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Biomedical subjects

A Kazmers

Publications and source records attributed to A Kazmers.

At least 55 records · Page 3Linked to original sources
PubMed1989

Treatment of acute renal artery occlusion after percutaneous transluminal angioplasty.

Four patients with occlusive complications after percutaneous transluminal renal artery angioplasty (PTA) have been treated from July 1, 1984, to March 14, 1988. During this interval such renal artery angioplasties were performed in 44 patients. Two resulted in complete main renal artery occlusion, one angioplasty resulted in occlusion of a stenotic renal artery bypass graft, and one renal PTA resulted in segmental branch renal artery narrowing, which was thought to represent a dissection. The latter segmental renal artery narrowing was treated expectantly with good long-term results. One of the main renal artery occlusions was treated by radiologic means by reentry and repeat transluminal dilation. The other two acute complete occlusions, one of an autogenous artery and the other of an aortorenal bypass graft, were treated by aortorenal or ileorenal bypass grafting, respectively. The overall incidence of main renal artery occlusion (including the bypass graft occlusion) after PTA requiring operative intervention was 4.5% (2/44). Revascularization was accomplished after 6 and 8 hours of renal ischemia time for the two surgical procedures. Despite this, the bypass grafts done emergently remain patent, and the involved kidneys appear to be functional. The incidence of main renal artery occlusion after PTA is not as low as would be apparent from a review of the literature. It is proposed that main renal artery occlusion after PTA can be treated successfully by surgical and interventional radiologic techniques because of the presence of protective renal collateral circulation whose formation was stimulated by the renal artery lesion that prompted PTA.

Aged↗
PubMed1988

The role of preoperative radionuclide left ventricular ejection fraction for risk assessment in carotid surgery.

Radionuclide ejection fraction (EF) and ventricular wall motion were determined in 73 patients before 82 carotid operations (79 carotid endarterectomies [CEAs] and three cervical carotid-subclavian bypasses). The EF was 55% +/- 13%, ranging from 21% to 77%. Thirty-three percent (24/73) had low EF (less than or equal to 50%), and 44% (28/63) had myocardial wall motion abnormalities. Perioperative cardiac complications, including myocardial infarction (MI), new ventricular arrhythmia, or severe congestive heart failure, were present after 12.2% (10/82) of the operations. Perioperative MI was present in 4.9% (4/82); in 50% of these it was fatal. Perioperative (30-day) stroke was present in 2.5% (2/79) of those undergoing CEA. Life table analysis revealed overall survival was lower in patients with EF of 35% or less vs those with EF over 35% during follow-up (522 +/- 280 days). Perioperative cardiac complications were more frequent with EF of 35% or less, occurring in 43% (3/7) vs 9% (7/75) of cases with EF over 35%. There was no statistical difference in perioperative mortality, but cumulative mortality differed, being 57% (4/7) in those with EF of 35% or less vs 11% (7/66) in patients with EF over 35%. Patients with EF of 35% or less are at increased risk for perioperative cardiac complications and reduced overall survival following carotid surgery.

Aged↗
PubMed1988

Reoperative carotid surgery.

Fourteen patients underwent carotid reoperation for symptomatic recurrent carotid stenosis after previous ipsilateral carotid endarterectomy. Eight of these patients presented with focal transient ischemic attacks, two with strokes, and four with vertebrobasilar insufficiency. Recurrent symptoms in eight patients were similar to those prompting the initial carotid endarterectomy. Symptoms recurred early after previous carotid endarterectomy in 2 patients and late in 12 patients. Eleven patients underwent repeat endarterectomy and carotid patch angioplasty, two patients underwent patch angioplasty alone, and one patient underwent carotid artery replacement with a vein graft. Persistent or recurrent focal symptoms referable to the reoperated carotid artery were not present during follow-up (mean 27.4 months, range 4 to 79 months). Vertebrobasilar symptoms were relieved by carotid reoperation in each patient. Although the natural history of asymptomatic postoperative carotid restenosis is unknown, reluctance to reoperate on symptomatic patients is unwarranted, since carotid reoperation can be performed safely with the expectation that recurrent focal and nonfocal vertebrobasilar symptoms will be relieved.

Aged↗
PubMed1988

Perioperative and late outcome in patients with left ventricular ejection fraction of 35% or less who require major vascular surgery.

Survival in patients with diminished left ventricular ejection fraction (EF) is reduced after major vascular surgery. The objective of this study was to determine perioperative (30-day) and subsequent outcome after major vascular surgery in those with severe cardiac dysfunction, defined by EF being 35% or less (normal EF greater than 50%). From Aug. 1, 1984 to Jan. 1, 1988, 35 patients with EF equal to 27.7% +/- 6.1% (mean +/- 1 standard deviation) have required 47 major vascular procedures: 53% (n = 25) were limb revascularizations; 21% (n = 10) were direct aortoiliac aneurysm repairs: 23% (n = 11) were carotid endarterectomies: one patient had transaortic renal endarterectomy. Two deaths occurred within the first 30 days, yielding a 4.3% perioperative mortality rate (2 of 47 procedures). The cumulative mortality rate for the entire group during follow-up of 410 +/- 390 days was 40% (14 of 35 patients). Most late deaths (71%) occurred within the first 6 months after surgery and each was due to cardiovascular complications. Survival for those with an EF of 29% or less was significantly worse than for those with an EF greater than 29%, determined by life-table analysis (p less than 0.012, Mantel-Cox). The cumulative mortality rate was 59% with an EF of 29% or less and 18% in those with an EF greater than 29% (p less than 0.029, two-tailed Fisher exact test). The perioperative mortality rate for those with an EF of 35% or less who require major vascular surgery is acceptable, but overall survival during follow-up is diminished.(ABSTRACT TRUNCATED AT 250 WORDS)

Actuarial Analysis↗
PubMed1988

Duplex ultrasound scanning in the diagnosis of renal artery stenosis: a prospective evaluation.

Since ultrasonic energy can be used to interrogate vessels at great depth, it is only natural that it should be applied to deeply placed arteries in the abdomen. Early studies suggested that high-grade stenoses of the renal artery could be detected by this approach as long as the peak systolic velocity in the renal artery was normalized by that measured in the abdominal aorta. A retrospective study comparing the peak velocity in the renal artery to that from the adjacent abdominal aorta (the renal aortic ratio) showed that if this value exceeded 3.5, it is likely to be associated with a greater than 60% diameter-reducing stenosis. To test this hypothesis, we used duplex scanning to prospectively evaluate 58 renal arteries in 29 patients in whom arteriograms were available. There were 39 renal arteries with 0% to 59% stenosis, 14 with 60% to 99% stenosis, and five occlusions by angiography. Renal duplex scanning accurately diagnosed 38 of 39, 11 of 14, and four of five of these, respectively, giving a sensitivity of 84%, a specificity of 97%, and a positive predictive value of 94% for the detection of a greater than 60% diameter-reducing stenosis. The overall agreement with angiography was 93%. These data show that renal duplex scanning can be used to diagnose renal artery stenosis in patients with hypertension or renal dysfunction, thus providing a rational basis for the selection of patients for angiography.

Adolescent↗
PubMed1988

The role of preoperative radionuclide ejection fraction in direct abdominal aortic aneurysm repair.

Preoperative radionuclide ventriculography was performed in 60 patients to assess whether such testing could define those at increased risk after direct abdominal aortic aneurysm (AAA) repair. None of the patients had prophylactic coronary artery reconstruction to reduce the risk of AAA repair despite angina in 27% and previous myocardial infarction (MI) in 42%. The mean ejection fraction (EF) was 52% +/- 15% (range 14% to 78%). Low EF (normal greater than 50%) was present in 40%, whereas ventricular wall motion abnormalities were present in 39% of patients. The overall perioperative (30-day) mortality rate was 5%. MI occurred in 7% within 30 postoperative days; none was fatal. Life-table analysis revealed that overall survival after AAA repair was significantly lower in patients with an EF of 50% or less (p less than 0.025, Mantel-Cox) during a follow-up of 20.1 +/- 11.9 months. Overall survival differences were even more striking for those with an EF of 35% or less (p = 0.003, Mantel-Cox). There was a marked difference in the cumulative mortality rate during follow-up, being 50% in those patients with an EF of 35% or less (n = 10) compared with 14% in those with an EF greater than 35% (n = 50, p = 0.036, Fisher exact test). There was no statistical difference in the incidence of perioperative MI or perioperative death for those with an EF of 35% or less vs EF greater than 35%.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1986

Effects of continuous intravenous infusions of nitroglycerin on canine systemic and hind limb microcirculatory hemodynamics.

Systemic and hind limb hemodynamics were assessed in anesthetized dogs during continuous 30-minute intravenous infusions of nitroglycerin at 1, 5, 10, and 25 micrograms/kg/min. Nitroglycerin at 1 microgram/kg/min redistributed hind limb blood flow; hind limb arteriovenous shunting increased from 5.6% +/- 4.0% to 17.8% +/- 7.4% after 30 minutes (p less than 0.01); absolute hind limb shunt flow increased from 12 +/- 10 ml/min to 31 +/- 26 ml/min at 10 minutes (p less than 0.01); whereas hind limb nutrient blood flow decreased from 184 +/- 81 ml/min to 150 +/- 55 ml/min and 132 +/- 32 ml/min, respectively, at 10 and 30 minutes (p less than 0.05). Such hind limb blood flow redistribution was absent during infusion of all other nitroglycerin dosages. Total catecholamines increased at 30 minutes during both 1 and 10 micrograms/kg/min nitroglycerin infusions (p less than 0.05) with perhaps a slightly greater catecholamine response to 10 micrograms/kg/min after 30 minutes (0.05 less than p less than 0.10). The renin-angiotensin response at 3 minutes differed between nitroglycerin infusions of 1 and 10 micrograms/kg/min with an initial significant reduction from baseline in plasma renin activity at the lower dose compared with a significant increase from baseline in plasma activity at the higher dose. Nitroglycerin did not increase femoral artery flow or cardiac output and did not lower total peripheral vascular resistance at any dose studied. Despite this, arterial pressure and cardiac work were reduced at all nitroglycerin doses tested. Massive volume loading prevented the anticipated blood pressure reduction and blunted the expected cardiac work reduction during nitroglycerin infusions of 10 micrograms/kg/min. This study demonstrates that nitroglycerin is not a potent peripheral arteriolar vasodilator, 1 microgram/kg/min nitroglycerin infusions increase hind limb arteriovenous shunting and decrease hind limb nutrient blood flow, and myocardial work and arterial pressure reductions during nitroglycerin infusions appear to be caused by mechanisms other than generalized peripheral arterial dilation.

Animals↗
PubMed1986

Noninvasive diagnosis of renal artery stenosis by ultrasonic duplex scanning.

We retrospectively studied the results of duplex scanning for evaluation of renal artery disease in 158 patients. Satisfactory examinations were achieved in 144 patients (90%). Arteriograms were available for 43 renal arteries. We used the ratio of the peak velocities in the renal artery and the aorta (RAR) to separate nonstenotic arteries (less than 60% diameter reduction) from stenotic arteries (greater than 60% diameter reduction). With an RAR of greater than 3.5 to indicate stenotic lesions, duplex scanning had a sensitivity of 91% (20 of 22 diseased arteries correctly identified) and specificity of 95% (20 of 21 normal or insignificantly diseased arteries correctly identified). One of four occluded arteries was incorrectly interpreted as patent because of misidentification of a collateral vessel. Prospective studies will be necessary to validate this test and establish other criteria for a more detailed classification of renal artery stenosis. The ratio of the end-diastolic to peak systolic velocities in the renal artery (EDR) tended to decrease with increasing serum creatinine levels, presumably because renal vascular resistance increases with end-stage parenchymal disease. EDR may prove useful in the detection of advanced parenchymal disease before renal artery revascularization is attempted.

Aorta, Abdominal↗
PubMed1985

Brachiocephalic arterial occlusions and stenoses. Manifestations and management of complex lesions.

Complex stenotic and occlusive lesions involving multiple brachiocephalic arteries were encountered in 17 symptomatic patients, 25 to 76 years of age. Symptoms included hemispheric transient ischemic attacks (16), visual symptoms (ten), global cerebral ischemia (11), true syncope (six), upper extremity ischemic symptoms (eight), and frank tissue loss (one). Of 68 brachiocephalic arteries, 53 exhibited hemodynamically significant stenoses, including 21 that were totally occluded. Transthoracic surgical reconstruction consisted of bypass grafting (11), innominate artery endarterectomy (five), or proximal left common carotid endarterectomy with reimplantation into the contralateral carotid artery (one). There were no operative deaths and only one transient perioperative neurologic deficit. All patients had relief of symptoms. When multiple brachiocephalic arterial occlusions and stenoses preclude standard cervical reconstructive procedures, direct transthoracic reconstruction is appropriate and may be undertaken with acceptable risk in properly selected patients.

Adult↗
PubMed1985

Nonpenetrating subclavian artery injuries.

Nonpenetrating subclavian artery trauma, a potentially catastrophic injury, has been recognized more frequently with the liberal use of angiography in evaluating blunt cervicothoracic trauma. Six patients, five men and one woman, recently underwent surgical treatment at the University of Michigan Hospital for blunt injury of the subclavian artery. The diagnoses were established by arteriography. Physical findings, chest roentgenograms, and results of noninvasive vascular evaluation were found to be nonspecific or unreliable. Operative treatment with resection of the injured arterial segments and either primary anastomosis or bypass grafting resulted in restoration of distal, upper extremity blood flow in all of the cases. One patient died 20 days after trauma from a severe associated cerebral injury. Among the five survivors, residual soft tissue and neurologic injury compromised full recovery in three. Thus, only two of the six patients survived without sequelae, a fact that underscores the seriousness of this type of subclavian artery injury.

Accidents, Traffic↗
PubMed1985

Effect of intravenous glucagon on the survival of rats after acute occlusive mesenteric ischemia.

The purpose of this study was to determine the optimal timing of intravenous glucagon infusion for the treatment of acute occlusive mesenteric ischemia. The superior mesenteric artery (SMA) was occluded for 85 min in 106 Sprague-Dawley anesthetized rats. The animals were divided into 12 treatment groups according to the timing of glucagon and saline administration, and survival was measured to 48 hr. Without treatment, all rats died within 24 hr. Intravenous saline (10 ml/kg/hr) for 2 hr did not significantly improve 48-hr survival (17-33%). Glucagon (1.6 micrograms/kg/min iv) plus saline (10 mg/kg/hr iv) for 2 hr after SMA occlusion significantly improved survival from 33% (saline control) to 83% (P less than 0.02). The same treatment begun 1 hr before SMA release (during ischemia) did not significantly improve survival (33% at 48 hr). Glucagon infusion during occlusive mesenteric ischemia was detrimental when added to effective postischemia treatment, reducing survival from 83 to 33% (P less than 0.02). Adequate saline infusion was required for glucagon efficacy after ischemia, as shown by an intermediate 48-hr survival of 50% when only maintenance saline (1.5 ml/kg/hr) was given. These data suggest that glucagon therapy should be delayed until after operative release of an acute SMA occlusion and should be accompanied by vigorous volume expansion.

Acute Disease↗
PubMed1985

Comparative hemodynamic effects of selective superior mesenteric arterial and peripheral intravenous glucagon infusions.

This experiment was designed to determine whether any hemodynamic benefits attend administration of equal pharmacologic doses of glucagon (1 micrograms/kg/m) by continuous intravenous infusion (Group I, n = 6) versus selective intraarterial infusion (Group II, n = 6) via the superior mesenteric artery (SMA) in dogs. Cardiac output, heart rate, mean arterial pressure, total peripheral resistance, pulmonary vascular resistance, superior mesenteric artery flow (SMAQ), SMA vascular resistance, and portal venous pressure were measured at baseline (BL) and at 5, 15, 30, and 45 min during glucagon infusion. SMAQ virtually doubled at 5 min from a baseline of 570 +/- 60 ml/min to 1158 +/- 146 ml/min in Group I (P less than 0.001), and from a baseline of 527 +/- 171 to 1018 +/- 331 ml/min in Group II (P less than 0.002). SMAQ was significantly higher in Group I at 30 and 45 min compared to Group II (P less than 0.03) despite similar peripheral plasma glucagon levels. SMA vascular resistance was significantly lowered in both groups, with a greater reduction occurring during intravenous glucagon administration at 45 min (P less than 0.05). Changes in systemic hemodynamic parameters, as well as glucagon and glucose levels were not statistically different between Groups I and II at any time period. Glucagon is a potent mesenteric vasodilator and the resultant profound splanchnic hemodynamic effects are as marked during intravenous administration as during selective SMA infusion.

Animals↗
PubMed1984

Early derangements of arteriovenous anastomotic and capillary blood flow in the canine hindlimb induced by supplemental pentobarbital anesthesia.

Vasoactive effects of supplemental pentobarbital anesthesia in the canine hindlimb microcirculation were documented in two groups of animals previously anesthetized with 30 mg/kg pentobarbital: Group I with a 5 mg/kg intravenous (iv) bolus of pentobarbital (n = 8) and Group II with a 5 mg/kg 2-min iv infusion of pentobarbital (n = 7). In Group I, measurements at baseline (BL) and 5, 15, 20, and 30 min (min) following pentobarbital administration included cardiac output, mean arterial pressure, total peripheral vascular resistance, common femoral artery flow (CFAQ) and resistance (CFAR), percentage hindlimb arteriovenous anastomotic shunt (AVA%), absolute shunt flow (AVAQ), and hindlimb nutrient capillary flow (NCQ). In Group II these same measurements were made, but the study was continued until all hindlimb hemodynamic parameters returned to control values. CFAQ, AVA%, AVAQ, and NCQ were significantly increased, and CFAR was decreased in both groups. CFAQ and NCQ remained significantly elevated at 30 min in Group I. In Group II CFAR, AVA%, and AVAQ remained elevated at 30 min, but did return to BL by 40 min, as did all other hindlimb hemodynamic parameters measured. Pentobarbital resulted in both AVA and arteriolar dilation, with an increase in the percentage total flow distributed to AVAs. These alterations of microcirculatory flow should be considered during investigations of the distribution of peripheral blood flow, as well as during metabolic studies assessing arteriovenous substrate differences, if interpretative errors are to be avoided.

Anesthesia↗
PubMed1984

Pharmacologic interventions in acute mesenteric ischemia: improved survival with intravenous glucagon, methylprednisolone, and prostacyclin.

An experimental model of acute mesenteric ischemia following 85 minutes of superior mesenteric artery (SMA) occlusion in male Wistar rats was used in this investigation. Untreated control animals had a 48-hour survival rate of 38% (n = 26), whereas sham laparotomy resulted in a 100% 48-hour survival rate (n = 10). Study groups received intravenous infusions of normal saline solution (16.6 ml/kg/hr; n = 26) or similar volumes of normal saline solution with the addition of glucagon (1.6 micrograms/kg/min; n = 26), dopamine (3.2 micrograms/kg/min; n = 26), or prostacyclin (PGI2) (10.7 ng/kg/min; n = 26). Infusions were begun 15 minutes after initiating 85 minutes of SMA occlusion and were continued for a total of 90 minutes. Glucagon increased the 48-hour survival rate to 85%, significantly greater than both control survival (p less than 0.001) and normal saline solution group survival rates (p less than 0.025). Neither normal saline solution alone nor dopamine significantly increased the 48-hour survival rate, which was 54% in both groups. The PGI2 group survival rate, 65% at 48 hours, was significantly greater than the control rate (p less than 0.05), was not statistically different from the normal saline solution group survival rate, and was 20% less than the glucagon group survival rate, the latter difference approaching statistical significance (p = 0.10). Methylprednisolone (40 mg/kg; n = 26) administered as an intravenous bolus 15 minutes after initiating SMA occlusion significantly increased the 48-hour survival rate to 73% (p less than 0.01), whereas neither intravenous heparin (150 U/kg; n = 26) nor superoxide dismutase (11,900 U/kg; n = 26) were beneficial. Glucagon, methylprednisolone, and PGI2 improved the survival rate in this model of acute mesenteric ischemia.

Animals↗
PubMed1984

Atherosclerotic extracranial carotid artery aneurysms.

Twenty-four atherosclerotic extracranial carotid artery aneurysms were encountered in 21 patients during a 25-year period. These represented 46% of all extracranial carotid artery aneurysms diagnosed at the University of Michigan during this period. Neurologic symptoms including amaurosis fugax, transient ischemic attacks, and stroke were present in 50% of the patients. An asymptomatic pulsatile neck mass occurred in 33%. Surgical therapy was undertaken for 18 aneurysms, and nonoperative treatment was pursued in the remaining six aneurysms. Operative therapy included 14 aneurysmectomies and four aneurysmorraphies. There were no surgical deaths. Transient perioperative neurologic deficits affected three of these patients (17%), and one individual (5%) experienced a permanent deficit. Transient cranial nerve deficits occurred in three patients (17%), and a permanent deficit was noted in one patient (5%). During a 7.6-year follow-up period no late strokes occurred among patients who were operated on. Nonoperative therapy was associated with three ipsilateral strokes during a mean follow-up period of 6.3 years. Atherosclerotic extracranial carotid artery aneurysms were associated with an exceptionally high stroke rate (50%) if treated nonoperatively. Prevention of late stroke justifies surgery, although perioperative neurologic deficits may accompany this therapy more often than with nonatherosclerotic carotid artery aneurysms.

Aged↗
PubMed1983

Limb-threatening potential of arteriosclerotic popliteal artery aneurysms.

Eighty-eight popliteal artery aneurysms were diagnosed in 59 men and two women (mean age 67 +/- 10 years). Bilateral aneurysms affected 27 patients (44%). Aneurysm diameter ranged from 1.3 to 12 cm (mean 4 +/- 2.6 cm). Most aneurysms were symptomatic (55%). Dominant symptoms included rest pain (19%), claudication (14%), local pain (13%), and gangrene (9%). The remainder of the aneurysms were asymptomatic (45%). Aneurysm thrombosis occurred in 24% of extremities. Associated aneurysms involved the abdominal aorta (62%), iliac artery (36%), and femoral artery (38%). Aneurysms that caused local pain were larger (6.2 +/- 1.9 cm) than asymptomatic aneurysms (2.9 +/- 2.1 cm, P less than 0.01). Aneurysms smaller than 2 cm were more likely to be asymptomatic than larger aneurysms (P less than 0.05). Operative intervention was undertaken for 56 aneurysms, with aneurysmal exclusion or excision with arterial reconstruction performed most often. Four primary and five secondary major amputations were associated with thrombosed aneurysms, compared to no amputations with asymptomatic aneurysms (P less than 0.01). Thirty-two aneurysms were not treated surgically. Limb loss resulted from ischemic complications which developed in 18% of aneurysms treated without operation. The duration of follow-up for patients who had operation and those who did not averaged 62 months and 25 months, respectively. Operative treatment for all bland popliteal artery aneurysms appears justified if complications leading to major amputation are to be avoided.

Adult↗