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Biomedical subjects

J J McNamara

Publications and source records attributed to J J McNamara.

At least 19 recordsLinked to original sources
PubMed1996

Measurement of oxygen free radicals in a rabbit shock lung model. Effect of superoxide dismutase and retinol.

OBJECTIVES: To develop an isolated rabbit lung model in which oxygen free radical activity could be measured and to examine the effects on the model of oxygen free radical scavengers. DESIGN: Prospective, randomized study. SETTING: A clinical and basic research facility attached to a teaching hospital. PARTICIPANTS: Twenty-five New Zealand white rabbits weighing 3.5 to 4.5 kg. INTERVENTIONS: The mechanism of lung injury by oleic acid or by phorbol myristate acetate (20 ng/mL) plus polymorphonuclear neutrophils (PMA-PMN) in an ex vivo rabbit shock lung model may be the production of oxygen free radicals. Using a standard heart-lung preparation from these rabbits, baseline mean pulmonary artery pressure was maintained at 15 mm Hg and the mean airway pressure at 10 mm Hg. Experimental perfusates were infused over 30 minutes, followed by Krebs-Henseleit solution, pH 7.4. Dimethyl pyrroline oxide trapped oxygen free radicals, levels of which were measured by electron paramagnetic resonance spectroscopy. Lung injury was assessed by light and scanning electron microscopy and by lung weight. RESULTS: A 5-fold increase in pulmonary artery pressure (P < .001) and a nearly 3-fold increase in mean airway pressure (P < .001) were observed in both the oleic acid and PMA-PMN models. Superoxide dismutase (20,000 U/kg), but not retinol palmitate (2000 U), prevented lung injury, the increases in pulmonary artery pressure and mean airway pressure, and the increase in oxygen free radicals in the PMA-PMN model. There were no increases in oxygen free radicals in the control, oleic acid, or PMA-PMN/superoxide dismutase groups (n = 5 in each group). Maximum mean +/- SD increases in oxygen free radicals were 112 +/- 22 nmol/L in the PMA-PMN group (P < .003, n = 5) and 108 +/- nmol/L in the PMA-PMN/retinol group (P < .003, n = 5). CONCLUSIONS: The mechanism of lung injury in the PMA-PMN model is an increase in oxygen free radicals, because superoxide dismutase prevents both the rise in oxygen free radicals and lung injury. Administration of retinol does not prevent lung injury. Oleic acid produces injury not by an increase in oxygen free radicals but rather by another, unknown mechanism.

Acute Disease↗
PubMed1996

A repetitive DNA sequence specific for Trypanosoma (Nannomonas) godfreyi.

The satellite DNA sequence of Trypanosoma (Nannomonas) godfreyi, a recently described parasite of Suidae, was determined. The sequence is 373bp in length, and contains two imperfect internal repeats of approximately 170bp. Like other trypanosome satellite DNAs, it has no extensive open reading frames and is probably non-coding. There is no significant homology with other major repetitive DNAs within subgenus Nannomonas. We have developed a PCR test that is specific for T. godfreyi and used it to identify the parasite in natural tsetse infections from Zimbabwe and Côte d'Ivoire. This test shows no cross reaction with non-target trypanosomes, even within subgenus Nannomonas, and will be invaluable in studies of the prevalence and distribution of T. godfreyi.

Animals↗
PubMed1996

A high prevalence of mixed trypanosome infections in tsetse flies in Sinfra, Côte d'Ivoire, detected by DNA amplification.

The prevalence of various species and subgroups of trypanosomes in the Sinfra area of Côte d'Ivoire was determined using the polymerase chain reaction (PCR). Using this technique to amplify specific satellite DNA targets, it was possible to identify developmental-stage trypanosomes in the midguts and the proboscides of tsetse without expansion of parasite populations. The predominant tsetse species in the area was Glossina palpalis, while G. pallicera and G. nigrofusca were also present. Microscopical examination of 811 non-teneral flies revealed an infection rate of 14% in midguts and/or proboscides. Three subgroups of Trypanosoma congolense (Savannah, Forest & Kilifi), T. simiae, T. godfreyi, West African T. vivax and T. brucei ssp. were identified using PCR. T. congolense Forest was the most abundant of the Nannomonas trypanosomes. Approximately 40% of all infections were mixed, and there was a significantly higher prevalence of apparently mature T. brucei ssp. trypanosomes than has previously been reported. The present study demonstrates that PCR facilitates the easy identification of mature trypanosome infections in tsetse, providing a reliable estimation of trypanosomiasis challenge.

Animals↗
PubMed1996

The relationship of oxygen consumption measured by indirect calorimetry to oxygen delivery in critically ill patients.

OBJECTIVE: The existence of oxygen supply dependency, defined as oxygen consumption (VO2) limited by oxygen delivery (DO2), is still questioned. This study examined the relationship between VO2 and DO2 in two groups of critically ill surgical patients 50 years and older in the first 24 hours of resuscitation after pulmonary artery catheter insertion. Group 1 patients had systemic inflammatory response syndrome (SIRS), sepsis, severe sepsis, septic shock, and adult respiratory distress syndrome (ARDS). Group 2 patients had hemorrhagic shock. METHODOLOGY: Study methodology included (1) augmenting DO2 with fluids, blood, and vasopressors, (2) measuring VO2 by indirect calorimetry to avoid the problem of mathematical coupling with DO2 calculation, and (3) analyzing data during steady states of temperature, sedation, paralyzing agents, and vasopressors. RESULTS: Six to 18 measurements collected on all study patients during a period within the first 24 hours were analyzed using a linear regression analysis. Statistical significance was set at p < or = 0.05. Seven of nine patients in group 1 demonstrated positive, statistically significant relationships between VO2 and DO2. Of six patients in group 2, one patient demonstrated a positive, significant relationship of VO2 and DO2, three demonstrated inverse relationships, and two patients did not show a DO2/VO2 relationship. Supply dependency did not exist in all patients but was present in seven out of nine patients with systemic inflammatory response syndrome, sepsis, severe sepsis, septic shock, and adult respiratory distress syndrome in the first 24 hours of treatment.

Aged↗
PubMed1996

Failure to detect free radicals in the isolated perfused rat heart.

Oxygen free radicals have been indirectly implicated in reperfusion injury following ischemia in the isolated rabbit heart. The authors moved to detect free radicals in an isolated rat heart model as a prerequisite to studying its effects during ischemia and reperfusion. Several different spin trapping agents and electron paramagnetic resonance (EPR) spectroscopy were used to detect free radicals being generated during ischemia and reperfusion. The possible roles of ferrous iron and hydrogen peroxide generation in reperfusion injury were also investigated. No free radical "bursts" were detected with any of the spin traps used in this model during ischemia or reperfusion. Hydrogen peroxide and hydroxyl free radicals do not appear to be involved in tissue reperfusion injury. This study suggests that free radicals are not produced in clinically significant quantities under these conditions to account for ischemic myocardial damage.

Animals↗
PubMed1996

An evaluation of streptokinase therapy in early coronary reperfusion in a primate model.

Efficacy of streptokinase (SK) administered beyond the period of coronary occlusion with regard to ultimate infarct size and the extent of hemorrhagic infarction was assessed in primates. Eleven macaques underwent coronary occlusion for two hours and were then reperfused. Five of them were given a 2,000 U IV bolus of SK followed by a 10,000 U IV infusion over ninety minutes. The remaining 6 served as controls. Macaques were sacrificed seven days postocclusion. The left ventricle was sectioned parallel to the minor axis, and these were examined histologically for infarct size and hemorrhage. Multiplying the planimetric values by the thickness of the sections yielded the total volumes of left ventricle, infarction, and hemorrhage. The mean percentage of left ventricle involved in infarction in the treated group was not significantly different from the controls (14.06 +/- 6.35 versus 16.50 +/- 4.67, P > 0.10). SK-treated animals had a significantly greater volume of infarct involved with hemorrhage as compared with controls (27.1 +/- 10.8 versus 4.0 +/- 1.4, P < 0.05). SK infusions done concurrently with reperfusion following a two-hour occlusion did not result in a significant reduction or increase in the size of infarct. However, SK infusions resulted in a significant increase in the amount of hemorrhagic infarction.

Animals↗
PubMed1996

Surgical management of ventricular septal rupture following myocardial infarction: the Hawaii experience.

OBJECTIVE: To assess the diagnostic and treatment methods of ventricular septal rupture following myocardial infarction in a small patient population. EXPERIMENTAL DESIGN: Retrospective medical record review. SETTING: Four Honolulu area teaching hospitals. PATIENTS OR PARTICIPANTS: Eighteen patients with ventricular septal rupture (VSR) following myocardial infarction (MI) between 1979 and 1993. RESULTS: Ventricular septal rupture occurred more frequently in the elderly, in females and in those presenting for the first time with an MI. Thirteen patients (72%) underwent surgical repair including the two survivors. Three patients (17%) also underwent coronary artery bypass grafting, one of who survived. Very few of the patients had a history of stable angina pectoris before MI. Sudden deterioration in the patient's condition as manifested by tachycardia, hypotension and signs of right heart failure in those with an acute MI, especially if accompanied by a systolic murmur should encourage a search for a mechanical cause, especially a VSR. CONCLUSIONS: Two dimensional echocardiography or Swan-Ganz catheterization is 100% diagnostic and can be rapidly done at the bed side. Early surgical repair is important to the overall prognosis.

Aged↗
PubMed1995

Variations in pediatric pneumonia and bronchitis/asthma admission rates. Is appropriateness a factor?

OBJECTIVE: To explore through a pilot study the relationship between appropriateness (medical necessity) and variations in pediatric hospital admission rates across several communities in the Boston (Mass) area for two common pediatric conditions with extremely variable admission rates: pneumonia and bronchitis/asthma. DESIGN: We identified five communities in the greater Boston area with high, average, and below-average ratios of observed to expected admissions for the study conditions. Diagnosis-specific, criteria-based utilization review instruments were developed by community-based pediatricians and applied by trained nurse reviewers to medical records. ADMISSIONS STUDIED: All admissions for pneumonia (diagnosis related group [DRG] 91) and bronchitis/asthma (DRG 98) of study area residents younger than 18 years to participating hospitals during fiscal year 1986. OUTCOME MEASURES: For each area, we calculated age-adjusted admission rates, age-adjusted observed to expected ratios, and rates of inappropriate admissions. We tested the hypothesis that admission rates and inappropriateness rates were directly related. RESULTS: We deemed 9.4% of pneumonia admissions and 4.4% of bronchitis/asthma admissions inappropriate. Rates of inappropriate admissions were not significantly associated with admission rates in this local pilot study for either study condition at P < .05. However, in one community both rates were high for both conditions. Feedback of findings to the key local hospital there resulted in sharp decreases in admission rates for DRGs 91 and 98 in subsequent years. CONCLUSIONS: Our results suggest that higher pediatric admission rates may not be associated with higher rates of inappropriateness. Further research is needed, with a larger number of communities, to differentiate practice patterns more precisely and explore patient and family preferences.

Adolescent↗
PubMed1995

Effects of hyaluronidase on reducing myocardial infarct size in a baboon model of ischemia-reperfusion injury.

Hyaluronidase has been reported to be beneficial in reducing injury to the ischemic myocardium in several experimental studies. This effect may involve an enhancement in either the cardiac blood supply or lymphatic flow or a combination there of. In this experiment, a baboon open chest model of myocardial ischemia and reperfusion was used to determine if treatment with hyaluronidase would result in a reduction in infarct size. Baboons underwent occlusion of the left anterior descending coronary artery for 2 hr. Fifteen minutes after occlusion, a treated group (n = 6) received bovine testicular hyaluronidase (500 national formulary units/kg) i.v. over a 10-min period. The ischemic period was followed by 22 hr of reperfusion. A control group (n = 8) underwent the same protocol minus the hyaluronidase infusion. At the end of the reperfusion period, the hearts were excised and the perfusion bed at risk for infarction was determined by the infusion of a microvascular dye. The hearts were then sectioned and stained for the histological determination of infarct size. The volume of the perfusion bed infarcted was 66 +/- 7% in the control group compared with 42 +/- 10% in the treated group (P > 0.05). In this study using a primate model that has a minimal collateral blood supply, hyaluronidase did not significantly reduce the ultimate infarct size.

Animals↗
PubMed1995

Pharmacokinetics of endotoxin in a rhesus macaque septic shock model.

Using a prospective, randomized, controlled study, we tested the hypothesis that the initial administered dose of endotoxin determines its pharmacokinetics in a rhesus macaque septic shock model. Twelve adult male rhesus macaques, weighing 6 to 10 kg, were equally divided into two groups. The first group received a 20 mg/kg intravenous bolus of the gram-negative endotoxin. The second group received a bolus comparable to the concentration of endotoxin found in the plasma of the first group, 12 hr postendotoxin injection. Both groups were monitored for 12 hr and sacrificed. Plasma endotoxin concentrations were measured using the limulus amebocyte lysate assay and a pharmacokinetic model was applied to the concentration curves. Results of the pharmacokinetic evaluation revealed differences in half-life, clearance, and total apparent volume of distribution between the two groups of animals, suggesting that the changes in these parameters may have a biphasic pattern and may be related to the initial dose of endotoxin injected.

Animals↗
PubMed1995

Multiple trypanosome infections in wild tsetse in Côte d'Ivoire detected by PCR analysis and DNA probes.

Trypanosomes were isolated from the midguts of Glossina palpalis palpalis, G. pallicera pallicera and G. nigrofusca nigrofusca captured around the village of Guediboua, South West of Daloa in Côte d'Ivoire. Seventy of the 124 isolates, obtained from 688 flies, were examined for four different kinds of trypanosome using the Polymerase Chain Reaction (PCR). Prevalences were: Trypanozoon 46%, riverine-forest T. congolense 86% and savannah T. congolense 54%. Only 29 samples were examined for T. simiae but it was not detected. Just 30% of the infections involved a single kind of trypanosome; the remainder were mixtures either of two (37%) or all three (27%) of the target organisms. 30 of the 70 isolates examined by PCR were successfully amplified to provide material for DNA probe hybridization. To a large extent, DNA probes confirmed the PCR results; all (28/28) of the riverine-forest and 82% (18/22) of the savannah T. congolense infections were identified. However, only 8% (1/13) of the PCR positives for Trypanozoon hybridized with the appropriate DNA probe. No T. simiae or T. godfreyi infections were identified using DNA probes but a large proportion (97%) (29/30) of the probed midguts were shown to contain Kilifi T. congolense. Four isolates out of 70 could not be identified by any method. There was no obvious association between the different species of flies and the infecting trypanosomes.

Animals↗
PubMed1995

International perspectives: USA/Hawaii.

Most of the factors that underlie Hawaii's current healthcare system were in place by 1950. Many of its healthcare features were shaped during the period from the eighth century AD until the revolution in 1893. Early chiefs made care available for the entire population through specially trained kahunas, or priests, who specialized in healing. There was a uniform, seamless healthcare system. The historical legacy, which came through from the early days, fostered the existence and acceptance of group and salaried practice by physicians, acceptance by employers of the responsibility to provide healthcare to workers, capitated payments to providers, focus on outpatient services, and historically short hospital lengths of stay. The success of Hawaii's system is rooted in its past. Whether other states could or should adopt Hawaii's system is conjectural. In Hawaii healthcare reform is not a new paradigm but rather an evolutionary phenomenon.

Cultural Diversity↗
PubMed1995

Atrial myxomas: experiences with 35 patients in Hawaii.

BACKGROUND: Thirty-five patients with an intracardiac myxoma underwent excision of the tumor in Hawaii between 1974 and 1993. PATIENTS AND METHODS: There were 28 female and 7 male patients in the group. Their ages ranged from 11 to 79 years (mean 48) with the majority (71%) between 30 and 60 years old. The patients' medical records were reviewed and special attention was paid to clinical presentation, methods of diagnosis, operative findings, and postoperative course. RESULTS: No ethnic predisposition was found. Forty-six percent of the presenting symptoms were cardiac (congestive heart failure 26%, palpitations 14%, and syncope 6%) while arterial embolization accounted for 11%. Diagnosis was made by angiography, echocardiography, or gated cardiac blood pool imaging. All were reliable, but two-dimensional (2-D) echocardiography was used most often, with no false-positive or false-negative results. There were 32 left atrial, 2 right atrial, and 1 biatrial myxomas. Limited septectomy was performed in most cases, but 9 patients (26%) required Dacron patch repair of the atrial septum. There was 1 death from a cerebrovascular accident the day after the removal of a left-sided atrial myxoma. Other patients had few minor postoperative complications. One patient presented with a recurrence 8 years after resection at another institution; no further recurrences were found. CONCLUSIONS: We conclude that due to the non-specific presentation of atrial myxoma, a high index of suspicion is needed. The diagnostic method of choice is 2-D echocardiography. Limited septectomy is a safe procedure, but close follow-up for at least 10 years may be needed to rule out recurrence.

Adolescent↗
PubMed1995

Effects of perfluorocarbon exchange transfusion on reducing myocardial infarct size in a primate model of ischemia-reperfusion injury: a prospective, randomized study.

BACKGROUND: This study was undertaken to test the hypothesis that perfluorocarbons were able to reduce myocardial infarct size in a baboon model of ischemia-reperfusion injury. Exchange transfusion of perfluorocarbons has been shown to reduce myocardial infarct size in the dog, who, unlike the baboon, has an extensive collateral circulation. METHODS: After 15 minutes of occlusion of the left anterior descending coronary artery, 14 baboons were bled to attain a hematocrit of 24% to 26% and were simultaneously transfused, six with Fluosol-DA 20% emulsion and eight with FC-43 emulsion. After 2 hours of ligation, the coronary arteries were reperfused. Baboons were killed 24 hours after ligation, and the hearts were excised. Microvascular dye was infused into the coronary artery to delineate its perfusion bed. Ratios of the mean volume of infarct to the mean volume of perfusion bed were calculated and compared by use of planimetry. A similar protocol was followed in two other groups of baboons except that lactated Ringer's solution was infused into six of them, whereas eight had no exchange transfusions. RESULTS: The ratios of the mean volume of infarct to the mean volume of perfusion bed of the four groups were as follows: Fluosol-DA, 38.1% +/- 7.5%; FC-43, 37.7% +/- 8.3%; lactated Ringer's, 46.9% +/- 10.5%; controls, 65.6% +/- 6.9%. Statistical significance was reached when comparing both perfluorocarbon-treated groups with the controls (p < 0.05 for both groups) but not significant when comparing them with the Ringer's lactate-treated group. CONCLUSIONS: Results suggest that the beneficial effects of exchange transfusion with the perfluorocarbons may be primarily due to hemodilution.

Animals↗
PubMed1995

Evaluation of the clinical usefulness of thermodilution volumetric catheters.

OBJECTIVE: To determine if treatment modalities (fluid, inotropes, and blood) would be altered based on preload measurements of right ventricular end-diastolic volume index measured by fast response thermodilution catheter, as compared with pulmonary artery occlusion pressure (PAOP). DESIGN: A prospective clinical trial. SETTING: An 11-bed surgical intensive care unit (ICU) at The Queen's Medical Center, an affiliate of the University of Hawaii Surgical Residency program. PATIENTS: Surgical ICU patients who required pulmonary artery catheters, except those patients with arrhythmias or history of tricuspid valve disease. INTERVENTIONS: During the first 48 hrs after catheter insertion, hemodynamic data were obtained at least every 4 hrs. Treatment of low preload was initiated only if clinical indications were present. These indications included a mean arterial pressure of < 70 mm Hg, heart rate of > 120 beats/min, urine output of < 40 mL/hr, stroke volume of < 40 mL/m2 with oxygen delivery of < 450 mL/min/m2, and lactic acidosis. Volume infusion was considered if PAOP was < 18 mm Hg and right ventricular end-diastolic volume index was < 140 mL/m2. Treatment was given tohigh preload, defined as a PAOP of > 18 mm Hg to prevent pulmonary edema. When PAOP and right ventricular end-diastolic volume index gave conflicting information, other clinical parameters were assessed to determine treatment. MEASUREMENTS AND MAIN RESULTS: Twenty-seven patients requiring 70 catheters were evaluated for the study. Thirteen patients with 46 pairs of data points completed the study. Fourteen patients were excluded from analysis due to irregular heart rate, poor quality of cardiac output at the time of volume infusion, or lack of major volume manipulation. PAOP and right ventricular end-diastolic volume index measurements agreed in 42 of 46 instances (PAOP of < 18 mm Hg, right ventricular end-diastolic volume index of < 140 mL/m2), leading to fluid treatment. In one instance, PAOP was > 18 mm Hg, right ventricular end-diastolic volume index was < 140 mL/m2, and the patient had normal blood pressure and good urine output. PAOP was used in this instance as a guide to diurese the patient, which led to improvement of heart rate and stroke volume index. Three measurements in two patients with high intra-abdominal pressure indicated a PAOP of > 18 mm Hg with right ventricular end-diastolic volume index of < 140 mL/m2. A rigid abdomen accompanied hypotension, tachycardia and low urine output. Thus, a fluid bolus was administered, resulting in improved blood pressure, stroke volume, and heart rate. PAOP were obtained at end-expiration. Positive end-expiratory pressure (PEEP) was removed for < 1 sec, if patients were on PEEP > or = 10 cm H2O, to avoid the effects of high intrapleural pressure on PAOP readings. Cardiac output was measured at end-expiration, and stroke volume index and right ventricular end diastolic volume index were derived. CONCLUSIONS: In this small sample of surgical patients with sepsis, adult respiratory distress syndrome, and hemorrhagic shock (n = 13), the additional information derived from right ventricular end-diastolic volume index did not change treatment in 43 of 46 instances. However, patients with increased intra-abdominal pressures may show misleadingly high PAOP despite low preload. These patients clearly benefitted from the additional information derived from ventricular volume measurements. Additionally, clinicians who are reluctant to take off-PEEP PAOP may also find this catheter useful.

Blood Pressure↗
PubMed1995

Frequency of mortality and myocardial infarction during maximizing oxygen delivery: a prospective, randomized trial.

OBJECTIVES: To determine the frequency of myocardial infarction and mortality during treatment that increased oxygen delivery (DO2) to > or = 600 mL/min/m2. To define the characteristics of patients achieving a high DO2 without inotropes in order to guide future studies. DESIGN: A prospective, randomized, controlled trial. SETTING: Two surgical intensive care units at The Queen's Medical Center in the University of Hawaii Surgical Residency Program. PATIENTS: Eighty-nine surgical patients (> or = 18 yrs of age), who were admitted to a surgical intensive care unit and who required pulmonary artery catheter monitoring, were selected for the study. Diagnoses included sepsis, septic shock, adult respiratory distress syndrome, or hypovolemic shock. Patients facing imminent death were excluded from the study. INTERVENTIONS: The treatment group received fluid boluses, blood products, and inotropes, as needed, to achieve a DO2 of > or = 600 mL/min/m2 in the first 24 hrs. Using the same interventions, we treated the control group to reach a DO2 of 450 to 550 mL/min/m2. MEASUREMENTS AND MAIN RESULTS: Hemodynamic measurements were obtained every 4 hrs until the pulmonary artery catheter was removed. DO2 and oxygen consumption were calculated by standard formulas. Serial creatine kinase myocardial fraction and electrocardiograms were documented for the first 48 hrs after study entry and for any new onset of arrhythmia or increasing hemodynamic instability. The patients who generated a high DO2 (> or = 600 mL/min/m2) with only preload treatment were reflective of patients with better cardiac reserve and low mortality rates. These patients, from both treatment and control groups, were excluded in the final analysis. The treatment group who received inotropes to achieve the high DO2 had a 14% mortality rate. Those patients who failed to achieve the high DO2 had a 67% mortality rate, and the control group who achieved a normal DO2 had a 62% mortality rate (p = .005). The frequency of myocardial infarction after study entry was 5.6% (five of 89 patients). This rate was not higher among the groups who received inotropes. Logistic regression analysis showed that age of > or = 50 yrs could be used to classify patients as not self-generating, with an 83% chance of being correct. CONCLUSIONS: The group that required catecholamines to achieve a DO2 of > or = 600 mL/min/m2 had a lower mortality rate, with no increase in the frequency of myocardial infarction. Future prospective, controlled trials examining select groups of patients (age > or = 50 yrs) may demonstrate a difference between control and treatment groups by eliminating the majority of patients who generate the high DO2 with only preload augmentation.

Aged↗
PubMed1995

Myocardial necrosis and QRS complex changes in the ischemia-reperfusion setting in a baboon model.

BACKGROUND: This study was performed in attempt to draw a correlation between the percentage of myocardial infarction across the left ventricular wall and changes in the QRS complex in the epicardial ECG in a primate model of ischemia-reperfusion injury. METHODS: Myocardial infarction was induced in six baboons by ligating the left anterior descending coronary artery for 2h. Using ECG leads, the presence of Q and R waves was recorded along with their associated left ventricular wall thickness. RESULTS AND CONCLUSIONS: The results indicate that Q-wave development and R-wave loss can be correlated with depth of infarct.

Animals↗