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Changes in Doppler waveforms can predict pressure reduction across internal carotid artery stenoses
484
Journd of VASCULAR SURGERY
Abstmm
to that needed in the older group of patients who receive a cemented prosthesis. Delineation of the effects of intramedullary injection of methylmethacrylate cement on the coagulation system would be helpful in explaining and treating this important difference. Several factors limit the applicability of the conclusions drawn by the authors. No preoperative baseline noninvasive venous studies or venograms were obtained for comparison to the postoperative studies: this problem is further exacerbated by the fact that a history of thromboembolic disease was not an exclusion criterion. Of the 103 patients evaluated, only 83 had venograms (and only 77 had bilateral venograms). Venous thrombosis, as defined by the study design, included both superficial and deep venous thrombosis. Finally no control group, subcutaneous heparm alone group, or intravenous antithrombin III alone group was studied. This trial presents an interesting premise that merits mrther investigation. Appropriate control groups complete preoperative and postoperative venous studies, and recognition of preexisting thromboembolic disease would yield valuable information that should allow more definite conclusions. Joseph R. Durham, MD The Ohio State University
Changes in Doppler waveforms can predict pressure reduction across internal carotid artery stenoses Sillesen H, Schroeder T. Ultrasound Med Biol 1988;
14:649-G. Most noninvasive carotid studies estimate the degree of luminal narrowing of the internal carotid artery (ICA) but do not take into account the contribution of collaterals to the overall hemodynamic effect of a lesion. This study evaluates the accuracy of simple Doppler measurements in detecting substantial pressure gradients across ICA stenoses. A 5 MHz continuous wave (CW) Doppler device was used in conjunction with a prototype FFT (fast Fourier transform) signal processor capable of determining both mean and peak frequencies. Unlike most prior studies that have measured velocity signals proximal to or at the stenosis, the signals were obtained as far distal as possible in the ICA to avoid the local turbulence and increased velocity produced by the plaque. Pulsatility index (PI), pulse rise time (RT), and systolic width (SW), the duration of systole measured at half the sum of peak systolic and end-diastolic frequencies, were determined for both mean and peak velocity tracings in 49 patients. An important advantage is that all three parameters are angle-independent, an important consideration when imaging is not being used. Direct common carotid artery (CCA) and ICA pressures were measured intraoperatively during normocapneic anesthesia. An ICAlCCA ratio >O.XO was defined as an abnormal perfusion pressure. All three parameters studied detected a pressure gradient of 20% with accuracies between 90% to 95%. Results
for RT and for SW were very similar for analysis of mean and peak velocity curves; however, with PI, better correlation was obtained with mean than with peak curve. The cutoff points, determined by receiver operator characteristics, were 0.71 for PI, 0.16 seconds for RT, and 0.8 seconds for SW. Review of the angiograms revealed that less than half of the stenoses >50% had pressure gradients >20%, emphasizing the need to evaluate hemodynamic compromise as well as the anatomic severity of carotid lesions. The study was limited by the fact that there were only 10 patients with gradients >20%. A possible shortcoming is that all three parameters can be affected by abnormalities in CCA flow resulting from proximal stenoses, cardiac abnormality, or drug effect. Ideally this initial project will lead to further investigation of the method. J. Dennis Baker, MD UCLA School of Medicine
Cigarette smoking arterial surgery Lassila R, Lepantalo
and the outcome
after lower
limb
M. Acta Chir Stand 1988;154:635-
40. The effect of cigarette smoking on reconstruction was studied in 202 consecutive patients undergoing their first arterial reconstruction. Both aortoiliac and leg operations were included. One hundred ninety patients were available with a full 3-year follow-up. Patients were stratified according to tobacco use. There were 12 nonsmokers, 53 exsmokers (off all tobacco for more than 1 year), 45 moderate smokers (less than 15 cigarettes per day), and X5 heavy smokers. The main comparison was between moderate and heavy smokers. These groups were comparable in terms of age, severity, and distribution of disease, frequency of indications and incidence of risk factors. Severe smokers had a higher incidence of deterioration of the reconstruction during the follow-up period (49% vs 33%) and a very significant difference in major amputations (21% vs 2%). Among the males the 3-year mortality for heavy smokers was 60% compared with 35% for moderate smokers. Cardiovascular disease was a much more frequent cause of death in the heavy smokers, 83% versus 33%. The authors did not make a direct comparison of smokers to nonsmokers since the latter group was very different with the patients being an average of 10 years older, being predominantly women, having more distal disease, and having a much higher incidence of concomitant diseases. This study confirms the marked effect that heavy tobacco smoking has on morbidity as well as mortality of patients who have had arterial reconstruction. The authors suggest that in addition to the accelerated progression of atherosclerosis in heavy smokers, increased platelet activation may contribute to the increased complication rate. J. Dennis Baker, .&ID UCLA School ofMedicine
Journd of VASCULAR SURGERY
Abstmm
to that needed in the older group of patients who receive a cemented prosthesis. Delineation of the effects of intramedullary injection of methylmethacrylate cement on the coagulation system would be helpful in explaining and treating this important difference. Several factors limit the applicability of the conclusions drawn by the authors. No preoperative baseline noninvasive venous studies or venograms were obtained for comparison to the postoperative studies: this problem is further exacerbated by the fact that a history of thromboembolic disease was not an exclusion criterion. Of the 103 patients evaluated, only 83 had venograms (and only 77 had bilateral venograms). Venous thrombosis, as defined by the study design, included both superficial and deep venous thrombosis. Finally no control group, subcutaneous heparm alone group, or intravenous antithrombin III alone group was studied. This trial presents an interesting premise that merits mrther investigation. Appropriate control groups complete preoperative and postoperative venous studies, and recognition of preexisting thromboembolic disease would yield valuable information that should allow more definite conclusions. Joseph R. Durham, MD The Ohio State University
Changes in Doppler waveforms can predict pressure reduction across internal carotid artery stenoses Sillesen H, Schroeder T. Ultrasound Med Biol 1988;
14:649-G. Most noninvasive carotid studies estimate the degree of luminal narrowing of the internal carotid artery (ICA) but do not take into account the contribution of collaterals to the overall hemodynamic effect of a lesion. This study evaluates the accuracy of simple Doppler measurements in detecting substantial pressure gradients across ICA stenoses. A 5 MHz continuous wave (CW) Doppler device was used in conjunction with a prototype FFT (fast Fourier transform) signal processor capable of determining both mean and peak frequencies. Unlike most prior studies that have measured velocity signals proximal to or at the stenosis, the signals were obtained as far distal as possible in the ICA to avoid the local turbulence and increased velocity produced by the plaque. Pulsatility index (PI), pulse rise time (RT), and systolic width (SW), the duration of systole measured at half the sum of peak systolic and end-diastolic frequencies, were determined for both mean and peak velocity tracings in 49 patients. An important advantage is that all three parameters are angle-independent, an important consideration when imaging is not being used. Direct common carotid artery (CCA) and ICA pressures were measured intraoperatively during normocapneic anesthesia. An ICAlCCA ratio >O.XO was defined as an abnormal perfusion pressure. All three parameters studied detected a pressure gradient of 20% with accuracies between 90% to 95%. Results
for RT and for SW were very similar for analysis of mean and peak velocity curves; however, with PI, better correlation was obtained with mean than with peak curve. The cutoff points, determined by receiver operator characteristics, were 0.71 for PI, 0.16 seconds for RT, and 0.8 seconds for SW. Review of the angiograms revealed that less than half of the stenoses >50% had pressure gradients >20%, emphasizing the need to evaluate hemodynamic compromise as well as the anatomic severity of carotid lesions. The study was limited by the fact that there were only 10 patients with gradients >20%. A possible shortcoming is that all three parameters can be affected by abnormalities in CCA flow resulting from proximal stenoses, cardiac abnormality, or drug effect. Ideally this initial project will lead to further investigation of the method. J. Dennis Baker, MD UCLA School of Medicine
Cigarette smoking arterial surgery Lassila R, Lepantalo
and the outcome
after lower
limb
M. Acta Chir Stand 1988;154:635-
40. The effect of cigarette smoking on reconstruction was studied in 202 consecutive patients undergoing their first arterial reconstruction. Both aortoiliac and leg operations were included. One hundred ninety patients were available with a full 3-year follow-up. Patients were stratified according to tobacco use. There were 12 nonsmokers, 53 exsmokers (off all tobacco for more than 1 year), 45 moderate smokers (less than 15 cigarettes per day), and X5 heavy smokers. The main comparison was between moderate and heavy smokers. These groups were comparable in terms of age, severity, and distribution of disease, frequency of indications and incidence of risk factors. Severe smokers had a higher incidence of deterioration of the reconstruction during the follow-up period (49% vs 33%) and a very significant difference in major amputations (21% vs 2%). Among the males the 3-year mortality for heavy smokers was 60% compared with 35% for moderate smokers. Cardiovascular disease was a much more frequent cause of death in the heavy smokers, 83% versus 33%. The authors did not make a direct comparison of smokers to nonsmokers since the latter group was very different with the patients being an average of 10 years older, being predominantly women, having more distal disease, and having a much higher incidence of concomitant diseases. This study confirms the marked effect that heavy tobacco smoking has on morbidity as well as mortality of patients who have had arterial reconstruction. The authors suggest that in addition to the accelerated progression of atherosclerosis in heavy smokers, increased platelet activation may contribute to the increased complication rate. J. Dennis Baker, .&ID UCLA School ofMedicine