Assessment of myocardium at risk with computerized vectorcardiography and technetium-99m-sestamibi-single photon emission computed tomography during coronary angioplasty

OBJECTIVE: To compare the myocardium at risk (MAR) as estimated by computerized vectorcardiography (cVCG) with MAR determined by Tc-99m-sestamibi-SPECT using coronary angioplasty as the model for transient transmural ischemia in humans. METHODS AND RESULTS: In 37 patients with stable angina pectoris, cVCG was recorded continuously during coronary angioplasty. The scintigraphic defect was quantified using an automated software program (CEqual). The ST vector magnitude (ST-VM) and the ST change vector magnitude (STC-VM) correlated well with MAR estimated by scintigraphy, ST-VM (r = 0.71, p < 0.001) and STC-VM (r = 0.84, p < 0.001). All patients with STC-VM <50 microV during occlusion had defects of less than 10% of the left ventricle. CONCLUSION: 1) ST-VM and STC-VM give a reasonable useful estimate of MAR size during transient coronary occlusion. 2) STC-VM <50 microV is a reliable limit to identify patients with MAR size less than 10%. 3) ST-VM does not add information to STC-VM with respect to detection of ischemia. 4) The existence of collateral vessels has great impact on both ST-vector changes and scintigraphic imaging of myocardial ischemia.     

Assessment of myocardium at risk in pigs with single photon emission computed tomography and computerized vectorcardiography during transient coronary occlusion

Since myocardium at risk (MAR) is the major prognosticator of final infarct size and outcome in patients with acute myocardial infarction, it is highly desirable to estimate the size of the acutely ischemic myocardium, that is the MAR, in these patients. We assessed MAR size by Tc-99m-sestamibi-SPECT and computerized vectorcardiography using autoradiography as reference method. Transient myocardial ischemia was achieved in 12 pigs by coronary artery occlusion with PTCA catheters. During the procedure, computerized vectorcardiography was continuously recorded. After injection of Tc-99m-sestamibi and gadolinium-153-labelled microspheres, MAR size was estimated by SPECT and post-mortem autoradiography. Different cut-off levels (50-70%) were compared with respect to MAR-SPECT. Tc-99m-sestamibi-SPECT showed a good correlation with autoradiography (r = 0.94). Computerized vectorcardiography showed a good correlation with autoradiography as well as with Tc-99m-sestamibi-SPECT (STC-VM: r = 0.75 and 0.80, respectively, ST-VM: 0.75 and 0.87, respectively). It was found that 1) MAR assessed by Tc-99m-sestamibi-SPECT correlates closely with the autoradiographic reference; 2) a lower cut-off point of 60% of maximum uptake for MAR by Tc-99m-sestamibi-SPECT gives the closest correlation with the autoradiographic reference; and 3) ST-VM and STC-VM correlate well with MAR assessed by Tc-99m-sestamibi-SPECT and autoradiography.     

Assessment of Myocardium at Risk in Pigs with Single Photon Emission Computed Tomography and Computerized Vectorcardiography During Transient Coronary Occlusion

Since myocardium at risk (MAR) is the major prognosticator of final infarct size and outcome in patients with acute myocardial infarction, it is highly desirable to estimate the size of the acutely ischemic myocardium, that is the MAR, in these patients. We assessed MAR size by Tc-99m-sestamibi-SPECT and computerized vectorcardiography using autoradiography as reference method. Transient myocardial ischemia was achieved in 12 pigs by coronary artery occlusion with PTCA catheters. During the procedure, computerized vectorcardiography was continuously recorded. After injection of Tc-99m-sestamibi and gadolinium-153-labelled microspheres, MAR size was estimated by SPECT and post-mortem autoradiography. Different cut-off levels (50-70%) were compared with respect to MAR-SPECT. Tc-99m-sestamibi-SPECT showed a good correlation with autoradiography (r = 0.94). Computerized vectorcardiography showed a good correlation with autoradiography as well as with Tc-99m-sestamibi-SPECT (STC-VM: r = 0.75 and 0.80, respectively, ST-VM: 0.75 and 0.87, respectively). It was found that 1) MAR assessed by Tc-99m-sestamibi-SPECT correlates closely with the autoradiographic reference; 2) a lower cut-off point of 60% of maximum uptake for MAR by Tc-99m-sestamibi-SPECT gives the closest correlation with the autoradiographic reference; and 3) ST-VM and STC-VM correlate well with MAR assessed by Tc-99m-sestamibi-SPECT and autoradiography.     

Contributions of myocardial ischemia and heart rate to ST segment changes in patients with or without coronary artery disease

Background: ST changes related to ischemia at different heart rates (HRs) have not been well described. We aimed to analyze ST dynamic changes by vectorcardiography (VCG) during pacing-induced HR changes for subjects with proven coronary artery disease (CAD) and without (non-CAD).
Methods: Symptomatic CAD patients scheduled for elective surgery were enrolled along with a non-CAD group. During anesthesia, both groups were placed at multiple ascending levels. VCG ST data, and in particular in ST change vector magnitude (STC-VM) from baseline, along with arterial and great coronary artery vein (GCV) blood samples were collected to determine regional myocardial lactate production.
Results: A total of 35 CAD and 10 non-CAD patients were studied over six incremental 10 beat/min HR increases. STC-VM mean levels increased in the CAD group from 9±5 to 131±37 μV (standard deviation) compared with non-CAD subjects with 8±3–76±34 μV. Myocardial ischemia (lactate production) was noted at higher HRs and the positive predictive value for STC-VM to detect ischemia was 58% with the negative predictive value being 88%. STC-VM at 54 μV showed a sensitivity of 88% and a specificity of 75% for identification of ischemia.
Conclusions: Both HR and ischemia at higher HRs contribute to VCG ST elevation. Established ST ischemia detection concerning HR levels is suboptimal, and further attention to the effects of HR on ST segments is needed to improve electrocardiographic ischemia criteria.     

Effects of hemodilution on acute myocardial ischemia

Systemic hemodilution with homologous plasma, Ringer's lactate, Dextran-70, and Dextran-40 was carried out in 32 dogs between repetitive occlusions of the left anterior descending coronary artery. Ringer's lactate and plasma produced no change in myocardial ischemia as determined by surface ECG mapping before and after LAD occlusion. Dextran-70 and Dextran-40 significantly (P < 0.01) improved the surface manifestations of ischemic myocardial injury as determined by ST segment elevation (Σ-ST) and number of sites of elevated ST segments (N-ST). D-70 administered after permanent ligation of the LAD also significantly (P < 0.05) decreased the number and magnitude of ST segment elevations. Radioactive microsphere determinations of regional coronary blood flow, before and after Dextran-70 hemodilution, indicated significant (P < 0.01) increases in coronary flow to nonischemic areas, but no increase in blood flow to the ischemic area itself. Dextran hemodilution reduces the surface manifestations of myocardial ischemia without increasing blood flow to the ischemic area. If Dextran hemodilution can be shown to result in improved survival of ischemic myocardium, its mechanism of action cannot be by increasing collateral blood flow but must be by altering myocardial oxygen demand in a fashion heretofore not described.     

Clinical Outcome after Successful Coronary Angioplasty: Impact of Intracoronary Stent Implantation

The clinical outcome after successful conventional coronary balloon angioplasty is compared with that of stent implantation after 30 days and 12 months. The study took place at the Divisions of Cardiology and Thoracic Radiology, Norrland University Hospital, Umeå, a referral centre for northern Sweden. The first 100 consecutive patients with stable or unstable angina undergoing successful percutaneous transluminal coronary angioplasty (PTCA) in 1994 and the first 100 consecutive patients undergoing successful coronary stent implantation in 1995 were included. The cardiac endpoints studied were death, myocardial infarction, need for repeat PTCA or coronary artery bypass grafting (CABG). Significantly more adverse cardiac events were observed in the PTCA group compared with the stent group. Event-free 12 months' follow-up (no deaths, myocardial infarction or re-intervention) was 64% in the PTCA group and 86% in the stent group (p &lt; 0.005). The main explanation for the observed difference was a reduction in the need for a repeat PTCA (7 vs 18, p &lt; 0.05) or CABG (4 vs 12, p &lt; 0.05) in the stent group. Patients with stable or unstable angina who can be treated with a stent have a better clinical outcome than those treated with coronary balloon angioplasty only.     

Intraoperative ischemia and long-term events after minimally invasive coronary surgery

Background

Concern has been raised about the effects of prolonged left anterior descending (LAD) artery occlusion during minimally invasive direct coronary artery bypass graft surgery (MIDCABG). We sought to assess the impact of myocardial dysfunction during MIDCABG on long-term outcome and the protective role of collateral circulation on myocardial ischemia.

Methods

Myocardial function was evaluated in 92 patients by intraoperative transesophageal echocardiography during MIDCABG.

Results

Wall motion score index increased during LAD occlusion (p < 0.00l) and reverted after LAD reopening (p < 0.001 versus occlusion and p = not significant versus baseline). The change in wall motion score index (occlusion versus baseline) was higher in patients with multivessel disease (p < 0.05) and in patients with LAD Thrombolysis in Myocardial Infarction study classification flow grade 2 or less without collateral circulation (p < 0.05). Myocardial stunning was documented in 12 patients (13%). The 5-year adverse event rate (including death, myocardial infarction, and revascularization) was 12%. By multivariate Cox regression analysis, multivessel disease, but not perioperative ischemia or stunning, was the only predictor of event-free survival.

Conclusions

During MIDCABG anterior wall dysfunction is transient, with prompt recovery after completion of the anastamosis in most cases; myocardial stunning can be documented in a minority of patients. Flow either antegrade or retrograde in the LAD territory plays a protective role against the development of ischemia. Multivessel disease, but not perioperative ischemia or stunning, predicts long-term event-free survival.     

The Protective Effect of St. Thomas Cardioplegia Enriched With Zacopride on the Isolated Rat Heart

The activation of the heart inward rectifier potassium channel (I_K1) can reduce the injury of myocardial cells by shortening the action potential duration and reducing intracellular calcium overload. Zacopride is a selective I_K1 agonist and suppresses triggered arrhythmias in rat hearts. This investigation studied the effects of St. Thomas (ST) cardioplegia enriched with Zacopride on the isolated rat heart model. Sprague‐Dawley rat hearts were harvested and perfused for 20 minutes with 37°C Krebs‐Henseleit (KH) buffer followed by 15 minute perfusion with 4°C calcium‐free KH buffer in the Control group (Con, n = 8), ST cardioplegia in the ST group (ST, n = 8) and ST cardioplegia with Zacopride in the STZ group (STZ, n = 8). After 45 minutes of arresting, all hearts were reperfused with 37°C KH buffer for 60 minutes. Hearts in the STZ group arrested faster than the Con and ST groups (9.25 ± 2.38 s vs. 72.25 ± 8.1 s, 12.75 ± 2.87 s). The recovery of the left ventricular developed pressure, ± dP/dtmax, heart rate, and coronary flow in the STZ group is significantly better than the other two groups during reperfusion. Compared with the Con and ST groups, the STZ group showed significant decreases in the maximum carciac troponin I level (P < 0.05) and the infarct size (P < 0.05). The superoxide dismutase level in the STZ group increased during the first 20 minutes of reperfusion (P < 0.05). ST cardioplegia enriched with Zacopride has beneficial effects against ischemia‐reperfusion injury in this isolated rat heart model.     

Continuous vectorcardiography in cardiac surgery: natural course of vector changes and relationship to myocardial oxygen uptake

Continuous vectorcardiography was registered before and during the first 18 hours after cardiac surgery in 53 patients. QRS vector changes (QRS-VD) occurred during the operation, but no further changes were observed postoperatively. The ST vector (ST-VM) increased during the operation, and a further slight increase occurred postoperatively. Perioperative myocardial infarction occurred in three patients. Their ST-VM was higher than the average in patients without myocardial infarction, while QRS-VD did not differ from the average pattern. Twelve other patients were studied in pacemaker-induced moderate tachycardia. QRS-VD increased in proportion to heart-rate changes (rs median = 0.93, p less than 0.01). QRS-VD also correlated with myocardial oxygen uptake (rs median = 0.62, p less than 0.05). The ST-VM responses were not uniform. The data suggest that vectorcardiogram variables can provide information related to myocardial energy metabolism.     

Every Minute Counts When the Renal Hilum Is Clamped During Partial Nephrectomy

Background

The safe duration of warm ischemia during partial nephrectomy remains controversial.

Objective

Our aim was to evaluate the short- and long-term renal effects of warm ischemia in patients with a solitary kidney.

Design, setting, and participants

Using the Cleveland Clinic and Mayo Clinic databases, we identified 362 patients with a solitary kidney who underwent open (n = 319) or laparoscopic (n = 43) partial nephrectomy using warm ischemia with hilar clamping.

Measurements

Associations of warm ischemia time with renal function were evaluated using logistic or Cox regression models first as a continuous variable and then in 5-min increments.

Results and limitations

Median tumor size was 3.4 cm (range: 0.7–18.0 cm), and median ischemia time was 21 min (range: 4–55 min). Postoperative acute renal failure (ARF) occurred in 70 patients (19%) including 58 (16%) who had a glomerular filtration rate (GFR) <15 ml/min per 1.73 m² within 30 d of surgery. Among the 226 patients with a preoperative GFR ≥ 30 ml/min per 1.73 m² and followed ≥30 d, 38 (17%) developed new-onset stage IV chronic kidney disease during follow-up. As a continuous variable, longer warm ischemia time was associated with ARF (odds ratio: 1.05 for each 1-min increase; p < 0.001) and a GFR < 15 (odds ratio: 1.06; p < 0.001) in the postoperative period, and it was associated with new-onset stage IV chronic kidney disease (hazard ratio: 1.06; p < 0.001) during follow-up. Similar results were obtained adjusting for preoperative GFR, tumor size, and type of partial nephrectomy in a multivariable analysis. Evaluating warm ischemia in 5-min increments, a cut point of 25 min provided the best distinction between patients with and without all three of the previously mentioned end points. Limitations include the retrospective nature of the study.

Conclusions

Longer warm ischemia time is associated with short- and long-term renal consequences. These results suggest that every minute counts when the renal hilum is clamped.     

Comparison of Warm Ischemia Versus No Ischemia During Partial Nephrectomy on a Solitary Kidney

Background

The safe duration of warm ischemia during partial nephrectomy (PN) remains controversial.

Objective

To compare the short- and long-term renal effects of warm ischemia versus no ischemia in patients with a solitary kidney.

Design, setting, and participants

Using the Cleveland Clinic and Mayo Clinic databases, we identified 458 patients who underwent open (n = 411) or laparoscopic (n = 47) PN for a renal mass in a solitary kidney between 1990 and 2008. Patients treated with cold ischemia were excluded.

Measurements

Associations of ischemia type (none vs warm) with short- and long-term renal function were evaluated using logistic or Cox regression models.

Results and limitations

No ischemia was used in 96 patients (21%), while 362 patients (79%) had a median of 21 min (range: 4–55) of warm ischemia. Patients treated with warm ischemia had a significantly higher preoperative glomerular filtration rate (GFR; median: 61 ml/min per 1.73 m² vs 54 ml/min per 1.73 m²; p < 0.001) and larger tumors (median: 3.4 cm vs 2.5 cm; p < 0.001) compared with patients treated with no ischemia. Warm ischemia patients were significantly more likely to develop acute renal failure (odds ratio [OR]: 2.1; p = 0.044) and a GFR <15 ml/min per 1.73 m² in the postoperative period (OR: 4.2; p = 0.007) compared with patients who did not have hilar clamping. Among the 297 patients with a preoperative GFR ≥30 ml/min per 1.73 m², patients with warm ischemia were significantly more likely to develop new-onset stage IV chronic kidney disease (hazard ratio: 2.3; p = 0.028) during a mean follow-up of 3.3 yr. Similar results were obtained adjusting for preoperative GFR, tumor size, and type of PN in a multivariable analysis. Limitations include surgeon selection bias when determining type of ischemia.

Conclusions

Warm ischemia during PN is associated with adverse renal consequences. Although selection bias is present, PN without ischemia should be used when technically feasible in patients with a solitary kidney.     

Early vectorcardiographic monitoring provides prognostic information in patients with ST-elevation myocardial infarction

Objective--To evaluate the prognostic value of specified vectorcardiographic data obtained during the first hours of ST-elevation myocardial infarction for cardiac outcomes up to 5 years. Design--Three hundred and five patients with ST-elevation myocardial infarction and chest pain for less than 12?h were monitored with continuous vectorcardiography. Results--All patients had follow-up for at least 1 year. The mortality was 5.9% at 30 days and 10.8% at 1 year. The estimated 5-year mortality was 24%. A total of 7.9% had recurrent infarction at 30 days and 11.2% at 1 year. Recurrent infarction or death occurred in 12.1% at 30 days and in 19.7% at 1 year. The presence of ST-VM[Formula: See Text]?≥?125?μV was highly predictive of the combined endpoint death or recurrent infarction at 1 year, OR 2.69 (95% CI 1.39-5.23). Multivariate analysis showed that age ≥75 years, anterior myocardial infarction, and the presence of ST-VM[Formula: See Text]?≥?125?μV, were independently associated with increased risk of recurrent infarction or death at 1 year and with death at 5-year follow-up. A start value of ST-VM ≤?100?μV identified a group of patients with low risk of death or re-infarction within 1 year. Conclusion--Continuous vectorcardiography during the first hours after thrombolytic treatment of patients with ST-elevation myocardial infarction provides important prognostic information. A new vectorcardiographic variable, ST-VM[Formula: See Text], identifies a group of patients with increased risk of recurrent infarction or death. As well, patients with low risk of recurrent infarction or death were identified by low start values of ST-VM.     

Change pattern of somatosensory-evoked potentials after occlusion of segmental vessels: possible indicator for spinal cord ischemia

Paraplegia was reported after occlusion of the segmental vessels during anterior spinal surgery. The aim of this study was to investigate the effect of occlusion of the segmental vessels on the somatosensory-evoked potential (SEP) monitoring and analyze its potential risk for cord ischemia. Thirty-one patients with thoracic scoliosis underwent anterior spinal surgery. T₅–T₁₁ segmental vessels on the convexity were occluded with microvascular clamps at the point 2 cm from the intravertebra foramen. The SEPs were recorded 5 min before occlusion and 2, 7, 12 and 17 min after occlusion. The SEPs were analyzed with two indices i.e. P40 latency and P40 amplitude. All SEP waveforms recorded during the test were regular and recognizable. Compared to 5 min before occlusion, the P40 latencies at 2 min and 7 min after occlusion significantly increased 3.39% and 2.76% on an average, the P40 amplitudes at 2 min after occlusion significantly declined 26% (peak to peak) or 22% (peak to baseline) on an average (P<0.05). But the changes of SEPs were temporary. The SEPs began to restore at 12 min after occlusion and returned to the pre-occlusion level at 17 min after occlusion. No neurologic complications occurred in all patients after surgery. These results suggest that SEP is a possible indicator for ischemia of the spinal cord which is a dynamic course and cannot be considered an all-or–none phenomenon. Without the factors such as developmental deformities of the spinal cord, vascular variation and potential cord ischemia, occlusion of the segmental vessels would be safe during the anterior spinal surgery.     

Angiotensin II inhibition increases cellular glucose transport during reperfusion but not ischemia in pig hearts

Objective --To study whether ACE inhibition and AT-II receptor blockade modulates myocardial glucose uptake during ischemia and reperfusion. Design --We developed a method for in vivo sampling of large trans -myocardial tissue samples from beating pig hearts and in vitro measurement of sarcolemmal glucose transport, in a series of experiments in which hearts were exposed to stimuli (glucose-insulin and pacing) known to promote cellular glucose transport. In the subsequent study we compared three experimental groups: (i) ACE inhibition (ACE-I, n &#114 = &#114 6): increasing oral doses of benazepril up to 40 &#114 mg daily for 3 weeks, (ii) angiotensin II receptor antagonist (AT II-A, n &#114 = &#114 7): increasing oral doses of valsartan up to 320 &#114 mg for 3 weeks, (iii) control ( n &#114 = &#114 7). Samples were harvested at baseline, following 20 &#114 min of regional ischemia, and following 5 and 15 &#114 min of reperfusion. The samples were incubated with 3-O-methylglucose (MeGlu), and cellular MeGlu uptake was measured. Results --Insulin-glucose, pacing, and ischemia increased cellular MeGlu transport two- to fourfold ( p &#114 < &#114 0.001). Cellular MeGlu transport was increased in ACE-I and AT II-A animals during reperfusion ( p &#114 < &#114 0.001), but not at baseline or during ischemia, compared with controls. Conclusion --Enhanced capacity for glucose transport during reperfusion may be a mechanism underlying the beneficial effects of ACE inhibition and AT II-antagonism in ischemic heart disease.     

Myocardial revascularization after failure of percutaneous transluminal coronary angioplasty

From 1980 to 1983, 299 procedures for percutaneous transluminal coronary angioplasty were performed in 265 patients. The procedure failed in 88 patients, 72 of whom underwent myocardial revascularization within 1 week following the angioplasty attempt. Operation on an emergency basis was required in 35 patients because of a major complication during or after coronary artery dilatation, whereas the remaining 37 patients underwent elective operation following failure without complication. Coronary occlusion occurred in 23 patients, coronary dissection without occlusion in four, perforation of the coronary artery in one patient, and no visible angiographic changes accounted for the severe myocardial ischemia in the remaining 7 patients. Signs of acute myocardial infarction were present preoperatively in 13 of the 35 patients (37.1%) who underwent emergent operation. Among the factors analyzed, only the absence of collateral circulation and the extent of coronary disease were directly related to the development of complications with percutaneous transluminal coronary angioplasty. There were no early or late deaths in this series. Postoperative complications occurred in seven patients (20%) of the group undergoing emergency operation and in none of the group having elective operation. New postoperative myocardial infarction developed in three patients (8.6%). In six of the 13 patients with preoperative evidence of necrosis, the electrocardiogram returned to normal without other signs of acute infarction after the operation, whereas myocardial infarction was complete in the remaining seven patients. Thus, patients who have complications from percutaneous transluminal coronary angioplasty should undergo immediate operation; for those in whom the procedure fails without complication, surgical treatment can be postponed and performed electively later on if indicated by the clinical incapacity of the patient.     

Reperfusion before Global Ischemic Arrest Improves the Salvage of Infarcting Myocardium

To study the effect of hypothermic global ischemic arrest on an evolving myocardial infarction and of perfusion of the ischemic zone or region at risk before global ischemia, 62 farm pigs underwent 15, 30, or 60 minutes of reversible coronary occlusion. Twenty-eight of these animals served as controls: reflow to the region at risk was established by removal of the coronary occluder without the addition of global ischemia. Another 26 animals had similar periods of coronary occlusion and then were placed on cardiopulmonary bypass; they underwent aortic cross-clamping and cardioplegia-induced global hypothermic arrest for 45 minutes. Eight additional pigs had two hours of reflow to the region at risk after removal of the occluder and before global ischemic arrest. When superimposed on regional ischemia, global ischemia resulted in a 6-fold increase in infarct size after 15 minutes of coronary occlusion (p < 0.05), a 2.2-fold increase after 30 minutes of coronary occlusion (p < 0.05), and no significant increase after 60 minutes of coronary occlusion. Reperfusion prior to global ischemia completely prevented infarct extension with 0.4% less infarction (not significant) in this group versus the controls without global ischemia.These results clearly demonstrate that infarct extension occurring when global ischemia is superimposed on regional ischemia is greatest early in infarct evolution but that reflow to the region at risk before global ischemic arrest prevents the additional infarction. These data suggest that ischemic myocardium must be supplied with oxygen and metabolic substrate prior to global ischemic arrest to obtain maximum myocardial salvage with surgical revascularization.     

Ischemic preconditioning during the use of the PercuSurge occlusion balloon for carotid angioplasty and stenting

Ischemic preconditioning (IP) uses transient ischemia to render tissues tolerant to subsequent, prolonged ischemia. This study sought to evaluate factors that contributed to the development of cerebral ischemia during PercuSurge balloon (Medtronic, Santa Rosa, CA) occlusion in patients undergoing carotid angioplasty and stenting (CAS). The PercuSurge occlusion balloon was used in 43 of 165 patients treated with CAS for high-grade stenosis; 20% were symptomatic. Symptoms of cerebral hypoperfusion during temporary occlusion of the internal carotid artery occurred in 10 of 43 patients and included dysarthria, agitation, decreased level of consciousness, and focal hemispheric deficit. The development of neurologic symptoms after initial PercuSurge balloon inflation and occluded internal carotid artery flow was associated with a decrease in the mean Glasgow Coma Scale (GCS) from 15 to 10 (range 9-14); the GCS returned to normal after occlusion balloon deflation. The mean time to spontaneous recovery of full neurologic function was 8 minutes (range 4-15 minutes). The mean subsequent procedure duration was 11.9 minutes (range 6-21 minutes). No recurrence of neurologic symptoms occurred when the occlusion balloon was reinflated. All 10 patients underwent successful CAS without occlusion, dissection, cerebrovascular accident, or death. Ischemic preconditioning can be used to enable CAS with embolic protection in patients who cannot tolerate initial interruption of antegrade cerebral perfusion by PercuSurge occlusion.     

Signs of myocardial ischaemia after injection of oxytocin: a randomized double-blind comparison of oxytocin and methylergometrine during Caesarean section

Background: ECG changes, similar to those seen during myocardial ischaemia,together with symptoms of chest pain, are common during Caesareansection (CS). We hypothesized that oxytocin administration hascardiovascular effects leading to these symptoms and ECG changes. Methods: Forty women undergoing elective CS under spinal anaesthesiawere given an i.v. bolus of either 10 IU of oxytocin (GroupOXY-CS, n=20) or 0.2 mg of methylergometrine (Group MET-CS,n=20), in a double-blind, randomized fashion after delivery.Ten healthy, non-pregnant, non-anaesthetized women were usedas normal controls (Group OXY-NC, n=10) and were given 10 IUof oxytocin i.v. Twelve-lead ECG, on-line, computerized vectorcardiography(VCG), and invasive arterial pressure were recorded. Results: Oxytocin produced a significant increase in heart rate, +28(SD 4) and +52 (3) beats min^–1 [mean (SEM); P<0.001],decreases in mean arterial pressure, –33 (2) and –30(3) mm Hg (P<0.001), and increases in the spatial ST-changevector magnitude (STC-VM), +77 (12) and +114 (8) µV (P<0.001),in CS patients and controls, respectively. Symptoms of chestpain and subjective discomfort were simultaneously present.Methylergometrine produced mild hypertension and no significantECG changes. Conclusions: Oxytocin administered as an i.v. bolus of 10 IU induces chestpain, transient profound tachycardia, hypotension, and concomitantsigns of myocardial ischaemia according to marked ECG and STC-VMchanges. The effects are related to oxytocin administrationand not to pregnancy, surgical procedure, delivery, or sympatheticblock from spinal anaesthesia.     

Treatment of acute right coronary artery occlusion during anesthesia

PURPOSE: Perioperative coronary artery occlusion is a potentially dangerous complication causing myocardial infarction and circulatory collapse. We report a case showing severe ST segment depression in leads II and V5 during anesthesia. Diltiazem and nifedipine, but not nitroglycerine, partially improved the ST changes which were normalized by a percutaneous cardiopulmonary system (PCPS). CLINICAL FEATURES: A 71-yr-old man with cerebrovascular disease was scheduled for coronary artery bypass grafting (CABG). Past medical history included myocardial infarction due to right coronary artery (RCA) occlusion. Both the femoral artery and vein were cannulated percutaneously before operation and the PCPS was prepared as a back-up system. Depression of the ST segments in leads V5 and II was observed following heparinization. Although hemodynamic stability was maintained with continuous infusion of catecholamines, the ST changes were not improved by intravenous nitroglycerine. Intravenous diltiazem followed by nasal nifedipine partially improved the ST changes. The changes were normalized after induction of PCPS. No neurological complications were observed. The postoperative coronary angiography confirmed the total occlusion of RCA. CONCLUSION: Calcium channel blockers were more effective than nitroglycerine in treating perioperative ST depression. However, none of them produced complete reversal of the ischemic changes which were normalized with PCPS.     

Surgical revascularization following failed percutaneous transluminal coronary angioplasty

Percutaneous transluminal coronary angioplasty (PTCA) was performed on 200 patients and failed in 36, 12 of whom underwent myocardial revascularization within 3 hours after the angioplasty attempt. Elective operations were performed without complications in the other 24 cases. The 12 emergency operations were necessitated by major complications during or after PTCA, viz, coronary occlusion (6 patients) coronary dissection (2) and failed catheter passage or dilation with severe myocardial ischemia (4). Three of these 12 patients had signs of acute myocardial infarction preoperatively, and new infarction appeared postoperatively in two cases. All eight patients with ST-segment elevation preoperatively had raised levels of myocardial enzymes postoperatively, and two of them had new Q-waves. Three of the 12 patients required inotropic drugs following revascularization. There was one postoperative death. When complications arise in PTCA, emergency operation should be undertaken. When PTCA fails, but without complications, surgery can be electively performed.