. The difference in hepatic venous ketone body ratios was more obvious, and the hepatic venous ketone body ratios in the normothermic group were statistically superior to those of the hypothermic group throughout the course (P <.05-.01).

CONCLUSIONS

Normothermic cardiopulmonary bypass provides adequate liver perfusion and results in a better hepatic mitochondrial redox potential than hypothermic cardiopulmonary bypass. Because arterial ketone body ratios reflect hepatic energy potential, normothermia was considered to be physiologically more advantageous for hepatic function.

Hemodynamic evaluation of 19-mm Carpentier-Edwards pericardial bioprosthesis in aortic position

BACKGROUND

The aortic Carpentier-Edwards pericardial bioprosthesis offers good long-term clinical outcomes with a low rate of structural deterioration. However, little in vivo hemodynamic data is available for this bioprosthesis.

METHODS

To determine the hemodynamic performance of the 19-mm Carpentier-Edwards pericardial valve, both cardiac catheterization and dobutamine stress echocardiography were electively performed in 10 patients. The mean age at the study was 71.6 +/- 4.4 years and the mean body surface area was 1.39 +/- 0.11 m2. The peak-to-peak gradient, instantaneous peak gradient, mean gradient, and valve orifice area were measured by standard cardiac catheterization. The Doppler-derived gradients and valve orifice area were also measured both at rest and during dobutamine infusion.

RESULTS

The average peak-to-peak gradient, instantaneous peak gradient, mean gradient, and valve orifice area measured by catheterization were 13.0 +/- 5.4 mmHg, 28.5 +/- 7.7 mmHg, 12.0 +/- 4.9 mmHg, and 1.55 +/- 0.45 cm2, respectively. The peak and mean Doppler gradients, and valve orifice area by resting echocardiography were 27.7 +/- 9.5 mmHg, 12.3 +/- 4.8 mmHg, and 1.39 +/- 0.26 cm2, respectively. At a dosage of 10 microg/kg/min of dobutamine, the mean Doppler gradient rose mildly to 22.2 +/- 4.8 mmHg, while the cardiac output increased from 4.49 +/- 0.44 to 6.64 +/- 0.87 L/min. The valve orifice area during the 10 microg/kg/min dobutamine infusion (1.55 +/- 0.25 cm2) was significantly larger than its value at rest (p < 0.05).

CONCLUSIONS

With acceptable hemodynamic performance, use of the aortic 19-mm Carpentier-Edwards pericardial valve is a reliable option for elderly patients with a small annulus.

[Combined use of ante- and retrograde cardioplegia: limited efficacy in elective coronary artery bypass]

One Hundred and twenty-four patients undergoing elective coronary bypass surgery were retrospectively selected and divided into two groups according to their difference of cardioplegic methods, either antegrade (AC) only (n = 65) or combination of ante- and retrograde (AC + RC) cardioplegic delivery (n = 64). Myocardial blood flow in the right (RV) and left ventricles (LV) was measured during the cardioplegia by a laser Doppler. Peak CPK-MB levels were compared postoperatively between the two groups and more in detail according to extent of coronary obstructive disease. 1) The antegrade administration of cardioplegic solution provided preferential flow to the RV compared to the LV, whereas the retrograde administration resulted in the opposite result (AC; LV 6.9 +/- 4.7, RV: 8.6 +/- 5.3, p < 0.05, RC; LV: 9.0 +/- 4.9, RV: 5.9 +/- 4.6 ml/min/100 g, p < 0.05). This result suggested that the combination of both administrations was meaningful to obtain uniform distribution of cardioplegic solution. 2) The peak CPK-MB, compared in the entire two groups, was slightly low in the combination use (AC; 48 +/- 16, AC + RC; 43 +/- 15 IU/l, p = 0.08), but the clinical meaning did not exist. However, in the severe cases, which involved two of following criteria (left main disease, severe occlusion of left or right coronary), the max CPK-MB level was statistically decreased by the combined use of ante- and retrograde cardioplegia (AC; 50 +/- 16, AC + RC; 40 +/- 12 IU/l, p < 0.05). We concluded that the merit of combined use was limited to the cases with severely extended coronary obstructive disease.

Influence of cardiopulmonary bypass temperature on circulatory pathophysiology and clinical outcomes

This study was designed to investigate the effects of cardiopulmonary bypass (CPB) perfusion temperature. Forty-four patients who had undergone elective coronary bypass surgery were randomly divided into 2 groups (22 patients each) according to their perfusion temperature (N group=36 degrees C; L group=30 degrees C). The concentrations of endogenous catecholamines, complements, elastase, serotonin, arachidonic acid metabolites and endothelin underwent various changes throughout the CPB but did not exhibit any statistical differences in either group. None of the substances measured correlated with systemic vascular resistance at any time. The temperature of the perfusion appears to be a major determinant of vascular tone. The postoperative PO2 was better, and postoperative pulmonary vascular resistance lower in the N group (p<0.05), most likely because of a much larger water balance during hypothermic CPB (p<0.01). The postoperative blood loss was statistically less in the N group (p<0.05). Although apparent brain damage, evidenced by the leakage of creatine kinase-BB, was not seen, the jugular bulb venous hemoglobin saturation levels (<50% in 27% of the N group, p<0.05) and higher lactate levels suggested that normothermic perfusion was relatively disadvantageous. It is concluded that normothermic CPB was relatively safe and advantageous with regard to hemostasis and pulmonary function.

Aortic valve replacement with concomitant annular enlargement for small aortic annulus of less than 19 mm

Three female patients with aortic stenosis associated with a severely small annulus underwent aortic valve replacement. In intraoperative measurements, a 19-mm obtulator could not pass through the aortic annulus in each case. We therefore concluded that it would be difficult to implant an appropriate-sized prosthesis in a routine fashion, so we performed an annular enlargement in a modified Nicks procedure. By using a wide teardrop-shaped patch for enlargement and slightly tilting insertion of a prosthesis, a 21 mm bileaflet mechanical prosthesis could be inserted into the enlarged annulus. Despite being a simpler method than other enlarging procedures, a two- or three-sizes larger prosthesis than the native annulus can be inserted with relative ease. Thus, the use of a 19 mm mechanical prosthesis may be avoidable in most adult cases.

[Thoracic aneurysm repair using circulatory arrest or retrograde cerebral perfusion]

Ascending aortic and transverse arch aneurysm repair requires some brain protection. At our hospital, profound hypothermia, circulatory arrest and retrograde cerebral perfusion have been used. Thirty patients for whom we used such brain protection techniques were studied with regard to incidence of stroke. Of these 30 patients, 7 underwent circulatory arrest with median arrest time was 31 minutes (range, 25 to 42 minutes), and 23 underwent retrograde cerebral perfusion with median perfusion time was 59 minutes (range, 24 to 123 minutes). The overall 30-day mortality rate was 16.6% (5 of 30 patients); these patients were all aortic dissection cases, and had exhibited signs of vital organs ischemia before the operation. Of the twenty-five patients who survived the operation, incidence of stroke was observed in 2 patients. One was a saccular transverse arch aneurysm, who underwent 71 minutes retrograde cerebral perfusion; debris was the cause of stroke in this case. The other was a Stanford type A aortic dissection, who underwent 32 minutes perfusion; malperfusion caused stroke in this case. Stroke did not occur in any of the 3 patients who underwent retrograde cerebral perfusion for more than 100 minutes. These results suggest that a uniform and constant cooling of the entire brain is important for brain protection. To this end, transapical aortic cannulation is effective to prevent malperfusion. It is also suggested that retrograde cerebral perfusion time can be up to 100 minutes, a longer duration hitherto accepted.

Patients' understanding and opinion about informed consent for coronary angiography in a rural Japanese hospital

Based on an anonymous questionnaire obtained from 102 Japanese in-patients at a rural Japanese hospital who underwent coronary angiography, the patients understanding of information about the procedure, their perception of consent and their attitude toward it were investigated. The patients were able to recall 63.8% of the contents of the information. There was a statistically significant correlation between the patients' educational status and the recall test score of the information. Older (65 years old and above) patients had a tendency to entrust decision making to their physicians. Only 19.6% of the patients made the decision to undergo a coronary angiography by themselves. After being informed of the risks 40.2% of the patients felt more anxious. In conclusion, our patients could not recall the contents of the information sufficiently. There still existed a tendency to entrust important decisions to the physician especially in older patients. The patients had a tendency not to face difficult problems solely by themselves but with the support of family members.

[Novel method for lower-half body perfusion at circulatory arrest]

It is generally accepted that patients with thoracic aortic aneurysma (TAA) require surgical reconstruction in the open distal anastomosis method. However, the optimal treatment of those with TAA remains controversial, as some of the postoperative complications are spinal-cord injury, rhabdomyolysis, MNMS and so forth caused by ischemia of lower-half body. Therefore the new Y connector with a one-way valve is useful for open distal anastomosis to avoid ischemia of the lower-half body. Through the branch of the Y connector between the femoral artery cannula and the arterial line, the occlusion balloon catheter is inserted and inflated at the descending aorta for perfusion of lower-half body. This procedure is safer and faster to perform than the conventional methodology in which a puncture is inserted, and a balloon catheter may be used only on the side of blood supply, thus making it possible to minimize the aggression of the patient.

[A surgical treatment of transverse arch aneurysm: use of ballooned venous cannula for maintenance of lower half body perfusion]

At present, open distal anastomosis method is widely used for the treatment of aneurysm of the transverse aortic arch during replacement, because anastomosis can be performed under direct vision. However, no established procedure is available for maintaining lower half body perfusion while this procedure is being performed, and various procedures have been employed, e.g. temporary circulatory arrest, low flow perfusion from the femoral artery by use of an occlusion catheter, or retrograde systemic perfusion. Spinal cord injury, MNMS, rhabdomyolysis and other complications cannot be completely prevented even by the use of these procedures. From this point of view, we have been using a ballooned venous cannula to be inserted in to the descending aorta while performing open distal anastomosis in order to prevent these complications. This procedure has the advantage of permitting the surgeon to perform the operation without clamping of the artery, hence without the cessation of the systemic circulation of blood, and we believe that this method will prove effective in the surgical treatment of transverse aortic arch aneurysm.