The efficacy of intraoperative internal intercostal nerve block during video-assisted thoracic surgery on postoperative pain.

BACKGROUND: Video-assisted thoracic surgery (VATS) is widely used for many thoracic surgical procedures. Post-operative pain is less after VATS than after conventional thoracic surgery, but is still significant. The objective of this study was to assess the efficacy of thoracoscopic, internal intercostal nerve block in alleviating immediate postoperative pain. METHODS: Thirty-two patients underwent VATS bilateral sympathectomy for the treatment of hyperhidrosis. The patients were randomly divided into two groups with similar demographic and preoperative physiologic parameters. Group A (n = 16) was submitted to thoracoscopic, internal intercostal nerve blocks performed at T2, T3, and T4 intercostal levels using 3 cc of 0.5% bupivacain in each intercostal space. The injections were performed bilaterally, immediately after the sympathectomy, through the same port. Group B (n = 16) underwent bilateral thoracic sympathectomy without the block. During the immediate postoperative period, heart rate, blood pressure, respiratory rate, pain score, and analgesic requirements were monitored every 30 minutes. RESULTS: No morbidity was recorded in association with the thoracoscopic, internal intercostal nerve block. The mean heart rates (77 +/- 6 vs 89 +/- 12 beats per minute, p < 0.001), respiratory rates (15 +/- 2 vs 18 +/- 3 respirations per minute, p < 0.01), pain score (1.9 +/- 0.6 vs 2.7 +/- 0.5, p < 0.01), and postoperative analgesic requirements (20 +/- 18 vs 50 +/- 21 mg pethidine HCL, p < 0.001) were significantly lower in group A. There was no significant difference in blood pressures. CONCLUSIONS: Thoracoscopic, internal intercostal nerve block with bupivacain 0.5% during VATS is safe and effectively reduced the immediate postoperative pain and analgesic requirements.

Novel thermoregulation system for enhancing cardiac function and hemodynamics during coronary artery bypass graft surgery.

BACKGROUND: Myocardial ischemia, arrhythmias, and coagulopathies are associated with postoperative hypothermia. This study assessed the efficacy of a novel thermoregulation system in alleviating these events during coronary artery bypass graft (CABG) surgery. METHODS: Elective CABG surgery patients were randomized into either Allon thermoregulation (AT, n = 40) or routine thermal care (RTC, n = 20) groups in whom the maintenance of normothermia during the nonbypass phases of the operation was compared. The AT used patients' rectal temperature as reference data to monitor the maintenance of the water temperature circulating at 37 degrees C in a garment. Rectal temperature, patient hemodynamics, and cardiac-specific troponin I (cTnI) levels were assessed at the induction of anesthesia, 30 minutes into surgery, at discontinuation of bypass, end of surgery, and 2 hours postoperatively. RESULTS: Body temperature was higher in the AT group compared to the RTC group at all five time points. Cardiac index (CI) (L/min) was higher in the AT group, 2.5 +/- 0.5, 2.6 +/- 0.5*, 3.2 +/- 0.6*, 3.3 +/- 0.5*, 3.1 +/- 0.7 at the respective time points, compared to the RTC group, 2.3 +/- 0.6, 2.1 +/- 0.2, 2.6 +/- 0.7, 2.7 +/- 0.7, 2.7 +/- 0.7 (*p < 0.05). Systemic vascular resistance (SVR) (dyne x s)/cm5) was consistently lower in the AT patients. Enzyme levels were elevated in both groups but were less so in the AT patients. CONCLUSIONS: The AT system can efficiently maintain normothermia. The beneficial effects are expressed by reduced SVR, elevated CI, and lower levels of cTnI, which may show a possible attenuation of myocardial injury.

Three-dimensional electromechanical mapping: imaging in the operating room of the future.

BACKGROUND: Three-dimensional electromechanical mapping has previously been shown to be a clinically important tool for cardiac imaging and intervention. We hypothesized that this technology may be beneficial as an intraoperative modality for assessing cardiac hemodynamics and viability during cardiac surgery. We report here the use of this technology as an imaging modality for intraoperative cardiac surgery. METHODS: The tip of a locatable catheter connected to an endocardial mapping and navigating system is accurately localized while simultaneously recording local electrical and mechanical functions. Thus the three-dimensional geometry of the beating cardiac chamber is reconstructed in real time. The system was tested on 6 goats that underwent acute dynamic cardiomyoplasty and on 5 dogs that underwent left anterior descending (LAD) coronary artery ligation. RESULTS: The electromechanical mapping system provided an accurate three-dimensional reconstruction of the beating left ventricle during cardiomyoplasty. After the wrapping procedure, significant end-diastolic area reduction was noted in the base and mid parts of the heart (948 +/- 194 mm2 vs 1245 +/- 33 mm2, p = 0.021; and 779 +/- 200 mm2 vs 1011 +/- 80 mm2, p = 0.016). The area of the cross-section of the apex did not change during the operation. Acute infarcted tissue was characterized 3 days after LAD ligation by concomitant deterioration in both electrical and mechanical function. CONCLUSIONS: By providing both a clear view of the anatomical changes that occur during cardiac surgery, and an accurate assessment of tissue viability, electroanatomic mapping may serve as an important adjunct tool for imaging and analysis of the heart during cardiac surgery

Acute descending aortomyoplasty induces coronary blood flow augmentation.

BACKGROUND: Aortomyoplasty is a procedure aimed to improve cardiac output in patients suffering from heart failure. Stimulation of the latissimus dorsi muscle around the aorta produces hemodynamic effects similar to those of the intraaortic balloon pump. These may be maintained without the accompanying complications or the need for anticoagulation. The objective of this study was to test the acute effects of aortomyoplasty on coronary artery blood flow. METHODS: Eight mongrel dogs (18 to 30 kg) underwent acute descending aortomyoplasty. Several stimulation protocols were applied after wrapping of the latissimus dorsi muscle around the aorta in different surgical configurations. The left anterior descending coronary blood flow was measured using a transonic Doppler flow probe. Left ventricular and aortic pressures, proximal and distal to the aortomyoplasty site, were monitored continuously. RESULTS: Significant aortic diastolic pressure augmentation was expressed both as an increase in peak values, from 110 +/- 24 mm Hg to 120 +/- 24 mm Hg (p < 0.001) and as an increase in the diastolic integral, from 64 +/- 23 mm Hg x s to 84 +/- 37 mm Hg x s (p < 0.001). Concomitantly, peak left anterior descending coronary blood flow increased from 26 +/- 10 mL/min to 32 +/- 12 mL/min (p < 0.001). This was associated with an increase in the diastolic flow integral from 11 +/- 4 mL to 14 +/- 6 mL (p < 0.001). CONCLUSIONS: Descending aortomyoplasty induces significant augmentation of coronary blood flow. Optimal timing of muscle stimulation is important in achieving the best assist. This procedure may prove beneficial for end-stage ischemic patients.

Using a video conference to teach clinical clerks in a one-week cardiothoracic clerkship.

BACKGROUND: Students report that their operating room experience during specialty clerkships has been less than satisfactory. To deal with this and other problems in a 1-week cardiothoracic clerkship, a video conference system was introduced. METHODS: Three teaching strategies were used: a seminar dealing with the disease process and a description of the operative procedure; bedside pre-operative assessment of the patient, with a tutor; and a live video conference of the operation. The tutor observed the live video presentation with the students, initiating interaction with the operating surgeon and facilitating questions and discussion. Video quality was maintained by one camera connected to the headlight of the surgeon and another placed above the operative field. RESULTS: Both students and staff expressed a high degree of satisfaction in debriefing sessions and on a standard faculty evaluation form. CONCLUSIONS: This innovation in surgery specialty teaching contributes to the acquisition of educational objectives in the operating room and in a cardiothoracic clerkship.

Anomalous origin of the left main coronary artery: anatomical correction and concomitant LIMA-to-LAD grafting.

A 55-year-old woman with angina pectoris and exertional dyspnea underwent surgical correction of an anomalous left main coronary artery (LMCA) originating from the right sinus of Valsalva. During the operation, the roof of the intramurally coursing LMCA was opened into the aortic lumen, and a neo-coronary ostium was created by suturing the circumference of the LMCA intima to the aortic intima. In addition, a left internal mammary artery (LIMA) to left anterior descending (LAD) coronary artery anastomosis was performed. Post-operative coronary angiography demonstrated two independent, patent orifices of both the LMCA and the right coronary artery. The technique presented herein, of combined anatomical correction and LIMA-to-LAD grafting, is feasible and leads to distinct angiographic and clinical improvement.

Hemodynamic evaluation of descending aortomyoplasty versus intra-aortic balloon pump performed in normal animals: an acute study.

OBJECTIVE: Aortomyoplasty is a surgical procedure that aims to induce hemodynamic benefits similar to those of the intra-aortic-balloon-pump (IABP). The objective of this study was to compare the coronary blood flow augmentation and afterload reduction produced by IABP and descending aortomyoplasty counterpulsation. METHODS: From a series of fifteen mongrel dogs (18-35 kg), eight underwent acute descending aortomyoplasty and seven had IABP application. Left anterior descending (LAD) coronary artery blood flow was measured using a Doppler flow probe. Left ventricular pressure in addition to aortic pressures both proximal and distal to either the aortomyoplasty site or the IABP position were monitored continuously. All experiments were acute and performed in normal hearts. RESULTS: Descending aortomyoplasty induced a 27% increase in the LAD blood flow integral during assisted beats (14.0+/-6 ml/min integral compared to 10.8+/-4 ml/min integral in unassisted beats [P<0.001]). This was comparable to an 18% rise in the LAD blood flow integral during IABP counterpulsation (from 8.6+/-3 ml/min to 10.2+/-4 ml/min [P<0.001]). Conversely, while IABP counterpulsation reduced the left ventricular afterload by 16% (from 102+/-23 mmHg to 86+/-26 mmHg [P<0.001]), descending aortomyoplasty did not result in afterload reduction. CONCLUSIONS: Descending aortomyoplasty produces coronary blood flow augmentation comparable to that achieved by the IABP. This may be important for end-stage ischemic patients. However, afterload reduction achieved by the IABP was not reproduced during descending aortomyoplasty counterpulsation. The surgical technique of descending aortomyoplasty should be modified to attain afterload reduction, thus improving treatment for congestive heart failure patients.

Cardiomyoplasty--the beginning of a new era.

Cardiomyoplasty is a surgical treatment for a well-defined group of patients who suffer from congestive heart failure. The procedure is not a contraindication to perform a future heart transplantation, when indicated. The clinical results up to 7 years after cardiomyoplasty are encouraging, but there is still a gap between the significant functional capacity improvement of the patients after cardiomyoplasty and the moderate hemodynamic change. Experimental data and recent measurements in patients provide new insights in understanding the physiologic effect of cardiomyoplasty.

Hemodynamic effects in acute cardiomyoplasty of different wrapped muscle activation times as measured by pressure-volume relations.

BACKGROUND: Correct timing of mechanical interaction between wrapped latissimus dorsi muscle (LDM) and the heart during cardiac systole has been poorly understood and remains a controversial issue. Therefore, left ventricular pressure-volume relations were analyzed in acute cardiomyoplasty while changing the synchronization delays. METHODS: Effects of different delays between the sensed cardiac R wave and wrapped muscle contraction were studied in goats submitted to acute left cardiomyoplasty. Conductance and micromanometer catheters were used to evaluate hemodynamics. Systolic contribution of the wrapped muscle was studied in preassisted and assisted beats, whereas diastolic effects were studied in assisted and postassisted beats. RESULTS: At best settings, cardiomyoplasty resulted in a significant (p < 0.05) increase in left ventricular ejection fraction (from 42.2 +/- 9.2 to 56.7% +/- 13%), in stroke work (from 2769 +/- 1140 to 4271 +/- 1717 gm/m2), in dP/dt (from 1185 +/- 342 to 1510 +/- 285 mmHg/sec), in end-systolic pressure (from 93.5 +/- 22.5 mmHg to 97.3 +/- 22.3 mmHg), and in peak ejection rate (from 282 +/- 64 to 533 +/- 241 mL/sec). Stroke volume showed a mean increase of 35% (from 42.2 +/- 9.9 mL to 56.9 +/- 20.1 mL) during assisted beats. Diastolic function was not substantially impaired at optimal stimulation delay. Incorrect timing of LD contraction resulted in suboptimal improvement or no change in comparison with unassisted hemodynamics. CONCLUSIONS: Our study documents support of cardiac performance by LDM. Incorrect timing of heart/wrapped muscle interaction led to suboptimal hemodynamic results. Muscle contraction timing is an important factor in cardiomyoplasty outcome.