Influence of lung volume on the interaction between cardiac output and cerebrovascular regulation during extreme apnoea.

NEW FINDINGS: What is the central question of this study? Does the reduction in cardiac output observed during extreme voluntary apnoea, secondary to high lung volume, result in a reduction in cerebral blood flow, perfusion pressure and oxygen delivery in a group of elite free divers? What is the main finding and its importance? High lung volumes reduce cardiac output and ventricular filling during extreme apnoea, but changes in cerebral blood flow are observed only transiently during the early stages of apnoea. This reveals that whilst cardiac output is important in regulating cerebral haemodynamics, the role of mean arterial pressure in restoring cerebral perfusion pressure is of greater significance to the regulation of cerebral blood flow. We investigated the role of lung volume-induced changes in cardiac output (Q̇) on cerebrovascular regulation during prolonged apnoea. Fifteen elite apnoea divers (one female; 185 ± 7 cm, 82 ± 12 kg, 29 ± 7 years old) attended the laboratory on two separate occasions and completed maximal breath-holds at total lung capacity (TLC) and functional residual capacity (FRC) to elicit disparate cardiovascular responses. Mean arterial pressure (MAP), internal jugular venous pressure and arterial blood gases were measured via cannulation. Global cerebral blood flow was quantified by ultrasound and cardiac output was quantified by via photoplethysmography. At FRC, stroke volume and Q̇ did not change from baseline (P > 0.05). In contrast, during the TLC trial stroke volume and Q̇ were decreased until 80 and 40% of apnoea, respectively (P < 0.05). During the TLC trial, global cerebral blood flow was significantly lower at 20%, but subsequently increased so that cerebral oxygen delivery was comparable to that during the FRC trial. Internal jugular venous pressure was significantly higher throughout the TLC trial in comparison to FRC. The MAP increased progressively in both trials but to a greater extent at TLC, resulting in a comparable cerebral perfusion pressure between trials by the end of apnoea. In summary, although lung volume has a profound effect on Q̇ during prolonged breath-holding, these changes do not translate to the cerebrovasculature owing to the greater sensitivity of cerebral blood flow to arterial blood gases and MAP; regulatory mechanisms that facilitate the maintenance of cerebral oxygen delivery.

CASTLEMAN'S DISEASE PRESENTING AS A TUMOROUS PARACARDIAC FORMATION.

Castleman's disease (in the literature also known as angiofollicular hyperplasia) is a rare benign lymphoproliferative disease. Clinically, it can manifest as unicentric or multicentric disease. Unicentric disease is most often diagnosed by accident or by symptomatology resulting from compression upon the adjoining anatomical structures. Considering its lymphatic origin, tumor mass can theoretically occur in any body region. We present a case of paracardiac localization of unicentric Castleman's disease in a previously healthy 24-year-old woman. In such clinical cases, the specific localization of the tumor and its radiological properties can pose a differential diagnostic dilemma. Correct diagnosis is only possible after complete surgical excision and histopathologic analysis, which is the optimal therapeutic approach in this disease.

Dynamic diaphragmatic MRI during apnea struggle phase in breath-hold divers.

The purpose of the study was to provide insight in diaphragmatic involuntary breathing movements (IBM) during struggle phase of apnea at total lung capacity (TLC) and functional residual capacity (FRC) using magnetic resonance imaging along with measurements of hemodynamics and arterial oxygenation. The study was performed in eight elite breath-hold divers. There was a similar increase in diaphragmatic cranio-caudal excursions towards the end of TLC and FRC apnea. The greatest diaphragmatic excursion in both apneas and during tidal breathing was in the middle and posterior part of the diaphragm. Diaphragm thickness in elite BHD was within the reference range of normal values suggesting no diaphragmatic hypertrophy in this population. We found that the range of diaphragmatic excursions increases toward the end of apneas. Additionally, our data suggest that the diaphragm participates in IBM occurrence and that various segments of the diaphragm behave nonhomogenously both in tidal breathing and IBMs.

Two Cases of Rare Basilar Hypoplasia.

In this article, we report two cases of basilar artery hypoplasia; the first case was a primitive trigeminal artery, and the second was an isolated basilar artery hypoplasia. Both patients had general neurologic disturbances, including periodic intention tremor of the left hand. Our data underscore the utility of complementary time of flight (TOF) magnetic resonance and multidetector computed tomography (MDCT) angiography as reliable first detection methods for steno-occlusive diseases and in cases of suspected congenital vascular anomalies.

[LEFT VENTRICULAR NON-COMPACTION]. / NEKOMPAKTNA LIJEVA KLIJETKA.

Left ventricular non-compaction (LVNC) is a rare cardiomyopathy, which is today, due to modern ultrasound technology more frequently detected in clinical practice. It is caused by the failure of normal embryonic development of the myocardium from loosely arranged muscle fibers to the mature compacted form of myocardium. Morphologic presentation consists of unique two-layered structure, a thick noncompacted endocardial and a thin compact epicardial layer, in infero-lateral and apical segments. The endocardial layer contains loosely arranged muscle fibers, prominent trabeculations and deep perfused intertrabecular recesses. It could be diagnosed both as an infantile or adult type, appearing sporadically or among families where it is transferred x-linked or autosomal dominant. The recognition of the disease is mandatory because of its high mortality and morbidity due to the progressive heart failure, thromboembolic events and lethal arrhythmias. Echocardiography is the procedure of choice to confirm the diagnosis and in the follow-up of patients with LVNC. A literature review about LVNC pathogenesis, diagnostis, and treatment was discussed.

Impact of late hospital admission on the prognosis of patients with acute myocardial infarction.

The objective of this study is to determine the time elapsed from the onset of pain in patients with AMI to their hospital admission (pain to door time) and fibrinolytic administration (door to needle time). The objective is also to determine whether there is a difference between the frequency of fibrinolytic administration to patients and the survival rate of patients with AMI with respect to the location they are transported from. This prospective clinical study included patients manifesting clear clinical, electrocardiographic and biochemical evidence of AMI, according to criteria of ECS (European Society of Cardiology), and who were admitted to the Coronary Care Unit of Split Clinical Hospital in the period from 1 January to 31 December 1999. On the basis of their residence, the patients were divided into three groups: 1. patients from Split and the surrounding area distant up to 15 km from the city; 2. patients from the surrounding area within 15 km from Split, 3. patients living on the islands of Central Dalmatia. 409 patients with AMI were admitted to hospital in the period in question. The first group consisted of 207, the second of 163, and the third of 39 subjects (254:39; p < 0.001). The median time from the onset of pain to hospital admission for all patients with AMI was 7.3 hours, for patients from the islands 13 hours, whereas for those coming from locations distant more than 15 km from Split it amounted to 7.6 hours (p < 0.001). The number of patients that were administered fibrinolysis is extremely low (17.1%) and there is no significant difference in the frequency of fibrinolytic administration between certain patient groups (p > 0.05). Similarly, the mortality rate prior to hospital discharge is high (18.8%) and does not vary among the three studied groups (p > 0.05). The results of this study are in opposition to the assumption that the mortality rate will be lower in patients living in Split and the immediate surroundings when compared to the mortality rate of patients living on the islands of Central Dalmatia (21.7%: 15.4%).

Cardiac magnetic resonance imaging during pulmonary hyperinflation in apnea divers.

PURPOSE: Apnea divers hyperinflate the lung by taking a deep breath followed by glossopharyngeal insufflation. The maneuver can lead to symptomatic arterial hypotension. We tested the hypotheses that glossopharyngeal insufflation interferes with cardiac function further reducing cardiac output (CO) using cardiac magnetic resonance imaging (MRI) to fully sample both cardiac chambers. METHODS: Eleven dive athletes (10 men, 1 woman; age = 26 ± 5 yr, body mass index = 23.5 ± 1.7 kg·m(-2)) underwent cardiac MRI during breath holding at functional residual capacity (baseline), at total lung capacity (apnea), and with submaximal glossopharyngeal insufflation. Lung volumes were estimated from anatomic images. Short-axis cine MR images were acquired to study biventricular function. Dynamic changes were followed by long-axis cine MRI. RESULTS: Left and right ventricular end-diastolic volumes (LVEDV, RVEDV) decreased during apnea with and without glossopharyngeal insufflation (baseline: LVEDV = 198 ± 19 mL, RVEDV = 225 ± 30 mL; apnea: LVEDV = 125 ± 38 mL, RVEDV = 148 ± 37 mL, P < 0.001; glossopharyngeal insufflation: LVEDV = 108 ± 26 mL, RVEDV = 136 ± 29 mL, P < 0.001 vs baseline). CO decreased during apnea (left = -29 ± 4 %, right = -29 ± 4 %) decreasing further with glossopharyngeal insufflation (left = -38% ± 4%, right = -39% ± 4%, P < 0.05). HR increased 16 ± 4 bpm with apnea and 17 ± 5 bpm with glossopharyngeal insufflation (P < 0.01). Ejection fraction moderately decreased (apnea: left = -5% ± 2%, right = -7% ± 2%, glossopharyngeal insufflation: left = -6% ± 2%, right = -10% ± 2%, P < 0.01). With continued apnea with and without glossopharyngeal insufflation, LVEDV and CO increased over time by a similar but small amount (P < 0.01). CONCLUSIONS: The major finding of our study was that submaximal glossopharyngeal insufflation decreased CO further albeit by a small amount compared to maximal inspiratory apnea. The response was not associated with severe biventricular dysfunction.

Pain to hospital times after myocardial infarction in patients from Dalmatian mainland and islands, southern Croatia.

AIM: To analyze pre-hospital delay in patients with myocardial infarction from mainland and islands of Split-Dalmatian County, southern Croatia. METHODS: The study included all patients with myocardial infarction transported by ambulance to the University Hospital Split in 1999, 2003, and 2005. Pre-hospital delay was analyzed in the following intervals: pain-to-call, call-to-ambulance, ambulance-to-door, and door-to-coronary care unit interval. Patients were categorized according to the location from which they were transported: Split, mainland >15 km from Split, and islands. RESULTS: There were 1314 patients (62.9% men) transported and hospitalized for myocardial infarction. Total pre-hospital delay (pain-to-hospital) was significantly reduced from 1999 to 2005 (5.2 hours vs 4.3 hours, P=0.011). Seventy-five patients (5.7%) were admitted to the coronary care unit within the recommended time-frame of less than 90 minutes, none of which was from the islands, while 248 patients (18.9%) were admitted more than 12 hours from the onset of pain. CONCLUSION: Pre-hospital delay in patients with myocardial infarction in southern Croatia is still too long, especially in patients coming from outside of Split. Prognosis and survival of such patients may be improved by introducing changes to the health care system in remote areas, such as out-of-hospital thrombolysis, greater use of telemedicine, training of lay persons and paramedics in defibrillation, introduction of quality assessment mechanisms, and improved patient transport.