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Zoran Valic

Publications and source records attributed to Zoran Valic.

At least 19 recordsLinked to original sources
PubMed2006

The effects of acute oral antioxidants on diving-induced alterations in human cardiovascular function.

Diving-induced acute alterations in cardiovascular function such as arterial endothelial dysfunction, increased pulmonary artery pressure (PAP) and reduced heart function have been recently reported. We tested the effects of acute antioxidants on arterial endothelial function, PAP and heart function before and after a field dive. Vitamins C (2 g) and E (400 IU) were given to subjects 2 h before a second dive (protocol 1) and in a placebo-controlled crossover study design (protocol 2). Seven experienced divers performed open sea dives to 30 msw with standard decompression in a non-randomized protocol, and six of them participated in a randomized trial. Before and after the dives ventricular volumes and function and pulmonary and brachial artery function were assessed by ultrasound. The control dive resulted in a significant reduction in flow-mediated dilatation (FMD) and heart function with increased mean PAP. Twenty-four hours after the control dive FMD was still reduced 37% below baseline (8.1 versus 5.1%, P = 0.005), while right ventricle ejection fraction (RV-EF), left ventricle EF and endocardial fractional shortening were reduced much less (approximately 2-3%). At the same time RV end-systolic volume was increased by 9% and mean PAP by 5%. Acute antioxidants significantly attenuated only the reduction in FMD post-dive (P < 0.001), while changes in pulmonary artery and heart function were unaffected by antioxidant ingestion. These findings were confirmed by repeating the experiments in a randomized study design. FMD returned to baseline values 72 h after the dive with pre-dive placebo, whereas for most cardiovascular parameters this occurred earlier (24-48 h). Right ventricular dysfunction and increased PAP lasted longer. Acute antioxidants attenuated arterial endothelial dysfunction after diving, while reduction in heart and pulmonary artery function were unchanged. Cardiovascular changes after diving are not fully reversed up to 3 days after a dive, suggesting longer lasting negative effects.

Administration, Oral↗
PubMed2006

Alpha-Adrenergic receptor responsiveness is preserved during prolonged exercise.

Our laboratory has previously reported a decline in sympathetic nervous system restraint of skeletal muscle blood flow during prolonged mild-intensity exercise. This decline may be explained by a decrease in alpha(1)- and alpha(2)-adrenergic receptor responsiveness over time. Thus the purpose of the present study was to investigate the effect of exercise duration on alpha(1)- and alpha(2)-adrenergic receptor responsiveness during prolonged constant-load exercise. Mongrel dogs (n = 6) were instrumented chronically with transit-time flow probes on the external iliac arteries and an indwelling catheter in a branch of the femoral artery. On separate days, flow-adjusted doses of selective alpha(1)- (phenylephrine) alpha(2)-adrenergic-receptor (clonidine) agonists, and tyramine (to evoke endogenous norepinephrine release) were infused following 5, 30 and 50 min of mild-intensity treadmill exercise (3 miles/h), with hindlimb blood flow (HBF) and mean arterial pressure (MAP) monitored continuously. Vascular conductance (VC) was calculated as HBF/MAP. While the dogs ran on the treadmill at 3 miles/h, infusion of phenylephrine resulted in similar decreases in VC after 5 [73% (SD 10)], 30 [76% (SD 9)], and 50 [73% (SD 10)] min of exercise. Infusion of the alpha(2)-agonist clonidine also produced similar decreases in VC after 5 [58% (SD 10)], 30 [58% (SD 11)], and 50 [53% (SD 12)] min of exercise. Infusion of tyramine resulted in similar decreases in VC after 5 [55% (SD 15)], 30 [51% (SD 10)], and 50 [50% (SD 7)] min of exercise. These results demonstrate that alpha(1)- and alpha(2)-adrenergic receptor responsiveness to infusion of selective alpha(1)- and alpha(2)-adrenergic-receptor agonists and endogenous norepinephrine release (tyramine) does not decline during prolonged mild-intensity exercise. Thus a decrease in alpha-adrenergic receptor responsiveness over time does not appear to be responsible for the decrease in sympathetic restraint of muscle blood flow during prolonged exercise.

Adaptation, Physiological↗
PubMed2006

Increased pulmonary vascular resistance and reduced stroke volume in association with CO2 retention and inferior vena cava dilatation.

Changes in cardiovascular parameters elicited during a maximal breath hold are well described. However, the impact of consecutive maximal breath holds on central hemodynamics in the postapneic period is unknown. Eight trained apnea divers and eight control subjects performed five successive maximal apneas, separated by a 2-min resting interval, with face immersion in cold water. Ultrasound examinations of inferior vena cava (IVC) and the heart were carried out at times 0, 10, 20, 40, and 60 min after the last apnea. The arterial oxygen saturation level and blood pressure, heart rate, and transcutaneous partial pressures of CO(2) and O(2) were monitored continuously. At 20 min after breath holds, IVC diameter increased (27.6 and 16.8% for apnea divers and controls, respectively). Subsequently, pulmonary vascular resistance increased and cardiac output decreased both in apnea divers (62.8 and 21.4%, respectively) and the control group (74.6 and 17.8%, respectively). Cardiac output decrements were due to reductions in stroke volumes in the presence of reduced end-diastolic ventricular volumes. Transcutaneous partial pressure of CO(2) increased in all participants during breath holding, returned to baseline between apneas, but remained slightly elevated during the postdive observation period (approximately 4.5%). Thus increased right ventricular afterload and decreased cardiac output were associated with CO(2) retention and signs of peripheralization of blood volume. These results indicate that repeated apneas may cause prolonged hemodynamic changes after resumption of normal breathing, which may suggest what happens in sleep apnea syndrome.

Adaptation, Physiological↗
PubMed2006

A single open sea air dive increases pulmonary artery pressure and reduces right ventricular function in professional divers.

After decompression from dives, bubbles are frequently observed in the right ventricular outflow tract and may lead to vascular damage, pulmonary arterial hypertension and right ventricular overload. No data exist on the effect of open sea diving on the pulmonary artery pressure (PAP). Eight professional divers performed an open sea air dive to 30 msw. Before and postdive a Doppler echocardiographic study was undertaken. Systolic pulmonary artery pressure (SPAP) was estimated from measurement of peak flow velocity of the tricuspid regurgitant jet; the ratio between pulmonary artery acceleration times (AccT) and right ventricular ejection time (RVET) was used as an estimate of the mean PAP. No evidence of either patent foramen ovale or intra-pulmonary shunt was found in any subject postdive after performing a Valsalva maneuver. SPAP increased from 25 +/- 3 to 33 +/- 2 mmHg and AccT/RVET ratio decreased from 0.44 +/- 0.04 to 0.3 +/- 0.02 20 min after the dive, respectively. Pulmonary vascular resistance increased from 1.2 +/- 0.1 to 1.4 +/- 0.1 Woods Units. Postdive right ventricle end-diastolic and end-systolic volumes were increased for about 19% (P = 0.001) and 33% (P = 0.001) and right ejection fraction decreased about for 6% (P = 0.001). Cardiac output decreased from 4.8 +/- 0.9 (l min(-1)) to 4.0 +/- 0.6 at 40 min postdive due to decreases in heart rate and stroke volume. This study shows that a single open sea dive may be associated with right heart overload due to increased pressure in the pulmonary artery.

Adult↗
PubMed2006

Postexercise hypotension in moderately trained athletes after maximal exercise.

PURPOSE: A similar postexercise hypotension (PEH) has been reported in sedentary and mildly endurance-trained individuals of both sexes after a single dynamic submaximal exercise. In endurance-trained men, the hypotension was associated with a reduction of cardiac output, whereas the peripheral vasodilatation was the main mechanism of this fall in other groups. The present study investigated the occurrence and mechanisms of PEH after a short maximal exercise in professional soccer players with greater endurance capacity than previously reported in PEH studies. METHODS: Arterial blood pressure, cardiac output (Q), heart rate (HR), and diffusing lung capacity for carbon monoxide (DLCO) before and 30 and 60 min after short maximal field exercise were studied in 20 professional soccer players. RESULTS: Diastolic blood pressure (DBP) and systolic blood pressure (SBP), Q, stroke volume, and DLCO decreased, whereas HR increased at both times after exercise. Decreases in DBP were greater in subjects with lesser VO2max (r = -0.73, P = 0.0001), whereas SBP was more decreased the higher it was at baseline (r = 0.51, P = 0.023). Total peripheral resistance (TPR) did not change significantly after exercise. CONCLUSION: These findings indicate that, in moderately trained athletes, postexercise hypotension is associated primarily with reduced cardiac output because of reduced stroke volume, suggesting venous pooling. In addition, the occurrence of hypotension is more frequent in trained subjects with lower cardiopulmonary fitness level or higher resting SBP.

Adult↗
PubMed2006

Exogenous nitric oxide and bubble formation in divers.

PURPOSE: Prevention of bubble formation is a central goal in standard decompression procedures. Previously we have shown that exercise 20-24 h prior to a dive reduces bubble formation and increases survival in rats exposed to a simulated dive. Furthermore, we have demonstrated that nitric oxide (NO) may be involved in this protection; blocking the production of NO increases bubble formation while giving rats a long-lasting NO donor 20 h and immediately prior to a dive reduces bubble formation. This study determined whether a short-lasting NO donor, nitroglycerine, reduced bubble formation after standard dives and decompression in man. METHODS: A total of 16 experienced divers were randomly assigned into two groups. One group performed two dives to 30 m of seawater (msw) for 30 min breathing air, and performed exercise at an intensity corresponding to 30% of maximal oxygen uptake during the bottom time. The second group performed two simulated dives to 18 msw for 80 min breathing air in a hyperbaric chamber, and remained sedentary during the bottom period. The first dive for each diver served as the control dive, whereas the divers received 0.4 mg of nitroglycerine by oral spray 30 min before the second dive. Following the dive, gas bubbles in the pulmonary artery were recorded using ultrasound. RESULTS: The open-water dive resulted in significantly more gas bubbles than the dry dive (0.87 +/- 1.3 vs 0.12 +/- 0.23 bubbles per square centimeter). Nitroglycerine reduced bubble formation significantly in both dives from 0.87 +/- 1.3 to 0.32 +/- 0.7 in the in-water dive and from 0.12 +/- 0.23 to 0.03 +/- 0.03 bubbles per square centimeter in the chamber dive. CONCLUSION: The present study demonstrates that intake of a short-lasting NO donor reduces bubble formation following decompression after different dives.

Adult↗
PubMed2006

Venous bubble count declines during strenuous exercise after an open sea dive to 30 m.

INTRODUCTION: The effect of post-dive exercise on bubble formation remains controversial, although the current practice of divers and aviators is to avoid strenuous exercise after diving. Previously, we have shown that exercising 24 h before a dive, or during a decompression stop, significantly reduces bubble formation in man. The objective of this study was to determine whether a short period of strenuous post-dive exercise promotes venous bubble formation. METHODS: Seven male military divers performed an open-sea field dive to a maximum depth of 30 m for 30 min. At maximum depth, subjects performed mild underwater fin swimming, followed by standard decompression. Diving was followed by a post-dive exercise session consisting of short, strenuous incremental upright cycle ergometry, up to 85% of maximal oxygen uptake, for about 10 min. Subjects were monitored for venous gas bubbles in the right heart with an echo-imaging system starting 20 min post-dive while in the supine position, during cycle ergometry in the seated upright position, and immediately after exercise in a supine position. RESULTS: The average number of bubbles was 1.5 +/- 1.4 bubbles x cm(-2) 20 min after diving. Changes in posture from supine to seated upright resulted in significant reduction of bubbles to 0.6 +/- 1.3 bubbles x cm(-2) (p = 0.043), with further reduction to 0.2 +/- 0.3 bubbles x cm(-2) at the end of exercise (p = 0.02). No cases of DCS or intra-pulmonary shunt were observed during or following post-dive exercise. DISCUSSION: These results suggest that post-dive strenuous exercise after a single field dive reduces post-dive gas bubble formation in well-trained military divers. Additional findings are needed for normal sports divers.

Adult↗
PubMed2006

Muscle oxygen supply during cold face immersion in breath-hold divers and controls.

INTRODUCTION: The human diving reflex is characterized by bradycardia, decreased cardiac output, and peripheral vasoconstriction, and has an oxygen-conserving effect both at rest and during exercise. However, the resultant time course and extent of muscle desaturation is unknown. METHODS: We used near-infrared spectroscopy to continuously measure the decrease in tissue oxygen saturation (StO2) in the calf muscle during a series of breath-holds. Subjects were seven trained divers (TD) and eight untrained controls (UC). Other measured variables included arterial blood pressure, heart rate, and arterial oxygen saturation (SaO2). Each subject performed five maximal apneas during face immersion in cold water with 2-min recovery intervals between breath-holds. RESULTS: On average, total apnea time for TD was significantly longer than for UC (772.6 +/- 40.9 s vs. 499.1 +/- 118.2 s, respectively). Further, TD had a more pronounced decrease in StO2 than UC (70.6 +/- 15.3% for TD vs. 87.9 +/- 6.1% UC for the fifth and longest apnea). When values for the two groups were compared at the mean breakpoint time for UC, there was no difference in StO2 and SaO2 remained at baseline. By contrast, at the same time point in all five apneas, UC experienced simultaneous, significantly larger reductions in SaO2 and StO2. DISCUSSION: These data indicate that TD have an attenuated diving reflex compared with UC at the same breath-hold times (the breakpoint for UC). In addition, muscle desaturation occurs earlier than arterial desaturation in both groups; the fact that this effect was less pronounced in TD suggests a training effect. This study provides further evidence for the oxygen-conserving effect of the human diving reflex in maintaining the oxygen supply of vital organs.

Adult↗
PubMed2005

Exercise-induced intrapulmonary shunting of venous gas emboli does not occur after open-sea diving.

Paradoxical arterializations of venous gas emboli can lead to neurological damage after diving with compressed air. Recently, significant exercise-induced intrapulmonary anatomical shunts have been reported in healthy humans that result in widening of alveolar-to-arterial oxygen gradient. The aim of this study was to examine whether intrapulmonary shunts can be found following strenuous exercise after diving and, if so, whether exercise should be avoided during that period. Eleven healthy, military male divers performed an open-sea dive to 30 m breathing air, remaining at pressure for 30 min. During the bottom phase of the dive, subjects performed mild exercise at approximately 30% of their maximal oxygen uptake. The ascent rate was 9 m/min. Each diver performed graded upright cycle ergometry up to 80% of the maximal oxygen uptake 40 min after the dive. Monitoring of venous gas emboli was performed in both the right and left heart with an ultrasonic scanner every 20 min for 60 min after reaching the surface pressure during supine rest and following two coughs. The diving profile used in this study produced significant amounts of venous bubbles. No evidence of intrapulmonary shunting was found in any subject during either supine resting posture or any exercise grade. Also, short strenuous exercise after the dive did not result in delayed-onset decompression sickness in any subject, but studies with a greater number of participants are needed to confirm whether divers should be allowed to exercise after diving.

Adaptation, Physiological↗
PubMed2005

Thermal pain perception after aerobic exercise.

OBJECTIVE: To examine thermal pain perception before, 5 minutes after, and 30 minutes after 30 minutes of treadmill exercise at 75% of maximal oxygen uptake (V o 2 max). DESIGN: Repeated-measures. SETTING: Sports science laboratory. PARTICIPANTS: Convenience sample of 14 healthy male and female volunteers (mean age +/- standard deviation, 32+/-3y). INTERVENTIONS: Sensory thresholds, pain thresholds, and pain ratings to hot and cold stimuli were measured before and after 30 minutes of treadmill exercise at 75% of V o 2 max. The hot and cold stimuli were delivered by using a thermode placed on the thenar eminence of the nondominant hand. Thermal sensory and pain thresholds were determined during continuous ramps in temperature of the thermode. MAIN OUTCOME MEASURES: Pain ratings were measured on a visual analog scale at 10-second intervals over 2 minutes of thermal pain stimulation. RESULTS: There were no significant changes in thermal sensitivity, pain thresholds, or pain ratings for either heat or cold after 30 minutes of exercise at 75% of V o 2 max. CONCLUSIONS: Pain perception to thermal stimuli was unaltered after 30 minutes of exercise at 75% of V o 2 max, an intensity and duration of exercise previously shown to alter pain perception to electric and mechanical stimuli.

Adult↗
PubMed2005

Effect of human splenic contraction on variation in circulating blood cell counts.

1. The human spleen sequesters 200-250 mL densely packed red blood cells. Up to 50% of this viscous blood is actively expelled into the systemic circulation during strenuous exercise or simulated apnoea (breath-hold) diving. The contribution of splenic contraction to changes in the circulating volume of red blood cells (RBCV), as well as the venous concentration of white blood cells (WBC) and platelets (PLT), was investigated following repeated breath-hold apnoeas. 2. Eighteen trained apnoea divers and 18 intact and six splenectomized subjects without diving experience repeated five maximal apnoeas with face immersion in cold water, with 2 min intervals between successive attempts. Venous blood samples were taken before and between consecutive apnoeas, as well as at 0, 10 and 20 min after the last breath hold. Arterial pressure, heart rate and transcutaneous partial pressure of oxygen and carbon dioxide were monitored continuously. 3. Plasma protein concentration decreased by 5.8, 2.2 and 9% in apnoea divers, untrained and splenectomized subjects, respectively, indicating an expansion of plasma volume. The RBCV and venous concentration of WBC, corrected for changes in plasma volume, increased in both trained apnoea divers (4.9+/-1.0 and 14.9+/-3.1%, respectively) and intact subjects (1.7+/-0.8 and 7.2+/-1.8%, respectively), whereas in splenectomized subjects there was no change in RBCV and a delayed increase in WBC concentration. Furthermore, an initial lymphocytosis detected during repeated breath holds in divers and intact subjects was completely absent in splenectomized subjects. None of the groups showed significant changes in PLT concentrations. The well-recognized diving response to apnoea (bradycardia and increased blood pressure) was seen during all breath-hold attempts in all subjects. 4. Repeated breath-holds (apnoeas) contribute to increased RBCV and venous blood concentrations of WBC through splenic contraction.

Adult↗
PubMed2005

Exercise during a 3-min decompression stop reduces postdive venous gas bubbles.

PURPOSE: Decompression sickness is initiated by the formation of gas bubbles in tissue and blood if the divers return to surface pressure too fast. The effect of exercise before, during, and after dive on bubble formation is still controversial. We have reported recently that strenuous aerobic exercise 24 h before simulated dive ameliorates venous bubble formation. The objective of this field study was to evaluate whether mild, continuous exercise during decompression has a similar impact. METHODS: Ten healthy, military male divers performed an open-sea field dive to 30 m of sea water breathing air, remaining at pressure for 30 min. During the bottom and decompression the subjects performed fin underwater swimming at about 30% of maximal oxygen uptake. Each diver underwent two randomly assigned dives, one with and one without exercise during the 3-min decompression period. Monitoring of venous gas emboli was performed in the right heart with ultrasonic scanner every 20 min for 60 min after reaching surface pressure in supine rest and during forced two-cough procedure. RESULTS: The study demonstrates that a mild, continuous exercise during decompression significantly reduced the average number of bubbles in the pulmonary artery from 0.9 +/- 0.8 to 0.3 +/- 0.5 bubbles per square centimeter in supine rest, as well as during two-cough procedure, which decreased from 4.6 +/- 4.5 to 0.9 +/- 0.9 bubbles per square centimeter. No symptoms of decompression sickness were observed in any subject. CONCLUSION: These results, obtained in the field conditions, indicate that a mild, underwater swimming during a 3-min decompression period reduces postdive gas bubbles formation.

Croatia↗
PubMed2004

Muscle blood flow response to contraction: influence of venous pressure.

The skeletal muscle pump is thought to be at least partially responsible for the immediate muscle hyperemia seen with exercise. We hypothesized that increases in venous pressure within the muscle would enhance the effectiveness of the muscle pump and yield greater postcontraction hyperemia. In nine anesthetized beagle dogs, arterial inflow and venous outflow of a single hindlimb were measured with ultrasonic transit-time flow probes in response to 1-s tetanic contractions evoked by electrical stimulation of the sciatic nerve. Venous pressure in the hindlimb was manipulated by tilting the upright dogs to a 30 degrees angle in the head-up or head-down positions. The volume of venous blood expelled during contractions was 2.2 +/- 0.2, 1.6 +/- 0.2, and 1.4 +/- 0.2 ml with the head-up, horizontal, and head-down positions, respectively. Although altering hindlimb venous pressure influenced venous expulsion during contraction, the increase in arterial inflow was similar regardless of position. Moreover, the volume of blood expelled was a small fraction of the cumulative arterial volume after the contraction. These results suggest that the muscle pump is not a major contributor to the hyperemic response to skeletal muscle contraction.

Animals↗
PubMed2004

Aerobic exercise before diving reduces venous gas bubble formation in humans.

We have previously shown in a rat model that a single bout of high-intensity aerobic exercise 20 h before a simulated dive reduces bubble formation and after the dive protects from lethal decompression sickness. The present study investigated the importance of these findings in man. Twelve healthy male divers were compressed in a hyperbaric chamber to 280 kPa at a rate of 100 kPa min(-1) breathing air and remaining at pressure for 80 min. The ascent rate was 9 m min(-1) with a 7 min stop at 130 kPa. Each diver underwent two randomly assigned simulated dives, with or without preceding exercise. A single interval exercise performed 24h before the dive consisted of treadmill running at 90% of maximum heart rate for 3 min, followed by exercise at 50% of maximum heart rate for 2 min; this was repeated eight times for a total exercise period of 40 min. Venous gas bubbles were monitored with an ultrasonic scanner every 20 min for 80 min after reaching surface pressure. The study demonstrated that a single bout of strenuous exercise 24h before a dive to 18 m of seawater significantly reduced the average number of bubbles in the pulmonary artery from 0.98 to 0.22 bubbles cm(-2)(P= 0.006) compared to dives without preceding exercise. The maximum bubble grade was decreased from 3 to 1.5 (P= 0.002) by pre-dive exercise, thereby increasing safety. This is the first report to indicate that pre-dive exercise may form the basis for a new way of preventing serious decompression sickness.

Adult↗
PubMed2004

Intensity and duration threshold for aerobic exercise-induced analgesia to pressure pain.

OBJECTIVE: To examine how exercise-induced analgesia is affected by the duration and intensity of aerobic exercise. DESIGN: Repeated-measures design. SETTING: Exercise science laboratory. PARTICIPANTS: Convenience sample of 12 healthy male and female volunteers (mean age +/- standard deviation, 32+/-9 y). INTERVENTIONS: Pain ratings were assessed before and at 5 and 30 minutes after treadmill exercise of 10 minutes at 75% maximal oxygen uptake (Vo(2)max), 30 minutes at 50% Vo(2)max, and 30 minutes at 75% Vo(2)max (randomized order and no less than 48 h between each bout). MAIN OUTCOME MEASURES: Pain ratings were measured on a visual analog scale at 10-second intervals during a 2-minute pressure-pain stimulus to the nondominant index finger. RESULTS: Pain ratings were significantly decreased (P<.05) from pre-exercise values 5 minutes after 30 minutes of exercise at 75% Vo(2)max but returned toward baseline by 30 minutes after exercise. There were no significant changes in pain ratings after 10 minutes of exercise or after exercise at 50% Vo(2)max. CONCLUSIONS: There are thresholds for both the intensity (>50% Vo(2)max) and duration (>10 min) of exercise required to elicit exercise analgesia.

Adult↗
PubMed2003

Spleen volume and blood flow response to repeated breath-hold apneas.

The purpose of this study was 1) to answer whether the reduction in spleen size in breath-hold apnea is an active contraction or a passive collapse secondary to reduced splenic arterial blood flow and 2) to monitor the spleen response to repeated breath-hold apneas. Ten trained apnea divers and 10 intact and 7 splenectomized untrained persons repeated five maximal apneas (A1-A5) with face immersion in cold water, with 2 min interposed between successive attempts. Ultrasonic monitoring of the spleen and noninvasive cardiopulmonary measurements were performed before, between apneas, and at times 0, 10, 20, 40, and 60 min after the last apnea. Blood flows in splenic artery and splenic vein were not significantly affected by breath-hold apnea. The duration of apneas peaked after A3 (143, 127, and 74 s in apnea divers, intact, and splenectomized persons, respectively). A rapid decrease in spleen volume ( approximately 20% in both apnea divers and intact persons) was mainly completed throughout the first apnea. The spleen did not recover in size between apneas and only partly recovered 60 min after A5. The well-known physiological responses to apnea diving, i.e., bradycardia and increased blood pressure, were observed in A1 and remained unchanged throughout the following apneas. These results show rapid, probably active contraction of the spleen in response to breath-hold apnea in humans. Rapid spleen contraction and its slow recovery may contribute to prolongation of successive, briefly repeated apnea attempts.

Adult↗
PubMed2003

Laser revascularization of ischemic skeletal muscle.

BACKGROUND: Clinical trials have shown that transmyocardial laser revascularization is an effective secondary treatment for ischemic heart disease patients. Laser revascularization may also provide an alternative method for treating peripheral vascular disease. METHODS: The purpose of this study was to investigate the potential for laser revascularization in ischemic skeletal muscle. Eighteen rabbits (3-4 kg) were instrumented chronically with transit time ultrasound flowprobes on both common iliac arteries. All rabbits performed graded exercise tests on a treadmill where maximal blood flow was recorded. Unilateral hindlimb ischemia was produced by ligation of one femoral artery. At week 3 postligation, 10 rabbits received laser therapy and 8 underwent a sham surgery. In each of four muscles (gracilius, medialis, sartorius, and biceps femoris) 5 to 22 laser channels were created (average = 52 channels per leg). RESULTS: At week 3 postligation the maximal blood flow of the ischemic limb for the treated group was 64 +/- 3 ml/min (mean +/- SEM) and at 6 weeks postlaser therapy maximal blood flow increased to 75 +/- 5 ml/min. The sham surgery group had a maximal blood flow of 58 +/- 4 ml/min at week 3 postligation and 66 +/- 3 ml/min at week 6 postsham surgery. CONCLUSION: These results indicate that laser therapy does not induce angiogenesis and vascular remodeling in the ischemic hindlimb of a rabbit which exceeds that seen with a sham surgery.

Animals↗