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PubMed1984

Complications of superior versus inferior vena cava occlusion in infants receiving central total parenteral nutrition.

During a 9-year period, 204 infants younger than 12 months of age had 294 Broviac central venous hyperalimentation catheters inserted. Fifty-nine adult-size and 235 infant-size Broviac catheters were used. Catheter insertion was via the saphenous vein (267), external jugular (7), internal jugular (16), cephalic (2), and transthoracic right atrial veins (2). General anesthesia was used for all internal jugular, but for only 11 saphenous catheters. Catheter function ranged from 6 to 925 days (mean, 112 days). Forty-four infants had malabsorption syndromes, 36 had short bowel syndrome, 38 had intractable diarrhea, and 86 required nutritional support for a variety of other conditions. Fifteen of the 204 infants developed inferior (10) or superior vena caval thrombosis (2), or both (3). Thrombosis occurred in 13 of the 267 infants with saphenous catheters (4.9%), and five of the 25 with jugular or cephalic venous catheters (20.0%). Obstruction to normal catheter infusion was the first sign of caval occlusion. Transient mild leg edema (4) and prominent venous pattern over the legs (3) were present with inferior vena caval (IVC) occlusion, but no patient had renal vein obstruction or died as a direct result of this condition. Each of the two patients with superior vena caval (SVC) occlusion experienced mild to moderate edema and venous suffusion of the head and upper extremities, and one developed a pleural effusion. Each of the three infants with combined superior and inferior vena caval thrombosis died from pulmonary insufficiency within six months after SVC occlusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Catheterization↗
PubMed2000

Early results of the fontan procedure in one hundred consecutive patients with hypoplastic left heart syndrome.

OBJECTIVES: The purpose of this study was to review a large, single institutional experience with the Fontan procedure for patients with hypoplastic left heart syndrome. METHODS: One hundred consecutive patients with "classic" hypoplastic left heart syndrome underwent Fontan palliation between February 1992 and April 1998. Patient demographic, morphologic, and procedural variables were examined and analyzed. In particular, two different surgical techniques were used: technique I (February 1992 to December 1995) employed cardiopulmonary bypass and moderate systemic hypothermia, and technique II (December 1995 to April 1998), profound hypothermia and circulatory arrest. A retrospective review of medical records was performed and variables were examined and analyzed. RESULTS: Hospital survival for the entire cohort was 89% (95% CI 83%-95%). The technique of operation, cardiopulmonary bypass time, and aortic crossclamp time were each strongly associated with survival. Survival for patients treated by technique I was 79% (95% CI 68-91%; n = 48) and for those treated by technique II, 98% (95% CI 94%-100%; n = 52). Cardiopulmonary bypass and crossclamp times were also highly correlated with time to extubation and length of intensive care unit stay. Preoperative pulmonary artery pressure was correlated with survival; preoperative oxygen saturation, right atrial pressure, pulmonary vascular resistance, pulmonary artery size, extent of aortopulmonary artery collaterals, and echocardiographic estimates of ventricular function and tricuspid regurgitation were not correlated with survival. CONCLUSIONS: Our recent experience with Fontan palliation for patients with hypoplastic left heart syndrome suggests that it is attended by low perioperative mortality. The precise operative technique used appears to be an important determinant of outcome, with the duration of cardiopulmonary bypass and crossclamping being particularly significant.

Child, Preschool↗
PubMed1972

A reflex increase in heart rate from distension of the junction between the superior vena cava and the right atrium.

1. Localized distension of the junction between the superior vena cava and the right atrium without obstructing venous return caused an increase in heart rate.2. This increase in heart rate was a reflex response; the afferent path was in the vagi and the efferent solely in the sympathetic nerves.3. The receptors most likely to be stimulated by the distension of the junction between the superior vena cava and the right atrium are the right atrial receptors located on the endocardial surface of the intrapericardial portion of the superior vena caval-right atrial junction.

Animals↗
PubMed2002

Theoretical analysis of the noncardiac limits to maximum exercise.

When right atrial pressure (Pra) is greater than zero (atmospheric pressure), cardiac output is determined by the intersection of two functions, cardiac function and return function, which is used here to mean the determinants of venous return. When Pra < or = 0, flow is only determined by circuit function. The objective of this analysis was to determine the potential changes in return function that need to occur to allow the maximum cardiac output during exercise when Pra < or = 0 or is constant. The analysis expands on the model of Green and Jackman and includes the effects of changes in circuit parameters, including venous resistance, changes in capacitance, and muscle contractions. The analysis is based on the model of the circulation proposed by Permutt and co-workers, which assumes that the systemic circulation has two lumped compliant regions in parallel with independent inflow and outflow resistances. Changes in total flow in this model can come about by changes in the distribution of flow between the regions, recruitment of unstressed vascular volume, and changes in the regional venous resistances. The data for the analysis are from previous animal studies and are normalized to a 70-kg man. The major conclusions are that, to achieve the high cardiac output that occurs at peak exercise, there need to be marked changes in the distribution of blood flow, recruitment of unstressed volume, and the venous resistance draining vascular beds. A consequence of the increase in peripheral flow is a marked increase in pressure in the veins of the working muscle. Muscle contractions are potentially a very important mechanism for transiently decreasing this pressure and preventing excessive filtration of plasma during exercise.

Animals↗
PubMed2003

Electrical and contractile remodeling during the first days of atrial fibrillation go hand in hand.

BACKGROUND: The mechanisms of the atrial contractile dysfunction induced by atrial fibrillation (AF) are not completely understood. In particular, the relation between the atrial dysfunction and electrical remodeling has not yet been studied. METHODS AND RESULTS: Seven goats were chronically instrumented with electrodes sutured to the atria and with ultrasonic piezoelectric crystals to record the atrial diameters. A pressure transducer was implanted in the right atrium. After 5 minutes, 3 hours, and throughout the first 5 days of artificially maintained AF, atrial contractile function was measured and the atrial effective refractory period (AERP) was monitored for comparison. Also, the positive inotropic effects of the L-type Ca2+-channel agonist BayY5959 and short trains of rapid atrial pacing were studied. After resumption of sinus rhythm, the recovery of atrial contractile function was followed. After 5 minutes of AF, atrial contractility was decreased by approximately 55% but recovered completely within 10 minutes. Five days of AF nearly completely abolished the atrial contractile function, and recovery took 2 days. During the first days of AF, the development of the contractile dysfunction followed the same time course as the shortening of AERP (electrical remodeling). In remodeled atria, BayY5959 increased atrial contractility to the same extent as it prolonged AERP. The inotropic effect of short trains of rapid atrial pacing was similar in normal and remodeled atria. CONCLUSIONS: Depending on the duration of AF, different mechanisms contribute to the AF-induced atrial hypocontractility. Atrial contractile remodeling during several days of AF goes hand in hand with electrical remodeling and might be caused by a reduction of the L-type Ca2+-current.

Adaptation, Physiological↗
PubMed2000

N-Type calcium channels control sympathetic neurotransmission in human heart atrium.

BACKGROUND: Because knowledge about the type of calcium channels involved in action potential-induced norepinephrine release from the human peripheral sympathetic nervous system is sparse, we investigated which types of calcium channels are functionally important in the sympathetic nerves of human cardiac tissue. METHODS AND RESULTS: In superfused segments of human right atrial appendages, the type of calcium channels that control [(3)H]norepinephrine release evoked by transmural electrical stimulation was determined. [(3)H]norepinephrine release was almost abolished by 0.2 micromol/L omega-conotoxin GVIA (a selective blocker of N-type channels) but was not modified by 0.1 micromol/L omega-agatoxin IVA (a selective blocker of P- and Q-type channels). Mibefradil (a T-type and N-type calcium channel blocker) at concentrations of 0.3 to 3 micromol/L reduced the evoked tritium overflow in a frequency- and calcium-dependent manner, whereas 0.1 to 10 micromol/L amlodipine, diltiazem, and verapamil (selective blockers of L-type channels) were ineffective. CONCLUSIONS: Norepinephrine release from cardiac sympathetic nerves is triggered by Ca(2+) influx via N-type but not L- and P/Q-type calcium channels. The inhibitory effect of mibefradil on norepinephrine release at clinically relevant concentrations is probably due to its blocking action on N-type Ca(2+) channels. This property of mibefradil is unique among the calcium channel blockers that have been or still are therapeutically applied and may considerably contribute to its slight negative chronotropic effect in vivo.

Adult↗
PubMed1980

Impulses of S-A block area.

Micro-electrode studies in 13 excised rabbit preparations were done to determine the site of S-A block. Previously the fastest S-A conduction occurred in the area connecting the sinus node and the right branch of the crista terminalis. When a small cut was made in this area, 5 of the 13 hearts showed the first degree S-A block. Two hearts exhibited the second degree S-A block of the Wenckebach phenomenon and 3 showed the third degree block after cutting the same area. All blocks were transient and, within 1 hour after cutting, they were of the first degree. When the caval area was subsequently cut in these 10 hearts, all of them developed the complete S-A block. Three other hearts showed the complete S-A block by cutting only the connectable area of the sinus node with the right branch of the crista terminalis. The first cutting of the caval area surrounding the sinus node excepting the above mentioned connection did not change the S-A conduction time. Conclusions from these experiments reveal that the dominant sino-atrial conduction occurs through the connectable area of the sinus node with the right branch of the crista terminalis. Functional impairment to this region is essential and necessary to the development of any degree of S-A block.

Animals↗
PubMed1988

The effect of angiotensin II and ADH on the secretion of atrial natriuretic factor.

Studies in intact animals have suggested that angiotensin II (AII) and antidiuretic hormone (ADH) increase the plasma concentration of atrial natriuretic factor (ANF). The purpose of these studies was to examine the effects of AII and ADH on ANF secretion in a rat heart-lung preparation under conditions where aortic pressure could be regulated and other indirect effects of these hormones eliminated. ANF secretion was estimated as the total amount of ANF present in a perfusion reservoir at the end of each 30-min period. A pump was used to deliver a fluorocarbon perfusate to the right atrium at rates of either 2 or 5 ml/min. In a time control series where venous return was maintained at 2 ml/min for three 30-min periods ANF secretion was 672 +/- 114, 794 +/- 91, and 793 +/- 125 pg/min (n = 6, P greater than 0.05). When venous return was increased from 2 to 5 ml/min ANF secretion increased from 669 +/- 81 to 1089 +/- 127 pg/min (P less than 0.01). The addition of AII to the perfusate in concentrations of 50, 100, or 200 pg/ml (n = 6 in each group) had no significant effect on basal ANF secretion or the ANF response to increasing venous return. Similarly, the addition of ADH to the perfusate in concentrations of 5, 25, or 100 pg/ml had no significant effect on ANF release from the heart. These results suggest that the ability of AII and ADH to increase plasma ANF concentration in vivo may be due to the effects of these hormones on right or left atrial pressure.

Angiotensin II↗
PubMed2001

[The second tissue harmonic signal: from physics principles to clinical application].

The second harmonic signals received from organs are due to the non linear properties of tissue which cause distortion of the transmitted signal and are not primarily caused by the transmission of a harmonic frequency. The velocity of ultrasound propagation depends on the density of the insonified material. During the compression phase, the tissue becomes denser, and the ultrasound waves travel faster through the tissue than during the rarefaction phase; the compression phase tends to overtake the rarefaction phase. The ultrasound waveform thus, undergoes a distortion that becomes greater as the distance from the transducer increases. Due to these effects, the tissue tends to generate harmonics and hence shifts energy from the fundamental to the harmonic bands. There are several reasons why harmonic tissue imaging increases the signal-to-noise ratio and facilitates interpretation. In technically difficult patients, there is often a diffuse haze due to distortion of the transmitted beam by shallow surface layers or to reverberations between the skin and ribs. These distortions and reverberations consist almost entirely of ultrasound energy at the fundamental frequency. When the returned signal is filtered at the harmonic so as to reject the fundamental frequency, the clutter and haze are removed and the image becomes more clear and defined. A further reason for the decrease in artifacts and clutter is the side-lobe level reduction in the second harmonic beam. Thus, harmonic beams are narrower and have lower side-lobe levels than fundamental ones. There are several clinical applications of harmonic tissue imaging. These include the correct definition of endocardial borders resulting in an improved assessment of left ventricular function at rest as well as during stress testing, the delineation of the left atrial appendage, the detection of atrial right to left shunting, and left atrial spontaneous echo contrast. Moreover, improved endocardial visualization leads to better endocardial tracking with acoustic quantification and to more segments being interpretable with the anatomic M-mode.

Acoustics↗
PubMed1991

[Pulmonary thromboembolectomy of subacute massive pulmonary thromboembolism in a patient with familial antithrombin III deficiency].

Reported is a case of successful pulmonary thromboembolectomy and inferior caval vein interruption in a patient with subacute massive pulmonary thromboembolism (PTE). He had been complicated by the right atrial and deep vein thrombosis due to type I familial antithrombin III (ATIII) deficiency. Pulmonary embolectomy and caval interruption was performed 20 days after the initial attack and followed by anti-coagulation therapy. Thrombi weighed 50 gm were removed mainly from the left pulmonary artery. The right atrial thrombus which had got smaller by the preoperative fibrinolytic therapy could not be found with right atriotomy. Respiratory function at rest and slightly elevated pulmonary arterial pressure was normalized post-operatively. Although the PTE in this patient was considered to be subacute by the histological findings of the fibrin thrombus removed, tapering of pulmonary arteries in PAG and obstructive intimal hypertrophy of the small vessels in the lungs suggests the chronic nature of the PTE (post-thrombotic obstruction of pulmonary arteries) caused by the hyper-coagulable state. In patients with familial ATIII deficiency, 50% of normal ATIII activity can be expected because they are heterozygotes, so the cardio-pulmonary bypass should be run with special caution to the heparin dosage. Caval vein interruption and warfarin therapy are recommended for prophylaxis of recurrent PTE.

Antithrombin III Deficiency↗
PubMed1994

The effect of peep-ventilation on cardiac function in closed chest pigs.

OBJECTIVE: Does ventilation with positive end-expiratory pressure (PEEP) depress myocardial contractility? DESIGN: Ten piglets were anaesthetized and prepared for the measurement of cardiac output (SV) and right (MRAPtm) and left (MLAPtm) mean transmural atrial pressure, the latter serving as indices of preload. 500 ml of autologous blood was re-transfused during intermittent positive pressure ventilation without PEEP (IPPV) and continuous positive pressure ventilation with 15 cm H2O PEEP (CPPV). MEASUREMENTS AND RESULTS: Right and left ventricular function curves were drawn by plotting MRAPtm and MLAPtm respectively versus the corresponding strokevolumes before and after re-transfusion. Similar inclinations were obtained during IPPV and CPPV on either side of the heart. CONCLUSIONS: Although the ventricular function curves during IPPV and CPPV covered partially different preload levels, the results suggest that CPPV i.e. PEEP does not affect myocardial contractility.

Animals↗
PubMed2000

Relationship between left atrial appendage function and plasma concentration of atrial natriuretic peptide.

BACKGROUND: It has been reported that the most intensely granuled cardiocytes secreting atrial natriuretic peptide (ANP) are located in the atrial appendages. AIMS: To evaluate the mechanisms of ANP release in congestive heart failure. METHODS AND RESULTS: The relationship between ANP and left atrial appendage (LAA) function was evaluated in 36 patients who underwent both transoesophageal echocardiography and cardiac catheterization. ANP level correlated positively with mean pulmonary capillary wedge pressure (mPCWP; r=0.75, P<0.0001), whereas it showed no significant correlation with the mean right atrial pressure. mPCWP correlated positively with the maximal LAA area (LAAa; r=0.79, P<0.0001) and negatively with the LAA ejection fraction during atrial contraction (LAA-EF; r=-0.61, P<0.0001) and peak late diastolic LAA emptying flow velocity (LAAF; r=-0.69, P<0.0001). ANP level correlated negatively with the LAA-EF (r=-0.56, P<0.001) and with LAAF (r=-0.61, P<0.0001). ANP level correlated more closely with the LAAa (r=0.79, P<0.0001) than with maximal LA volume (r=0.34, P<0.05). Multiple stepwise regression analysis selected LAAa as the only factor independently related to the plasma concentration of ANP (ANP=-22.4+28.6 LAAa, r=0.79, P<0.0001). CONCLUSIONS: We conclude that the factor most predictive for ANP in patients with left-sided cardiac dysfunction is distension of the LAA wall rather than elevation in the LA pressure or distension of the body of LA. This is consistent with the known distribution of ANP-secreting cardiocytes.

Adult↗
PubMed1992

[Conventional roentgen functional diagnosis--videodensitometry. 4. Conventional roentgen videodensitometry exemplified with peri-cardiac vessels].

It is possible to record movement-parameters by means of roentgen videodensitometry of the great central vessels as well the pulmonary artery as the thoracic aorta visible in fluoroscopic image (provided by videorecorder). We could noninvasively measure pre-ejection periods (PEP) for the right heart (PEP f) as well for the left heart (PEP g) by synchronous electrocardiography for each cardiac action and for each examination process. It is important to form a quotient between PEP f and PEP g in the individual case. First findings in patients with cardiac septal defects (with and without right heart block and pulmonary hypertension) show characteristic quotients and figures of the curves. In cases with electrocardiographic left heart block the elongated PEP g can be stated in graduated form. Further investigations on the mechanic interaction between the right and left heart, especially in cases of disorders in the heart conduction system, might be of interest.

Absorptiometry, Photon↗
PubMed2001

Combined atrial and arterial switch operations for congenitally corrected transposition.

Conventional repair of congenitally corrected transposition of the great arteries (CCTGA) is directed at eliminating the associated defects and leaves the right ventricle in a systemic position. The long-term outcome of this procedure may involve deterioration of right ventricular function with tricuspid regurgitation and failure of the conduction system. We describe two consecutive patients with CCTGA, one of whom had apicocaval juxtaposition. The patients were aged 19 and 16 months, respectively, and both underwent a combination of atrial and arterial switch. These are the first two reported cases of successful completion of this type of operation in Taiwan. Our review of previously reported cases suggested that no significant difference exists in the outcome of patients with this condition who undergo either arterial switch or Rastelli-type repair plus atrial redirection. However, reported patients who underwent anatomic repair had lower early mortality, late mortality, and incidence of complete heart block than those who underwent conventional repair. The present two cases and our review of the literature suggest that, among patients with apicocaval juxtaposition, 1) Mustard operation is optimal for patients with small atrial volume; 2) one-and-one-half ventricular repair may be helpful to the outcome, especially when treatment is combined with Rastelli-type repair; and 3) excellent access to the ventricular septal defect through the tricuspid valve is afforded via a left atriotomy. From the present two cases and our review of the literature, we conclude that anatomic repair is superior to conventional repair of CCTGA in terms of protection against dysfunction and failure of the anatomic right ventricle, tricuspid valve, and conduction system. Long-term follow-up is mandatory.

Cardiac Surgical Procedures↗
PubMed1997

Expression pattern of connexin gene products at the early developmental stages of the mouse cardiovascular system.

The synchronized contraction of myocytes in cardiac muscle requires the structural and functional integrity of the gap junctions present between these cells. Gap junctions are clusters of intercellular channels formed by transmembrane proteins of the connexin (Cx) family. Products of several Cx genes have been identified in the mammalian heart (eg, Cx45, Cx43, Cx40, and Cx37), and their expression was shown to be regulated during the development of the myocardium. Cx43, Cx40, and Cx45 are components of myocyte gap junctions, and it has also been demonstrated that Cx40 was expressed in the endothelial cells of the blood vessels. The aim of the present work was to investigate the expression and regulation of Cx40, Cx43, and Cx37 during the early stages of mouse heart maturation, between 8.5 days post coitum (dpc), when the first rhythmic contractions appear, and 14.5 dpc, when the four-chambered heart is almost completed. At 8.5 dpc, only the reverse-transcriptase polymerase chain reaction technique has allowed identification of Cx43, Cx40, and Cx37 gene transcripts in mouse heart, suggesting a very low activity level of these genes. From 9.5 dpc, all three transcripts became detectable in whole-mount in situ-hybridized embryos, and the most obvious result was the labeling of the vascular system with Cx40 and Cx37 anti-sense riboprobes. Cx40 and Cx37 gene products (transcript and/or protein) were demonstrated to be expressed in the vascular endothelial cells at all stages examined. By contrast, only Cx37 gene products were found in the endothelial cells of the endocardium. In heart, Cx37 was expressed exclusively in these cells, which rules out any direct involvement of this Cx in the propagation of electrical activity between myocytes and the synchronization of contractions. Between 9.5 and 11.5 dpc, Cx40 gene activation in myocytes was demonstrated to proceed according to a caudorostral gradient involving first the primitive atrium and the common ventricular chamber (9.5 dpc) and then the right ventricle (11.5 dpc). During this period of heart morphogenesis, there is clearly a temporary and asymmetrical regionalization of the Cx40 gene expression that is superimposed on the functional regionalization. In addition, comparison of Cx40 and Cx43 distribution at the above developmental stages has shown that these Cxs have overlapping (left ventricle) or complementary (atrial tissue and right ventricle) expression patterns.

Amino Acid Sequence↗
PubMed1986

Conduction pattern of excitation in the amphibian atrium assessed by multiple-site optical recording of action potentials.

Spontaneous action potentials were monitored from multiple sites in the bullfrog atrium using a voltage-sensitive merocyanine-rhodanine dye together with a 100-element photodiode matrix array, and we have assessed the spread of the excitation from the pacemaker. Isochrone curves of conduction were obtained by timing the initiation of the action potential-related optical signals: we constructed maps of the spread. Excitatory waves appeared to conduct radially from the pacemaking area over the atrium, and the conduction velocity in the left atrium exceeded that in the right atrium.

Animals↗
PubMed2003

New method of determining the atrial fibrillation cycle length during human atrial fibrillation.

INTRODUCTION: The aim of this study was to investigate the usefulness of the autocorrelation function (reversed fast Fourier transform analysis) in determining the atrial fibrillation cycle length (AFCL) during human atrial fibrillation (AF). METHODS AND RESULTS: From 30 episodes of atrial electrograms recorded for 30 seconds from the high right atrium during type I AF in 16 patients, the mean, 5th percentile (p5), and 95th percentile (p95) of the AFCLs were measured by using a computer-picked activation time. The peak, minimum, and maximum AFCLs also were measured by using the autocorrelation function. The mean AFCL was retrieved at the point of the maximum peak of the coefficient of the first positive autocorrelogram. The minimum AFCL (min AFCL) was chosen as the point where the first positive autocorrelogram crossed the baseline from negative to positive, and the maximum AFCL (max AFCL) was chosen as the point where the first positive autocorrelogram crossed the baseline from positive to negative. There was a significantly strong correlation between the mean and peak AFCLs (r = 0.995, P < 0.0001), p5 and min AFCLs (r = 0.953, P < 0.0001), and p95 and max AFCLs (r = 0.98, P < 0.0001). CONCLUSION: The autocorrelation function was useful in determining the AFCLs, at least during type I AF. The min AFCL may be used as an index of the refractory period during AF when the p5 AFCL approximates the refractory period.

Aged↗