Location and hemodynamic role of perforating veins independent of saphenous veins.

BACKGROUND: The perforating veins of the lower limbs (LL) have valves that enable the blood flow to be directed from the superficial vein system to the deep vein system and they may or may not be connected to the saphenous vein system.
OBJECTIVES: To use vascular ultrasonography (VUS) to identify the frequency, location, caliber, and hemodynamic role of perforating veins that do not connect to saphenous veins, during preoperative mapping of LL varicose veins.
METHODS: A cross-sectional study was conducted using VUS in women to study the frequency, location, distance from the sole of the foot, and hemodynamic role of perforating veins.
RESULTS: The frequencies of perforating veins independent of the saphenous veins were 92.6%, 5.1%, and 2.3%, in the leg, thigh, and knee, respectively, and 25.2% of them were incompetent while 72.3% were drainage veins. The mean diameters of perforating veins were 2.9 mm, 3.5 mm, and 3.7 mm, in the leg, thigh, and knee, respectively. Perforating veins were located at mean distances of 23.8 cm, 43.6 cm, and 59.4 cm above the sole of the foot in the leg, knee, and thigh, respectively. Perforating veins with reflux had a mean caliber of 3.5 mm, irrespective of location.
CONCLUSIONS: Perforating veins independent of the saphenous veins are most frequent in the leg, draining reflux from tributary veins. Irrespective of location, perforating veins with reflux had mean caliber of 3.5 mm.

INTRODUCTION

The venous system of the lower limbs (LL) comprises the deep system, responsible for 85% of venous drainage, and the superficial system, responsible for the remaining 15%. Between these two systems there are an average of 64 perforating veins, between the foot and the groin, that communicate directly or indirectly, enabling flow to drain from superficial veins to deep veins. 1

There are four groups of perforating veins in the calf: the paratibial perforators, communicating between the great saphenous and posterior tibial veins; the perforators connecting the posterior accessory saphenous vein to the posterior tibial vein; and the lateral and anterior perforators of the leg. In the knee, the perforating veins are designated as lateral or medial, suprapatellar or infrapatellar, and popliteal fossa perforators. In the thigh, the perforators are medial, anterior, lateral, and posterior. 2

The perforating veins drain flow from the great and small saphenous veins to the deep veins or muscular veins or drain flow from tributary veins that are independent from the saphenous vein system, and which may play different hemodynamic roles.

Competent perforating veins drain flow to the deep system without interfering in the caliber of the saphenous or tributary veins. Incompetent perforating veins exhibit significant reflux and may transfer this reflux to saphenous or tributary veins, causing them to dilate. Drainage perforating veins drain reflux from saphenous or tributary veins. 3

During venous mapping with vascular ultrasonography (VUS), the medial, anterior, lateral, and posterior perforating veins of the thigh, knee, and leg should be examined. They can be identified in mode B by their course connecting superficial and deep veins and perforating the muscle fascia, thereby identifying their hemodynamic role in the venous system.

The objective of this study was to use VUS to identify the frequency, location, caliber, and hemodynamic role of perforating veins independent of the saphenous veins during preoperative mapping of LL varicose veins.

METHODS

A cross-sectional study was conducted with women with signs or symptoms of chronic venous insufficiency (CVI) who had been referred to a vascular laboratory for venous mapping of the LL using VUS.

The study recruited women over the age of 18 with LL varicose veins of primary etiology and clinical classes C1 to C3 according to the clinical, etiology, anatomical and pathophysiology (CEAP) classification. The study excluded men; women with LL congenital varicose veins or varicose veins of secondary etiology or CEAP C4 to C6; and patients who had previously undergone surgical treatment for varicose veins.

The study was approved by the Research Ethics Commission at the Pontifícia Universidade Católica do Paraná (PUCPR), under CAAE nº 61368016.2.0000.0020 and certificate nº 111358/2016.

Ultrasonographic examination

All patients included in the study were assessed using Siemens®Antares and Siemens®X 700 ultrasonography scanners with color Doppler (Issaquah, United States).

Deep vein system flow was assessed to exclude recent or historic venous thrombosis, with the patient in decubitus dorsal, with transverse ultrasound sweeps in B mode and maneuvers to assess vein compressibility, using a low frequency transducer (5 Mhz).

The great and small saphenous veins were examined with the patient standing upright, using a high frequency transducer (7 Mhz) to obtain images of the veins with longitudinal ultrasound sweeps in mode B. With the aid of color flow mapping, valve function was assessed using a manual muscle compression maneuver distal to the position of the transducer, in order to produce and detect reflux in the superficial vein system and the perforating veins.

Perforating veins connected to or independent of the saphenous veins were located and assessed for reflux with the patient standing upright and reflux was quantified in terms of duration of reflux exceeding 0.35 seconds. 4

Evaluation of perforating veins independent of the saphenous veins considered location (medial, lateral, or posterior surface of the thigh, knee, and leg); height in relation to the sole of the foot; and hemodynamic role (reflux drainage, source of reflux, and competence).

Competent perforating veins with caliber less than 3 mm were not considered in the analysis, since they are not clinically relevant and are difficult to identify by clinical examination.

The results for quantitative variables were expressed as means, medians, minimum and maximum values, and standard deviations. Qualitative variables were expressed as frequencies and percentages.

Analysis of perforating veins, considering height from the sole of the foot, diameter, and hemodynamic role, was performed separately for each anatomic segment of thigh, knee, and leg, considering the total number of perforating veins per segment, including veins on the medial, lateral, and posterior aspects. Data were analyzed with IBM SPSS Statistics v.20.

RESULTS

A total of 361 LL were analyzed in 258 women with ages ranging from 18 to 88 years (mean of 48 years): 205 right limbs (56.8%) and 156 left limbs (43.2%).

Of the 361 limbs assessed, 155 (42.9%) had reflux in the great saphenous vein and 93 (25.7%) had reflux in the small saphenous vein.

A total of 475 perforating veins independent of the saphenous veins were identified in the 361 LL assessed: 24 (5.1%) perforators in the thigh, 11 (2.3%) in the knee, and 440 (92.6%) in the leg.

Eighty-three (23.0%) of the 361 LL had more than one perforating vein in the same segment, breaking down as one with two perforators in the thigh and 82 limbs with two or more perforators in the leg. Sixty-three (76.8%) of the limbs with two or more perforators in the leg had two perforators, 14 (17.1%) had three perforators, five (6.1%) had four perforators, and the majority (70%) had veins in more than one location (medial, lateral, or posterior aspect).

In turn, 14 (58.4%) of the perforating veins in the thigh were identified in the lateral area, five (20.8%) in the medial area and five (20.8%) in the posterior area. Seventeen (70.8%) of the perforating veins in the thigh had reflux to tributary veins and seven (29.2%) drained reflux from tributary veins. All perforating veins in the thigh with diameters exceeding 3 mm were incompetent or provided drainage.

In relation to location and caliber ( Table 1 ), perforating veins in the thigh were a mean distance of 59.4 cm above the sole of the foot and had a mean caliber of 3.5 mm. Considering only perforating veins in the thigh with reflux, mean caliber was 3.6 mm, varying from 2.6 to 4.6 mm.

Table 1

Location and caliber of perforating veins.

	N	Mean	Median	Minimum	Maximum	Standard deviation
Thigh
Location (cm)	24	59.4	59	47.5	74	7.4
Diameter (mm)	24	3.5	3.5	2	4.6	0.7
Knee
Location (cm)	11	43.6	43	36	53.5	5.2
Diameter (mm)	11	3.7	3.5	2.6	5.5	0.8
Leg
Location (cm)	440	23.8	23	3.5	46	6.6
Diameter (mm)	440	2.9	2.8	1.6	6.3	0.7

With regard to perforating veins in the knee, seven (63.6%) were identified in the posterior region of the knee, two (18.2%) in the medial region, and two (18.2%) in the lateral region. Six (54.5%) of the perforating veins in the knee had reflux into tributary veins and five (45.5%) drained reflux from tributary veins. All of the perforating veins in the knee larger than 3 mm were incompetent or provided drainage.

In terms of location and caliber ( Table 1 ), the perforating veins of the knee were located a mean distance of 43.6 cm above the sole of the foot and had a mean caliber of 3.7 mm. Considering only the perforating veins of the knee that had reflux, mean caliber was 3.8 mm, ranging from 3.2 to 4.8 mm.

With regard to perforating veins in the leg, 289 (65.7%) were identified in the medial region of the leg, 90 (20.4%) in the lateral region and 61 (13.9%) in the posterior region. Ninety-seven (22.0%) of the perforating veins in the leg exhibited reflux flowing to tributary veins, 330 (75.0%) drained reflux from tributary veins, and 13 (3.0%) were competent and connected to tributary veins without reflux.

In terms of location and caliber ( Table 1 ), the perforating veins in the leg were a mean distance of 23.8 cm above the sole of the foot and had a mean caliber of 2.9 mm. Considering only perforating veins in the leg that exhibited reflux, mean caliber was 3.4 mm, ranging from 2.0 to 6.3 mm.

A total of 475 perforating veins were assessed for this study, 120 (25.2%) of which exhibited reflux in the thigh, knee, or leg, with a mean caliber of 3.5 mm, ranging from 2.0 to 6.3 mm.

DISCUSSION

Vascular ultrasound is the method of choice for detecting reflux of blood in specific veins, primarily using color flow mapping, which enables the extent and distribution of venous reflux to be identified with precision. 3

Depending on study population, the incidence of sources of superficial venous reflux unrelated to the saphenous trunk veins can range from 10 to 43%. 5 , 6

The most important sources of reflux that are not connected to saphenous veins and should be examined are the tributary veins of the posterior accessory saphenous vein, the accessory veins of the thigh, groin veins (vulvar and gluteal veins), perforating veins of the lateral and posterior surfaces of the thigh (veins of the sciatic nerve), and perforating veins of the medial, lateral, and posterior (popliteal fossa vein) aspects of the knee and leg. 5 , 7 - 11

Our study only focused on perforating veins that are independent of the saphenous veins and identified perforating veins in the thigh, knee, and leg in 5.1%, 2.3%, and 92.6% of the limbs assessed, respectively.

With relation to the perforating veins of the thigh, in our study the great majority (70.8%) were incompetent and 58.3% were located in the lateral thigh. Gianesini et al. 12 assessed 2820 LL and found 26 incompetent lateral perforating veins in 24 LL, at depths of 12 to 25 mm, and connected to the femoral, deep femoral, or muscular veins.

In our study, just 7 (1.4%) perforating veins were identified in the posterior knee. Similarly, Delis et al. 11 assessed 818 LL and detected perforating veins of the popliteal fossa in 24 (2.9%) of the LL, and in 96% of cases there was drainage to the popliteal vein around 1.5 cm above the popliteal fold.

The majority (92.6%) of the perforating veins in our study were identified in the leg, 65% in the medial leg, with the primary function of draining reflux from tributary veins. Just 22% of perforating veins in the leg exhibited reflux flowing into tributary veins. It is important to highlight that competent perforating veins with calibers smaller than 3 mm were excluded from the study because they are not clinically relevant and are difficult to detect by physical examination.

Labropoulos et al. 13 studied 581 perforating veins in 103 limbs of 75 patients with CVI and found that 28% (163) of the veins with reflux had subfascial caliber exceeding 3.9 mm. Both competent veins and veins with reflux had smaller caliber in the lower thigh, knee, ankle, and anterior leg.

Sandri et al. 14 studied 500 perforators in patients with LL varicose veins, relating caliber to the probability of reflux, and observed that perforating veins with caliber greater than or equal to 3.5 mm in the thigh or leg were associated with reflux in more than 90% of cases.

In our study, considering only perforating veins with reflux at the thigh, knee, and leg (25%), mean calibers were 3.6 mm, 3.8 mm, and 2.9 mm, respectively. Irrespective of location, the caliber of perforating veins with reflux ranged from 2 to 6.3 mm, with mean caliber of 3.5 mm, which is similar to results from a study by Sandri et al. 14

The authors conclude that perforating veins independent of saphenous veins are more frequent in the leg, draining reflux from tributary veins. Irrespective of location, perforating veins with reflux had a mean caliber of 3.5 mm.

INTRODUÇÃO

O sistema venoso dos membros inferiores (MMII) é composto pelo sistema profundo, responsável por 85% da drenagem venosa, e o superficial, responsável pelos 15% restantes. Entre esses dois sistemas, existem em média 64 veias perfurantes, entre o pé e a região inguinal, que fazem uma comunicação direta ou indireta, possibilitando a drenagem do fluxo das veias superficiais para as veias profundas 1 .

Na panturrilha são identificados quatro grupos de veias perfurantes: as perfurantes paratibiais, comunicando a safena magna e a veia tibial posterior; as perfurantes conectando o arco posterior da safena magna com a veia tibial posterior; e as perfurantes laterais e anteriores da perna. No joelho, as veias perfurantes são designadas como laterais ou mediais, supra ou infrapatelares e perfurantes da fossa poplítea. Na coxa, as perfurantes são mediais, anteriores, laterais e posteriores 2 .

As veias perfurantes drenam o fluxo das veias safenas magna e parva para as veias profundas ou musculares ou o fluxo de veias tributárias independentes do sistema das veias safenas, e podem desempenhar diferentes papéis hemodinâmicos. As veias perfurantes competentes drenam o fluxo para o sistema profundo sem interferir no calibre das veias safenas ou tributárias. As veias perfurantes incompetentes apresentam refluxo significativo e podem transferir esse refluxo para as veias safenas ou tributárias, causando a dilatação destas. As veias perfurantes de drenagem escoam refluxo das safenas ou tributárias 3 .

Durante o mapeamento venoso com ultrassonografia vascular (USV), devem ser pesquisadas as veias perfurantes mediais, anteriores, laterais e posteriores na coxa, joelho e perna, as quais são identificadas no modo B pelo seu trajeto de conexão entre as veias superficiais e profundas, perfurando a fáscia muscular, identificando o papel hemodinâmico no sistema venoso.

O objetivo deste trabalho foi identificar, pela USV, a frequência, localização, calibre e o papel hemodinâmico das veias perfurantes independentes das veias safenas no mapeamento pré-operatório das varizes dos MMII.

MÉTODOS

Foi realizado um estudo transversal em mulheres com sinais ou sintomas de insuficiência venosa crônica (IVC), encaminhadas ao laboratório vascular para realização de mapeamento venoso dos MMII utilizando USV.

Foram incluídas no estudo mulheres maiores de 18 anos com varizes em MMII de etiologia primária e pertencentes às classes clínicas C1 a C3 da classificação clínica, etiológica, anatômica e fisiopatológica (CEAP). Foram excluídos homens; mulheres com varizes em MMII de etiologia secundária ou congênita ou com CEAP C4 a C6; e pacientes que foram submetidas a tratamento cirúrgico das varizes.

O estudo foi aprovado pelo Comitê e Ética em Pesquisa da Pontifícia Universidade Católica do Paraná (PUCPR), com CAAE nº 61368016.2.0000.0020 e comprovante nº 111358/2016.

Avaliação ultrassonográfica

Todas as pacientes incluídas no estudo foram avaliadas em aparelhos de ultrassonografia com Doppler colorido Siemens®Antares e Siemens® X 700 (Issaquah, EUA).

Foi realizada avaliação do fluxo no sistema venoso profundo para a exclusão de trombose venosa recente ou antiga, com a paciente em decúbito dorsal, com cortes ultrassonográficos transversais em modo B e manobras de compressibilidade das veias, utilizando-se transdutores de baixa frequência (5 Mhz).

O estudo das veias safenas magna e parva foi realizado com a paciente em posição ortostática, utilizando transdutor de alta frequência (7 Mhz), para a obtenção das imagens das veias em cortes ultrassonográficos longitudinais em modo B. Com o auxílio do mapeamento do fluxo a cores, avaliou-se o funcionamento valvular pela manobra de compressão muscular manual distal ao posicionamento do transdutor, a fim de produzir e detectar refluxo no sistema venoso superficial e nas veias perfurantes.

Foi realizada a localização e pesquisa do refluxo nas veias perfurantes conectadas ou independentes das veias safenas, com a paciente também em posição ortostática, além da quantificação do refluxo considerando o tempo de duração do refluxo superior a 0,35 segundos 4 .

Para a avaliação das veias perfurantes independentes das veias safenas foi considerada a localização (face medial, lateral ou posterior na coxa, joelho e perna); altura em relação à base do pé; e o papel hemodinâmico (drenagem de refluxo, fonte de refluxo e competência).

Para fins de análise, foram desconsideradas as veias perfurantes competentes com calibre inferior a 3 mm, por não apresentarem relevância clínica e serem de difícil identificação ao exame clínico.

Os resultados de variáveis quantitativas foram descritos por médias, medianas, valores mínimos, valores máximos e desvios padrões. Para variáveis qualitativas, foram apresentados frequências e percentuais.

A análise das veias perfurantes, considerando a altura em relação à base do pé, diâmetro e o papel hemodinâmico, foi realizada separadamente por segmento anatômico de coxa, joelho e perna, considerando a totalidade das veias perfurantes para cada segmento, incluindo as veias na face medial, lateral e posterior. Os dados foram analisados com o programa computacional IBM SPSS Statistics v.20.

RESULTADOS

Foram avaliados 361 MMII de 258 mulheres com idade variando entre 18 e 88 anos (média de 48 anos), sendo 205 membros direitos (56,8%) e 156 membros esquerdos (43,2%).

Dos 361 membros avaliados, 155 (42,9%) apresentaram refluxo na veia safena magna e 93 (25,7%) refluxo na veia safena parva.

Nos 361 MMII avaliados, foram identificadas 475 veias perfurantes independentes das veias safenas, sendo 24 (5,1%) perfurantes na coxa, 11 (2,3%) no joelho e 440 (92.6%) na perna.

Dos 361 MMII, 83 membros (23,0%) apresentaram mais de uma veia perfurante no mesmo segmento, sendo um membro com duas perfurantes na coxa e 82 membros com duas ou mais perfurantes na perna. Dos membros com duas ou mais perfurantes na perna, 63 (76,8%) apresentaram duas perfurantes, 14 (17,1%) apresentaram três perfurantes, e cinco (6,1%) apresentaram quatro perfurantes, sendo que a maioria (70%) apresentava veias em mais de uma localização (face medial, lateral ou posterior).

Quanto às veias perfurantes na coxa, 14 (58,4%) foram identificadas na região lateral, cinco (20,8%) na região medial e cinco (20,8%) na região posterior. Do total de veias perfurantes na coxa, 17 (70,8%) apresentaram refluxo para veias tributárias, e sete (29,2%) drenavam refluxo de veias tributárias. Todas as veias perfurantes maiores que 3 mm na coxa eram incompetentes ou de drenagem.

Em relação à localização e ao calibre ( Tabela 1 ), as veias perfurantes na coxa localizaram-se em média 59,4 cm acima da base do pé, com calibre médio de 3,5 mm. Considerando somente as veias perfurantes na coxa que apresentavam refluxo, o calibre médio foi de 3,6 mm, variando entre 2,6 e 4,6 mm.

Tabela 1

Localização e calibre das veias perfurantes.

	N	Média	Mediana	Mínimo	Máximo	Desvio padrão
Coxa
Localização (cm)	24	59,4	59,0	47,5	74,0	7,4
Diâmetro (mm)	24	3,5	3,5	2,0	4,6	0,7
Joelho
Localização (cm)	11	43,6	43,0	36,0	53,5	5,2
Diâmetro (mm)	11	3,7	3,5	2,6	5,5	0,8
Perna
Localização (cm)	440	23,8	23,0	3,5	46,0	6,6
Diâmetro (mm)	440	2,9	2,8	1,6	6,3	0,7

Quanto às veias perfurantes no joelho, sete (63,6%) foram identificadas na região posterior do joelho, duas (18,2%) na região medial e duas (18,2%) na região lateral. Do total de veias perfurantes no joelho, seis (54,5%) apresentaram refluxo para veias tributárias e cinco (45,5%) drenavam refluxo de veias tributárias. Todas as veias perfurantes maiores que 3 mm no joelho eram incompetentes ou de drenagem.

Em relação à localização e calibre ( Tabela 1 ), as veias perfurantes no joelho localizaram-se em média 43,6 cm acima da base do pé, com calibre médio de 3,7 mm. Considerando somente as veias perfurantes no joelho que apresentavam refluxo, o calibre médio foi de 3,8 mm, variando entre 3,2 e 4,8 mm.

Quanto às veias perfurantes na perna, 289 (65,7%) foram identificadas na região medial da perna, 90 (20,4%) na região lateral e 61 (13,9%) na região posterior. Do total de veias perfurantes na perna, 97 (22,0%) apresentaram refluxo para veias tributárias, 330 (75,0%) drenavam refluxo de veias tributárias, e 13 (3,0%) eram competentes e conectadas a veias tributárias sem refluxo.

Em relação à localização e calibre ( Tabela 1 ), as veias perfurantes na perna localizaram-se em média 23,8 cm acima da base do pé, com calibre médio de 2,9 mm. Considerando somente as veias perfurantes na perna que apresentavam refluxo, o calibre médio foi de 3,4 mm, variando entre 2,0 e 6,3 mm.

Do total de 475 veias perfurantes avaliadas no estudo, 120 veias (25,2%) apresentaram refluxo na coxa, joelho ou perna, com calibre médio de 3,5 mm, variando entre 2,0 e 6,3 mm.

DISCUSSÃO

A ecografia vascular é o método de escolha para detectar refluxo sanguíneo em veias específicas, principalmente com a utilização do mapeamento a cores do fluxo, sendo possível identificar com precisão a distribuição e a extensão do refluxo venoso 3 .

Dependendo da população estudada, a incidência de fontes de refluxo venoso superficial independentes do tronco das veias safenas pode variar de 10 a 43% 5 , 6 .

As principais fontes de refluxo independentes das veias safenas que devem ser pesquisadas são veias tributárias do arco posterior de perna, veias acessórias da coxa, veias da região inguinal (vulvares e glúteas), veias perfurantes na face lateral e posterior (veias do nervo ciático) de coxa e veias perfurantes na face medial, lateral e posterior (veia da fossa poplítea) do joelho e perna 5 , 7 - 11 .

O nosso estudo focou somente nas veias perfurantes independentes das veias safenas e identificou veias perfurantes na coxa, joelho e perna em 5,1%, 2,3% e 92,6% dos membros avaliados, respectivamente.

Com relação às veias perfurantes na coxa, no nosso estudo a grande maioria (70,8%) era insuficiente e 58,3% localizadas na região lateral da coxa. Gianesini et al. 12 avaliaram 2820 MMII e encontraram 26 veias perfurantes laterais na coxa insuficientes em 24 MMII, com 12 a 25 mm de profundidade, conectadas com as veias femoral, femoral profunda ou musculares.

No nosso estudo, foram identificadas somente sete (1,4%) veias perfurantes na região posterior do joelho. Da mesma forma, Delis et al. 11 avaliaram 818 MMII e detectaram veias perfurantes da fossa poplítea em 24 (2,9%) dos MMII, apresentando em 96% dos casos drenagem para veia poplítea em torno de 1,5 cm acima da prega poplítea.

A maioria (92,6%) das veias perfurantes no nosso estudo foi identificada na perna, sendo 65% na região medial da perna, cuja função principal foi de drenar refluxo de veias tributárias. Somente 22% das veias perfurantes na perna apresentaram refluxo para veias tributárias. É importante destacar que veias perfurantes competentes com calibres inferiores a 3 mm foram excluídas do estudo por não apresentarem relevância clínica e serem de difícil detecção no exame físico.

Labropoulos et al. 13 estudaram 581 veias perfurantes em 103 membros de 75 pacientes com IVC e encontraram 28% (163) das veias com refluxo com calibre subfascial maior que 3,9 mm. Tanto as veias competentes quanto as com refluxo apresentaram menor calibre na coxa inferior, joelho, tornozelo e região anterior da perna.

Sandri et al. 14 estudaram 500 perfurantes de pacientes com varizes nos MMII, relacionando o calibre com a probabilidade de refluxo, e observaram que veias perfurantes com calibre igual ou superior a 3,5 mm na coxa ou perna estavam associadas a refluxo em mais de 90% dos casos.

No nosso estudo, considerando somente as veias perfurantes com refluxo na coxa, joelho e perna (25%) o calibre médio foi de 3,6 mm, 3,8 mm e 2,9 mm, respectivamente. Independentemente da localização, o calibre das veias perfurantes com refluxo variou entre 2 e 6,3 mm, com calibre médio de 3,5 mm, semelhante ao estudo de Sandri et al. 14 .

Os autores concluem que as veias perfurantes independentes das veias safenas são mais frequentes na perna, drenando refluxo de veias tributárias. Independentemente da localização, as veias perfurantes com refluxo apresentam calibre médio de 3,5 mm.